Lithium mobilisation during metapelite melting: insights and open questions

Lithium mobilisation during metapelite melting: insights and open questions | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Lithium mobilisation during metapelite melting: insights and open questions Elisa Oliveira da Costa, Ina Alt, Tom W. Argles, Sander Bas Hoogendoorn, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7104523/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The growing demand for Lithium – due to its use in modern economies and green energy – is prompting closer examination of all geological processes that control Li mobilisation. For example, while studies on the genesis of enriched peraluminous granitoids and pegmatites have traditionally focused on the final magmatic-hydrothermal stages of enrichment, recent studies have addressed how the preceding metapelite melting stage controls Li mobilisation. However, these studies employed different partition coefficients to estimate Li fluxes and thus predict contrasting Li behaviour. In this study, we investigate Li mobilisation during metapelite melting by comparing experimental and natural examples (starting compositions, partition coefficients and in-situ mineral concentrations) with equilibrium melting models. Melting models based on experimental partition coefficients predict that biotite-dehydration melting producing either peritectic garnet or cordierite generates more enriched melts; however, the model predicted concentrations in cordierite are lower, and concentrations in muscovite are higher than those observed in nature. In contrast, equilibrium melting models based on natural partition coefficients suggest that initial muscovite melts will be more enriched, and biotite-dehydration melts more enriched, if formed with peritectic garnet (as cordierite sequesters Li). In addition, the lack of temperature-dependent partition coefficients fails to optimally reproduce natural mineral concentration trends. Based on the comparison of experiments and natural examples, we suggest that Li behaviour during equilibrium melting is affected by protolith and mineral major element compositions, particularly water and fluorine contents. Migmatites LA-ICP-MS MAGEMin Phase equilibria modelling Trace element modelling Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 INTRODUCTION The global demand for lithium (Li) is rapidly increasing due to its application in technologies related to the green energy transition, such as rechargeable batteries for electric vehicles and energy storage systems (e.g., Ding et al., 2023; Lindagato et al., 2023; Peng et al., 2024; Zhang et al., 2022). To meet this growing demand, Li production is projected to rise by nearly 500% by 2050 (Hund et al., 2019). This anticipated surge has already impacted critical raw material strategies, as reflected in the designation of Li as a critical element in multiple national and international assessments (e.g., Bauer et al., 2023; Grohol & Veeh, 2023; Josso et al., 2023). Such pressure on supply chains is likely to lower the minimum grade required for the economic exploitation of conventional deposits, such as pegmatites and brines, and prompt the exploration efforts towards less-conventional sources, such as Li-enriched clays and geothermal brines (e.g., Bowell et al., 2020; Kesler et al., 2012). Therefore, a comprehensive understanding of all the geological processes that affect Li mobilisation – particularly those involved in the genesis of Li deposits – is crucial to support society’s transition to a sustainable future. A major reserve of Li is peraluminous granitoids and pegmatites (Bowell et al., 2020). The main processes associated with the genesis of trace element-rich granitoids are protolith enrichment (e.g., Romer and Kroner, 2015; 2015), crustal melting of (typically) metasedimentary protoliths and magmatic-hydrothermal processes (e.g., Gardiner et al., 2024; London, 2018 - Fig. 1 ). However, current petrogenetic models differ about the relative importance of each of these processes. Some studies suggest that extreme fractional crystallisation of a large magmatic body is the main enrichment process, arguing that many deposits are spatially and/or genetically linked to parent granites (e.g., Černý et al., 2005; London, 2018). In contrast, others propose an “anatectic model” whereby Li-rich melts are formed through the partial melting of enriched protoliths or subsequent remelting of peraluminous orthogneisses, without extensive magmatic fractionation, which is supported by the occurrence of many “parentless” deposits (e.g., Ballouard et al., 2024; Koopmans et al., 2024; Müller et al., 2017; Shaw et al., 2016). Ultimately, assessing these models requires precise constraints on the enrichment factors associated with each process involved in the genesis of Li deposits. A key process for which we still lack precise constraints on Li enrichment factors is metapelite partial melting. The key factors that control trace element redistribution during equilibrium melting are the relative abundances of reactant minerals and product (peritectic) minerals and the partition coefficient (Kd) of trace elements between minerals and melt. While the relative abundances of minerals in metapelites can be routinely estimated through phase equilibria modelling software (e.g., MAGEMin, Perple_X, THERMOCALC), available partition coefficients indicate contrasting affinities for some of the main mineral phases in metapelites at suprasolidus conditions, notably biotite and cordierite (Acosta-Vigil et al., 2012; Ballouard et al., 2023; Evensen & London, 2002, 2003; Icenhower & London, 1995). This variation in available partition coefficients translates to different predictions of which melting reaction mobilises Li, as clearly illustrated by two recent studies: ( 1 ) Ballouard et al. (2023) – based mostly on naturally derived partition coefficients – indicate that the highest Li concentrations in the melt are associated with muscovite melting followed by biotite dehydration melting with peritectic garnet at higher pressures (since cordierite efficiently sequesters Li at lower pressures); while ( 2 ) Koopmans et al. (2024) – based mostly on experimentally derived partition coefficients – shows higher Li concentrations in the melt are reached at lower pressures. Hence, it is still uncertain which model better represents nature. In this study, we investigate Li mobilisation during metapelite melting to provide insights into which model best fits natural observations and identify the remaining knowledge gaps regarding Li behaviour during partial melting. To do so, we use: ( 1 ) novel and literature in-situ measurements of Li concentrations in the main rock-forming metamorphic minerals in metapelitic migmatites; ( 2 ) novel and existing temperature estimates; ( 3 ) phase equilibria modelling; and ( 4 ) trace element modelling during partial melting at 4 and 8 kbar using experimentally- and naturally-constrained partition coefficients, as well as solely natural concentration trends. Our results highlight important mismatches between modelled Li concentrations and natural observations. Lastly, we enumerate specific physicochemical parameters that likely explain the different Li behaviour observed in experiments versus nature. MATERIALS AND METHODS Mineral Li concentration variation with temperature Novel trace element concentrations and temperature estimates paired with literature data from metapelitic migmatites were compiled to constrain concentrations of Li in the main mineral phases and how these concentrations vary with temperature (Table 1 ). Novel data were acquired from four high-grade terranes within the Paleozoic Variscan Orogen in Europe, all of which were subject to metamorphic conditions consistent with partial melting in the biotite dehydration field (Johnson & Brown, 2004; Silva, 2014; Siron et al., 2020; Žák et al., 2011). Novel temperature estimates were constrained through the Na-in-cordierite geothermometer (Tropper et al., 2018) and phase equilibria modelling. Information related to our novel data (sample locations, geological settings and summary of P-T estimates) is provided in the Supplementary Text. Table 1 Summary of all datasets used in this study. *Indicates average information per sample was used. **Indicates temperature estimate was (re)calculated in this study. Source Area X Mg Temperature range (°C) Temperature estimate method Bt Crd This study Mindelo, Portugal 0.48 0.63–0.65 699 Na-in-Crd Moldanubian Zone, Czech Republic 0.41–0.46 0.58–0.60 752 Na-in-Crd Britany, France 0.43–0.50 0.55–0.65 720 Na-in-Crd Agly, France 0.42–0.52 0.58–0.76 760 Na-in-Crd and Pseudosection J. Blundy (unpublished) Cooma, Australia 0.51–0.58 748 Na-in-Crd Cambalong, Australia 0.54–0.55 774 Na-in-Crd Cambalong, Australia 0.45–0.58 761 Na-in-Crd I. Alt (unpublished) Moldanubian Zone, Czech Republic 0.41–0.52 0.58–0.64 700–750 Pseudosection and Na-in-Crd Hoogendoorn, 2024* El Hoyazo, Spain 0.3–0.37 780–820 Ti in Biotite Agly, France 0.3–0.53 0.56–0.65 650–680 Pseudosection Ballouard et al., 2024* Velay Dome, France 0.3–0.45 0.54–0.57 536–740 Ti in Biotite, Pseudosection, Na in Crd Oldman, 2023 Himalaya, India 0.28–0.49 678–784 Ti-in-Bt Kunz et al., 2022* Sikkim, India 0.37–0.5 Ti-in-Bt Ivrea, Italy 0.39–0.75 Ti-in-Bt, Thermocalc, Zr-in-Rt Langtang, Nepal 0.32–0.47 Geothermometry Phillips, 2021* Himalaya, Bhutan 0.34–0.69 546–689 Ti-in-Bt Bertoldi et al., 2004 Lake Cauchon, Manitoba, Canada 0.77 799 Na-in-Crd** Chiaravalle, Calabria, Italy; 0.67 785 Colombo, Sri Lanka 0.67 809 Polia, Calabria, Italy 0.71 791 Kiranur, South India 0.88 701 Lhosy, Central Madagascar 0.63 805 Sundsvall, Sweden 0.76 781 Cerro del Hoyazo, Spain 0.38 748 Tsihombe, South Madagascar 0.86 750 Manik Ganga, Sri Lanka 0.94 772 Sopparjok, Norway 0.66 793 Airport Ivalo, Finland 0.69 791 Malcherek et al., 2001 Salem, India 0.99 752 Na-in-Crd** Manik Ganga, Sri Lanka 0.91 686 Tanzania 0.81 746 Orijarvi, Finland 0.81 746 Mt. Bity, Madagaskar 0.74 729 Great Bear Lake, Canada 0.73 762 Rawling Wyoming, USA 0.72 686 Cerro del Hoyazo, Spain 0.50 699 Pena Negra Complex, Spain 0.36 676 Dolni Bory, Czech Republic 0.11 540 Dolni Bory, Czech Republic 0.09 545 Bea et al., 1994 Peña Negra Complex, Spain 0.40–0.41 0.49–0.53 750 Thermometry** Visser et al., 1994 Bamble Sector, Norway 0.76–0.95 689–792 Na-in-Crd** Kalt et al., 1998 Island of Kos, Greece 0.31–0.59 554–743 Na-in-Crd** Major element compositions for cordierite, biotite, garnet, muscovite, and feldspars were determined using a combination of in-situ techniques at the Open University, England. Analyses were conducted with both a Tescan Clara Energy-Dispersive Spectroscopy Scanning Electron Microscope (EDS-SEM) and a Cameca SX100 electron probe micro analyser (EPMA). Analytical quality was monitored through comparison with a natural almandine standard from the GEO MkII block, with results within 7% of the standard preferred values. Rutile and ilmenite compositions were acquired at the University of Utrecht, Netherlands, using a JEOL 5-spectrometer JXA-8530F (EPMA), with data quality verified via R10 standard measurements at the start and end of the session (Luvizotto et al., 2009). Relative standard deviations ranged from 0.9–2.5% for Ti, Cr, Fe, Nb, and Zr, and up to 13% for Ta. Full analytical parameters are detailed in the Supplementary Text. Trace element concentrations of individual mineral grains were obtained at the Open University using a Photon Machines Analyte G2 193 nm excimer laser system, equipped with a HelEX II laser ablation cell and coupled with an Agilent 8800 Triple Quadrupole ICP-MS (LA-ICP-MS). Biotite, muscovite, chlorite, feldspars, cordierite, and pinite were analysed in-situ with a laser fluence of 3.63 J/cm², 10 Hz repetition rate, and spot sizes of 50 or 30 µm. In contrast, ilmenite and rutile were analysed using a 3.63 J/cm² laser fluence, 5 Hz repetition rate, and 20 µm spot size. Data reduction was performed with Iolite v3.71 (Paton et al., 2011). Analytical precision and accuracy were assessed using BCR-2G and R10 standards, which typically fell within 10% of the preferred values. Full analytical parameters are detailed in the Supplementary Text. Phase equilibria and trace element modelling Phase equilibria and trace element modelling aimed to constrain variations in Li concentration at different pressures, temperatures and melting reactions. We used the starting composition, parameters and solid solutions as the metapelite pseudosection of White et al. (2014) and the database ds62. The complete pseudosection is shown in the Supplementary Figure. Both phase equilibria and trace element modelling were computed using the mineral assemblage Gibbs energy minimiser software MAGEMin (Riel et al., 2022). Melt trace element concentrations were estimated using the batch melting equation (Shaw, 1970), as follows: $$\:{C}_{L}={C}_{0}*\frac{1}{(D+F\left(1-D\right))}$$ (1) where C L and C 0 correspond to the concentration of the element in the melt and protolith, respectively; F is the weight fraction of melt, and D is the bulk partition coefficient for the residual minerals, which consists of the sum of the partition coefficients (Kd) of each mineral times their weight percentage in the restite. The concentration of Li in the protolith was calculated based on the median mineral Li concentration from this study and their weight fractions at subsolidus conditions as extracted from MAGEMin (C 0 = 55 ppm – calculation shown in the Supplementary Materials). Four sets of partition coefficients were introduced to MAGEMin (Table 2 ): ( 1 ) mostly natural partition coefficients as used in Ballouard et al. (2023); ( 2 ) natural partition coefficients constrained between minerals and melt/glass inclusions from the El Hoyazo migmatitic xenoliths (Acosta-Vigil et al., 2012); ( 3 ) experimental partition coefficients with temperature variation for cordierite (Kd = -0.0021 * T (°C) + 1.933 - Evensen & London, 2003) and biotite (Kd = -0.0076 * T (°C) + 6.5775 - based on higher temperature Kd of Evensen & London, 2002; and lower Kd of Icenhower & London, 1995); and ( 4 ) mostly experimental partition coefficients, but without temperature variations (as used in Koopmans et al., 2023). Table 2 Summary of mineral/melt Li partition coefficients added to MAGEMin. Distribution Coefficients Natural Experimental Mineral Acosta-Vigil et al. (2012) Ballouard et al. (2023) and ref. therein Icenhower and London (1995), Evensen and London (2002; 2003) As used in Koopmans et al. (2023) Muscovite 0.08–0.33 0.8* 0.8 Biotite 0.31–0.71 0.41–1.67 1.67 (650°C) − 1.01 (750°C)* 1.67 0.46 − 0.16 Cordierite 1.43–1.95 0.82–3.34 0.44 (700°C) − 0.12 (850°C) 0.44 Garnet 0.06–0.37 0.07–0.28 Plagioclase 0.28–1.48 0.01 0.26–0.84 0.02 K-feldspar 0.017–0.25 0.01 0.06–0.38* 0.01 llmenite 0.09 0.01 * Values from experiments without Crd Models shown were either in a closed system at constant pressure or various geothermal gradients, or in an open system at 4 and 8 kbar. Open system models were only run at 4 and 8 kbar since no critical differences occur at intermediate pressures, as shown in the closed system models. Melt extractions were done once around 7–8 vol.% melt had been generated, close to the melt connectivity threshold (Rosenberg & Handy, 2005), and 2 vol.% melt was assumed to remain in the source. Melt extractions were not done after the complete breakdown of biotite. Variations of the system and melt compositions during extraction are shown in the Supplementary Materials. RESULTS Li concentrations Based on this study and the literature data, Li is hosted in the following minerals from highest to lowest concentration (Fig. 2 ): ( 1 ) cordierite (median of 197 ppm based on 261 analyses); ( 2 ) biotite (152 ppm, n = 873); ( 3 ) muscovite (33 ppm, n = 326); ( 4 ) garnet (13 ppm, n = 65); ( 5 ) alkali-feldspar (4 ppm, n = 119); ( 6 ) ilmenite (1.8 ppm, n = 20) and ( 7 ) plagioclase (0.5 ppm, n = 219). Our compilation of Li concentrations in the main metamorphic minerals of metapelitic migmatites indicates that cordierite and biotite concentrations vary with temperature (Fig. 3 ). For cordierite, the decrease of Li concentrations with increasing temperature has already been experimentally shown (Evensen & London, 2003); but experimental cordierite Li concentrations are lower than the main trend observed in our compiled dataset (Fig. 3 .A). Moreover, both natural and experimental cordierites with ‘lower than expected’ Li concentrations all have higher X Mg (Fig. 3 .B). For biotite, our compilation confirms that Li concentrations remain more or less constant up-temperature until around 750°C – the onset of biotite dehydration melting – and then decrease with increasing temperature, as previously shown by (Kunz et al., 2022). Phase equilibria and trace element modelling Different metapelite melting reactions occur over a range of pressures and temperatures (Fig. 4 ). At pressures higher than ~ 4.5 kbar, melting starts with water-present muscovite melting at ~ 670°C (Ms + H 2 O + Pl + Qtz = Als + melt), followed by muscovite dehydration melting at slightly higher temperatures (Ms + Pl + Qtz = Als + Kfs + melt) and biotite dehydration melting with peritectic garnet from ~ 700°C at 5 kbar to ~ 750°C at 10 kbar (Bt + Als + Qtz ± Pl = Grt + Kfs + melt). Biotite is completely consumed at around 800°C at 5 kbar and 850°C at pressures ≥ 7 kbar. At pressures lower than ~ 4.5 kbar, melting starts with water-present melting of quartz and feldspar at ~ 680–700°C followed by biotite dehydration melting with peritectic cordierite at slightly higher temperatures (Bt + Als + Qtz ± Pl = Crd). Biotite is completely consumed around 800–810°C. It is important to note that variations in X Mg (= MgO/[MgO + FeO]) will affect the stability of Crd (favoured by higher X Mg ) and Grt (favoured by lower X Mg ), and higher TiO 2 will extend the stability field of biotite to higher temperatures (Patiño-Douce, 1993; Tajčmanová et al., 2009). Modelled Li concentrations at constant pressures (4, 6 and 8 kbar) and different geothermal gradients (30, 40, 50 and 60°Ckm − 1 ) and using both natural and experimental Kd values indicate melt Li concentrations increase at higher pressures and lower geothermal gradients (Figs. 5 and 6 ). However, models with experimental Kd values indicate biotite dehydration melting will more effectively mobilise Li, especially at temperatures of 800–820°C (Figs. 5 and 6 –A.1-A.2), while models with natural Kd values indicate initial muscovite and quartz-feldspar melting will form more enriched melts (Figs. 5 and 6 – B.1-B.2). Moreover, the effect of peritectic cordierite in each model is different. Experimental Kd models predict that the melt Li concentration increases regardless of the presence of cordierite, while natural Kd models predict that cordierite sequesters Li from the melt more effectively. Modelled mineral Li concentrations for some phases, however, show the most striking differences. Models with experimental Kd values match biotite trends observed in natural pelitic migmatites but yield much higher muscovite and lower cordierite concentrations (65–100 ppm and 55 − 10 ppm, respectively – Figs. 5 and 6 – A.3). Models with natural Kd values predict lower muscovite concentrations (~ 25 ppm) and somewhat similar biotite and cordierite concentrations to those found in natural examples; however, cordierite and biotite trends are clearly unlike natural trends – Figs. 5 and 6 – B.3). When melt extraction is considered, modelled melt Li concentrations at 4 and 8 kbar display trends like those of the closed-system model using natural Kd values, but increased enrichment when experimental Kd values are applied (Fig. 7 ). The observed