Differentiation of arc magmas and crustal growth: a Nd isotope perspective

Differentiation of arc magmas and crustal growth: a Nd isotope perspective | 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 Article Differentiation of arc magmas and crustal growth: a Nd isotope perspective Massimo Chiaradia This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3870583/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 Arc magmas form new continental crust and are responsible for volcanic eruptions as well as for major metallic ore deposits. It is generally accepted that arc magmas are generated above subduction zones by partial melting of the mantle wedge and differentiate within the crust of the overriding plate through fractional crystallization, magma mixing and crustal assimilation. However, it is not clear in which proportions mantle and the above different intracrustal processes contribute to the broad geochemical variability of arc magmas. Here, using Nd isotope systematics and their geochemical modelling, I show that the thicker the crust of the overriding plate, the higher the assimilation rate of crustal rocks by mantle-derived magmas and the older the assimilated rocks. This highlights a systematic increase of crustal contribution to arc magma chemical and isotopic composition with the thickening of the overriding plate crust. The data presented are also consistent with growth and maturation of the continental crust through time by continuously increasing thickness, SiO 2 content and Nd isotopically evolved composition. Earth and environmental sciences/Planetary science Earth and environmental sciences/Planetary science/Geochemistry Earth and environmental sciences/Planetary science/Petrology Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Arc magmatism is responsible for the cycling of volatile compounds 1 , which control Earth’s climate 2 and cause devastating eruptions 3 , for some of the highest concentrations of Cu and S in the Earth’s crust 4 , 5 , and for continental crust formation and growth 6 . Arc magmas display a broad range of major element compositions, e.g., from MgO 10 wt.% and from SiO 2 > 70 to SiO 2 < 50 wt.%. The main processes responsible for such a broad range of chemical compositions are fractional crystallization of parental basalts and assimilation of crustal rocks 7 with mixing between the products of these processes also contributing to the more or less continuous range in composition 8 . Various works have highlighted that derivative arc magmas display systematic geochemical differences related to crustal thickness, e.g., in Cu, FeO tot 9 and Zn 10 contents, and Sr/Y as well as La/Yb values of intermediate magmas 11 , 12 . These features have been attributed to the different fractionating assemblages (plagioclase-rich versus amphibole ± garnet-rich) in magmas occurring in arcs of different thicknesses because fractionation of contrasting mineral assemblages is controlled by pressure and therefore by the average depth at which differentiation occurs. Other recent works 13 , 14 , building upon concepts advanced several decades ago 15 , 16 , have shown that also the geochemical composition of primitive basalts may be controlled by the thickness of the lithosphere of the overriding plate. This has been attributed to the different partial melting degrees occurring under thin (higher partial melt fraction) and thick (lower partial melt fraction) crust 13 , 14 , induced by the different thermal structures of the mantle wedge in relation to the thickness of the lithosphere of the overriding plate 17 : this results in a systematic increase in incompatible element concentrations in the most primitive magmas of arcs as the arc thickness increases 13 , 14 . Whereas fractional crystallization and mixing processes have received large attention as general processes responsible for the chemical differentiation and heterogeneity of arc magmas, a global role of crustal assimilation in the geochemical composition of arc magmas has not been thoroughly addressed. Here, I focus on the differentiation paths of arc magmas according to crust thickness using Nd isotopes and their relationship to compatible elements (MgO, Co) to evaluate the contribution of crustal material to intermediate and felsic arc magmas and gain insight into their petrogenesis with implications for processes of continental crust growth. The data show that arc magmas from arcs with increasing crustal thickness show systematically higher contributions of assimilated crustal rock material. Additionally, the data also show that the assimilated material in arcs becomes increasingly older as the arc thickness increases, supporting views of crustal growth and maturation through continuous reworking of previous, more immature, arc building stages. Results and discussion Data acquisition and treatment. Geochemical data of bulk volcanic rocks from 16 recent arcs (Supplementary Data S1) collected from the Georoc database ( http://georoc.mpch-mainz.gwdg.de/georoc/ ) were filtered and treated according to the method described by ref. 9 (Methods). Median values of 143 Nd/ 144 Nd for bins of 0.5 wt.% MgO display distinct evolutionary trends with typical differentiation indices, such as MgO and Co, for arcs with different crustal thicknesses (Fig. 1 ; see Figs. S1 and S2 for the plots of all individual arcs). The choice of Co was determined by the relatively well constrainable bulk coefficients of this compatible element for modelling purposes and by the fact that, because Co is not very chalcophile, sulfide fractionation occurring in thick arcs 9 is unlikely to significantly affect this element, as it would affect other compatible trace elements (e.g., Ni). Nonetheless, the correlations between 143 Nd/ 144 Nd and Co reported here are also found using other compatible and incompatible elements instead of Co as it should be expected due to the fact that strong correlations occur between 143 Nd/ 144 Nd and MgO (Fig. 2 a) and that MgO is a universal hallmark of magma differentiation that shows strong (positive or negative) correlations with nearly all major and trace elements. In thin arcs, 143 Nd/ 144 Nd displays a flat trend for decreasing MgO and Co, whereas in increasingly thick arcs 143 Nd/ 144 Nd values steadily decrease with MgO and Co along slopes that increase with increasing thickness of the arc (Figs. 1 and 2 ; Figs. S1-S2). Indeed, slopes of the linear trends of 143 Nd/ 144 Nd-MgO and 143 Nd/ 144 Nd-Co of arc magmas ranging between MgO 10 wt.% correlate significantly with crustal thickness (Fig. 2 ; see Tables S1 and S2 for the full parameters of the linear correlations). Whereas the significance (p < 0.0001) of these correlations (R = 0.921 for the 143 Nd/ 144 Nd-MgO slope and R = 0.914 for the 143 Nd/ 144 Nd-Co slope) might seem to be strongly enhanced by the value of the Andean Central Volcanic Zone (CVZ), the correlations are statistically significant also disregarding CVZ (R = 0.796 with p = 0.0001 for the 143 Nd/ 144 Nd-MgO slope and R = 0.778 with p = 0.0002 for the 143 Nd/ 144 Nd-Co slope). The intercept values of the trends at MgO = 0 wt.% or Co = 0 ppm, i.e., a proxy for the crustal assimilant, also display significant correlations with crustal thickness (Fig. 2 c). The correlations for the intercept values using the 143 Nd/ 144 Nd-MgO slopes have R = 0.921 with p < 0.0001 including CVZ and R = 0.787 with p = 0.0002 excluding CVZ, whereas correlations using the intercept values of the 143 Nd/ 144 Nd-Co slopes have R = 0.922 with p < 0.0001 including CVZ and R = 0.791 with p = 0.0002 excluding CVZ. The two sets of intercept values strongly correlate with each other along a slope of ~ 1 ( 143 Nd/ 144 Nd = 1.0403 + 0.0207, R = 0.995) which indicates that the intercept values for each arc are nearly the same using both 143 Nd/ 144 Nd-MgO and 143 Nd/ 144 Nd-Co regressions. The Nd model ages of the intercept values calculated for the Sm/Nd value of the bulk continental crust (0.195 18 ), which obviously also display a correlation with crustal thickness, range in age between ~ 200 and ~ 1400 Ma (Fig. 2 c). The values of 143 Nd/ 144 Nd MgO12 (and corresponding Nd model ages) calculated from the regression trends above for 12 wt.% MgO, a plausible proxy of primary magmas in subduction zones, display less significant correlations with crustal thickness (R = 0.735 and p = 0.0005 with CVZ), especially if CVZ is excluded (R = 0.505, p = 0.0387) (Fig. 2 d). Correlations were also checked for Pb and Sr isotopes. Whereas Pb isotopes did not show any significant correlations, Sr isotopes display a similar behavior to Nd isotopes (Fig. S3; Supplementary Data S2). However, the Sr isotope variation with arc thickness is less significant than that of Nd isotopes resulting in a lower resolving power among arcs, except for the very thick CVZ arc (Fig. S3). Additionally, the Sr partition coefficient during magmatic differentiation may be very different in thick versus thin arcs depending on plagioclase stability with pressure 11 , adding complexity to the modeling discussed below. In contrast Nd and Co have more straightforward behaviors during magmatic differentiation. Therefore, the discussion is limited to Nd isotopes. Modelling of Nd isotope systematics of arc magmas. A large number of petrographic, geochemical and isotopic studies have shown that arc magmas are the result of various processes including fractional crystallization, mixing (e.g., through recharge of mafic magmas), and assimilation of host rocks 7 , 8 , 19 . The combined use of isotopic compositions of magmas and incompatible or compatible trace elements, whose behavior can be modeled through their bulk partition coefficients between crystallizing minerals and residual melt, provides first order information on the prevalent magma evolutionary processes occurring in specific volcanic edifices 20 . The application of such type of modeling to entire arc segments, although rocks may have different ages, may be sourced from more or less different mantle domains and may interact with more or less different crustal rocks, is informative of first order differences in large-scale processes related to crustal architecture and geodynamic setting, including crustal thickness 9 – 14 . Several recent papers have highlighted the role that the crustal thickness of the overriding plate plays in the geochemistry of both parental arc magmas 13 , 14 , 21 and their derivatives 9 – 12 , 22 . Because this study focuses on geochemical and isotopic data of arc magmas for MgO values between 10 wt.