Formation of deep mantle heterogeneities through basal exsolution contaminated magma ocean

Formation of deep mantle heterogeneities through basal exsolution contaminated magma ocean | 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 Formation of deep mantle heterogeneities through basal exsolution contaminated magma ocean JIE DENG, Yoshinori Miyazaki, Zhixue Du This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3263305/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 12 Sep, 2025 Read the published version in Nature Geoscience → Version 1 posted You are reading this latest preprint version Abstract Earth’s mantle harbors two large low shear-wave velocity provinces (LLSVPs) with patches of ultra-low velocity zones (ULVZs) distributed in the bottom. These structures exhibit distinct seismic and geochemical signatures compared to the surrounding mantle. Yet, their origin remains enigmatic. One proposed explanation is the differentiation of an early basal magma ocean (BMO). However, the presence of an excessively thick layer of iron-rich ferropericlase in the crystallized BMO conflicts with seismic tomography. Here, we investigate the crystallization of a BMO continuously contaminated by oxide exsolutions from the core, termed BECMO, and find significant suppression of ferropericlase crystallization and consequently a mineralogical profile consistent with LLSVPs and ULVZs. In addition, diapirs of core exsolution entrained into the solid mantle may cause small-scale scattering. The BECMO inherits the light silicon isotope composition from the core and exhibits trace element enrichments, suggesting its potential role as a source material for ocean island basalts potentially sampling the lowermost LLSVPs, pointing to a unified mechanism for forming deep mantle heterogeneities. Figures Figure 1 Figure 2 Figure 3 One-Sentence Summary A novel mechanism called basal exsolution contaminated magma ocean (BECMO) provides a unified mechanism for the formation of deep mantle heterogeneities. Main Text Earth’s lower mantle, considered mostly homogeneous, harbors two prominent large low shear-wave velocity provinces (LLSVPs) positioned beneath the Pacific and Africa 1 . These LLSVPs exhibit mild reductions in P-wave ( V P ) and S-wave ( V s) velocities, and a comparable increase in bulk sound velocity ( V Φ ), along with the decorrelation observed between V s and density anomalies in normal mode tomography 2 , the excess density in tidal tomography 3 , the presence of sharp margins 4 , and the occurrence of ultralow velocity zones (ULVZs) within or near the edges 1 . In addition, ocean island basalts (OIBs) that potentially sample the lowermost LLSVPs contain distinct isotope ratios compared with mid-ocean ridge basalts (MORBs) and other mantle reservoirs 5 . For major elements, Si of some OIBs is isotopically lighter than that of MORBs 6 . Anomalies in primordial and/or short-lived isotopic systematics of trace elements further indicate an early origin of the source of OIBs, and hence LLSVPs and ULVZs 7-10 . These characteristics collectively suggest the existence of primordial and intrinsically dense thermochemical piles enriched in iron and silicon 1,11 . Despite these observations, the origin of LLSVPs remains a topic of ongoing debate. One prominent mechanism proposed for generating primordial, deep, and dense materials characteristic of LLSVPs is the differentiation of a primordial basal magma ocean (BMO) 12-14 . Following the Moon-forming giant impact, extensive melting of Earth likely led to the formation of a BMO, wherein iron favored the liquid phase and subsequent crystallization generated negatively buoyant silicate melts 15-18 . The BMO holds significant intrigue, as it may not only produce heterogeneous seismic structures such as LLSVPs and ULVZs but also offer a compelling explanation for the ancient geodynamo 19 and the preservation of primordial geochemical signatures 7-9 . Phase equilibrium calculations suggest that the solidification of BMO quickly depletes the silicate melts of Si due to the crystallization of the first liquidus phase, bridgmanite, leading to a 1000-km bottom layer that contains approximately 20 wt% of ferropericlase 20 . However, this contrasts sharply with inferences drawn from seismic tomography which favor a low ferropericlase content of ~6-10 wt% 21,22 . If LLSVPs originate from