difference is due to experimental partition coefficient models producing Li-enriched melts during the later stages of biotite-dehydration melting at higher temperatures. As a result, the removal of less enriched, lower-temperature melts limits the dilution of more enriched higher higher-temperature melts. Hence, melts formed in a closed system only reach around 160 and 180 ppm Li at 4 and 8 kbar, respectively (Fig. 5 – A.1-A.2), while melts formed in an open system reach around 280 and 390 ppm at the same pressures (Fig. 7 .A.2). Mineral Li concentrations in open system models show different behaviours: ( 1 ) muscovite is not affected, as it is only stable before the first melt extraction at 8 kbar (Fig. 7 .B.3); ( 2 ) cordierite Li concentrations remain more or less constant from the first to the last extraction (Fig. 7 .A.3); and ( 3 ) biotite concentrations are similar to those in the closed system model at 4 kbar with natural Kd values, remaining constant or slightly increasing in the other scenarios (Fig. 7 – A.3-B.3). DISCUSSION Insights from the main mineral hosts of Li in pelitic migmatites Knowing which minerals host which critical elements and the role these phases play during melting reactions allows us to understand which melting reactions most effectively mobilise these elements. Additionally, understanding whether the concentrations of these elements vary with temperature is essential for knowing when the elements hosted in each mineral start to be mobilised to the melt (or other mineral phase). For instance, biotite and muscovite are the reactants in most partial melting reactions in metapelitic migmatites and are the main mineral hosts of Li compared to the other reactant minerals. In metapelitic migmatites, biotite hosts up to one order of magnitude more Li than muscovite (this study; Dahl et al., 1993; Dutrow et al., 1986; Kunz et al., 2022; Yang & Rivers, 2000). During muscovite melting, the concentrations of Li in biotite remain constant (Fig. 3 ). Hence, biotite melting reactions are more likely to generate melts enriched in Li (e.g., Kunz et al., 2022; Simons et al., 2017), rather than the previously assumed minimum-temperature melting of muscovite, which was based on the experimental evidence that biotite trace elements would be mobilised into the melt from the onset of muscovite melting (e.g., Černý, 1991; Icenhower & London, 1995). Understanding which peritectic products of the melting reactions host critical elements is also fundamental to understanding the mobilisation of these elements. Biotite dehydration melting may produce peritectic garnet and/or cordierite, depending on pressure and rock composition. While garnet hosts only around 10 ppm Li, cordierite has long been known as a key host of Li in metapelites (e.g., Armbruster & Irouschek, 1983; Bea et al., 1994; Dutrow et al., 1986; Ferry, 1979; Malcherek et al., 2001). In fact, some general formulas for natural cordierite even include Li (e.g., Ch [Na, K] 0−1 VI [Mg, Fe 2+ , Mn, Li ] 2 IV Si 5 VI Al 3 IV [Al, Be, Mg, Fe 2+ , Fe 3+ ] O 18 *x Ch [H 2 O, CO 2 , …] – Bertoldi et al., 2004). Hence, the formation of peritectic cordierite during biotite dehydration melting is likely to affect how Li mobilises into the melt. However, key aspects of the effect of cordierite on Li mobilisation remain open, such as how Li partitions between cordierite and melt at different temperatures and which partition coefficients better reproduce nature. Variation of cordierite Li concentrations and partition coefficients with temperature have already been shown experimentally and indirectly explained. Evensen & London (2003) experiments showed that both cordierite concentrations and partition coefficients decrease with increasing temperature, but their experimental cordierite Li concentrations were lower than the main trend observed in our compiled dataset (Fig. 3 .A). The temperature dependency of Li concentrations in cordierite was already indirectly explained by two previous findings: ( 1 ) Li is mainly incorporated in natural cordierites by exchange mechanisms involving Na ( Ch Na + + VI Li + = Ch □+ VI Mg 2+ ; as from Schreyer, 1985), as shown by Bertoldi et al. (2004); and ( 2 ) Na contents of cordierites are inversely correlated with temperature and are independent of pressure, as demonstrated by experimental studies (Knop & Mirwald, 1998; Mirwald, 1986; Tropper et al., 2018). In other words, Li concentrations in cordierite co-vary with Na, and Na concentration varies with temperature; thus, Li concentrations vary with temperature. Our findings, however, suggest that cordierites with X Mg ≥ 0.7 exhibit different behaviour to cordierites with X Mg ≤ 0.7 (Fig. 3 .A-B). The significance of this observation is discussed further in the open questions section below. Insights from the comparison of natural versus modelled trends The comparison of mineral/mineral partition coefficients for Li from natural examples, experimental studies, and El Hoyazo xenoliths provides initial evidence that all available partition coefficient datasets have limitations (Table 3 ). Partition coefficients for Li between cordierite and biotite derived from experimental studies (0.75–0.95) are consistently lower than those observed in natural samples (1.03–3.42), whereas values from El Hoyazo xenoliths partially overlap with natural data but extend to significantly higher ranges (2.01–6.26). Similarly, Li partition coefficients between muscovite and biotite in experimental studies (0.49) exceed the range observed in natural settings (0.08–0.37). These discrepancies suggest that experimental Kd values may overestimate the role of muscovite and underestimate that of cordierite in controlling Li partitioning, while natural Kd values from El Hoyazo likely overestimate Li incorporation into cordierite. Table 3 Mineral-mineral Li distribution coefficients from natural examples and previous studies with constrained natural and/or experimental partition coefficients. Li Mineral/Mineral distribution coefficients Source Area Crd/Bt Ms/Bt This study and Alt (unpublished) Moldanubiam Zone, Czech Republic 1.08–1.51 This study and Hoogendoorn, 2024 Agly, France 1.03–2.99 This study Brittany, France 3.06–3.32 Mindelo, Portugal 2.14 Ballouard et al., 2023 Velay Dome, France 1.81–2.7 0.08–0.41 Bea et al., 1994 Peña Negra Complex, Spain 3.42 Kunz et al., 2022 Ivrea Zone, Italy 0.11–0.18 Langtang, Nepal 0.17–0.37 Sikkim, India 0.11–0.18 Oldman, 2023 Himalaya, India 0.1–0.22 Phillips, 2021 Himalaya, Bhutan 0.12–0.22 Source Crd/Bt Ms/Bt Experimental Kds Ms/Bt = Icenhower and London (1995); Crd/Bt = Evensen and London (2002; 2003) 0.75–0.95 0.49 Natural Kds Acosta-Vigil et al. (2012) 2.01–6.26 The comparison of Li concentration trends in natural minerals and the models highlights that neither partition coefficient set perfectly reproduces natural trends. Models with experimental Kd values better reproduce the decrease in Li concentrations in natural biotite with increasing temperature, but overestimate Li concentrations in muscovite and underestimate those in cordierite. In contrast, models using Kd values derived from natural samples yield similar concentrations and trends to natural muscovite, but predicted cordierite and muscovite trends (despite being in the same range as natural examples) do not precisely reproduce these minerals' decrease in Li concentration with increasing temperature. This imprecise prediction of the temperature dependence of cordierite and biotite Li concentrations was expected since the natural Kd values used are constants. Open questions: Which physicochemical parameters affect Li behaviour during metapelite melting? As highlighted throughout our study, the available sets of partition coefficients indicate that different melting reactions will mobilise Li (Figs. 5 , 6 and 7 ), and the comparison of natural and modelled trends does not unequivocally indicate which model better represents nature. Hence, there is currently no comprehensive reasoning as to whether experimental or natural partition coefficients better represent nature. These two sets of contrasting partition coefficient values imply that Li behaviour is influenced by unknown factors. To further assess which set of Kd values better represents nature and what explains their contrasting values, we compared the parameters associated with natural migmatites and experimentally and naturally derived Li distribution coefficients. It is important to note that such a comparison is not straightforward since there are key differences between these systems (Fig. 8 ). Experiments are closed systems composed of minerals and glass produced in weeks and quenched at specific P-T conditions. The El Hoyazo enclaves are composed of minerals and melt/glass inclusions produced on a geological timescale and then rapidly frozen due to their entrainment in a volcanic system; thus, these show melt-producing followed by melt-consuming reactions (Kriegsman & Álvarez-Valero 2010). The partial melting of metapelites is an open system, in which we only have access to restitic minerals and minerals crystallised from the remaining melt (leucosome), which likely underwent retrograde reactions and/or back-reaction with melt during cooling and exhumation. Nevertheless, although not ideal, this comparison highlights key differences between physicochemical parameters known to affect partition coefficients and that possibly explain why experimental and natural distribution coefficients don’t match. Li has high diffusion rates . Experiments are quenched at specific P-T conditions, hence, they might record precise equilibrium distribution coefficients, while migmatites and volcanic rocks (and xenoliths as at El Hoyazo) cool over geological timescales during which Li concentrations may re-equilibrate (e.g., Fig. 3 of Marschall & Tang, 2020). Therefore, the natural distribution coefficients may reflect post-peak re-equilibration rather than equilibrium under peak conditions. However, this explanation is dependent on future studies to show/explain the change of preference of Li for biotite over cordierite during melting (as in the experiment) and then for cordierite over biotite during cooling (as in natural examples). The experimental system and mineral compositions are different from the average pelite (Fig. 9 and Table 4 ). The experimental starting compositions (Icenhower and London, 1995; Evensen and London, 2002; 2003) contain lower Al 2 O 3 , TiO 2 or FeO compared with the average pelite (Forshaw & Pattison, 2023) and the samples investigated here (Fig. 8 .D). The bulk composition affects the stability fields of the main metamorphic phases. This is clearly illustrated by the X Mg of cordierite. In experiments, X Mg varies from 68.7 to 85% from 700 to 850°C. In contrast, among our novel cordierite analysis, only one sample formed at T > 800°C reached similar values (71–75%); and among compiled cordierite analysis, only samples with known distinct bulk rock compositions display X Mg ≥ 0.7 at lower temperatures (Visser et al., 1994). Based on the pseudosections calculated for the samples of this study and those of White et al. (2014), higher X Mg only occur at temperatures higher than 780°C. Hence, although the experiments run at temperatures of 700 to 850°C (Evensen and London, 2002; 2003), their cordierite compositions resemble higher temperature cordierites or cordierites formed with protoliths with higher X Mg . Similarly, biotite compositions of the experiment (X Mg =69–72%)occur only at the pseudosections at temperatures of around 850° C. Therefore, the different system and mineral compositions may affect Li partitioning. The experimental water content (10 wt. %) is different from the composition and conditions that most migmatites experienced during their formation (Table 4 ). Higher water contents lower the solidus, increase melt volumes, change melt composition, and – in combination with lower water solubility in melts at lower pressures – may generate water-saturated melts (Holtz & Johannes, 1994; Weinberg & Hasalová, 2015). In fact, Evensen and London (2003) mention that the experiments are water-saturated and may or may not apply to water-undersaturated melts. Three key arguments support the hypothesis that Li distribution coefficients vary depending on the melt H 2 O contents. Firstly, the melt water-contents are positively correlated with Na 2 O in the melt (Holtz & Johannes, 1991), and – as discussed previously – Na and Li are intrinsically connected during cordierite substitution mechanisms. Hence, more water will generate melts with higher Na concentrations, which means there will be less Na available for the substitution mechanism of Li in cordierite. For comparison, the melt Na/K composition in Evensen and London (2002; 2003) lies between 0.83–1.19, while the Na/K of the El Hoyazo melt inclusions are 0.57–0.72 (Acosta-Vigil et al., 2007). Moreover, extra Na in hydrous melt shouldn’t affect Li in biotite in the way that it would affect cordierite since Li substitution mechanisms in biotite do not involve Na (e.g., substitution mechanisms in Breiter et al., 2017). Secondly, the increase in water has been shown to increase Li diffusion in silicic melts by one order of magnitude since it reduces melt polymerisation, which provides more pathways for Li diffusion (Troch et al., 2024). Hence, it is not unrealistic to expect higher water content melts to accommodate more Li. Thirdly, the water content of experimental charges is so high (10 wt. % + the water contained in micas) that there must be free H 2 O present even above the solidus, which implies that some Li might have been dissolved in the supercritical fluid. The F content of experiment charges is higher than most pelitic migmatites (Fig. 10 ). The experimental starting compositions used biotite with 3.67 wt.% fluorine. However, fluorine concentrations in natural biotite from metapelites have been shown to be generally lower than 1 wt. % until the onset of biotite dehydration melting around 750°C, and then increasing with increasing temperatures (Finch & Tomkins, 2017; Kunz et al., 2022). The fluorine in the biotite affects the resulting melt chemistry; for example, experimental glasses have 0.18 to 0.29 wt.% F (Evensen and London, 2002; 2003); whilst the El Hoyazo melt inclusions average F concentrations range from 0.06–0.08 wt.% (Acosta-Vigil et al., 2007). Although there is no direct research that shows higher fluorine contents in the melt will increase lithium solubility, fluorine is likely to affect the D Li mineral/melt since it is known to enhance depolymerisation through fluorine complexes (e.g., Giordano et al., 2004), which can involve Li (Shchekina et al., 2020). Table 4 Comparison of system composition in average pelites, El Hoyazo migmatitic xenoliths and experiments. Oxide (wt. %) Average metapelite (Forshaw & Pattison, 2023) White et al., (2014) El Hoyazo (Bartoli, 2017) SP-Crd1-C and SP-Crd2-C (Evensen and London, 2002; 2003) 4–8 (Icenhower and London, 1995) SiO 2 60.47–70.60 57.32 45.37–54.45 59.37–61.99 49.85–58.37 TiO 2 0.60–1.08 1.07 0.94–1.43 0.31 − 0.23 0.19–0.51 Al 2 O 3 15.87–21.41 20.56 23.87–29.91 13.40-12.91 18.89–21.33 Fe 2 O 3 0.42–0.47 0.00-0.63 FeO 4.61–7.84 8.52 8.89–13.24 5.16–3.54 1.21–3.39 MnO 0.05–0.15 0.18 0.17–0.32 0.09–0.15 MgO 1.89–3.37 3.29 1.38–2.13 3.31–2.39 0.34–2.33 CaO 0.23–0.83 1.31 1.66–2.37 0.77 − 0.16 0.01–0.01 Na 2 O 1.05–2.52 1.83 2.68–2.91 2.62–3.01 1.62–3.19 K 2 O 3.38–4.41 4.09 2.48–3.39 3.38–3.58 4.67–6.31 H 2 O 1.66 0.39–2.56 10.68–10.72 11.36–11.95 F 0.41 − 0.37 0.57–1.81 CONCLUSIONS AND FINAL REMARKS This study provides new insights into lithium (Li) mobilisation during metapelite melting by combining novel and compiled in-situ mineral chemistry data, temperature estimates, and trace element modelling at suprasolidus pressure-temperature conditions. Our findings highlight the following key insights and open questions in understanding Li behaviour in migmatitic systems: Lithium concentrations in biotite and muscovite in migmatites confirm previous suggestions that concentrations in micas are temperature-dependent. Our new data suggest that Li concentrations in cordierite are also temperature dependent. The decrease in Li concentrations in cordierite with increasing temperature matches previous experimental results and is expected since the substitution mechanism of Li in cordierite involves Na, and concentrations of Na in cordierite are already known to be temperature dependent. Contrasting Li concentrations in the melt are predicted depending on the partition coefficients used in the calculations. Models using experimentally derived coefficient values predict higher Li concentrations in melts generated from biotite-dehydration melting reactions. Models based on naturally-derived partition coefficients suggest that lower temperature melts are the most enriched, and the effect of cordierite is more pronounced. The comparison of natural and modelled mineral trends highlights that neither model perfectly reproduces the natural distribution of Li in minerals and melts. Experimental partition coefficients reproduce biotite trends but underestimate Li concentrations in cordierite and overestimate those in muscovite. In contrast, partition coefficients derived empirically maintain mineral/mineral distribution coefficients similar to those in nature but fail to reproduce temperature-varying Li concentrations in biotite and cordierite due to the lack of partition coefficient data constrained at a range of temperatures. Based on the comparison of parameters associated with pelitic migmatites and the experimental and natural partition coefficients, we identified that Li diffusion during cooling, different system and mineral compositions, and water and fluorine contents may explain the contrasting Li behaviours observed. Overall, this study highlights the importance of integrating natural observations, experimental data, and modelling to track trace element behaviour during metapelite melting and assess if/which models are most representative of natural systems. It is clear from the lack of consistency between natural and modelled trends that further studies are essential to refine petrogenetic models for Li-rich granitoids and pegmatites and, ultimately, to support more effective exploration strategies for unconventional Li resources. Declarations Funding: We acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie [grant agreement No. 956125] for E.O.C.’s PhD as part of the Innovative Training Network “FluidNET”. N.R. acknowledges the German Research Foundation (DFG) (project number 521637679) and the ERC (Consolidator Grant no. 771143). Conflicts of interest/Competing interests (include appropriate disclosures): The authors declare that they have no conflict of interest. Availability of data and material: The online version of this article contains supplementary material, which is available to authorised users. Code availability: The version of the software used to produce the equilibrium thermodynamics calculations are available on Zenodo at MAGEMin v1.7.6: https://zenodo.org/records/15619738, MAGEMin_C v1.8.7: https://zenodo.org/records/15699695 and MAGEMinApp v0.9.2: (link will be available soon). ACKNOWLEDGMENTS We acknowledge Michelle Higgins and Kay Knight for their help with sample preparation at The Open University, Giulia Degli-Alessandrini with the scanning electron microscope and electron probe microanalysis at The Open University, and Eric Hellebrand for all his help with electron probe microanalysis at the University of Utrecht. Also, we thank J. Blundy and M. Brown for sharing data and samples, respectively. AUTHOR CONTRIBUTIONS Elisa Oliveira da Costa: Conceptualisation, Methodology, Investigation, Formal