% it necessarily bears on the control that crustal thickness exerts on the intracrustal evolution of magmas. Nonetheless, intracrustal evolutionary paths may also be partly or significantly controlled by the initial geochemistry of parental magmas, which is in turn controlled by mantle source processes 13 , 14 . Deconvolving these two processes is a difficult and debated task 22 . The control that crustal thickness may play on the differentiation processes of parental arc basalts is intuitive. Parental basalts intruded into thin crust cool rapidly and evolve toward derivative terms dominantly through fractional crystallization processes 23 . Because of the low temperature of the host rocks, due to intrusion of parental basalts at overall shallow levels in a thin crust, assimilation should be, intuitively, minor. The bulk of the geochemical differences in thin arc magma sequences should be therefore controlled by fractional crystallization and by mixing between more or less fractionated terms. In this situation, radiogenic isotope compositions of the whole evolutionary sequence are expected to remain those of the parental magma with limited variations reflecting minor assimilation of a thin oceanic crust that is anyway likely to be isotopically similar to the parental magma. In a plot of compatible elements versus 143 Nd/ 144 Nd, such evolution corresponds to a subhorizontal trend in which 143 Nd/ 144 Nd does not vary significantly whereas the compatible element decreases continuously due to its sequestration into fractionating minerals. This behavior is shown by the evolution of thin arc magmas in Fig. 1 . In contrast, parental magmas ascending from the mantle wedge through a thicker crust encounter hotter crustal rocks in the deeper parts of the arc and should interact more significantly with these rocks 23 , at least because they travel through a thicker warm lower crustal section. Under these conditions, interaction processes, such as assimilation and mixing with partial melts of the crust, are plausible 24 , in addition to the processes of recharge from continuously incoming basalt from the mantle, the latter feature also occurring in thin arcs. This has been described as MASH processes 25 or hot zones 19 occurring in the lower crust of thick arcs and might result in systematic radiogenic isotope changes in derivative magmas should the crust into which the parental basalt intrudes be isotopically different from the basalts themselves. Indeed, the trends of intermediate to thick arcs (Cascades, Northern Volcanic Zone NVZ, Mexico) to very thick ones (CVZ) show a continuous, albeit different, decrease in 143 Nd/ 144 Nd values with decreasing MgO and Co, which is indicative of such a process (Fig. 1 ). Table 1 Ranges of values for the parameters used in the equations describing the AFC model. The range of parent Nd and Co concentrations are from the range of oceanic and continental basalts of ref. 26 . The ranges of Nd and Co concentrations of the assimilant are the same as that of the parent for thin arcs and are from ref. 18 for thick arcs and CVZ. Parameter Range for thin arcs Range for thick arcs Range for CVZ Remaining melt 0-100 0-100 0-100 R 0–1 0.05-1 0.05-1 Nd parent (ppm) 10–15 14–15 14–15 Nd assimilant (ppm) 10–15 11–25 11–25 143 Nd/ 144 Nd parent 0.5130–0.5132 0.51293–0.51294 0.51293–0.51294 143 Nd/ 144 Nd assimilant 0.5080–0.5139 0.5114–0.5132 0.5115–0.5126 Co parent (ppm) 40–42 40–42 40–42 Co assimilant (ppm) 40–42 20–30 20–30 DNd 0.1–0.2 0.1–0.3 0.1–0.3 DCo 1–6 1–6 1–6 To quantify these processes, assimilation fractional crystallization (AFC) modeling was carried out in the 143 Nd/ 144 Nd versus Co space using DePaolo’s 27 equations with input parameters of the elemental (Nd, Co) concentrations in the parent and assimilant, the Nd isotope composition of the parent and assimilant, the bulk partition coefficients for Nd and Co, the fraction of remaining melt and the ratio (r) of the mass of the assimilant to the mass of crystallized melt. In particular, the latter value is informative of the thermal status of the crustal level at which the AFC process is occurring, with r = 0 corresponding to pure fractional crystallization, low r values ( 0.5) being typical of high assimilation rates in the lower crust and r nearing 1 virtually corresponding to pure mixing 27 . A Monte Carlo approach was used due to the loosely constrained nature of most of the parameters used in the model (see Methods). Geologically significant ranges used for each of the parameters are reported in Table 1 . Dependency of crust assimilation by arc magmas on overriding plate thickness. The trends with slopes changing for different arc thicknesses in the 143 Nd/ 144 Nd-MgO and 143 Nd/ 144 Nd-Co spaces suggest that, whereas arc magmas differentiating in thin crust arcs are consistent with a pure fractional crystallization process, mantle-derived arc basalts differentiating in increasingly thick crust require assimilation of crustal rocks, with increasingly lower 143 Nd/ 144 Nd values as the crustal thickness increases. To evaluate the output of the Monte Carlo-based model of AFC, the model results have been filtered to fit the different arc trends in the 143 Nd/ 144 Nd-Co space. Figures 3 a, 3 b, and 3 c show the forced fitting of the model to the data available for thin-intermediate arcs (Kermadec and Mariana as examples: Fig. 3 a), thick arcs (Cascades and NVZ as examples: Fig. 3 b) and the very thick CVZ arc (Fig. 3 c). Figures 3 d, 3 e, and 3 f show the density scatterplots returning the most probable values of r and 143 Nd/ 144 Nd assimilant in successfully reproducing the 143 Nd/ 144 Nd-Co trends of Figs. 3 a, 3 b, and 3 c. The results of r for the thin arcs must be considered maximum values because the subhorizontal trends of all these arcs are consistent with a pure fractional crystallization process without any assimilation, a situation that cannot be modeled in these plots because not having an assimilant would result in no 143 Nd/ 144 Nd assimilant values returned by the model and therefore in the impossibility of drawing Fig. 3 d. The results suggest that the most probable solutions for the r values of the AFC process (highest density areas in Figs. 3 d, e, f) steadily increase with arc thickness, passing from 0.75 for the very thick CVZ arc. The 143 Nd/ 144 Nd assimilant in contrast steadily decreases from ~ 0.51290 through ~ 0.51265 to ~ 0.51235 for thin-intermediate, thick and very thick arcs, respectively. Solutions for differential assimilation (different r values) of a similar low radiogenic assimilant (e.g., ≤ 0.5123) in both thick and very thick arcs are less probable, according to the model (see density contours in Figs. 3 d, 3 e, 3 f). Although the absolute r values of the model output have to be considered with caution, due to the uncertainties in the parameters used (Table 1 ), the model results strongly support the intuitive hypothesis that arc magma differentiation in increasingly thicker arcs occurs in average at deeper crustal levels 11 , 23 and is therefore characterized by an increasing assimilation rate (r value) of the continental crust until a nearly pure mixing trend between crustal melts and mantle-derived components in the CVZ (r approaching 1). Systematic variations in incompatible elements and their ratios in primitive magmas from arcs of different crustal thicknesses suggest that crustal thickness controls the degree of element enrichment also by modulating the partial melting of the mantle 13 , 14 . It has been suggested that under thick continental arcs (and therefore under a thick lithosphere) the degree of partial melting of the mantle wedge is lower than under thin arcs because of a systematic change in the thermal structure of the mantle wedge with crustal thickness of the overriding plate 17 . In contrast, radiogenic isotopes, including those of Nd, do not seem to be significantly affected by this process 13 , 14 , although local correlations of 143 Nd/ 144 Nd of primitive arc rocks with crustal thickness have been reported and attributed to systematic along-arc changes in ambient mantle 29 . The results of the present study show a poor correlation of 143 Nd/ 144 Nd MgO12 of putative parent arc magmas with crustal thickness, which becomes more significant if the CVZ data are included (Fig. 2 d). A possible mechanism explaining the much less radiogenic composition of putative parental magmas of the CVZ could be fertilization of the mantle wedge by subduction