the BMO, a mechanism enriching Si content is required to replenish the crystallizing BMO and suppress the production of ferropericlase. Recently, oxide exsolutions such as MgO and SiO 2 have been proposed as a new form of mass flux from the core into the mantle 23-26 . Core exsolutions deliver distinctive core-like geochemical signatures and may serve as the source materials for OIBs 27,28 . However, the interaction between these oxides and the BMO has not been systematically explored 29 . Here, we study the crystallization of basal exsolution contaminated magma ocean (BECMO), where synchronous BMO solidification and core exsolution occur (Fig. 1). Our results demonstrate that the continuous supply of core exsolutions significantly inhibits the crystallization of ferropericlase within the BECMO, particularly at the late stage. Core exsolutions also reduces Fe contents of the final-stage MO cumulates which may serve as the source material to generate the LLSVPs and ULVZs by convective mixing. In the region where BECMO is solidified, core exsolution may be entrained in the solid mantle as diapirs, causing small-scale seismic scattering in the deep mantle. Geochemically, BECMO materials may possess both the BMO-like signature with enriched trace elements and core-like signature such as enrichment in primordial 3 He and depletion in 182 W 27 . The solidified mantle from the BECMO and the SiO 2 -rich diapirs entrained also inherits the light Si isotope signature from core and thus may represent a potential source material for OIBs. Results and Discussion Transfer and dissolution of core exsolution Several studies have proposed that as Earth cools, light elements such as Mg 23 , 24 , 30 , 31 , Si, and O 26 become saturated in the core and precipitate in the forms of SiO 2 and MgO. The high melting points of MgO and SiO 2 , i.e., around 8000 K and 6000 K at the core-mantle boundary (CMB), respectively 32 – 35 , indicate that these precipitates occur as crystalline solids. Although trace elements like iron may slightly lower their melting points 36 , their concentrations are not significant 23 , 26 . In this study, we focus on the exsolution of MgO and SiO 2 from the core at the CMB as crystalline particles. Both SiO 2 and MgO are buoyant in the lowermost mantle (Fig. S1). Due to the large density contrast with the core fluid, the exsolved particles can only grow to nanometer sizes before sedimenting towards the topmost outer core (Supplementary Information). The fate of these core exsolutions largely depends on the state of the overlying mantle. If the mantle is in a solid state, the significant rheological contrast between the exsolution and solid silicate causes the exsolved particles to accumulate as a layer at the CMB. Rayleigh-Taylor instability then develops, leading to the formation of diapirs that rise through the mantle for thousands of kilometers until they reach a neutral buoyancy depth (Fig. 1 ) 37 . Conversely, if the overlying mantle is in a liquid state, as in the case of a BMO, the core exsolutions float into the magma ocean and dissolve immediately (Fig. S2; Supplementary Information). As a result, the cooling core continuously supplies MgO and SiO 2 to the crystalizing magma ocean. In our model, we assume that only Mg, Si, and O precipitate out of the core and do not consider the reverse diffusion of elements 38 . We follow ref. 39 to assume that light elements dissolved into the core form a stably stratified layer below the CMB, which resists mixing with the rest of the core fluid. Solidification of the basal exsolution contaminated magma ocean We model the solidification and differentiation of a BMO and a BECMO using the self-consistent thermodynamic model of ref. 40 with a simplified pyrolitic bulk composition (42.2 wt%, FeO: 8.7 wt%, and SiO 2 : 49.1 wt%). For both cases, we assume that a BMO of a ~ 500 km thickness is initially formed as a result of melt-solid density crossover 15 , 16 (Supplementary Information). The preferential partitioning of iron into the melt phase makes it heavier than the coexisting solid at pressures greater than ~ 80 GPa, and percolation would extract iron-rich melt from the mushy layer and transport it towards the CMB (Fig. 1 ). We calculate the amount and composition of newly formed crystals within the BMO, as the temperature of the CMB decreases from 5000 K to ~ 3700 K at