Analyses, Data Curation, Writing – Original Draft, Visualisation. Ina Alt: Formal Analyses, Writing – Review and Editing. Tom Argles: Writing – Review and Editing, Supervision. Sander Bas Hoogendoorn: Formal Analyses, Writing – Review and Editing. Leo Kriegsman: Validation, Methodology, Data Curation, Writing – Review and Editing, Supervision. Barbara Kunz: Methodology, Resources, Validation, Writing – Review and Editing, Supervision. Nicolas Riel: Methodology, Validation, Writing – Review and Editing. Clare Warren: Writing – Review and Editing, Supervision, Project administration, Funding acquisition. References Acosta-Vigil A, Buick I, Cesare B, London D, Morgan GB (2012) The Extent of Equilibration between Melt and Residuum during Regional Anatexis and its Implications for Differentiation of the Continental Crust: A Study of Partially Melted Metapelitic Enclaves. J Petrol 53(7):1319–1356. https://doi.org/10.1093/PETROLOGY/EGS018 Acosta-Vigil A, Cesare B, London D, Morgan GB (2007) Microstructures and composition of melt inclusions in a crustal anatectic environment, represented by metapelitic enclaves within El Hoyazo dacites, SE Spain. Chem Geol 237(3–4):450–465. https://doi.org/10.1016/J.CHEMGEO.2006.07.014 Armbruster T, Irouschek A (1983) Cordierites from the Lepontine Alps: Na + Be → Al substitution, gas content, cell parameters, and optics. Contrib Miner Petrol 82(4):389–396. https://doi.org/10.1007/BF00399715/METRICS Ballouard C, Couzinié S, Bouilhol P, Harlaux M, Mercadier J, Montel JM (2024) A felsic meta-igneous source for Li-F-rich peraluminous granites: Insights from the Variscan Velay dome (French Massif Central) and implications for rare-metal magmatism. Contrib Miner Petrol 178(11):75–75. https://doi.org/10.1007/s00410-023-02057-1 Bartoli O (2017) Phase equilibria modelling of residual migmatites and granulites: An evaluation of the melt-reintegration approach. J Metamorph Geol 35(8):919–942. https://doi-org.libezproxy.open.ac.uk/ 10.1111/jmg.12261 Bauer DJ, Khazdozian H, Mehta J, Nguyen RT, Severson MH, Vaagensmith BC, Toba L, Zhang B, Hossain T, Sibal AP, Smith BJ, Riddle ME, Graziano DJ, Mathew T, Cuscaden P, Dai Q, Iloeje C, Edgemon L, Sarna C, Quaresima J (2023) 2023 Critical Materials Strategy . https://doi.org/10.2172/1998242 Bea F, Pereira MD, Stroh A (1994) Mineral/leucosome trace-element partitioning in a peraluminous migmatite (a laser ablation-ICP-MS study). Chem Geol 117(1–4):291–312. https://doi.org/10.1016/0009-2541(94)90133-3 Bertoldi C, Proyer A, Garbe-Schönberg D, Behrens H, Dachs E (2004) Comprehensive chemical analyses of natural cordierites: Implications for exchange mechanisms. Lithos 78(4):389–409. https://doi.org/10.1016/J.LITHOS.2004.07.003 Bowell RJ, Lagos L, de los Hoyos CR, Declercq J (2020) Classification and Characteristics of Natural Lithium Resources. Elements 16(4):259–264. https://doi.org/10.2138/GSELEMENTS.16.4.259 Breiter K, Vaňková M, Galiová MV, Korbelová Z, Kanický V (2017) Lithium and trace-element concentrations in trioctahedral micas from granites of different geochemical types measured via laser ablation ICP-MS. Mineral Mag 81(1):15–33. https://doi.org/10.1180/MINMAG.2016.080.137 Černý P (1991) Fertile granites of Precambrian rare-element pegmatite fields: Is geochemistry controlled by tectonic setting or source lithologies? Precambrian Res 51(1–4):429–468. https://doi.org/10.1016/0301-9268(91)90111-M Černý P, Blevin PL, Cuney M, London D (2005) Granite-Related Ore Deposits. In J. W. Hedenquist, J. F. H. Thompson, R. J. Goldfarb, & J. P. Richards (Eds.), One Hundredth Anniversary Volume (p. 0). Society of Economic Geologists. https://doi.org/10.5382/AV100.12 Dahl PS, Wehn DC, Feldmann SG, Dahl PS, Wehn DC, Feldmann SG (1993) The systematics of trace-element partitioning between coexisting muscovite and biotite in metamorphic rocks from the Black Hills, South Dakota, USA. GeCoA 57(11):2487–2505. https://doi.org/10.1016/0016-7037(93)90412-P Ding J-F, Zhang Y-T, Xu R, Zhang R, Xiao Y, Zhang S, Bi C-X, Tang C, Xiang R, Park HS, Zhang Q, Huang J-Q (2023) Review on lithium metal anodes towards high energy density batteries. Green Energy Environ 8(6):1509–1530. https://doi.org/10.1016/j.gee.2022.08.002 Dutrow BL, Holdaway MJ, Hinton RW (1986) Lithium in staurolite and its petrologic significance. Contrib Miner Petrol 94(4):496–506. https://doi.org/10.1007/BF00376341/METRICS Evensen JM, London D (2002) Experimental silicate mineral/melt partition coefficients for beryllium and the crustal Be cycle from migmatite to pegmatite. Geochim Cosmochim Acta 66(12):2239–2265. https://doi.org/10.1016/S0016-7037(02)00889-X Evensen JM, London D (2003) Experimental partitioning of Be, Cs, and other trace elements between cordierite and felsic melt, and the chemical signature of S-type granite. Contrib Miner Petrol 2003 144:6(6):739–757. https://doi.org/10.1007/S00410-002-0426-X . 144 Ferry JM (1979) Reaction mechanisms, physical conditions, and mass transfer during hydrothermal alteration of mica and feldspar in granitic rocks from south-central Maine, USA. Contrib Miner Petrol 68(2):125–139. https://doi.org/10.1007/BF00371895 Finch EG, Tomkins AG (2017) Fluorine and chlorine behaviour during progressive dehydration melting: Consequences for granite geochemistry and metallogeny. J Metamorph Geol 35(7):739–757. https://doi.org/10.1111/JMG.12253 Forshaw JB, Pattison DRM (2023) Major-element geochemistry of pelites. Geology 51(1):39–43. https://doi.org/10.1130/G50542.1 Gardiner NJ, Palin RM, Koopmans L, Mangler MF, Robb LJ (2024) On tin and lithium granite systems: A crustal evolution perspective. Earth Sci Rev 258:104947. https://doi.org/10.1016/j.earscirev.2024.104947 Giordano D, Romano C, Dingwell DB, Poe B, Behrens H (2004) The combined effects of water and fluorine on the viscosity of silicic magmas. Geochim Cosmochim Acta 68(24):5159–5168. https://doi.org/10.1016/J.GCA.2004.08.012 Grohol M, Veeh C (2023) Study on the critical raw materials for the EU 2023—Final report Holtz FO, Johannes W (1991) Genesis of Peraluminous Granites I. Experimental Investigation of Melt Compositions at 3 and 5 kb and Various H2O Activities. J Petrol 32(5):935–958. https://doi.org/10.1093/petrology/32.5.935 Holtz F, Johannes W (1994) Maximum and minimum water contents of granitic melts: Implications for chemical and physical properties of ascending magmas. Lithos 32(1–2):149–159. https://doi.org/10.1016/0024-4937(94)90027-2 Hoogendoorn SB (2024) Argon Mobility in the Mid-Lower Continental Crust: Insights from the Agly Massif and El Hoyazo . Doctor of Philosophy (PhD) thesis The Open University. https://doi.org/10.21954/ou.ro.00102127 Hund K, La Porta D, Fabregas TP, Laing T, Drexhage J (2019) Minerals for Climate Action: The Mineral Intensity of the Clean Energy Transition Icenhower J, London D (1995) An experimental study of element partitioning among biotite, muscovite, and coexisting peraluminous silicic melt at 200 MPa (H2O). Am Mineral 80(11–12):1229–1251. https://doi.org/10.2138/AM-1995-11-1213 Johnson T, Brown M (2004) Quantitative Constraints on Metamorphism in the Variscides of Southern Brittany—A Complementary Pseudosection Approach. J Petrol 45(6):1237–1259. https://doi.org/10.1093/PETROLOGY/EGH012 Josso P, Lusty P, Gunn A, Shaw R, Singh N, Horn S, Petavratzi E (2023) Review and development of the methodology and data used to produce the UK Criticality Assessment of Technology-critical Minerals (pp. 1–93) Kalt A, Altherr R, Ludwig T (1998) Contact Metamorphism in Pelitic Rocks on the Island of Kos (Greece, Eastern Aegean Sea): A Test for the Na-in-Cordierite Thermometer. J Petrol 39(4):663–688. https://doi.org/10.1093/PETROJ/39.4.663 Kesler SE, Gruber PW, Medina PA, Keoleian GA, Everson MP, Wallington TJ (2012) Global lithium resources: Relative importance of pegmatite, brine and other deposits. Ore Geol Rev 48:55–69. https://doi.org/10.1016/j.oregeorev.2012.05.006 Knop E, Mirwald PW (1998) Sodic cordierites: comparison of natural data and incorporation experiments. Mitteilungen der Österreichischen Mineralogischen Gesellschaft 143:316–321 Kriegsman LM, Álvarez-Valero AM (2010) Melt-producing versus melt-consuming reactions in pelitic xenoliths and migmatites. Lithos 116:310–320. https://doi.org/10.1016/j.lithos.2009.09.001 Koopmans L, Martins T, Linnen R, Gardiner NJ, Breasley CM, Palin RM, Groat LA, Silva D, Robb LJ (2024) The formation of lithium-rich pegmatites through multi-stage melting. Geology 52(1):7–11. https://doi.org/10.1130/G51633.1 Kunz B, Warren C, Jenner F, Harris N, Argles T (2022) Critical metal enrichment in crustal melts: The role of metamorphic mica. Geology . http://oro.open.ac.uk/83598/ Lindagato P, Li Y, Macháček J, Yang G, Mungwarakarama I, Ndahimana A, Ntwali HPK (2023) Lithium Metal: The Key to Green Transportation. Appl Sci 13(1). Article 1. https://doi.org/10.3390/app13010405 London D (2018) Ore-forming processes within granitic pegmatites. Ore Geol Rev 101:349–383. https://doi.org/10.1016/J.OREGEOREV.2018.04.020 Luvizotto GL, Zack T, Meyer HP, Ludwig T, Triebold S, Kronz A, Münker C, Stockli DF, Prowatke S, Klemme S, Jacob DE, von Eynatten H (2009) Rutile crystals as potential trace element and isotope mineral standards for microanalysis. Chem Geol 261(3–4):346–369. https://doi.org/10.1016/J.CHEMGEO.2008.04.012 Malcherek T, Domeneghetti MC, Tazzali V, Ottolini L, McCammon C, Carpenter MA (2001) Structural properties of ferromagnesian cordierites. Am Mineral 86(1–2):66–79. https://doi.org/10.2138/AM-2001-0108 Marschall HR, Tang M (2020) High-temperature processes: is it time for lithium isotopes? Elements: Int Magazine Mineralogy Geochem Petrol 16(4):247–252. https://doi-org.libezproxy.open.ac.uk/ 10.2138/gselements.16.4.247 Mirwald PW (1986) Ist Cordierit ein Geothermometer? Fortschr Mineral 64:113 Müller A, Romer RL, Pedersen R-B (2017) The Sveconorwegian Pegmatite Province – Thousands of Pegmatites Without Parental Granites. Can Mineral 55(2):283–315. https://doi.org/10.3749/canmin.1600075 Oldman CJ (2023) The Formation and Age of Leucogranitic Melt in the Garhwal Himalaya . PhD thesis The Open University. https://doi.org/10.21954/ou.ro.00016216 Patiño-Douce AEP (1993) Titanium substitution in biotite: An empirical model with applications to thermometry, O2 and H2O barometries, and consequences for biotite stability. Chem Geol 108(1):133–162. https://doi.org/10.1016/0009-2541(93)90321-9 Paton C, Hellstrom J, Paul B, Woodhead J, Hergt J (2011) Iolite: Freeware for the visualisation and processing of mass spectrometric data. J Anal At Spectrom 26(12):2508–2518. https://doi.org/10.1039/C1JA10172B Peng H, Li Y, Shangguan L, Li S, Zhang N (2024) Research on the optimization of tribological performance of wind power lubricating grease based on carbon emission. J Eng Res. https://doi.org/10.1016/J.JER.2024.05.022 Phillips S (2021) The Petrogenesis of Kyanite Migmatites in Eastern Bhutan . PhD thesis The Open University. https://oro.open.ac.uk/74774/ Riel N, Kaus BJP, Green ECR, Berlie N (2022) MAGEMin, an Efficient Gibbs Energy Minimizer: Application to Igneous Systems. Geochemistry, Geophysics, Geosystems , 23 (7), e2022GC010427. https://doi.org/10.1029/2022GC010427 Romer RL, Kroner U (2015) Sediment and weathering control on the distribution of Paleozoic magmatic tin–tungsten mineralization. Miner Deposita 50:327–338. https://doi-org.libezproxy.open.ac.uk/ 10.1007/s00126-014-0540-5 Romer RL, Kroner U (2016) Phanerozoic tin and tungsten mineralization—Tectonic controls on the distribution of enriched protoliths and heat sources for crustal melting. Gondwana Res 31:60–95. https://doi-org.libezproxy.open.ac.uk/ 10.1007/s00126-014-0540-5 Rosenberg CL, Handy MR (2005) Experimental deformation of partially melted granite revisited: implications for the continental crust. J Metamorph Geol 23(1):19–28. https://doi-org.libezproxy.open.ac.uk/ 10.1111/j.1525-1314.2005.00555.x Rudnick RL, Gao S (2014) Composition of the Continental Crust. In Treatise on Geochemistry (pp. 1–51). Elsevier. https://doi.org/10.1016/B978-0-08-095975-7.00301-6 Schreyer W (1985) Experimental studies on cation substitutions and fluid incorporation in cordierite. Bull Minéral 108(3):273–291. https://doi.org/10.3406/BULMI.1985.7829 Shaw DM (1970) Trace element fractionation during anatexis. Geochim Cosmochim Acta 34(2):237–243. https://doi.org/10.1016/0016-7037(70)90009-8 Shaw RA, Goodenough KM, Roberts NMW, Horstwood MSA, Chenery SR, Gunn AG (2016) Petrogenesis of rare-metal pegmatites in high-grade metamorphic terranes: A case study from the Lewisian Gneiss Complex of north-west Scotland. Precambrian Res 281:338–362. https://doi.org/10.1016/j.precamres.2016.06.008 Shchekina TI, Rusak AA, Alferyeva YO, Gramenitskiy EN, Kotelnikov AR, Zinovieva NG, Bychkov AY, Bychkova YV, Khvostikov VA (2020) REE, Y, Sc, and Li Partition between Aluminosilicate and Aluminofluoride Melts, Depending on Pressure and Water Content in the Model Granite System. Geochem Int 58(4):391–407. https://doi.org/10.1134/S0016702920040102/FIGURES/8 Silva MA (2014) Petrogenesis of a variscan migmatite complex (NW Portugal): Petrography, geochemistry and fluids . https://www.proquest.com/docview/1914879078?pq-origsite=gscholar&fromopenview=true Simons B, Andersen JCØ, Shail RK, Jenner FE (2017) Fractionation of Li, Be, Ga, Nb, Ta, In, Sn, Sb, W and Bi in the peraluminous Early Permian Variscan granites of the Cornubian Batholith: Precursor processes to magmatic-hydrothermal mineralisation. Lithos , 278–281 , 491–512. https://doi.org/10.1016/J.LITHOS.2017.02.007 Siron G, Goncalves P, Marquer D, Pierre T, Paquette J-L, Vanardois J (2020) Contribution of magmatism, partial melting buffering and localized crustal thinning on the late Variscan thermal structure of the Agly massif (French Pyrenees). J Metamorph Geol 38(8):799–829. https://doi.org/10.1111/JMG.12549 Stepanov AS (2021) A review of the geochemical changes occurring during metamorphic devolatilization of metasedimentary rocks. Chem Geol 568:120080–120080. https://doi.org/10.1016/J.CHEMGEO.2021.120080 Tajčmanová L, Connolly JAD, Cesare B (2009) A thermodynamic model for titanium and ferric iron solution in biotite. J Metamorph Geol 27(2):153–165. https://doi.org/10.1111/j.1525-1314.2009.00812.x Troch J, Huber C, Kueter N, Guillong M, Ackerson M, Ulmer P, Bachmann O (2024) The effect of water on alkali trace element diffusion (Li, Rb, Cs) in silicic melts. Geochim Cosmochim Acta 365:101–113. https://doi.org/10.1016/J.GCA.2023.11.031 Tropper P, Wyhlidal S, Haefeker UA, Mirwald PW (2018) An experimental investigation of Na incorporation in cordierite in low P/high T metapelites. Mineral Petrol 112(2):199–217. https://doi.org/10.1007/S00710-017-0522-2/FIGURES/11 Visser D, Kloprogge JT, Maijer C (1994) An infrared spectroscopic (IR) and light element (Li, Be, Na) study of cordierites from the Bamble Sector, South Norway. Lithos 32(1–2):95–107. https://doi.org/10.1016/0024-4937(94)90023-X Weinberg RF, Hasalová P (2015) Water-fluxed melting of the continental crust: A review. Lithos , 212–215 , 158–188. https://doi.org/10.1016/J.LITHOS.2014.08.021 White RW, Powell R, Holland TJB, Johnson TE, Green ECR (2014) New mineral activity–composition relations for thermodynamic calculations in metapelitic systems. J Metamorph Geol 32(3):261–286. org.libezproxy.open.ac.uk/ 10.1111/jmg.12071 Yang P, Rivers T (2000) Trace element partitioning between coexisting biotite and muscovite from metamorphic rocks, Western Labrador: Structural, compositional and thermal controls. Geochim Cosmochim Acta 64(8):1451–1472. https://doi.org/10.1016/S0016-7037(99)00425-1 Žák J, Verner K, Finger F, Faryad SW, Chlupácová M, Veselovskỳ F (2011) The generation of voluminous S-type granites in the Moldanubian unit, Bohemian Massif, by rapid isothermal exhumation of the metapelitic middle crust. Lithos 121(1–4):25–40. https://doi.org/10.1016/J.LITHOS.2010.10.002 Zhang X, Li Z, Luo L, Fan Y, Du Z (2022) A review on thermal management of lithium-ion batteries for electric vehicles. Energy 238:121652–121652. https://doi.org/10.1016/J.ENERGY.2021.121652 Additional Declarations The authors declare no competing interests. Supplementary Files SuplementaryMaterial.xlsx Supplementary Material SupplementaryText.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7104523","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":484245267,"identity":"a150b262-7652-439a-b179-32c2e7ad68b7","order_by":0,"name":"Elisa Oliveira da Costa","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABUElEQVRIie2RMUvDQBSALwSS5bBrStrkFwhXAk4h/gvnC4FkacExoOCVQLoUXYWA/QsNgvOFA7sU/AEuhq4OySIRRLwkWkmbQTeRfHD3eNx9vPfuAOjo+IvIAinDQOIb5atOOVq50acWRazvwB0FA6NScJtSB/iVbxWb1HGPnigGWQFMeKA4CfPPwfCKiGn6Wlje4oSlvIqlHZKG0g+EsD8HLpQUFyfre2BcU8kwIHYm8aOLuOIYR7ShICaEvCsGJbhGCZF4PxRKKsDiJI5wqVD7rqkcMyHI3yrlIUvIO7AXXOkX+MIbRV7WpiD+YmpVRZ6DZBoCe8kVBWKGdXXcWkXhjakDxGeRQ5RMLxUjZuUs7mq0VMenFKO9WXqz2SZ/9k1ND8RNTl7M4c0qSNPCPNP1yLvNMt/SdpTP9r6rbn8KINo8+gE6+c3tjo6Ojn/MByyXdRg/ye23AAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0001-8478-6255","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Elisa","middleName":"Oliveira da","lastName":"Costa","suffix":""},{"id":484245268,"identity":"21a03352-66ac-4e33-b526-c98cd3e850e9","order_by":1,"name":"Ina Alt","email":"","orcid":"https://orcid.org/0009-0005-5885-3342","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Ina","middleName":"","lastName":"Alt","suffix":""},{"id":484245269,"identity":"dff72228-a7ae-426c-9ed1-aa85228deebb","order_by":2,"name":"Tom W. Argles","email":"","orcid":"https://orcid.org/0000-0002-0484-4230","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Tom","middleName":"W.","lastName":"Argles","suffix":""},{"id":484245270,"identity":"da906743-2f38-444b-bdcf-37639a0fd5d7","order_by":3,"name":"Sander Bas Hoogendoorn","email":"","orcid":"https://orcid.org/0009-0007-2735-9151","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Sander","middleName":"Bas","lastName":"Hoogendoorn","suffix":""},{"id":484245271,"identity":"09150b10-cbef-443d-b25a-3ec967fc701d","order_by":4,"name":"Leo M. Kriegsman","email":"","orcid":"https://orcid.org/0000-0001-5510-127X","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Leo","middleName":"M.","lastName":"Kriegsman","suffix":""},{"id":484245272,"identity":"bd991bf2-e30c-444a-9417-9979c1ea6678","order_by":5,"name":"Barbara E. Kunz","email":"","orcid":"https://orcid.org/0000-0002-9492-1497","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Barbara","middleName":"E.","lastName":"Kunz","suffix":""},{"id":484245273,"identity":"cef26d26-97d1-45b8-8a80-d91151b72a58","order_by":6,"name":"Nicolas Riel","email":"","orcid":"https://orcid.org/0000-0002-5037-5519","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Nicolas","middleName":"","lastName":"Riel","suffix":""},{"id":484245274,"identity":"d4c597bb-cb0a-4425-9d4a-9e694c930247","order_by":7,"name":"Clare J. Warren","email":"","orcid":"https://orcid.org/0000-0003-2444-9737","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Clare","middleName":"J.","lastName":"Warren","suffix":""}],"badges":[],"createdAt":"2025-07-11 21:16:38","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-7104523/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7104523/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":86741420,"identity":"f848fed3-a952-4b16-be8e-4bba68b8bc75","added_by":"auto","created_at":"2025-07-15 06:54:11","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":106452,"visible":true,"origin":"","legend":"\u003cp\u003eSimplified genetic path of peraluminous granitoids showing controlling processes and concentrations of Li in different lithologies. References: upper continental crust average from Rudnick \u0026amp; Gao (2014); isochemical subsolidus metamorphism as suggested by Stepanov (2021); multiple stage melting as suggested by Koopmans et al. (2024) and Ballouard et al. (2024); and magmatic hydrothermal processes as suggested by, for example, Gardiner et al. (2024); London, 2018.