erosion of the lower portion of the overriding plate crust, which has been suggested to occur in the CVZ since ~ 19 Myr, with the highest rates during the last 7 Myr 30 , 31 . Subduction erosion likely occurs also in other arcs 32 – 34 . The poor correlation of Fig. 2 d leaves open the possibility of subduction erosion or any other process progressively enriching the mantle wedge source of arc magmas through time (i.e., decreasing its 143 Nd/ 144 Nd value) as the arc thickness increases. Nonetheless, even considering such a potential decrease in the 143 Nd/ 144 Nd values of putative primitive magmas of arcs with crustal thickness (Fig. 2 d), the comparison between Figs. 2 a and 2 b shows that the Nd isotope systematics of derivative magmas of arcs increasingly thicker are controlled to a larger extent by the isotopic composition of the assimilant and therefore by intracrustal processes rather than by primary mantle-related differences. This lends strong support to the important role of arc thickness in modulating the elemental and isotopic compositions of derivative arc magmas through intracrustal processes that significantly overprint systematic geochemical trends caused by variable arc thicknesses in primitive magmas, especially in thicker arcs. Implications for continental crust growth processes. Another interesting and not straightforward outcome of the above data analysis is that the thickness of the arc crust correlates with the Nd isotopic composition of the assimilant (Figs. 2 a, 3 d, 3 e, 3 f), suggesting that an increasingly thicker crust is characterized by overall increasingly lower 143 Nd/ 144 Nd values. This suggests thickening of the continental crust in arcs by continuous reworking of previously formed (“isotopically older”) crust by subsequent episodes of “isotopically younger” arc magmatism 23 , 28 . Although the model ages returned by the assimilants through the regression of the slopes in the 143 Nd/ 144 Nd-MgO and 143 Nd/ 144 Nd-Co spaces do not have an absolute geological meaning, they roughly represent the time-integrated “average” model ages of the reworked continental crust in the investigated arcs, suggesting reworking of progressively older crust as the arc thickness increases. In its turn, crustal thickness controls arc magma chemistry both at the source and in the crust through a feedback loop process. In fact, increasing crustal thickness, achieved through arc magmatism reworking of previous thinner crust segments, results in primitive magmas with increasingly higher contents of incompatible elements 13 , 14 and perhaps an increasingly crustal Nd isotope composition (i.e., lower 143 Nd/ 144 Nd) of the ambient mantle wedge (Fig. 2 d), e.g., through subduction erosion or other processes. Parental magmas, during intracrustal evolution, become increasingly contaminated by their interaction with a thicker, older and more felsic crust (Fig. 2 c) driving it into an even thicker, more felsic and isotopically evolved crust. The thicker and older the crust the parental arc magmas are interacting with, the stronger the divergence of parental and derivative magmas from parental and especially derivative magmas of previous stages of arc crust build-up (Fig. 4 ), highlighting the significant role of magmatic reworking in crustal growth processes. The results of this study, therefore, in addition to vindicating a role of crustal thickness on the chemistry and isotopic composition of arc magmas both at their source and during crustal differentiation, are consistent with views of crustal growth as a continuous process characterized by increasing thickness, SiO 2 content and isotopically evolved compositions through time 6 , 28 , of which thin-intermediate and variably thick recent arcs could be a present-day snapshot. Materials and Methods Data selection and treatment Whole rock geochemical data ( https://georoc.eu/georoc/new-start.asp ) of 16 arcs were filtered for ages (younger than Mio-Pliocene) and alteration (not or weakly altered). As in ref. 9 , to reduce the bias induced by outliers and to extract information on general trends, median values of 143 Nd/ 144 Nd, MgO, and Co for subpopulations corresponding to bins of 0.5 wt% MgO were calculated (Supplementary Data S1) and plotted for each arc (Supplementary Figs. S1 and S2). For the Kurile arc, the data corresponding to two bins of MgO < 1 wt.% (0.165 and 0.74 wt.%) were excluded because these rhyolites are formed by partial melting of crustal rocks 35 . The data of these two bins significantly deviate from the main arc trend having much less radiogenic Nd isotope compositions (Supplementary Data S1). Additionally, the data corresponding to the MgO bin = 0.19 wt.% of Honshu and 0.22 wt.% of Bismark-New Britain were excluded because they had anomalously low 143 Nd/ 144 Nd values. Honshu rhyolites with low radiogenic values were formed during a rift stage associated with back-arc opening 36 . Bismark-New Britain rhyolitic and trachytic samples were also formed in a rift environment, possibly involving partial melting of the lower crust of the Australian continent 37 . Overall, the few anomalous values that were excluded always correspond to very evolved rocks (MgO < 1 wt.%), which were formed by peculiar processes different from those of the main evolutionary trend of the arcs. For some arcs, a few bins did not have any reported value of either 143 Nd/ 144 Nd or Co and could not be plotted (e.g., MgO bins 0.725, 1.17, 1.8, 2.32, 8.7 wt.% for New Hebrides do not have any reported 143 Nd/ 144 Nd value in the Georoc database). Supplementary Data S1 reports all data, including those excluded from the regressions for the reasons discussed above. AFC modeling Assimilation-fractional crystallization (AFC) modeling in the 143 Nd/ 144 Nd-Co space was carried out using the equations of DePaolo 27 . AFC is a simple but powerful model that incorporates two main processes resulting in magma differentiation in magmatic arcs, namely, fractional crystallization and assimilation. The r value, i.e., the ratio of the mass of the assimilant to the mass of crystallized melt, of the AFC model can also provide broad estimates of the thermal state at which assimilation occurs because high r values mean a high rate of assimilation that may only occur for host rocks at high temperatures, i.e., a situation typical of the lower crust, whereas lower r values correspond to assimilation at shallower levels. Although it may not capture all their complex combination, AFC offers first-order control on the occurrence of evolutionary processes in arc magmas. Because the parameters involved in such equations cannot be given fixed values, I let them vary within geologically and geochemically sound ranges as indicated in Table 1 and run the equations for 5’000’000 simulations using a Monte Carlo approach with a homemade script written in RStudio 38 (Supplementary Notes 1–3). The outputs of the model can then be evaluated in probabilistic terms against the real data to infer the most probable values of the unknown parameters returned by the model and therefore the most likely petrogenetic processes. 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Melting of crustal rocks as a possible origin for Middle Miocene to Quaternary rhyolites of northeast Hokkaido, Japan: Constraints from Sr and Nd isotopes and major- and trace-element chemistry. Journal of Volcanology and Geothermal Research 221–222, 52–70 (2012). Shuto, K. et al. Geochemical secular variation of magma source during Early to Middle Miocene time in the Niigata area, NE Japan: Asthenospheric mantle upwelling during back-arc basin opening. Lithos 86, 1–33 (2006). Hegner, E. & Smith, I. E. M. Isotopic compositions of late Cenozoic volcanics from southeast Papua New Guinea: Evidence for multi-component sources in arc and rift environments. Chemical Geology 97, 233–249 (1992). R Core Team. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. (2013). Additional Declarations No competing interests reported. Supplementary Files DatasetS1.xlsx DatasetS2.xlsx NdisoMsSICOMMENV.pdf 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-3870583","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":268013357,"identity":"35a3ae64-41af-4ac3-97f2-aea7297c781d","order_by":0,"name":"Massimo Chiaradia","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABA0lEQVRIiWNgGAWjYLCCBBAhwdgAJJl5GNgbYCJEa+E5QIQWBoQCZiAjAUUEA+i2H3/84WGODQP/7ObGzxU11jL8M9+YPXjwCyTSgFWL2ZkcM4nEbWkMEncONkueOZbOI3E7x9wgsQ8kcgC7lgM5bAyJ2w4zGEgkNkg2sB3mYbgNMqQHJJKAXcv5548/QLU0/2z4d5hH/uYZkJb/uLXcSAAqhmhpk2xsO8xjcIPHTCLhxwE8Wt6A/cIjcSOxzbKxL53H8ExaGdCRyUARXA5Lf/zx5zYbOf4Z6Y9vNnyztpc7fnib5I8/dkAR7FpggAeVy9iGLkIY/CFVwygYBaNgFAxjAABCmGCxLMVCKAAAAABJRU5ErkJggg==","orcid":"","institution":"University of Geneva","correspondingAuthor":true,"prefix":"","firstName":"Massimo","middleName":"","lastName":"Chiaradia","suffix":""}],"badges":[],"createdAt":"2024-01-16 17:44:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3870583/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3870583/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":49879521,"identity":"3a473db4-d6c3-4037-936d-3c4510627876","added_by":"auto","created_at":"2024-01-19 15:08:59","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":363016,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003ePlots of \u003c/strong\u003e\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u003cstrong\u003e143\u003c/strong\u003e\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e\u003cstrong\u003eNd/\u003c/strong\u003e\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u003cstrong\u003e144\u003c/strong\u003e\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e\u003cstrong\u003eNd versus MgO (a) and Co (b) for arc groups of different thickness.\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e Each point is the average of median values of \u003c/em\u003e\u003csup\u003e\u003cem\u003e143\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd/\u003c/em\u003e\u003csup\u003e\u003cem\u003e144\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd, MgO and Co for 0.5 wt.% intervals of MgO for thin (South Sandwich, Mariana, Kermadec, New Hebrides, Kurile, Tonga, Izu-Bonin, Bismark-New Britain), intermediate (Kamchatka, Lesser Antilles, Central America), and thick arcs (Honshu, Mexico, Andean Northern Volcanic Zone NVZ, Cascades). Very thick arc is represented by the Andean Central Volcanic Zone (CVZ).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-3870583/v1/f7dfadaa3b7961c87c32769a.jpeg"},{"id":49879519,"identity":"4b1d770c-4a8e-4933-84b5-1afd7bc6bfc9","added_by":"auto","created_at":"2024-01-19 15:08:59","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":453881,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003ePlots of the correlations of crustal thickness with parameters of the intra-arc correlations of Nd isotopes with MgO and Co.\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e Panels \u003c/em\u003e\u003cem\u003e\u003cstrong\u003ea\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e and \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eb\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e show the correlations of crustal thickness with the slopes of the linear regressions in the \u003c/em\u003e\u003csup\u003e\u003cem\u003e143\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd/\u003c/em\u003e\u003csup\u003e\u003cem\u003e144\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd-MgO and \u003c/em\u003e\u003csup\u003e\u003cem\u003e143\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd/\u003c/em\u003e\u003csup\u003e\u003cem\u003e144\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd-Co spaces, respectively (see Figs. S1-S2 and Tables S1-S2). Panels c and d show the correlations of crustal thickness with the intercepts of the above correlations at 0 wt.% MgO and with the values of \u003c/em\u003e\u003csup\u003e\u003cem\u003e143\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd/\u003c/em\u003e\u003csup\u003e\u003cem\u003e144\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd calculated at MgO = 12 wt.% (see Figs. S1-S2 and Tables S1-S2). Symbols and color codes correspond to those of Fig. 1.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-3870583/v1/9104ad5efd0d49ee9c8e7480.jpeg"},{"id":49879524,"identity":"47d7c332-c4c3-4d53-8d93-b1be40fa86d3","added_by":"auto","created_at":"2024-01-19 15:08:59","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":377191,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003ePlots of the AFC modelling for thin-intermediate, thick and very thick arcs.\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e In panels \u003c/em\u003e\u003cem\u003e\u003cstrong\u003ea\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e, \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eb\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e, \u003c/em\u003e\u003cem\u003e\u003cstrong\u003ec\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e, successful simulations are shown which reproduce the distribution of Kermadec and Mariana arc compositions (median values binned for 0.5 wt.% MgO intervals) in the \u003c/em\u003e\u003csup\u003e\u003cem\u003e143\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd/\u003c/em\u003e\u003csup\u003e\u003cem\u003e144\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd versus Co space. In panels \u003c/em\u003e\u003cem\u003e\u003cstrong\u003ed\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e, \u003c/em\u003e\u003cem\u003e\u003cstrong\u003ee\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e, \u003c/em\u003e\u003cem\u003e\u003cstrong\u003ef\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e, the density distributions of the successful simulations in the \u003c/em\u003e\u003csup\u003e\u003cem\u003e143\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd/\u003c/em\u003e\u003csup\u003e\u003cem\u003e144\u003c/em\u003e\u003c/sup\u003e\u003cem\u003eNd\u003c/em\u003e\u003csub\u003e\u003cem\u003eassimilant\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e versus r space are shown.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-3870583/v1/f0fea02d7ab9116bcd9c8d9f.jpeg"},{"id":49879823,"identity":"e0bf19d1-30e5-4ae8-abea-82b95fd7bae2","added_by":"auto","created_at":"2024-01-19 15:16:59","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":104193,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003ePlot of the correlation between crustal thickness and the difference between \u003c/strong\u003e\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u003cstrong\u003e143\u003c/strong\u003e\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e\u003cstrong\u003eNd/\u003c/strong\u003e\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u003cstrong\u003e144\u003c/strong\u003e\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e\u003cstrong\u003eNd at 12 and 0 wt.% MgO calculated from the linear regressions of each arc in the \u003c/strong\u003e\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u003cstrong\u003e143\u003c/strong\u003e\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e\u003cstrong\u003eNd/\u003c/strong\u003e\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u003cstrong\u003e144\u003c/strong\u003e\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e\u003cstrong\u003eNd space.\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e Symbols and color codes correspond to those of Fig. 1.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-3870583/v1/dc6ad5808555486a6bd9c6e9.jpeg"},{"id":51522607,"identity":"22b22208-bcee-4e22-b385-5466dbfb3db3","added_by":"auto","created_at":"2024-02-23 04:29:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":736150,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3870583/v1/af2a0c7a-d6de-481c-8d59-e0190efd2ff1.pdf"},{"id":49879522,"identity":"d8e983f0-070c-411f-89bf-c6af51c42ce0","added_by":"auto","created_at":"2024-01-19 15:08:59","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2879521,"visible":true,"origin":"","legend":"","description":"","filename":"DatasetS1.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-3870583/v1/bdbf2dfe6db758b5457e2d35.xlsx"},{"id":49879518,"identity":"f7f5e1ae-1f29-400d-9752-f3de5da2edea","added_by":"auto","created_at":"2024-01-19 15:08:58","extension":"xlsx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":21562,"visible":true,"origin":"","legend":"","description":"","filename":"DatasetS2.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-3870583/v1/617d0bb66fc653cbe2b41bd0.xlsx"},{"id":49879824,"identity":"86d59c1f-da7c-4b8f-8dfd-7c89b9577e29","added_by":"auto","created_at":"2024-01-19 15:16:59","extension":"pdf","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":1932314,"visible":true,"origin":"","legend":"","description":"","filename":"NdisoMsSICOMMENV.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3870583/v1/f18d8abea2d39b1b7d2c1dbd.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Differentiation of arc magmas and crustal growth: a Nd isotope perspective","fulltext":[{"header":"Introduction","content":"\u003cp\u003eArc magmatism is responsible for the cycling of volatile compounds\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e, which control Earth\u0026rsquo;s climate\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e and cause devastating eruptions\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e, for some of the highest concentrations of Cu and S in the Earth\u0026rsquo;s crust\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e, and for continental crust formation and growth\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. Arc magmas display a broad range of major element compositions, e.g., from MgO\u0026thinsp;\u0026lt;\u0026thinsp;1 to MgO\u0026thinsp;\u0026gt;\u0026thinsp;10 wt.% and from SiO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;\u0026gt;\u0026thinsp;70 to SiO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;\u0026lt;\u0026thinsp;50 wt.