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/30f2b9471e6779e49e10acd9.png"},{"id":86741413,"identity":"7d9a8d5a-ecea-42a0-ac59-e0396dd9586a","added_by":"auto","created_at":"2025-07-15 06:54:10","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":57249,"visible":true,"origin":"","legend":"\u003cp\u003eLithium concentrations in the main mineral phases of pelitic migmatites.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/029a70a0416c0bd126b1a92d.png"},{"id":86741379,"identity":"7831fdec-72a6-42f4-9fe2-7e09d535da9d","added_by":"auto","created_at":"2025-07-15 06:54:05","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":259680,"visible":true,"origin":"","legend":"\u003cp\u003eCordierite lithium concentration trends with (A) increasing temperature and (B) increasing X\u003csub\u003eMg\u003c/sub\u003e, and (C) cordierite, biotite and muscovite trends with increasing temperature.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/fbd36b2d1a8b4f6dac9d9e0d.png"},{"id":86741407,"identity":"92f00c71-c508-43a7-8751-eac5d247c45e","added_by":"auto","created_at":"2025-07-15 06:54:09","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":107549,"visible":true,"origin":"","legend":"\u003cp\u003eSimplified pseudosection from White et al. (2014) as calculated in MAGEMin.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/244badb06f9cd049cd3eba94.png"},{"id":86741403,"identity":"bfda0691-c71a-4031-981d-d4dec8ca26fb","added_by":"auto","created_at":"2025-07-15 06:54:07","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":283824,"visible":true,"origin":"","legend":"\u003cp\u003eModelled melt concentration in P-T space (A.1, B.1), at constant pressures of 4, 6 and 8 kbar with increasing temperature (B.1, B.2), and modelled mineral Li concentrations with constant pressure and increasing temperature (C.1, C.2). Modelled results shown in figures A.1, A.2 and A.3 were calculated with experimental partition coefficients, and figures B.1, B.2 and B.3 were calculated with natural partition coefficients.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/e254f125d1bbb198be4b080d.png"},{"id":86741386,"identity":"be5cb4db-ee6d-4d8b-8667-fcfcd9abd09f","added_by":"auto","created_at":"2025-07-15 06:54:05","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":333334,"visible":true,"origin":"","legend":"\u003cp\u003eModelled melt compositions in P-T space (A.1, B.1), on different geothermal gradients with increasing temperature (B.1, B.2), and modelled mineral Li concentrations on different geothermal gradients and increasing temperature (C.1, C.2). Modelled results shown in figures A.1, A.2 and A.3 were calculated with experimental partition coefficients, and figures B.1, B.2 and B.3 were calculated with natural partition coefficients.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/b3d57eab888ac1883a5c6b1b.png"},{"id":86741380,"identity":"840c6f45-e2f7-4fed-bdd6-06d195d26fb8","added_by":"auto","created_at":"2025-07-15 06:54:05","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":154482,"visible":true,"origin":"","legend":"\u003cp\u003eTrace element modelling with melt extraction. Cumulative phase fraction and predicted melt and mineral Li concentrations with increasing temperature at 4 kbar (A.1, A.2, A.3) and 8 kbar (B.1, B.2, B.3).\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/3aef6e6b8d977f93089a9608.png"},{"id":86741405,"identity":"c6f94e39-8633-47cc-971f-efb870b2e26c","added_by":"auto","created_at":"2025-07-15 06:54:08","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":133964,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram of key differences between (A) experimental studies, (B) El Hoyazo migmatitic xenoliths, and (C) pelitic migmatites.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/5f6ad13888bc3b492c816f34.png"},{"id":86741387,"identity":"8d5275f9-f3e7-4c15-ad62-f9c60f45ff99","added_by":"auto","created_at":"2025-07-15 06:54:05","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":53662,"visible":true,"origin":"","legend":"\u003cp\u003eTernary showing different starting compositions between experiments, El Hoyazo migmatitic xenoliths and average metapelites.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/cc6f816f770e3a73e2fe2188.png"},{"id":86741404,"identity":"e57a0868-0d38-427c-af34-995ff754862b","added_by":"auto","created_at":"2025-07-15 06:54:08","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":39404,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of F contents in natural versus experimental biotites.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/b62db9f04dfccd158ff03c1b.png"},{"id":86741739,"identity":"085823d7-e2fa-406f-b4d9-826852d8d70f","added_by":"auto","created_at":"2025-07-15 07:02:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2695474,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/54a3c07e-941f-4126-86e0-9fa73b6582cd.pdf"},{"id":86741436,"identity":"783a34f3-4455-46e0-8cd5-52b8777d56eb","added_by":"auto","created_at":"2025-07-15 06:54:13","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":49720520,"visible":true,"origin":"","legend":"\u003cp\u003eSupplementary Material\u003c/p\u003e","description":"","filename":"SuplementaryMaterial.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/995e0fca463df5c9bd7b2858.xlsx"},{"id":86741393,"identity":"98bf827b-57df-4d0f-9040-f5821a3f2471","added_by":"auto","created_at":"2025-07-15 06:54:07","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":1585067,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryText.docx","url":"https://assets-eu.researchsquare.com/files/rs-7104523/v1/88cbcd733f9c938a224c3414.docx"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eLithium mobilisation during metapelite melting: insights and open questions\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eThe global demand for lithium (Li) is rapidly increasing due to its application in technologies related to the green energy transition, such as rechargeable batteries for electric vehicles and energy storage systems (e.g., Ding et al., 2023; Lindagato et al., 2023; Peng et al., 2024; Zhang et al., 2022). To meet this growing demand, Li production is projected to rise by nearly 500% by 2050 (Hund et al., 2019). This anticipated surge has already impacted critical raw material strategies, as reflected in the designation of Li as a critical element in multiple national and international assessments (e.g., Bauer et al., 2023; Grohol \u0026amp; Veeh, 2023; Josso et al., 2023). Such pressure on supply chains is likely to lower the minimum grade required for the economic exploitation of conventional deposits, such as pegmatites and brines, and prompt the exploration efforts towards less-conventional sources, such as Li-enriched clays and geothermal brines (e.g., Bowell et al., 2020; Kesler et al., 2012). Therefore, a comprehensive understanding of all the geological processes that affect Li mobilisation \u0026ndash; particularly those involved in the genesis of Li deposits \u0026ndash; is crucial to support society\u0026rsquo;s transition to a sustainable future.\u003c/p\u003e\u003cp\u003eA major reserve of Li is peraluminous granitoids and pegmatites (Bowell et al., 2020). The main processes associated with the genesis of trace element-rich granitoids are protolith enrichment (e.g., Romer and Kroner, 2015; 2015), crustal melting of (typically) metasedimentary protoliths and magmatic-hydrothermal processes (e.g., Gardiner et al., 2024; London, 2018 - Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). However, current petrogenetic models differ about the relative importance of each of these processes. Some studies suggest that extreme fractional crystallisation of a large magmatic body is the main enrichment process, arguing that many deposits are spatially and/or genetically linked to parent granites (e.g., Čern\u0026yacute; et al., 2005; London, 2018). In contrast, others propose an \u0026ldquo;anatectic model\u0026rdquo; whereby Li-rich melts are formed through the partial melting of enriched protoliths or subsequent remelting of peraluminous orthogneisses, without extensive magmatic fractionation, which is supported by the occurrence of many \u0026ldquo;parentless\u0026rdquo; deposits (e.g., Ballouard et al., 2024; Koopmans et al., 2024; M\u0026uuml;ller et al., 2017; Shaw et al., 2016). Ultimately, assessing these models requires precise constraints on the enrichment factors associated with each process involved in the genesis of Li deposits.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eA key process for which we still lack precise constraints on Li enrichment factors is metapelite partial melting. The key factors that control trace element redistribution during equilibrium melting are the relative abundances of reactant minerals and product (peritectic) minerals and the partition coefficient (Kd) of trace elements between minerals and melt. While the relative abundances of minerals in metapelites can be routinely estimated through phase equilibria modelling software (e.g., MAGEMin, Perple_X, THERMOCALC), available partition coefficients indicate contrasting affinities for some of the main mineral phases in metapelites at suprasolidus conditions, notably biotite and cordierite (Acosta-Vigil et al., 2012; Ballouard et al., 2023; Evensen \u0026amp; London, 2002, 2003; Icenhower \u0026amp; London, 1995). This variation in available partition coefficients translates to different predictions of which melting reaction mobilises Li, as clearly illustrated by two recent studies: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) Ballouard et al. (2023) \u0026ndash; based mostly on naturally derived partition coefficients \u0026ndash; indicate that the highest Li concentrations in the melt are associated with muscovite melting followed by biotite dehydration melting with peritectic garnet at higher pressures (since cordierite efficiently sequesters Li at lower pressures); while (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) Koopmans et al. (2024) \u0026ndash; based mostly on experimentally derived partition coefficients \u0026ndash; shows higher Li concentrations in the melt are reached at lower pressures. Hence, it is still uncertain which model better represents nature.\u003c/p\u003e\u003cp\u003eIn this study, we investigate Li mobilisation during metapelite melting to provide insights into which model best fits natural observations and identify the remaining knowledge gaps regarding Li behaviour during partial melting. To do so, we use: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) novel and literature \u003cem\u003ein-situ\u003c/em\u003e measurements of Li concentrations in the main rock-forming metamorphic minerals in metapelitic migmatites; (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) novel and existing temperature estimates; (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) phase equilibria modelling; and (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) trace element modelling during partial melting at 4 and 8 kbar using experimentally- and naturally-constrained partition coefficients, as well as solely natural concentration trends. Our results highlight important mismatches between modelled Li concentrations and natural observations. Lastly, we enumerate specific physicochemical parameters that likely explain the different Li behaviour observed in experiments versus nature.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003e\u003cb\u003eMineral Li concentration variation with temperature\u003c/b\u003e\u003c/p\u003e\u003cp\u003eNovel trace element concentrations and temperature estimates paired with literature data from metapelitic migmatites were compiled to constrain concentrations of Li in the main mineral phases and how these concentrations vary with temperature (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Novel data were acquired from four high-grade terranes within the Paleozoic Variscan Orogen in Europe, all of which were subject to metamorphic conditions consistent with partial melting in the biotite dehydration field (Johnson \u0026amp; Brown, 2004; Silva, 2014; Siron et al., 2020; Ž\u0026aacute;k et al., 2011). Novel temperature estimates were constrained through the Na-in-cordierite geothermometer (Tropper et al., 2018) and phase equilibria modelling. Information related to our novel data (sample locations, geological settings and summary of P-T estimates) is provided in the Supplementary Text.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSummary of all datasets used in this study. *Indicates average information per sample was used. **Indicates temperature estimate was (re)calculated in this study.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eSource\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eArea\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eX\u003csub\u003eMg\u003c/sub\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTemperature range (\u0026deg;C)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTemperature estimate method\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBt\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCrd\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003eThis study\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMindelo, Portugal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.63\u0026ndash;0.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e699\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa-in-Crd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMoldanubian Zone, Czech Republic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.41\u0026ndash;0.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.58\u0026ndash;0.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e752\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa-in-Crd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBritany, France\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.43\u0026ndash;0.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.55\u0026ndash;0.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e720\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa-in-Crd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAgly, France\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.42\u0026ndash;0.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.58\u0026ndash;0.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e760\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa-in-Crd and Pseudosection\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eJ. Blundy (unpublished)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCooma, Australia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.51\u0026ndash;0.58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e748\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa-in-Crd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCambalong, Australia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.54\u0026ndash;0.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e774\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa-in-Crd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCambalong, Australia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.45\u0026ndash;0.58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e761\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa-in-Crd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eI. Alt (unpublished)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMoldanubian Zone, Czech Republic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.41\u0026ndash;0.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.58\u0026ndash;0.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e700\u0026ndash;750\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003ePseudosection and Na-in-Crd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eHoogendoorn, 2024*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEl Hoyazo, Spain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.3\u0026ndash;0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e780\u0026ndash;820\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTi in Biotite\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAgly, France\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.3\u0026ndash;0.53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.56\u0026ndash;0.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e650\u0026ndash;680\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003ePseudosection\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBallouard et al., 2024*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVelay Dome, France\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.3\u0026ndash;0.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.54\u0026ndash;0.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e536\u0026ndash;740\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTi in Biotite, Pseudosection, Na in Crd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOldman, 2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHimalaya, India\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.28\u0026ndash;0.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e678\u0026ndash;784\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTi-in-Bt\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eKunz et al., 2022*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSikkim, India\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.37\u0026ndash;0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTi-in-Bt\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIvrea, Italy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.39\u0026ndash;0.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTi-in-Bt, Thermocalc, Zr-in-Rt\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLangtang, Nepal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.32\u0026ndash;0.47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eGeothermometry\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePhillips, 2021*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHimalaya, Bhutan\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.34\u0026ndash;0.