%. The main processes responsible for such a broad range of chemical compositions are fractional crystallization of parental basalts and assimilation of crustal rocks\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e with mixing between the products of these processes also contributing to the more or less continuous range in composition\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eVarious works have highlighted that derivative arc magmas display systematic geochemical differences related to crustal thickness, e.g., in Cu, FeO\u003csub\u003etot\u003c/sub\u003e\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e and Zn\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e contents, and Sr/Y as well as La/Yb values of intermediate magmas\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. These features have been attributed to the different fractionating assemblages (plagioclase-rich versus amphibole\u0026thinsp;\u0026plusmn;\u0026thinsp;garnet-rich) in magmas occurring in arcs of different thicknesses because fractionation of contrasting mineral assemblages is controlled by pressure and therefore by the average depth at which differentiation occurs. Other recent works\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, building upon concepts advanced several decades ago\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e, have shown that also the geochemical composition of primitive basalts may be controlled by the thickness of the lithosphere of the overriding plate. This has been attributed to the different partial melting degrees occurring under thin (higher partial melt fraction) and thick (lower partial melt fraction) crust\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, induced by the different thermal structures of the mantle wedge in relation to the thickness of the lithosphere of the overriding plate\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e: this results in a systematic increase in incompatible element concentrations in the most primitive magmas of arcs as the arc thickness increases\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eWhereas fractional crystallization and mixing processes have received large attention as general processes responsible for the chemical differentiation and heterogeneity of arc magmas, a global role of crustal assimilation in the geochemical composition of arc magmas has not been thoroughly addressed. Here, I focus on the differentiation paths of arc magmas according to crust thickness using Nd isotopes and their relationship to compatible elements (MgO, Co) to evaluate the contribution of crustal material to intermediate and felsic arc magmas and gain insight into their petrogenesis with implications for processes of continental crust growth. The data show that arc magmas from arcs with increasing crustal thickness show systematically higher contributions of assimilated crustal rock material. Additionally, the data also show that the assimilated material in arcs becomes increasingly older as the arc thickness increases, supporting views of crustal growth and maturation through continuous reworking of previous, more immature, arc building stages.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cp\u003e \u003cb\u003eData acquisition and treatment.\u003c/b\u003e Geochemical data of bulk volcanic rocks from 16 recent arcs (Supplementary Data S1) collected from the Georoc database (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://georoc.mpch-mainz.gwdg.de/georoc/\u003c/span\u003e\u003cspan address=\"http://georoc.mpch-mainz.gwdg.de/georoc/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) were filtered and treated according to the method described by ref. \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e (Methods). Median values of \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd for bins of 0.5 wt.% MgO display distinct evolutionary trends with typical differentiation indices, such as MgO and Co, for arcs with different crustal thicknesses (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e; see Figs. S1 and S2 for the plots of all individual arcs). The choice of Co was determined by the relatively well constrainable bulk coefficients of this compatible element for modelling purposes and by the fact that, because Co is not very chalcophile, sulfide fractionation occurring in thick arcs\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e is unlikely to significantly affect this element, as it would affect other compatible trace elements (e.g., Ni). Nonetheless, the correlations between \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd and Co reported here are also found using other compatible and incompatible elements instead of Co as it should be expected due to the fact that strong correlations occur between \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd and MgO (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea) and that MgO is a universal hallmark of magma differentiation that shows strong (positive or negative) correlations with nearly all major and trace elements.\u003c/p\u003e \u003cp\u003eIn thin arcs, \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd displays a flat trend for decreasing MgO and Co, whereas in increasingly thick arcs \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd values steadily decrease with MgO and Co along slopes that increase with increasing thickness of the arc (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; Figs. S1-S2). Indeed, slopes of the linear trends of \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-MgO and \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co of arc magmas ranging between MgO\u0026thinsp;\u0026lt;\u0026thinsp;1 and \u0026gt;\u0026thinsp;10 wt.% correlate significantly with crustal thickness (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; see Tables S1 and S2 for the full parameters of the linear correlations). Whereas the significance (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) of these correlations (R\u0026thinsp;=\u0026thinsp;0.921 for the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-MgO slope and R\u0026thinsp;=\u0026thinsp;0.914 for the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co slope) might seem to be strongly enhanced by the value of the Andean Central Volcanic Zone (CVZ), the correlations are statistically significant also disregarding CVZ (R\u0026thinsp;=\u0026thinsp;0.796 with p\u0026thinsp;=\u0026thinsp;0.0001 for the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-MgO slope and R\u0026thinsp;=\u0026thinsp;0.778 with p\u0026thinsp;=\u0026thinsp;0.0002 for the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co slope). The intercept values of the trends at MgO\u0026thinsp;=\u0026thinsp;0 wt.% or Co\u0026thinsp;=\u0026thinsp;0 ppm, i.e., a proxy for the crustal assimilant, also display significant correlations with crustal thickness (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). The correlations for the intercept values using the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-MgO slopes have R\u0026thinsp;=\u0026thinsp;0.921 with p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001 including CVZ and R\u0026thinsp;=\u0026thinsp;0.787 with p\u0026thinsp;=\u0026thinsp;0.0002 excluding CVZ, whereas correlations using the intercept values of the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co slopes have R\u0026thinsp;=\u0026thinsp;0.922 with p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001 including CVZ and R\u0026thinsp;=\u0026thinsp;0.791 with p\u0026thinsp;=\u0026thinsp;0.0002 excluding CVZ. The two sets of intercept values strongly correlate with each other along a slope of ~\u0026thinsp;1 (\u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd = 1.0403\u0026thinsp;+\u0026thinsp;0.0207, R\u0026thinsp;=\u0026thinsp;0.995) which indicates that the intercept values for each arc are nearly the same using both \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-MgO and \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co regressions. The Nd model ages of the intercept values calculated for the Sm/Nd value of the bulk continental crust (0.195\u003csup\u003e18\u003c/sup\u003e), which obviously also display a correlation with crustal thickness, range in age between ~\u0026thinsp;200 and ~\u0026thinsp;1400 Ma (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe values of \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd\u003csub\u003eMgO12\u003c/sub\u003e (and corresponding Nd model ages) calculated from the regression trends above for 12 wt.% MgO, a plausible proxy of primary magmas in subduction zones, display less significant correlations with crustal thickness (R\u0026thinsp;=\u0026thinsp;0.735 and p\u0026thinsp;=\u0026thinsp;0.0005 with CVZ), especially if CVZ is excluded (R\u0026thinsp;=\u0026thinsp;0.505, p\u0026thinsp;=\u0026thinsp;0.0387) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed).\u003c/p\u003e \u003cp\u003eCorrelations were also checked for Pb and Sr isotopes. Whereas Pb isotopes did not show any significant correlations, Sr isotopes display a similar behavior to Nd isotopes (Fig. S3; Supplementary Data S2). However, the Sr isotope variation with arc thickness is less significant than that of Nd isotopes resulting in a lower resolving power among arcs, except for the very thick CVZ arc (Fig. S3). Additionally, the Sr partition coefficient during magmatic differentiation may be very different in thick versus thin arcs depending on plagioclase stability with pressure\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e, adding complexity to the modeling discussed below. In contrast Nd and Co have more straightforward behaviors during magmatic differentiation. Therefore, the discussion is limited to Nd isotopes.\u003c/p\u003e \u003cp\u003e \u003cb\u003eModelling of Nd isotope systematics of arc magmas.