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e546\u0026ndash;689\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTi-in-Bt\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"11\" rowspan=\"12\"\u003e\u003cp\u003eBertoldi et al., 2004\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLake Cauchon, Manitoba, Canada\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e799\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"11\" rowspan=\"12\"\u003e\u003cp\u003eNa-in-Crd**\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChiaravalle, Calabria, Italy;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e785\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eColombo, Sri Lanka\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e809\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePolia, Calabria, Italy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e791\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eKiranur, South India\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e701\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLhosy, Central Madagascar\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e805\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSundsvall, Sweden\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e781\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCerro del Hoyazo, Spain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e748\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTsihombe, South Madagascar\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e750\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eManik Ganga, Sri Lanka\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e772\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSopparjok, Norway\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e793\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAirport Ivalo, Finland\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e791\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"10\" rowspan=\"11\"\u003e\u003cp\u003eMalcherek et al., 2001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSalem, India\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e752\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"10\" rowspan=\"11\"\u003e\u003cp\u003eNa-in-Crd**\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eManik Ganga, Sri Lanka\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e686\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTanzania\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e746\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOrijarvi, Finland\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e746\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMt. Bity, Madagaskar\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e729\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGreat Bear Lake, Canada\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e762\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRawling Wyoming, USA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e686\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCerro del Hoyazo, Spain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e699\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePena Negra Complex, Spain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e676\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDolni Bory, Czech Republic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e540\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDolni Bory, Czech Republic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e545\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBea et al., 1994\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePe\u0026ntilde;a Negra Complex, Spain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.40\u0026ndash;0.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.49\u0026ndash;0.53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e750\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eThermometry**\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVisser et al., 1994\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBamble Sector, Norway\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.76\u0026ndash;0.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e689\u0026ndash;792\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa-in-Crd**\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eKalt et al., 1998\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIsland of Kos, Greece\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.31\u0026ndash;0.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e554\u0026ndash;743\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNa-in-Crd**\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eMajor element compositions for cordierite, biotite, garnet, muscovite, and feldspars were determined using a combination of \u003cem\u003ein-situ\u003c/em\u003e techniques at the Open University, England. Analyses were conducted with both a Tescan Clara Energy-Dispersive Spectroscopy Scanning Electron Microscope (EDS-SEM) and a Cameca SX100 electron probe micro analyser (EPMA). Analytical quality was monitored through comparison with a natural almandine standard from the GEO MkII block, with results within 7% of the standard preferred values. Rutile and ilmenite compositions were acquired at the University of Utrecht, Netherlands, using a JEOL 5-spectrometer JXA-8530F (EPMA), with data quality verified via R10 standard measurements at the start and end of the session (Luvizotto et al., 2009). Relative standard deviations ranged from 0.9\u0026ndash;2.5% for Ti, Cr, Fe, Nb, and Zr, and up to 13% for Ta. Full analytical parameters are detailed in the Supplementary Text.\u003c/p\u003e\u003cp\u003eTrace element concentrations of individual mineral grains were obtained at the Open University using a Photon Machines Analyte G2 193 nm excimer laser system, equipped with a HelEX II laser ablation cell and coupled with an Agilent 8800 Triple Quadrupole ICP-MS (LA-ICP-MS). Biotite, muscovite, chlorite, feldspars, cordierite, and pinite were analysed \u003cem\u003ein-situ\u003c/em\u003e with a laser fluence of 3.63 J/cm\u0026sup2;, 10 Hz repetition rate, and spot sizes of 50 or 30 \u0026micro;m. In contrast, ilmenite and rutile were analysed using a 3.63 J/cm\u0026sup2; laser fluence, 5 Hz repetition rate, and 20 \u0026micro;m spot size. Data reduction was performed with Iolite v3.71 (Paton et al., 2011). Analytical precision and accuracy were assessed using BCR-2G and R10 standards, which typically fell within 10% of the preferred values. Full analytical parameters are detailed in the Supplementary Text.\u003c/p\u003e\u003cp\u003e\u003cb\u003ePhase equilibria and trace element modelling\u003c/b\u003e\u003c/p\u003e\u003cp\u003ePhase equilibria and trace element modelling aimed to constrain variations in Li concentration at different pressures, temperatures and melting reactions. We used the starting composition, parameters and solid solutions as the metapelite pseudosection of White et al. (2014) and the database ds62. The complete pseudosection is shown in the Supplementary Figure. Both phase equilibria and trace element modelling were computed using the mineral assemblage Gibbs energy minimiser software MAGEMin (Riel et al., 2022).\u003c/p\u003e\u003cp\u003eMelt trace element concentrations were estimated using the batch melting equation (Shaw, 1970), as follows:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:{C}_{L}={C}_{0}*\\frac{1}{(D+F\\left(1-D\\right))}$$\u003c/div\u003e\u003c/div\u003e(1) \u003c/p\u003e\u003cp\u003ewhere C\u003csub\u003eL\u003c/sub\u003e and C\u003csub\u003e0\u003c/sub\u003e correspond to the concentration of the element in the melt and protolith, respectively; F is the weight fraction of melt, and D is the bulk partition coefficient for the residual minerals, which consists of the sum of the partition coefficients (Kd) of each mineral times their weight percentage in the restite. The concentration of Li in the protolith was calculated based on the median mineral Li concentration from this study and their weight fractions at subsolidus conditions as extracted from MAGEMin (C\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;55 ppm \u0026ndash; calculation shown in the Supplementary Materials). Four sets of partition coefficients were introduced to MAGEMin (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e): (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) mostly natural partition coefficients as used in Ballouard et al. (2023); (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) natural partition coefficients constrained between minerals and melt/glass inclusions from the El Hoyazo migmatitic xenoliths (Acosta-Vigil et al., 2012); (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) experimental partition coefficients with temperature variation for cordierite (Kd = -0.0021 * T (\u0026deg;C)\u0026thinsp;+\u0026thinsp;1.933 - Evensen \u0026amp; London, 2003) and biotite (Kd = -0.0076 * T (\u0026deg;C)\u0026thinsp;+\u0026thinsp;6.5775 - based on higher temperature Kd of Evensen \u0026amp; London, 2002; and lower Kd of Icenhower \u0026amp; London, 1995); and (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) mostly experimental partition coefficients, but without temperature variations (as used in Koopmans et al., 2023).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSummary of mineral/melt Li partition coefficients added to MAGEMin.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"5\" nameend=\"c7\" namest=\"c3\"\u003e\u003cp\u003eDistribution Coefficients\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eNatural\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003eExperimental\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMineral\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAcosta-Vigil et al. (2012)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBallouard et al. (2023) and ref. therein\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eIcenhower and London (1995), Evensen and London (2002; 2003)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eAs used in Koopmans et al. (2023)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMuscovite\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.08\u0026ndash;0.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.8*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eBiotite\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.31\u0026ndash;0.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.41\u0026ndash;1.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.67 (650\u0026deg;C) \u0026minus;\u0026thinsp;1.01 (750\u0026deg;C)*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e1.67\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.46\u0026thinsp;\u0026minus;\u0026thinsp;0.16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCordierite\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.43\u0026ndash;1.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.82\u0026ndash;3.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.44 (700\u0026deg;C) \u0026minus;\u0026thinsp;0.12 (850\u0026deg;C)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.44\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eGarnet\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.06\u0026ndash;0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.07\u0026ndash;0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePlagioclase\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.28\u0026ndash;1.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.26\u0026ndash;0.84\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eK-feldspar\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.017\u0026ndash;0.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.06\u0026ndash;0.38*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ellmenite\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\u003cp\u003e* Values from experiments without Crd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eModels shown were either in a closed system at constant pressure or various geothermal gradients, or in an open system at 4 and 8 kbar. Open system models were only run at 4 and 8 kbar since no critical differences occur at intermediate pressures, as shown in the closed system models. Melt extractions were done once around 7\u0026ndash;8 vol.% melt had been generated, close to the melt connectivity threshold (Rosenberg \u0026amp; Handy, 2005), and 2 vol.% melt was assumed to remain in the source. Melt extractions were not done after the complete breakdown of biotite. Variations of the system and melt compositions during extraction are shown in the Supplementary Materials.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003e\u003cb\u003eLi concentrations\u003c/b\u003e\u003c/p\u003e\u003cp\u003eBased on this study and the literature data, Li is hosted in the following minerals from highest to lowest concentration (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e): (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) cordierite (median of 197 ppm based on 261 analyses); (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) biotite (152 ppm, n\u0026thinsp;=\u0026thinsp;873); (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) muscovite (33 ppm, n\u0026thinsp;=\u0026thinsp;326); (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) garnet (13 ppm, n\u0026thinsp;=\u0026thinsp;65); (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) alkali-feldspar (4 ppm, n\u0026thinsp;=\u0026thinsp;119); (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e) ilmenite (1.8 ppm, n\u0026thinsp;=\u0026thinsp;20) and (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e) plagioclase (0.5 ppm, n\u0026thinsp;=\u0026thinsp;219).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eOur compilation of Li concentrations in the main metamorphic minerals of metapelitic migmatites indicates that cordierite and biotite concentrations vary with temperature (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). For cordierite, the decrease of Li concentrations with increasing temperature has already been experimentally shown (Evensen \u0026amp; London, 2003); but experimental cordierite Li concentrations are lower than the main trend observed in our compiled dataset (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.A). Moreover, both natural and experimental cordierites with \u0026lsquo;lower than expected\u0026rsquo; Li concentrations all have higher X\u003csub\u003eMg\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.B). For biotite, our compilation confirms that Li concentrations remain more or less constant up-temperature until around 750\u0026deg;C \u0026ndash; the onset of biotite dehydration melting \u0026ndash; and then decrease with increasing temperature, as previously shown by (Kunz et al., 2022).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003ePhase equilibria and trace element modelling\u003c/b\u003e\u003c/p\u003e\u003cp\u003eDifferent metapelite melting reactions occur over a range of pressures and temperatures (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). At pressures higher than ~\u0026thinsp;4.5 kbar, melting starts with water-present muscovite melting at ~\u0026thinsp;670\u0026deg;C (Ms\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;Pl\u0026thinsp;+\u0026thinsp;Qtz\u0026thinsp;=\u0026thinsp;Als\u0026thinsp;+\u0026thinsp;melt), followed by muscovite dehydration melting at slightly higher temperatures (Ms\u0026thinsp;+\u0026thinsp;Pl\u0026thinsp;+\u0026thinsp;Qtz\u0026thinsp;=\u0026thinsp;Als\u0026thinsp;+\u0026thinsp;Kfs\u0026thinsp;+\u0026thinsp;melt) and biotite dehydration melting with peritectic garnet from ~\u0026thinsp;700\u0026deg;C at 5 kbar to ~\u0026thinsp;750\u0026deg;C at 10 kbar (Bt\u0026thinsp;+\u0026thinsp;Als\u0026thinsp;+\u0026thinsp;Qtz\u0026thinsp;\u0026plusmn;\u0026thinsp;Pl\u0026thinsp;=\u0026thinsp;Grt\u0026thinsp;+\u0026thinsp;Kfs\u0026thinsp;+\u0026thinsp;melt). Biotite is completely consumed at around 800\u0026deg;C at 5 kbar and 850\u0026deg;C at pressures\u0026thinsp;\u0026ge;\u0026thinsp;7 kbar. At pressures lower than ~\u0026thinsp;4.5 kbar, melting starts with water-present melting of quartz and feldspar at ~\u0026thinsp;680\u0026ndash;700\u0026deg;C followed by biotite dehydration melting with peritectic cordierite at slightly higher temperatures (Bt\u0026thinsp;+\u0026thinsp;Als\u0026thinsp;+\u0026thinsp;Qtz\u0026thinsp;\u0026plusmn;\u0026thinsp;Pl\u0026thinsp;=\u0026thinsp;Crd). Biotite is completely consumed around 800\u0026ndash;810\u0026deg;C. It is important to note that variations in X\u003csub\u003eMg\u003c/sub\u003e (=\u0026thinsp;MgO/[MgO\u0026thinsp;+\u0026thinsp;FeO]) will affect the stability of Crd (favoured by higher X\u003csub\u003eMg\u003c/sub\u003e) and Grt (favoured by lower X\u003csub\u003eMg\u003c/sub\u003e), and higher TiO\u003csub\u003e2\u003c/sub\u003e will extend the stability field of biotite to higher temperatures (Pati\u0026ntilde;o-Douce, 1993; Tajčmanov\u0026aacute; et al., 2009).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eModelled Li concentrations at constant pressures (4, 6 and 8 kbar) and different geothermal gradients (30, 40, 50 and 60\u0026deg;Ckm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and using both natural and experimental Kd values indicate melt Li concentrations increase at higher pressures and lower geothermal gradients (Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). However, models with experimental Kd values indicate biotite dehydration melting will more effectively mobilise Li, especially at temperatures of 800\u0026ndash;820\u0026deg;C (Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e \u0026ndash;A.1-A.2), while models with natural Kd values indicate initial muscovite and quartz-feldspar melting will form more enriched melts (Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e \u0026ndash; B.1-B.2). Moreover, the effect of peritectic cordierite in each model is different. Experimental Kd models predict that the melt Li concentration increases regardless of the presence of cordierite, while natural Kd models predict that cordierite sequesters Li from the melt more effectively. Modelled mineral Li concentrations for some phases, however, show the most striking differences. Models with experimental Kd values match biotite trends observed in natural pelitic migmatites but yield much higher muscovite and lower cordierite concentrations (65\u0026ndash;100 ppm and 55\u0026thinsp;\u0026minus;\u0026thinsp;10 ppm, respectively \u0026ndash; Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e \u0026ndash; A.3). Models with natural Kd values predict lower muscovite concentrations (~\u0026thinsp;25 ppm) and somewhat similar biotite and cordierite concentrations to those found in natural examples; however, cordierite and biotite trends are clearly unlike natural trends \u0026ndash; Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e \u0026ndash; B.3).\u003c/p\u003e\u003cp\u003eWhen melt extraction is considered, modelled melt Li concentrations at 4 and 8 kbar display trends like those of the closed-system model using natural Kd values, but increased enrichment when experimental Kd values are applied (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The observed difference is due to experimental partition coefficient models producing Li-enriched melts during the later stages of biotite-dehydration melting at higher temperatures. As a result, the removal of less enriched, lower-temperature melts limits the dilution of more enriched higher higher-temperature melts. Hence, melts formed in a closed system only reach around 160 and 180 ppm Li at 4 and 8 kbar, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e \u0026ndash; A.1-A.2), while melts formed in an open system reach around 280 and 390 ppm at the same pressures (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e.A.2). Mineral Li concentrations in open system models show different behaviours: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) muscovite is not affected, as it is only stable before the first melt extraction at 8 kbar (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e.B.3); (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) cordierite Li concentrations remain more or less constant from the first to the last extraction (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e.A.3); and (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) biotite concentrations are similar to those in the closed system model at 4 kbar with natural Kd values, remaining constant or slightly increasing in the other scenarios (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e \u0026ndash; A.3-B.3).