\u003c/b\u003e A large number of petrographic, geochemical and isotopic studies have shown that arc magmas are the result of various processes including fractional crystallization, mixing (e.g., through recharge of mafic magmas), and assimilation of host rocks\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. The combined use of isotopic compositions of magmas and incompatible or compatible trace elements, whose behavior can be modeled through their bulk partition coefficients between crystallizing minerals and residual melt, provides first order information on the prevalent magma evolutionary processes occurring in specific volcanic edifices\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. The application of such type of modeling to entire arc segments, although rocks may have different ages, may be sourced from more or less different mantle domains and may interact with more or less different crustal rocks, is informative of first order differences in large-scale processes related to crustal architecture and geodynamic setting, including crustal thickness\u003csup\u003e\u003cspan additionalcitationids=\"CR10 CR11 CR12 CR13\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eSeveral recent papers have highlighted the role that the crustal thickness of the overriding plate plays in the geochemistry of both parental arc magmas\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e and their derivatives\u003csup\u003e\u003cspan additionalcitationids=\"CR10 CR11\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Because this study focuses on geochemical and isotopic data of arc magmas for MgO values between \u0026lt;\u0026thinsp;1 and \u0026gt;\u0026thinsp;10 wt.% it necessarily bears on the control that crustal thickness exerts on the intracrustal evolution of magmas. Nonetheless, intracrustal evolutionary paths may also be partly or significantly controlled by the initial geochemistry of parental magmas, which is in turn controlled by mantle source processes\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. Deconvolving these two processes is a difficult and debated task\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe control that crustal thickness may play on the differentiation processes of parental arc basalts is intuitive. Parental basalts intruded into thin crust cool rapidly and evolve toward derivative terms dominantly through fractional crystallization processes\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. Because of the low temperature of the host rocks, due to intrusion of parental basalts at overall shallow levels in a thin crust, assimilation should be, intuitively, minor. The bulk of the geochemical differences in thin arc magma sequences should be therefore controlled by fractional crystallization and by mixing between more or less fractionated terms. In this situation, radiogenic isotope compositions of the whole evolutionary sequence are expected to remain those of the parental magma with limited variations reflecting minor assimilation of a thin oceanic crust that is anyway likely to be isotopically similar to the parental magma. In a plot of compatible elements versus \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd, such evolution corresponds to a subhorizontal trend in which \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd does not vary significantly whereas the compatible element decreases continuously due to its sequestration into fractionating minerals. This behavior is shown by the evolution of thin arc magmas in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eIn contrast, parental magmas ascending from the mantle wedge through a thicker crust encounter hotter crustal rocks in the deeper parts of the arc and should interact more significantly with these rocks\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e, at least because they travel through a thicker warm lower crustal section. Under these conditions, interaction processes, such as assimilation and mixing with partial melts of the crust, are plausible\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e, in addition to the processes of recharge from continuously incoming basalt from the mantle, the latter feature also occurring in thin arcs. This has been described as MASH processes\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e or hot zones\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e occurring in the lower crust of thick arcs and might result in systematic radiogenic isotope changes in derivative magmas should the crust into which the parental basalt intrudes be isotopically different from the basalts themselves. Indeed, the trends of intermediate to thick arcs (Cascades, Northern Volcanic Zone NVZ, Mexico) to very thick ones (CVZ) show a continuous, albeit different, decrease in \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd values with decreasing MgO and Co, which is indicative of such a process (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\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\u003e\u003cb\u003eRanges of values for the parameters used in the equations describing the AFC model.\u003c/b\u003e \u003cem\u003eThe range of parent Nd and Co concentrations are from the range of oceanic and continental basalts of ref.\u003c/em\u003e \u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e. \u003cem\u003eThe ranges of Nd and Co concentrations of the assimilant are the same as that of the parent for thin arcs and are from ref.\u003c/em\u003e \u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e \u003cem\u003efor thick arcs and CVZ.\u003c/em\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eParameter\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eRange for thin arcs\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eRange for thick arcs\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eRange for CVZ\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRemaining melt\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0-100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0-100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0-100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u0026ndash;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.05-1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.05-1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNd parent (ppm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u0026ndash;15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14\u0026ndash;15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14\u0026ndash;15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNd assimilant (ppm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u0026ndash;15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11\u0026ndash;25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11\u0026ndash;25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd\u003csub\u003eparent\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.5130\u0026ndash;0.5132\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.51293\u0026ndash;0.51294\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.51293\u0026ndash;0.51294\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd\u003csub\u003eassimilant\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.5080\u0026ndash;0.5139\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.5114\u0026ndash;0.5132\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.5115\u0026ndash;0.5126\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCo parent (ppm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e40\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCo assimilant (ppm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20\u0026ndash;30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20\u0026ndash;30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDNd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.1\u0026ndash;0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.1\u0026ndash;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1\u0026ndash;0.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDCo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u0026ndash;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u0026ndash;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u0026ndash;6\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\u003eTo quantify these processes, assimilation fractional crystallization (AFC) modeling was carried out in the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd versus Co space using DePaolo\u0026rsquo;s\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e equations with input parameters of the elemental (Nd, Co) concentrations in the parent and assimilant, the Nd isotope composition of the parent and assimilant, the bulk partition coefficients for Nd and Co, the fraction of remaining melt and the ratio (r) of the mass of the assimilant to the mass of crystallized melt. In particular, the latter value is informative of the thermal status of the crustal level at which the AFC process is occurring, with r\u0026thinsp;=\u0026thinsp;0 corresponding to pure fractional crystallization, low r values (\u0026lt;\u0026thinsp;0.3) being typical of the upper crust, high r values (\u0026gt;\u0026thinsp;0.5) being typical of high assimilation rates in the lower crust and r nearing 1 virtually corresponding to pure mixing\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. A Monte Carlo approach was used due to the loosely constrained nature of most of the parameters used in the model (see Methods). Geologically significant ranges used for each of the parameters are reported in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cb\u003eDependency of crust assimilation by arc magmas on overriding plate thickness.\u003c/b\u003e The trends with slopes changing for different arc thicknesses in the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-MgO and \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co spaces suggest that, whereas arc magmas differentiating in thin crust arcs are consistent with a pure fractional crystallization process, mantle-derived arc basalts differentiating in increasingly thick crust require assimilation of crustal rocks, with increasingly lower \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd values as the crustal thickness increases.\u003c/p\u003e \u003cp\u003eTo evaluate the output of the Monte Carlo-based model of AFC, the model results have been filtered to fit the different arc trends in the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co space. Figures\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb, and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec show the forced fitting of the model to the data available for thin-intermediate arcs (Kermadec and Mariana as examples: Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea), thick arcs (Cascades and NVZ as examples: Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb) and the very thick CVZ arc (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). Figures\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee, and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef show the density scatterplots returning the most probable values of r and \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd\u003csub\u003eassimilant\u003c/sub\u003e in successfully reproducing the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co trends of Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb, and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec. The results of r for the thin arcs must be considered maximum values because the subhorizontal trends of all these arcs are consistent with a pure fractional crystallization process without any assimilation, a situation that cannot be modeled in these plots because not having an assimilant would result in no \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd\u003csub\u003eassimilant\u003c/sub\u003e values returned by the model and therefore in the impossibility of drawing Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe results suggest that the most probable solutions for the r values of the AFC process (highest density areas in Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, e, f) steadily increase with arc thickness, passing from \u0026lt;\u0026thinsp;0.25 (most likely close to 0 for the above discussion) in thin-intermediate arcs to 0.25\u0026ndash;0.50 for thick arcs and to \u0026gt;\u0026thinsp;0.75 for the very thick CVZ arc. The \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd\u003csub\u003eassimilant\u003c/sub\u003e in contrast steadily decreases from ~\u0026thinsp;0.51290 through ~\u0026thinsp;0.51265 to ~\u0026thinsp;0.51235 for thin-intermediate, thick and very thick arcs, respectively. Solutions for differential assimilation (different r values) of a similar low radiogenic assimilant (e.g., \u0026le;\u0026thinsp;0.5123) in both thick and very thick arcs are less probable, according to the model (see density contours in Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef).\u003c/p\u003e \u003cp\u003eAlthough the absolute r values of the model output have to be considered with caution, due to the uncertainties in the parameters used (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), the model results strongly support the intuitive hypothesis that arc magma differentiation in increasingly thicker arcs occurs in average at deeper crustal levels\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e and is therefore characterized by an increasing assimilation rate (r value) of the continental crust until a nearly pure mixing trend between crustal melts and mantle-derived components in the CVZ (r approaching 1).\u003c/p\u003e \u003cp\u003eSystematic variations in incompatible elements and their ratios in primitive magmas from arcs of different crustal thicknesses suggest that crustal thickness controls the degree of element enrichment also by modulating the partial melting of the mantle\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. It has been suggested that under thick continental arcs (and therefore under a thick lithosphere) the degree of partial melting of the mantle wedge is lower than under thin arcs because of a systematic change in the thermal structure of the mantle wedge with crustal thickness of the overriding plate\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. In contrast, radiogenic isotopes, including those of Nd, do not seem to be significantly affected by this process\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, although local correlations of \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd of primitive arc rocks with crustal thickness have been reported and attributed to systematic along-arc changes in ambient mantle\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. The results of the present study show a poor correlation of \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd\u003csub\u003eMgO12\u003c/sub\u003e of putative parent arc magmas with crustal thickness, which becomes more significant if the CVZ data are included (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). A possible mechanism explaining the much less radiogenic composition of putative parental magmas of the CVZ could be fertilization of the mantle wedge by subduction erosion of the lower portion of the overriding plate crust, which has been suggested to occur in the CVZ since ~\u0026thinsp;19 Myr, with the highest rates during the last 7 Myr\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. Subduction erosion likely occurs also in other arcs\u003csup\u003e\u003cspan additionalcitationids=\"CR33\" citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. The poor correlation of Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed leaves open the possibility of subduction erosion or any other process progressively enriching the mantle wedge source of arc magmas through time (i.e., decreasing its \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd value) as the arc thickness increases.\u003c/p\u003e \u003cp\u003eNonetheless, even considering such a potential decrease in the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd values of putative primitive magmas of arcs with crustal thickness (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed), the comparison between Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb shows that the Nd isotope systematics of derivative magmas of arcs increasingly thicker are controlled to a larger extent by the isotopic composition of the assimilant and therefore by intracrustal processes rather than by primary mantle-related differences. This lends strong support to the important role of arc thickness in modulating the elemental and isotopic compositions of derivative arc magmas through intracrustal processes that significantly overprint systematic geochemical trends caused by variable arc thicknesses in primitive magmas, especially in thicker arcs.\u003c/p\u003e \u003cp\u003e \u003cb\u003eImplications for continental crust growth processes.\u003c/b\u003e Another interesting and not straightforward outcome of the above data analysis is that the thickness of the arc crust correlates with the Nd isotopic composition of the assimilant (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef), suggesting that an increasingly thicker crust is characterized by overall increasingly lower \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd values. This suggests thickening of the continental crust in arcs by continuous reworking of previously formed (\u0026ldquo;isotopically older\u0026rdquo;) crust by subsequent episodes of \u0026ldquo;isotopically younger\u0026rdquo; arc magmatism\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e. Although the model ages returned by the assimilants through the regression of the slopes in the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-MgO and \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co spaces do not have an absolute geological meaning, they roughly represent the time-integrated \u0026ldquo;average\u0026rdquo; model ages of the reworked continental crust in the investigated arcs, suggesting reworking of progressively older crust as the arc thickness increases. In its turn, crustal thickness controls arc magma chemistry both at the source and in the crust through a feedback loop process. In fact, increasing crustal thickness, achieved through arc magmatism reworking of previous thinner crust segments, results in primitive magmas with increasingly higher contents of incompatible elements\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e and perhaps an increasingly crustal Nd isotope composition (i.e., lower \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd) of the ambient mantle wedge (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed), e.g., through subduction erosion or other processes. Parental magmas, during intracrustal evolution, become increasingly contaminated by their interaction with a thicker, older and more felsic crust (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec) driving it into an even thicker, more felsic and isotopically evolved crust. The thicker and older the crust the parental arc magmas are interacting with, the stronger the divergence of parental and derivative magmas from parental and especially derivative magmas of previous stages of arc crust build-up (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e), highlighting the significant role of magmatic reworking in crustal growth processes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe results of this study, therefore, in addition to vindicating a role of crustal thickness on the chemistry and isotopic composition of arc magmas both at their source and during crustal differentiation, are consistent with views of crustal growth as a continuous process characterized by increasing thickness, SiO\u003csub\u003e2\u003c/sub\u003e content and isotopically evolved compositions through time\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e, of which thin-intermediate and variably thick recent arcs could be a present-day snapshot.