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003e\u003cstrong\u003eInsights from the main mineral hosts of Li in pelitic migmatites\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eKnowing which minerals host which critical elements and the role these phases play during melting reactions allows us to understand which melting reactions most effectively mobilise these elements. Additionally, understanding whether the concentrations of these elements vary with temperature is essential for knowing when the elements hosted in each mineral start to be mobilised to the melt (or other mineral phase). For instance, biotite and muscovite are the reactants in most partial melting reactions in metapelitic migmatites and are the main mineral hosts of Li compared to the other reactant minerals. In metapelitic migmatites, biotite hosts up to one order of magnitude more Li than muscovite (this study; Dahl et al., 1993; Dutrow et al., 1986; Kunz et al., 2022; Yang \u0026amp; Rivers, 2000). During muscovite melting, the concentrations of Li in biotite remain constant (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). Hence, biotite melting reactions are more likely to generate melts enriched in Li (e.g., Kunz et al., 2022; Simons et al., 2017), rather than the previously assumed minimum-temperature melting of muscovite, which was based on the experimental evidence that biotite trace elements would be mobilised into the melt from the onset of muscovite melting (e.g., Čern\u0026yacute;, 1991; Icenhower \u0026amp; London, 1995).\u003c/p\u003e\n\u003cp\u003eUnderstanding which peritectic products of the melting reactions host critical elements is also fundamental to understanding the mobilisation of these elements. Biotite dehydration melting may produce peritectic garnet and/or cordierite, depending on pressure and rock composition. While garnet hosts only around 10 ppm Li, cordierite has long been known as a key host of Li in metapelites (e.g., Armbruster \u0026amp; Irouschek, 1983; Bea et al., 1994; Dutrow et al., 1986; Ferry, 1979; Malcherek et al., 2001). In fact, some general formulas for natural cordierite even include Li (e.g., \u003csup\u003eCh\u003c/sup\u003e[Na, K]\u003csub\u003e0\u0026minus;1\u003c/sub\u003e\u003csup\u003eVI\u003c/sup\u003e [Mg, Fe\u003csup\u003e2+\u003c/sup\u003e, Mn, \u003cstrong\u003eLi\u003c/strong\u003e]\u003csub\u003e2\u003c/sub\u003e \u003csup\u003eIV\u003c/sup\u003eSi\u003csub\u003e5\u003c/sub\u003e \u003csup\u003eVI\u003c/sup\u003eAl\u003csub\u003e3\u003c/sub\u003e \u003csup\u003eIV\u003c/sup\u003e[Al, Be, Mg, Fe\u003csup\u003e2+\u003c/sup\u003e, Fe\u003csup\u003e3+\u003c/sup\u003e] O\u003csub\u003e18\u003c/sub\u003e *x\u003csup\u003eCh\u003c/sup\u003e[H\u003csub\u003e2\u003c/sub\u003eO, CO\u003csub\u003e2\u003c/sub\u003e, \u0026hellip;] \u0026ndash; Bertoldi et al., 2004). Hence, the formation of peritectic cordierite during biotite dehydration melting is likely to affect how Li mobilises into the melt. However, key aspects of the effect of cordierite on Li mobilisation remain open, such as how Li partitions between cordierite and melt at different temperatures and which partition coefficients better reproduce nature.\u003c/p\u003e\n\u003cp\u003eVariation of cordierite Li concentrations and partition coefficients with temperature have already been shown experimentally and indirectly explained. Evensen \u0026amp; London (2003) experiments showed that both cordierite concentrations and partition coefficients decrease with increasing temperature, but their experimental cordierite Li concentrations were lower than the main trend observed in our compiled dataset (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e.A). The temperature dependency of Li concentrations in cordierite was already indirectly explained by two previous findings: (\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e) Li is mainly incorporated in natural cordierites by exchange mechanisms involving Na (\u003csup\u003eCh\u003c/sup\u003eNa\u003csup\u003e+\u003c/sup\u003e+\u003csup\u003eVI\u003c/sup\u003eLi\u003csup\u003e+\u003c/sup\u003e=\u003csup\u003eCh\u003c/sup\u003e□+\u003csup\u003eVI\u003c/sup\u003eMg\u003csup\u003e2+\u003c/sup\u003e; as from Schreyer, 1985), as shown by Bertoldi et al. (2004); and (\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e) Na contents of cordierites are inversely correlated with temperature and are independent of pressure, as demonstrated by experimental studies (Knop \u0026amp; Mirwald, 1998; Mirwald, 1986; Tropper et al., 2018). In other words, Li concentrations in cordierite co-vary with Na, and Na concentration varies with temperature; thus, Li concentrations vary with temperature. Our findings, however, suggest that cordierites with X\u003csub\u003eMg\u003c/sub\u003e\u0026ge; 0.7 exhibit different behaviour to cordierites with X\u003csub\u003eMg\u003c/sub\u003e \u0026le; 0.7 (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e.A-B). The significance of this observation is discussed further in the open questions section below.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInsights from the comparison of natural versus modelled trends\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe comparison of mineral/mineral partition coefficients for Li from natural examples, experimental studies, and El Hoyazo xenoliths provides initial evidence that all available partition coefficient datasets have limitations (Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). Partition coefficients for Li between cordierite and biotite derived from experimental studies (0.75\u0026ndash;0.95) are consistently lower than those observed in natural samples (1.03\u0026ndash;3.42), whereas values from El Hoyazo xenoliths partially overlap with natural data but extend to significantly higher ranges (2.01\u0026ndash;6.26). Similarly, Li partition coefficients between muscovite and biotite in experimental studies (0.49) exceed the range observed in natural settings (0.08\u0026ndash;0.37). These discrepancies suggest that experimental Kd values may overestimate the role of muscovite and underestimate that of cordierite in controlling Li partitioning, while natural Kd values from El Hoyazo likely overestimate Li incorporation into cordierite.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eMineral-mineral Li distribution coefficients from natural examples and previous studies with constrained natural and/or experimental partition coefficients.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eLi Mineral/Mineral distribution coefficients\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSource\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eArea\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCrd/Bt\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMs/Bt\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eThis study and Alt (unpublished)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMoldanubiam Zone, Czech Republic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.08\u0026ndash;1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eThis study and Hoogendoorn, 2024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAgly, France\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.03\u0026ndash;2.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eThis study\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBrittany, France\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.06\u0026ndash;3.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMindelo, Portugal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBallouard et al., 2023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVelay Dome, France\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.81\u0026ndash;2.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.08\u0026ndash;0.41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBea et al., 1994\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePe\u0026ntilde;a Negra Complex, Spain\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\n \u003cp\u003eKunz et al., 2022\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIvrea Zone, Italy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.11\u0026ndash;0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLangtang, Nepal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.17\u0026ndash;0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSikkim, India\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.11\u0026ndash;0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOldman, 2023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHimalaya, India\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.1\u0026ndash;0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePhillips, 2021\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHimalaya, Bhutan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.12\u0026ndash;0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eSource\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eCrd/Bt\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eMs/Bt\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eExperimental Kds\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMs/Bt\u0026thinsp;=\u0026thinsp;Icenhower and London (1995); Crd/Bt\u0026thinsp;=\u0026thinsp;Evensen and London (2002; 2003)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.75\u0026ndash;0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural Kds\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAcosta-Vigil et al. (2012)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.01\u0026ndash;6.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThe comparison of Li concentration trends in natural minerals and the models highlights that neither partition coefficient set perfectly reproduces natural trends. Models with experimental Kd values better reproduce the decrease in Li concentrations in natural biotite with increasing temperature, but overestimate Li concentrations in muscovite and underestimate those in cordierite. In contrast, models using Kd values derived from natural samples yield similar concentrations and trends to natural muscovite, but predicted cordierite and muscovite trends (despite being in the same range as natural examples) do not precisely reproduce these minerals\u0026apos; decrease in Li concentration with increasing temperature. This imprecise prediction of the temperature dependence of cordierite and biotite Li concentrations was expected since the natural Kd values used are constants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOpen questions: Which physicochemical parameters affect Li behaviour during metapelite melting?\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAs highlighted throughout our study, the available sets of partition coefficients indicate that different melting reactions will mobilise Li (Figs. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e, \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e), and the comparison of natural and modelled trends does not unequivocally indicate which model better represents nature. Hence, there is currently no comprehensive reasoning as to whether experimental or natural partition coefficients better represent nature. These two sets of contrasting partition coefficient values imply that Li behaviour is influenced by unknown factors.\u003c/p\u003e\n\u003cp\u003eTo further assess which set of Kd values better represents nature and what explains their contrasting values, we compared the parameters associated with natural migmatites and experimentally and naturally derived Li distribution coefficients. It is important to note that such a comparison is not straightforward since there are key differences between these systems (Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e). Experiments are closed systems composed of minerals and glass produced in weeks and quenched at specific P-T conditions. The El Hoyazo enclaves are composed of minerals and melt/glass inclusions produced on a geological timescale and then rapidly frozen due to their entrainment in a volcanic system; thus, these show melt-producing followed by melt-consuming reactions (Kriegsman \u0026amp; \u0026Aacute;lvarez-Valero 2010). The partial melting of metapelites is an open system, in which we only have access to restitic minerals and minerals crystallised from the remaining melt (leucosome), which likely underwent retrograde reactions and/or back-reaction with melt during cooling and exhumation. Nevertheless, although not ideal, this comparison highlights key differences between physicochemical parameters known to affect partition coefficients and that possibly explain why experimental and natural distribution coefficients don\u0026rsquo;t match.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLi has high diffusion rates\u003c/strong\u003e. Experiments are quenched at specific P-T conditions, hence, they might record precise equilibrium distribution coefficients, while migmatites and volcanic rocks (and xenoliths as at El Hoyazo) cool over geological timescales during which Li concentrations may re-equilibrate (e.g., Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e of Marschall \u0026amp; Tang, 2020). Therefore, the natural distribution coefficients may reflect post-peak re-equilibration rather than equilibrium under peak conditions. However, this explanation is dependent on future studies to show/explain the change of preference of Li for biotite over cordierite during melting (as in the experiment) and then for cordierite over biotite during cooling (as in natural examples).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe experimental system and mineral compositions are different from the average pelite\u003c/strong\u003e (Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e and Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). The experimental starting compositions (Icenhower and London, 1995; Evensen and London, 2002; 2003) contain lower Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, TiO\u003csub\u003e2\u003c/sub\u003e or FeO compared with the average pelite (Forshaw \u0026amp; Pattison, 2023) and the samples investigated here (Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e.D). The bulk composition affects the stability fields of the main metamorphic phases. This is clearly illustrated by the X\u003csub\u003eMg\u003c/sub\u003e of cordierite. In experiments, X\u003csub\u003eMg\u003c/sub\u003e varies from 68.7 to 85% from 700 to 850\u0026deg;C. In contrast, among our novel cordierite analysis, only one sample formed at T\u0026thinsp;\u0026gt;\u0026thinsp;800\u0026deg;C reached similar values (71\u0026ndash;75%); and among compiled cordierite analysis, only samples with known distinct bulk rock compositions display X\u003csub\u003eMg\u003c/sub\u003e \u0026ge; 0.7 at lower temperatures (Visser et al., 1994). Based on the pseudosections calculated for the samples of this study and those of White et al. (2014), higher X\u003csub\u003eMg\u003c/sub\u003e only occur at temperatures higher than 780\u0026deg;C. Hence, although the experiments run at temperatures of 700 to 850\u0026deg;C (Evensen and London, 2002; 2003), their cordierite compositions resemble higher temperature cordierites or cordierites formed with protoliths with higher X\u003csub\u003eMg\u003c/sub\u003e. Similarly, biotite compositions of the experiment (X\u003csub\u003eMg\u003c/sub\u003e=69\u0026ndash;72%)occur only at the pseudosections at temperatures of around 850\u0026deg; C. Therefore, the different system and mineral compositions may affect Li partitioning.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe experimental water content (10 wt. %) is different from the composition and conditions that most migmatites experienced during their formation\u003c/strong\u003e (Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). Higher water contents lower the solidus, increase melt volumes, change melt composition, and \u0026ndash; in combination with lower water solubility in melts at lower pressures \u0026ndash; may generate water-saturated melts (Holtz \u0026amp; Johannes, 1994; Weinberg \u0026amp; Hasalov\u0026aacute;, 2015). In fact, Evensen and London (2003) mention that the experiments are water-saturated and may or may not apply to water-undersaturated melts. Three key arguments support the hypothesis that Li distribution coefficients vary depending on the melt H\u003csub\u003e2\u003c/sub\u003eO contents. Firstly, the melt water-contents are positively correlated with Na\u003csub\u003e2\u003c/sub\u003eO in the melt (Holtz \u0026amp; Johannes, 1991), and \u0026ndash; as discussed previously \u0026ndash; Na and Li are intrinsically connected during cordierite substitution mechanisms. Hence, more water will generate melts with higher Na concentrations, which means there will be less Na available for the substitution mechanism of Li in cordierite. For comparison, the melt Na/K composition in Evensen and London (2002; 2003) lies between 0.83\u0026ndash;1.19, while the Na/K of the El Hoyazo melt inclusions are 0.57\u0026ndash;0.72 (Acosta-Vigil et al., 2007). Moreover, extra Na in hydrous melt shouldn\u0026rsquo;t affect Li in biotite in the way that it would affect cordierite since Li substitution mechanisms in biotite do not involve Na (e.g., substitution mechanisms in Breiter et al., 2017). Secondly, the increase in water has been shown to increase Li diffusion in silicic melts by one order of magnitude since it reduces melt polymerisation, which provides more pathways for Li diffusion (Troch et al., 2024). Hence, it is not unrealistic to expect higher water content melts to accommodate more Li. Thirdly, the water content of experimental charges is so high (10 wt. % + the water contained in micas) that there must be free H\u003csub\u003e2\u003c/sub\u003eO present even above the solidus, which implies that some Li might have been dissolved in the supercritical fluid.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe F content of experiment charges is higher than most pelitic migmatites\u003c/strong\u003e (Fig. \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e). The experimental starting compositions used biotite with 3.67 wt.% fluorine. However, fluorine concentrations in natural biotite from metapelites have been shown to be generally lower than 1 wt. % until the onset of biotite dehydration melting around 750\u0026deg;C, and then increasing with increasing temperatures (Finch \u0026amp; Tomkins, 2017; Kunz et al., 2022). The fluorine in the biotite affects the resulting melt chemistry; for example, experimental glasses have 0.18 to 0.29 wt.% F (Evensen and London, 2002; 2003); whilst the El Hoyazo melt inclusions average F concentrations range from 0.06\u0026ndash;0.08 wt.% (Acosta-Vigil et al., 2007). Although there is no direct research that shows higher fluorine contents in the melt will increase lithium solubility, fluorine is likely to affect the D\u003csup\u003eLi\u003c/sup\u003e\u003csub\u003emineral/melt\u003c/sub\u003e since it is known to enhance depolymerisation through fluorine complexes (e.g., Giordano et al., 2004), which can involve Li (Shchekina et al., 2020).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab4\" border=\"1\" class=\"fr-table-selection-hover\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison of system composition in average pelites, El Hoyazo migmatitic xenoliths and experiments.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOxide\u003c/p\u003e\n \u003cp\u003e(wt. %)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAverage metapelite (Forshaw \u0026amp; Pattison, 2023)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWhite et al., (2014)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eEl Hoyazo (Bartoli, 2017)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eSP-Crd1-C and SP-Crd2-C (Evensen and London, 2002; 2003)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e4\u0026ndash;8 (Icenhower and London, 1995)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60.47\u0026ndash;70.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e57.