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eData selection and treatment\u003c/h2\u003e \u003cp\u003eWhole rock geochemical data (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://georoc.eu/georoc/new-start.asp\u003c/span\u003e\u003cspan address=\"https://georoc.eu/georoc/new-start.asp\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) of 16 arcs were filtered for ages (younger than Mio-Pliocene) and alteration (not or weakly altered). As in ref. \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e, to reduce the bias induced by outliers and to extract information on general trends, median values of \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd, MgO, and Co for subpopulations corresponding to bins of 0.5 wt% MgO were calculated (Supplementary Data S1) and plotted for each arc (Supplementary Figs. S1 and S2).\u003c/p\u003e \u003cp\u003eFor the Kurile arc, the data corresponding to two bins of MgO\u0026thinsp;\u0026lt;\u0026thinsp;1 wt.% (0.165 and 0.74 wt.%) were excluded because these rhyolites are formed by partial melting of crustal rocks\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. The data of these two bins significantly deviate from the main arc trend having much less radiogenic Nd isotope compositions (Supplementary Data S1). Additionally, the data corresponding to the MgO bin\u0026thinsp;=\u0026thinsp;0.19 wt.% of Honshu and 0.22 wt.% of Bismark-New Britain were excluded because they had anomalously low \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd values. Honshu rhyolites with low radiogenic values were formed during a rift stage associated with back-arc opening\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e. Bismark-New Britain rhyolitic and trachytic samples were also formed in a rift environment, possibly involving partial melting of the lower crust of the Australian continent\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e. Overall, the few anomalous values that were excluded always correspond to very evolved rocks (MgO\u0026thinsp;\u0026lt;\u0026thinsp;1 wt.%), which were formed by peculiar processes different from those of the main evolutionary trend of the arcs. For some arcs, a few bins did not have any reported value of either \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd or Co and could not be plotted (e.g., MgO bins 0.725, 1.17, 1.8, 2.32, 8.7 wt.% for New Hebrides do not have any reported \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd value in the Georoc database). Supplementary Data S1 reports all data, including those excluded from the regressions for the reasons discussed above.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eAFC modeling\u003c/h2\u003e \u003cp\u003eAssimilation-fractional crystallization (AFC) modeling in the \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e144\u003c/sup\u003eNd-Co space was carried out using the equations of DePaolo\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. AFC is a simple but powerful model that incorporates two main processes resulting in magma differentiation in magmatic arcs, namely, fractional crystallization and assimilation. The r value, i.e., the ratio of the mass of the assimilant to the mass of crystallized melt, of the AFC model can also provide broad estimates of the thermal state at which assimilation occurs because high r values mean a high rate of assimilation that may only occur for host rocks at high temperatures, i.e., a situation typical of the lower crust, whereas lower r values correspond to assimilation at shallower levels. Although it may not capture all their complex combination, AFC offers first-order control on the occurrence of evolutionary processes in arc magmas.\u003c/p\u003e \u003cp\u003eBecause the parameters involved in such equations cannot be given fixed values, I let them vary within geologically and geochemically sound ranges as indicated in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and run the equations for 5\u0026rsquo;000\u0026rsquo;000 simulations using a Monte Carlo approach with a homemade script written in RStudio\u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e (Supplementary Notes 1\u0026ndash;3). The outputs of the model can then be evaluated in probabilistic terms against the real data to infer the most probable values of the unknown parameters returned by the model and therefore the most likely petrogenetic processes. This is done by keeping only those solutions of the model that reproduce the trends observed in thin, thick and very thick arcs, using best fit equations and allowing a fixed uncertainty in the parameters of those best fits to include most of the observed data in the successful simulations (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee and Supplementary Notes 1\u0026ndash;3).\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFunding:\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSwiss National Science Foundation N. 200021_169032 (MC)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization: MC\u003c/p\u003e\n\u003cp\u003eMethodology: MC\u003c/p\u003e\n\u003cp\u003eInvestigation: MC\u003c/p\u003e\n\u003cp\u003eVisualization: MC\u003c/p\u003e\n\u003cp\u003eSupervision: MC\u003c/p\u003e\n\u003cp\u003eWriting\u0026mdash;original draft: MC\u003c/p\u003e\n\u003cp\u003eWriting\u0026mdash;review \u0026amp; editing: MC\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAuthor declares that he has no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData and materials availability:\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll data are available in the main text and in the Supplementary Information and Supplementary Data.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eZellmer, G. F., Edmonds, M. \u0026amp; Straub, S. M. Volatiles in subduction zone magmatism. Geological Society, London, Special Publications 410, 1\u0026ndash;17 (2015).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRobock, A. Volcanic eruptions and climate. Reviews of Geophysics 38, 191\u0026ndash;219 (2000).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSheldrake, T., Caricchi, L. \u0026amp; Scutari, M. Tectonic Controls on Global Variations of Large-Magnitude Explosive Eruptions in Volcanic Arcs. Front. Earth Sci. 8, (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChiaradia, M. Distinct magma evolution processes control the formation of porphyry Cu\u0026ndash;Au deposits in thin and thick arcs. Earth and Planetary Science Letters 599, 117864 (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChiaradia, M. \u0026amp; Caricchi, L. Supergiant porphyry copper deposits are failed large eruptions. 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(2013).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","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":"","lastPublishedDoi":"10.21203/rs.3.rs-3870583/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3870583/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eArc magmas form new continental crust and are responsible for volcanic eruptions as well as for major metallic ore deposits. It is generally accepted that arc magmas are generated above subduction zones by partial melting of the mantle wedge and differentiate within the crust of the overriding plate through fractional crystallization, magma mixing and crustal assimilation. However, it is not clear in which proportions mantle and the above different intracrustal processes contribute to the broad geochemical variability of arc magmas. Here, using Nd isotope systematics and their geochemical modelling, I show that the thicker the crust of the overriding plate, the higher the assimilation rate of crustal rocks by mantle-derived magmas and the older the assimilated rocks. This highlights a systematic increase of crustal contribution to arc magma chemical and isotopic composition with the thickening of the overriding plate crust. The data presented are also consistent with growth and maturation of the continental crust through time by continuously increasing thickness, SiO\u003csub\u003e2\u003c/sub\u003e content and Nd isotopically evolved composition.\u003c/p\u003e","manuscriptTitle":"Differentiation of arc magmas and crustal growth: a Nd isotope perspective","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-19 15:08:54","doi":"10.21203/rs.3.rs-3870583/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":"92bda615-abc9-4444-9bac-28024bdb777c","owner":[],"postedDate":"January 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":28241449,"name":"Earth and environmental sciences/Planetary science"},{"id":28241450,"name":"Earth and environmental sciences/Planetary science/Geochemistry"},{"id":28241451,"name":"Earth and environmental sciences/Planetary science/Petrology"}],"tags":[],"updatedAt":"2024-02-23T04:21:46+00:00","versionOfRecord":[],"versionCreatedAt":"2024-01-19 15:08:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3870583","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3870583","identity":"rs-3870583","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}