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45.37\u0026ndash;54.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e59.37\u0026ndash;61.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e49.85\u0026ndash;58.37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.60\u0026ndash;1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.94\u0026ndash;1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.31\u0026thinsp;\u0026minus;\u0026thinsp;0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.19\u0026ndash;0.51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.87\u0026ndash;21.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.87\u0026ndash;29.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e13.40-12.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e18.89\u0026ndash;21.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.42\u0026ndash;0.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.00-0.63\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFeO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.61\u0026ndash;7.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.89\u0026ndash;13.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e5.16\u0026ndash;3.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e1.21\u0026ndash;3.39\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMnO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.05\u0026ndash;0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.17\u0026ndash;0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.09\u0026ndash;0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMgO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.89\u0026ndash;3.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.38\u0026ndash;2.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e3.31\u0026ndash;2.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.34\u0026ndash;2.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCaO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.23\u0026ndash;0.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.66\u0026ndash;2.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.77\u0026thinsp;\u0026minus;\u0026thinsp;0.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.01\u0026ndash;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.05\u0026ndash;2.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.68\u0026ndash;2.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e2.62\u0026ndash;3.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e1.62\u0026ndash;3.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eK\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.38\u0026ndash;4.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.48\u0026ndash;3.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e3.38\u0026ndash;3.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e4.67\u0026ndash;6.31\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.39\u0026ndash;2.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e10.68\u0026ndash;10.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e11.36\u0026ndash;11.95\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.41\u0026thinsp;\u0026minus;\u0026thinsp;0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.57\u0026ndash;1.81\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"CONCLUSIONS AND FINAL REMARKS","content":"\u003cp\u003eThis study provides new insights into lithium (Li) mobilisation during metapelite melting by combining novel and compiled \u003cem\u003ein-situ\u003c/em\u003e mineral chemistry data, temperature estimates, and trace element modelling at suprasolidus pressure-temperature conditions. Our findings highlight the following key insights and open questions in understanding Li behaviour in migmatitic systems:\u003c/p\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eLithium concentrations in biotite and muscovite in migmatites confirm previous suggestions that concentrations in micas are temperature-dependent. Our new data suggest that Li concentrations in cordierite are also temperature dependent.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eThe decrease in Li concentrations in cordierite with increasing temperature matches previous experimental results and is expected since the substitution mechanism of Li in cordierite involves Na, and concentrations of Na in cordierite are already known to be temperature dependent.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eContrasting Li concentrations in the melt are predicted depending on the partition coefficients used in the calculations. Models using experimentally derived coefficient values predict higher Li concentrations in melts generated from biotite-dehydration melting reactions. Models based on naturally-derived partition coefficients suggest that lower temperature melts are the most enriched, and the effect of cordierite is more pronounced.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eThe comparison of natural and modelled mineral trends highlights that neither model perfectly reproduces the natural distribution of Li in minerals and melts. Experimental partition coefficients reproduce biotite trends but underestimate Li concentrations in cordierite and overestimate those in muscovite. In contrast, partition coefficients derived empirically maintain mineral/mineral distribution coefficients similar to those in nature but fail to reproduce temperature-varying Li concentrations in biotite and cordierite due to the lack of partition coefficient data constrained at a range of temperatures.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eBased on the comparison of parameters associated with pelitic migmatites and the experimental and natural partition coefficients, we identified that Li diffusion during cooling, different system and mineral compositions, and water and fluorine contents may explain the contrasting Li behaviours observed.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003cp\u003eOverall, this study highlights the importance of integrating natural observations, experimental data, and modelling to track trace element behaviour during metapelite melting and assess if/which models are most representative of natural systems. It is clear from the lack of consistency between natural and modelled trends that further studies are essential to refine petrogenetic models for Li-rich granitoids and pegmatites and, ultimately, to support more effective exploration strategies for unconventional Li resources.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eFunding: We acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie [grant agreement No. 956125] for E.O.C.’s PhD as part of the Innovative Training Network “FluidNET”. N.R. acknowledges the German Research Foundation (DFG) (project number 521637679) and the ERC (Consolidator Grant no. 771143).\u003c/p\u003e\n\u003cp\u003eConflicts of interest/Competing interests (include appropriate disclosures): The authors declare that they have no conflict of interest.\u003c/p\u003e\n\u003cp\u003eAvailability of data and material: The online version of this article contains supplementary material, which is available to authorised users.\u003c/p\u003e\n\u003cp\u003eCode availability: The version of the software used to produce the equilibrium thermodynamics calculations are available on Zenodo at MAGEMin v1.7.6: https://zenodo.org/records/15619738, MAGEMin_C v1.8.7: https://zenodo.org/records/15699695 and MAGEMinApp v0.9.2: (link will be available soon).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eACKNOWLEDGMENTS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe acknowledge Michelle Higgins and Kay Knight for their help with sample preparation at The Open University, Giulia Degli-Alessandrini with the scanning electron microscope and electron probe microanalysis at The Open University, and Eric Hellebrand for all his help with electron probe microanalysis at the University of Utrecht. Also, we thank J. Blundy and M. Brown for sharing data and samples, respectively. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAUTHOR CONTRIBUTIONS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eElisa Oliveira da Costa: \u003c/strong\u003eConceptualisation, Methodology, Investigation, Formal Analyses, Data Curation, Writing – Original Draft, Visualisation. \u003cstrong\u003eIna Alt:\u003c/strong\u003e Formal Analyses, Writing – Review and Editing. \u003cstrong\u003eTom Argles: \u003c/strong\u003eWriting – Review and Editing, Supervision. \u003cstrong\u003eSander Bas Hoogendoorn:\u003c/strong\u003e Formal Analyses, Writing – Review and Editing. \u003cstrong\u003eLeo Kriegsman:\u003c/strong\u003e Validation, Methodology, Data Curation, Writing – Review and Editing, Supervision. \u003cstrong\u003eBarbara Kunz:\u003c/strong\u003e Methodology, Resources, Validation, Writing – Review and Editing, Supervision. \u003cstrong\u003eNicolas Riel: \u003c/strong\u003eMethodology, Validation, Writing – Review and Editing. \u003cstrong\u003eClare Warren:\u003c/strong\u003e Writing – Review and Editing, Supervision, Project administration, Funding acquisition. \u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAcosta-Vigil A, Buick I, Cesare B, London D, Morgan GB (2012) The Extent of Equilibration between Melt and Residuum during Regional Anatexis and its Implications for Differentiation of the Continental Crust: A Study of Partially Melted Metapelitic Enclaves. J Petrol 53(7):1319\u0026ndash;1356. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/PETROLOGY/EGS018\u003c/span\u003e\u003cspan address=\"10.1093/PETROLOGY/EGS018\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAcosta-Vigil A, Cesare B, London D, Morgan GB (2007) Microstructures and composition of melt inclusions in a crustal anatectic environment, represented by metapelitic enclaves within El Hoyazo dacites, SE Spain. Chem Geol 237(3\u0026ndash;4):450\u0026ndash;465. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.CHEMGEO.2006.07.014\u003c/span\u003e\u003cspan address=\"10.1016/J.CHEMGEO.2006.07.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eArmbruster T, Irouschek A (1983) Cordierites from the Lepontine Alps: Na\u0026thinsp;+\u0026thinsp;Be \u0026rarr; Al substitution, gas content, cell parameters, and optics. Contrib Miner Petrol 82(4):389\u0026ndash;396. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00399715/METRICS\u003c/span\u003e\u003cspan address=\"10.1007/BF00399715/METRICS\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBallouard C, Couzini\u0026eacute; S, Bouilhol P, Harlaux M, Mercadier J, Montel JM (2024) A felsic meta-igneous source for Li-F-rich peraluminous granites: Insights from the Variscan Velay dome (French Massif Central) and implications for rare-metal magmatism. Contrib Miner Petrol 178(11):75\u0026ndash;75. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00410-023-02057-1\u003c/span\u003e\u003cspan address=\"10.1007/s00410-023-02057-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBartoli O (2017) Phase equilibria modelling of residual migmatites and granulites: An evaluation of the melt-reintegration approach. J Metamorph Geol 35(8):919\u0026ndash;942. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi-org.libezproxy.open.ac.uk/\u003c/span\u003e\u003cspan address=\"https://doi-org.libezproxy.open.ac.uk/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/jmg.12261\u003c/span\u003e\u003cspan address=\"10.1111/jmg.12261\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBauer DJ, Khazdozian H, Mehta J, Nguyen RT, Severson MH, Vaagensmith BC, Toba L, Zhang B, Hossain T, Sibal AP, Smith BJ, Riddle ME, Graziano DJ, Mathew T, Cuscaden P, Dai Q, Iloeje C, Edgemon L, Sarna C, Quaresima J (2023) \u003cem\u003e2023 Critical Materials Strategy\u003c/em\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2172/1998242\u003c/span\u003e\u003cspan address=\"10.2172/1998242\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBea F, Pereira MD, Stroh A (1994) Mineral/leucosome trace-element partitioning in a peraluminous migmatite (a laser ablation-ICP-MS study). Chem Geol 117(1\u0026ndash;4):291\u0026ndash;312. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0009-2541(94)90133-3\u003c/span\u003e\u003cspan address=\"10.1016/0009-2541(94)90133-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBertoldi C, Proyer A, Garbe-Sch\u0026ouml;nberg D, Behrens H, Dachs E (2004) Comprehensive chemical analyses of natural cordierites: Implications for exchange mechanisms. Lithos 78(4):389\u0026ndash;409. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.LITHOS.2004.07.003\u003c/span\u003e\u003cspan address=\"10.1016/J.LITHOS.2004.07.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBowell RJ, Lagos L, de los Hoyos CR, Declercq J (2020) Classification and Characteristics of Natural Lithium Resources. Elements 16(4):259\u0026ndash;264. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2138/GSELEMENTS.16.4.259\u003c/span\u003e\u003cspan address=\"10.2138/GSELEMENTS.16.4.259\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBreiter K, Vaňkov\u0026aacute; M, Galiov\u0026aacute; MV, Korbelov\u0026aacute; Z, Kanick\u0026yacute; V (2017) Lithium and trace-element concentrations in trioctahedral micas from granites of different geochemical types measured via laser ablation ICP-MS. Mineral Mag 81(1):15\u0026ndash;33. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1180/MINMAG.2016.080.137\u003c/span\u003e\u003cspan address=\"10.1180/MINMAG.2016.080.137\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eČern\u0026yacute; P (1991) Fertile granites of Precambrian rare-element pegmatite fields: Is geochemistry controlled by tectonic setting or source lithologies? Precambrian Res 51(1\u0026ndash;4):429\u0026ndash;468. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0301-9268(91)90111-M\u003c/span\u003e\u003cspan address=\"10.1016/0301-9268(91)90111-M\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eČern\u0026yacute; P, Blevin PL, Cuney M, London D (2005) Granite-Related Ore Deposits. In J. W. Hedenquist, J. F. H. Thompson, R. J. Goldfarb, \u0026amp; J. P. Richards (Eds.), \u003cem\u003eOne Hundredth Anniversary Volume\u003c/em\u003e (p. 0). Society of Economic Geologists. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5382/AV100.12\u003c/span\u003e\u003cspan address=\"10.5382/AV100.12\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDahl PS, Wehn DC, Feldmann SG, Dahl PS, Wehn DC, Feldmann SG (1993) The systematics of trace-element partitioning between coexisting muscovite and biotite in metamorphic rocks from the Black Hills, South Dakota, USA. GeCoA 57(11):2487\u0026ndash;2505. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0016-7037(93)90412-P\u003c/span\u003e\u003cspan address=\"10.1016/0016-7037(93)90412-P\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDing J-F, Zhang Y-T, Xu R, Zhang R, Xiao Y, Zhang S, Bi C-X, Tang C, Xiang R, Park HS, Zhang Q, Huang J-Q (2023) Review on lithium metal anodes towards high energy density batteries. Green Energy Environ 8(6):1509\u0026ndash;1530. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gee.2022.08.002\u003c/span\u003e\u003cspan address=\"10.1016/j.gee.2022.08.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDutrow BL, Holdaway MJ, Hinton RW (1986) Lithium in staurolite and its petrologic significance. Contrib Miner Petrol 94(4):496\u0026ndash;506. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00376341/METRICS\u003c/span\u003e\u003cspan address=\"10.1007/BF00376341/METRICS\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEvensen JM, London D (2002) Experimental silicate mineral/melt partition coefficients for beryllium and the crustal Be cycle from migmatite to pegmatite. Geochim Cosmochim Acta 66(12):2239\u0026ndash;2265. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0016-7037(02)00889-X\u003c/span\u003e\u003cspan address=\"10.1016/S0016-7037(02)00889-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEvensen JM, London D (2003) Experimental partitioning of Be, Cs, and other trace elements between cordierite and felsic melt, and the chemical signature of S-type granite. Contrib Miner Petrol 2003 144:6(6):739\u0026ndash;757. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/S00410-002-0426-X\u003c/span\u003e\u003cspan address=\"10.1007/S00410-002-0426-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. \u003cem\u003e144\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFerry JM (1979) Reaction mechanisms, physical conditions, and mass transfer during hydrothermal alteration of mica and feldspar in granitic rocks from south-central Maine, USA. Contrib Miner Petrol 68(2):125\u0026ndash;139. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00371895\u003c/span\u003e\u003cspan address=\"10.1007/BF00371895\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFinch EG, Tomkins AG (2017) Fluorine and chlorine behaviour during progressive dehydration melting: Consequences for granite geochemistry and metallogeny. J Metamorph Geol 35(7):739\u0026ndash;757. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/JMG.12253\u003c/span\u003e\u003cspan address=\"10.1111/JMG.12253\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eForshaw JB, Pattison DRM (2023) Major-element geochemistry of pelites. Geology 51(1):39\u0026ndash;43. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1130/G50542.1\u003c/span\u003e\u003cspan address=\"10.1130/G50542.1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGardiner NJ, Palin RM, Koopmans L, Mangler MF, Robb LJ (2024) On tin and lithium granite systems: A crustal evolution perspective. Earth Sci Rev 258:104947. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.earscirev.2024.104947\u003c/span\u003e\u003cspan address=\"10.1016/j.earscirev.2024.104947\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGiordano D, Romano C, Dingwell DB, Poe B, Behrens H (2004) The combined effects of water and fluorine on the viscosity of silicic magmas. Geochim Cosmochim Acta 68(24):5159\u0026ndash;5168. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.GCA.2004.08.012\u003c/span\u003e\u003cspan address=\"10.1016/J.GCA.2004.08.012\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGrohol M, Veeh C (2023) \u003cem\u003eStudy on the critical raw materials for the EU 2023\u0026mdash;Final report\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHoltz FO, Johannes W (1991) Genesis of Peraluminous Granites I. Experimental Investigation of Melt Compositions at 3 and 5 kb and Various H2O Activities. J Petrol 32(5):935\u0026ndash;958. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/petrology/32.5.935\u003c/span\u003e\u003cspan address=\"10.1093/petrology/32.5.935\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHoltz F, Johannes W (1994) Maximum and minimum water contents of granitic melts: Implications for chemical and physical properties of ascending magmas. Lithos 32(1\u0026ndash;2):149\u0026ndash;159. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0024-4937(94)90027-2\u003c/span\u003e\u003cspan address=\"10.1016/0024-4937(94)90027-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHoogendoorn SB (2024) \u003cem\u003eArgon Mobility in the Mid-Lower Continental Crust: Insights from the Agly Massif and El Hoyazo\u003c/em\u003e. Doctor of Philosophy (PhD) thesis The Open University. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.21954/ou.ro.00102127\u003c/span\u003e\u003cspan address=\"10.21954/ou.ro.00102127\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHund K, La Porta D, Fabregas TP, Laing T, Drexhage J (2019) \u003cem\u003eMinerals for Climate Action: The Mineral Intensity of the Clean Energy Transition\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eIcenhower J, London D (1995) An experimental study of element partitioning among biotite, muscovite, and coexisting peraluminous silicic melt at 200 MPa (H2O). Am Mineral 80(11\u0026ndash;12):1229\u0026ndash;1251. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2138/AM-1995-11-1213\u003c/span\u003e\u003cspan address=\"10.2138/AM-1995-11-1213\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJohnson T, Brown M (2004) Quantitative Constraints on Metamorphism in the Variscides of Southern Brittany\u0026mdash;A Complementary Pseudosection Approach. J Petrol 45(6):1237\u0026ndash;1259. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/PETROLOGY/EGH012\u003c/span\u003e\u003cspan address=\"10.1093/PETROLOGY/EGH012\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJosso P, Lusty P, Gunn A, Shaw R, Singh N, Horn S, Petavratzi E (2023) \u003cem\u003eReview and development of the methodology and data used to produce the UK Criticality Assessment of Technology-critical Minerals\u003c/em\u003e (pp. 1\u0026ndash;93)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKalt A, Altherr R, Ludwig T (1998) Contact Metamorphism in Pelitic Rocks on the Island of Kos (Greece, Eastern Aegean Sea): A Test for the Na-in-Cordierite Thermometer. J Petrol 39(4):663\u0026ndash;688. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/PETROJ/39.4.663\u003c/span\u003e\u003cspan address=\"10.1093/PETROJ/39.4.663\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKesler SE, Gruber PW, Medina PA, Keoleian GA, Everson MP, Wallington TJ (2012) Global lithium resources: Relative importance of pegmatite, brine and other deposits. Ore Geol Rev 48:55\u0026ndash;69. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.oregeorev.2012.05.006\u003c/span\u003e\u003cspan address=\"10.1016/j.oregeorev.2012.05.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKnop E, Mirwald PW (1998) Sodic cordierites: comparison of natural data and incorporation experiments. Mitteilungen der \u0026Ouml;sterreichischen Mineralogischen Gesellschaft 143:316\u0026ndash;321\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKriegsman LM, \u0026Aacute;lvarez-Valero AM (2010) Melt-producing versus melt-consuming reactions in pelitic xenoliths and migmatites. Lithos 116:310\u0026ndash;320. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.lithos.2009.09.001\u003c/span\u003e\u003cspan address=\"10.1016/j.lithos.2009.09.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKoopmans L, Martins T, Linnen R, Gardiner NJ, Breasley CM, Palin RM, Groat LA, Silva D, Robb LJ (2024) The formation of lithium-rich pegmatites through multi-stage melting. Geology 52(1):7\u0026ndash;11. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1130/G51633.1\u003c/span\u003e\u003cspan address=\"10.1130/G51633.1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKunz B, Warren C, Jenner F, Harris N, Argles T (2022) Critical metal enrichment in crustal melts: The role of metamorphic mica. \u003cem\u003eGeology\u003c/em\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://oro.open.ac.uk/83598/\u003c/span\u003e\u003cspan address=\"http://oro.open.ac.uk/83598/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLindagato P, Li Y, Mach\u0026aacute;ček J, Yang G, Mungwarakarama I, Ndahimana A, Ntwali HPK (2023) Lithium Metal: The Key to Green Transportation. Appl Sci 13(1). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003eArticle 1. https://doi.org/10.3390/app13010405\u003c/span\u003e\u003cspan address=\"Article 1. 10.3390/app13010405\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLondon D (2018) Ore-forming processes within granitic pegmatites. Ore Geol Rev 101:349\u0026ndash;383. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.OREGEOREV.2018.04.020\u003c/span\u003e\u003cspan address=\"10.1016/J.OREGEOREV.2018.04.020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLuvizotto GL, Zack T, Meyer HP, Ludwig T, Triebold S, Kronz A, M\u0026uuml;nker C, Stockli DF, Prowatke S, Klemme S, Jacob DE, von Eynatten H (2009) Rutile crystals as potential trace element and isotope mineral standards for microanalysis. Chem Geol 261(3\u0026ndash;4):346\u0026ndash;369. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.CHEMGEO.2008.04.012\u003c/span\u003e\u003cspan address=\"10.1016/J.CHEMGEO.2008.04.012\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMalcherek T, Domeneghetti MC, Tazzali V, Ottolini L, McCammon C, Carpenter MA (2001) Structural properties of ferromagnesian cordierites. Am Mineral 86(1\u0026ndash;2):66\u0026ndash;79. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2138/AM-2001-0108\u003c/span\u003e\u003cspan address=\"10.2138/AM-2001-0108\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMarschall HR, Tang M (2020) High-temperature processes: is it time for lithium isotopes? Elements: Int Magazine Mineralogy Geochem Petrol 16(4):247\u0026ndash;252. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi-org.libezproxy.open.ac.uk/\u003c/span\u003e\u003cspan address=\"https://doi-org.libezproxy.open.ac.uk/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.2138/gselements.16.4.247\u003c/span\u003e\u003cspan address=\"10.2138/gselements.16.4.247\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMirwald PW (1986) Ist Cordierit ein Geothermometer? Fortschr Mineral 64:113\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eM\u0026uuml;ller A, Romer RL, Pedersen R-B (2017) The Sveconorwegian Pegmatite Province \u0026ndash; Thousands of Pegmatites Without Parental Granites. Can Mineral 55(2):283\u0026ndash;315. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3749/canmin.1600075\u003c/span\u003e\u003cspan address=\"10.3749/canmin.1600075\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOldman CJ (2023) \u003cem\u003eThe Formation and Age of Leucogranitic Melt in the Garhwal Himalaya\u003c/em\u003e. PhD thesis The Open University. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.21954/ou.ro.00016216\u003c/span\u003e\u003cspan address=\"10.21954/ou.ro.00016216\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePati\u0026ntilde;o-Douce AEP (1993) Titanium substitution in biotite: An empirical model with applications to thermometry, O2 and H2O barometries, and consequences for biotite stability. Chem Geol 108(1):133\u0026ndash;162. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0009-2541(93)90321-9\u003c/span\u003e\u003cspan address=\"10.1016/0009-2541(93)90321-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePaton C, Hellstrom J, Paul B, Woodhead J, Hergt J (2011) Iolite: Freeware for the visualisation and processing of mass spectrometric data. J Anal At Spectrom 26(12):2508\u0026ndash;2518. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1039/C1JA10172B\u003c/span\u003e\u003cspan address=\"10.1039/C1JA10172B\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePeng H, Li Y, Shangguan L, Li S, Zhang N (2024) Research on the optimization of tribological performance of wind power lubricating grease based on carbon emission. J Eng Res. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.JER.2024.05.022\u003c/span\u003e\u003cspan address=\"10.1016/J.JER.2024.05.022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePhillips S (2021) \u003cem\u003eThe Petrogenesis of Kyanite Migmatites in Eastern Bhutan\u003c/em\u003e. PhD thesis The Open University. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://oro.open.ac.uk/74774/\u003c/span\u003e\u003cspan address=\"https://oro.open.ac.uk/74774/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRiel N, Kaus BJP, Green ECR, Berlie N (2022) MAGEMin, an Efficient Gibbs Energy Minimizer: Application to Igneous Systems. \u003cem\u003eGeochemistry, Geophysics, Geosystems\u003c/em\u003e, \u003cem\u003e23\u003c/em\u003e(7), e2022GC010427. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1029/2022GC010427\u003c/span\u003e\u003cspan address=\"10.1029/2022GC010427\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRomer RL, Kroner U (2015) Sediment and weathering control on the distribution of Paleozoic magmatic tin\u0026ndash;tungsten mineralization. Miner Deposita 50:327\u0026ndash;338. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi-org.libezproxy.open.ac.uk/\u003c/span\u003e\u003cspan address=\"https://doi-org.libezproxy.open.ac.uk/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00126-014-0540-5\u003c/span\u003e\u003cspan address=\"10.1007/s00126-014-0540-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRomer RL, Kroner U (2016) Phanerozoic tin and tungsten mineralization\u0026mdash;Tectonic controls on the distribution of enriched protoliths and heat sources for crustal melting. Gondwana Res 31:60\u0026ndash;95. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi-org.libezproxy.open.ac.uk/\u003c/span\u003e\u003cspan address=\"https://doi-org.libezproxy.open.ac.uk/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00126-014-0540-5\u003c/span\u003e\u003cspan address=\"10.1007/s00126-014-0540-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRosenberg CL, Handy MR (2005) Experimental deformation of partially melted granite revisited: implications for the continental crust. J Metamorph Geol 23(1):19\u0026ndash;28. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi-org.libezproxy.open.ac.uk/\u003c/span\u003e\u003cspan address=\"https://doi-org.libezproxy.open.ac.uk/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/j.1525-1314.2005.00555.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1525-1314.2005.00555.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRudnick RL, Gao S (2014) Composition of the Continental Crust. In \u003cem\u003eTreatise on Geochemistry\u003c/em\u003e (pp. 1\u0026ndash;51). Elsevier. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/B978-0-08-095975-7.00301-6\u003c/span\u003e\u003cspan address=\"10.1016/B978-0-08-095975-7.00301-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSchreyer W (1985) Experimental studies on cation substitutions and fluid incorporation in cordierite. Bull Min\u0026Atilde;\u0026copy;ral 108(3):273\u0026ndash;291. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3406/BULMI.1985.7829\u003c/span\u003e\u003cspan address=\"10.3406/BULMI.1985.7829\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShaw DM (1970) Trace element fractionation during anatexis. Geochim Cosmochim Acta 34(2):237\u0026ndash;243. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0016-7037(70)90009-8\u003c/span\u003e\u003cspan address=\"10.1016/0016-7037(70)90009-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShaw RA, Goodenough KM, Roberts NMW, Horstwood MSA, Chenery SR, Gunn AG (2016) Petrogenesis of rare-metal pegmatites in high-grade metamorphic terranes: A case study from the Lewisian Gneiss Complex of north-west Scotland. Precambrian Res 281:338\u0026ndash;362. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.precamres.2016.06.008\u003c/span\u003e\u003cspan address=\"10.1016/j.precamres.2016.06.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShchekina TI, Rusak AA, Alferyeva YO, Gramenitskiy EN, Kotelnikov AR, Zinovieva NG, Bychkov AY, Bychkova YV, Khvostikov VA (2020) REE, Y, Sc, and Li Partition between Aluminosilicate and Aluminofluoride Melts, Depending on Pressure and Water Content in the Model Granite System. Geochem Int 58(4):391\u0026ndash;407. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1134/S0016702920040102/FIGURES/8\u003c/span\u003e\u003cspan address=\"10.1134/S0016702920040102/FIGURES/8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSilva MA (2014) \u003cem\u003ePetrogenesis of a variscan migmatite complex (NW Portugal): Petrography, geochemistry and fluids\u003c/em\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.proquest.com/docview/1914879078?pq-origsite=gscholar\u0026amp;fromopenview=true\u003c/span\u003e\u003cspan address=\"https://www.proquest.com/docview/1914879078?pq-origsite=gscholar\u0026amp;fromopenview=true\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSimons B, Andersen JC\u0026Oslash;, Shail RK, Jenner FE (2017) Fractionation of Li, Be, Ga, Nb, Ta, In, Sn, Sb, W and Bi in the peraluminous Early Permian Variscan granites of the Cornubian Batholith: Precursor processes to magmatic-hydrothermal mineralisation. \u003cem\u003eLithos\u003c/em\u003e, \u003cem\u003e278\u0026ndash;281\u003c/em\u003e, 491\u0026ndash;512. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.LITHOS.2017.02.007\u003c/span\u003e\u003cspan address=\"10.1016/J.LITHOS.2017.02.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSiron G, Goncalves P, Marquer D, Pierre T, Paquette J-L, Vanardois J (2020) Contribution of magmatism, partial melting buffering and localized crustal thinning on the late Variscan thermal structure of the Agly massif (French Pyrenees). J Metamorph Geol 38(8):799\u0026ndash;829. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/JMG.12549\u003c/span\u003e\u003cspan address=\"10.1111/JMG.12549\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStepanov AS (2021) A review of the geochemical changes occurring during metamorphic devolatilization of metasedimentary rocks. Chem Geol 568:120080\u0026ndash;120080. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.CHEMGEO.2021.120080\u003c/span\u003e\u003cspan address=\"10.1016/J.CHEMGEO.2021.120080\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTajčmanov\u0026aacute; L, Connolly JAD, Cesare B (2009) A thermodynamic model for titanium and ferric iron solution in biotite. J Metamorph Geol 27(2):153\u0026ndash;165. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1525-1314.2009.00812.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1525-1314.2009.00812.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTroch J, Huber C, Kueter N, Guillong M, Ackerson M, Ulmer P, Bachmann O (2024) The effect of water on alkali trace element diffusion (Li, Rb, Cs) in silicic melts. Geochim Cosmochim Acta 365:101\u0026ndash;113. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.GCA.2023.11.031\u003c/span\u003e\u003cspan address=\"10.1016/J.GCA.2023.11.031\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTropper P, Wyhlidal S, Haefeker UA, Mirwald PW (2018) An experimental investigation of Na incorporation in cordierite in low P/high T metapelites. Mineral Petrol 112(2):199\u0026ndash;217. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/S00710-017-0522-2/FIGURES/11\u003c/span\u003e\u003cspan address=\"10.1007/S00710-017-0522-2/FIGURES/11\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVisser D, Kloprogge JT, Maijer C (1994) An infrared spectroscopic (IR) and light element (Li, Be, Na) study of cordierites from the Bamble Sector, South Norway. Lithos 32(1\u0026ndash;2):95\u0026ndash;107. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0024-4937(94)90023-X\u003c/span\u003e\u003cspan address=\"10.1016/0024-4937(94)90023-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWeinberg RF, Hasalov\u0026aacute; P (2015) Water-fluxed melting of the continental crust: A review. \u003cem\u003eLithos\u003c/em\u003e, \u003cem\u003e212\u0026ndash;215\u003c/em\u003e, 158\u0026ndash;188. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.LITHOS.2014.08.021\u003c/span\u003e\u003cspan address=\"10.1016/J.LITHOS.2014.08.021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWhite RW, Powell R, Holland TJB, Johnson TE, Green ECR (2014) New mineral activity\u0026ndash;composition relations for thermodynamic calculations in metapelitic systems. J Metamorph Geol 32(3):261\u0026ndash;286. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003eorg.libezproxy.open.ac.uk/\u003c/span\u003e\u003cspan address=\"http://org.libezproxy.open.ac.uk/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/jmg.12071\u003c/span\u003e\u003cspan address=\"10.1111/jmg.12071\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYang P, Rivers T (2000) Trace element partitioning between coexisting biotite and muscovite from metamorphic rocks, Western Labrador: Structural, compositional and thermal controls. Geochim Cosmochim Acta 64(8):1451\u0026ndash;1472. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0016-7037(99)00425-1\u003c/span\u003e\u003cspan address=\"10.1016/S0016-7037(99)00425-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eŽ\u0026aacute;k J, Verner K, Finger F, Faryad SW, Chlup\u0026aacute;cov\u0026aacute; M, Veselovskỳ F (2011) The generation of voluminous S-type granites in the Moldanubian unit, Bohemian Massif, by rapid isothermal exhumation of the metapelitic middle crust. Lithos 121(1\u0026ndash;4):25\u0026ndash;40. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.LITHOS.2010.10.002\u003c/span\u003e\u003cspan address=\"10.1016/J.LITHOS.2010.10.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang X, Li Z, Luo L, Fan Y, Du Z (2022) A review on thermal management of lithium-ion batteries for electric vehicles. Energy 238:121652\u0026ndash;121652. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/J.ENERGY.2021.121652\u003c/span\u003e\u003cspan address=\"10.1016/J.ENERGY.2021.121652\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"The Open University","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Migmatites, LA-ICP-MS, MAGEMin, Phase equilibria modelling, Trace element modelling","lastPublishedDoi":"10.21203/rs.3.rs-7104523/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7104523/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe growing demand for Lithium \u0026ndash; due to its use in modern economies and green energy \u0026ndash; is prompting closer examination of all geological processes that control Li mobilisation. For example, while studies on the genesis of enriched peraluminous granitoids and pegmatites have traditionally focused on the final magmatic-hydrothermal stages of enrichment, recent studies have addressed how the preceding metapelite melting stage controls Li mobilisation. However, these studies employed different partition coefficients to estimate Li fluxes and thus predict contrasting Li behaviour. In this study, we investigate Li mobilisation during metapelite melting by comparing experimental and natural examples (starting compositions, partition coefficients and in-situ mineral concentrations) with equilibrium melting models. Melting models based on experimental partition coefficients predict that biotite-dehydration melting producing either peritectic garnet or cordierite generates more enriched melts; however, the model predicted concentrations in cordierite are lower, and concentrations in muscovite are higher than those observed in nature. In contrast, equilibrium melting models based on natural partition coefficients suggest that initial muscovite melts will be more enriched, and biotite-dehydration melts more enriched, if formed with peritectic garnet (as cordierite sequesters Li). In addition, the lack of temperature-dependent partition coefficients fails to optimally reproduce natural mineral concentration trends. Based on the comparison of experiments and natural examples, we suggest that Li behaviour during equilibrium melting is affected by protolith and mineral major element compositions, particularly water and fluorine contents.\u003c/p\u003e","manuscriptTitle":"Lithium mobilisation during metapelite melting: insights and open questions","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-15 06:53:18","doi":"10.21203/rs.3.rs-7104523/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d595bc5d-2ac2-45aa-8852-ab7ef970b9e0","owner":[],"postedDate":"July 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-15T06:53:18+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-15 06:53:18","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7104523","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7104523","identity":"rs-7104523","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}