which both BMO and BECMO completely solidify. Crystals are considered to form a fractionated layer at the top of BMO, and the BMO thickness decreases with time. The major difference between BECMO and BMO is that, for the former, MgO and SiO 2 solids exsolved from the core are continuously dissolved into the magma ocean. Without the addition of exsolutions, the fractionation within the BMO creates a deep layer extremely enriched in FeO in the lowermost 200 km (Fig. 2 ). This is due to the sequestration of the liquidus mineral, Mg-rich bridgmanite into the solidified mantle, and thus the enrichment of FeO correlates with the depletion of SiO 2 , leading to the formation of a thick bottom layer composed of mostly FeO. Fe-rich ferropericlase significantly reduces V Φ and thus cannot generate the observed the anti-correlation of V s and V Φ . The general trend of variation of element concentration with depth is consistent with another thermodynamic calculation 20 . Such an outcome is always expected as long as a small iron partitioning coefficient between bridgmanite and melt is adopted in a thermodynamic model, which, however, is not the case for ref. 41 . We note that an early study 20 predicts an even stronger enrichment of FeO at the CMB than in Fig. 2 . The difference arises because we assume that some amounts of Fe-rich melt are trapped within the fractionated layer due to a relatively low effective percolation efficiency (Fig. S3; Supplementary Information). The addition of the exsolutions significantly changes the composition and mineralogy of the lowermost mantle, with minimal effects on the shallow part (Fig. 2 ). This is expected as the magma ocean is voluminous initially and the effects of exsolution dissolution are diluted. Since the SiO 2 yield is much larger than the MgO yield (Supplementary Information), the compositional response of the magma ocean is dominated by SiO 2 addition. SiO 2 consumed due to the crystallization of bridgmanite is replenished by the exsolution, resulting in a nearly constant molar fraction of SiO 2 for most depths in the solidified mantle at pressures smaller than approximately 132 GPa. Note overall the SiO 2 content of the residual liquid still decrease with time as the consumption of SiO 2 due to bridgmanite crystallization exceeds the rate of SiO 2 assimilation (Fig. S4). Nevertheless, the addition of core exsolution significantly delay the depletion of SiO 2 component to the state where ferropericlase is the liquidus phase 29 . Consequently, silicate phases dominate most depths, with ferropericlase concentrated towards the very bottom of the mantle. As a result, the solidification of the BECMO can simultaneously explain the SiO 2 and FeO enrichment in the LLSVPs as well as the Fe-rich and dense ultralow-velocity zones in the base of the mantle, as inferred from the tomography models 21 , 22 . We note that the amount of MgO and SiO 2 added to the mantle by exsolution could be as large as ~ 10 23 kg (Supplementary Information), which is a few percent of the present-day mantle mass. This large amount of exsolution leads to an increase in the CMB pressure by over 5 GPa and, equivalently a recession of the CMB of over 70 km, diluting the effect of FeO concentration near the lowermost layer. Density of solidified BECMO and its long-term stability We further compare the density of the solidified mantles of the two fractionated models as well as the unfractionated mantle of the same bulk composition (Fig. S5). As expected, the unfractionated mantle closely mimics that of the PREM 42 . Mantles crystallized from BMO and BECMO share nearly identical densities for most of the depths except for the lowermost ~ 200 km. Both solidified BMO and BECMO mantles are around 1.3% less dense than the unfractionated mantle at depths shallower than around 2700 km. Such a small difference is generated by considering a relatively large melt retention during magma ocean solidification (Supplementary Information). The sharp increase in densities for both BMO and BECMO mantles below around 2700 km depth is a result of the accumulation of Fe-rich ferropericlase or magnesiowüstite. Due to the suppressed production of ferropericlase in BECMO, the bottom dense layer of the BECMO mantle is significantly thinner, and the maximum density is less extreme than that of BMO (Fig. S4). Density is the most important parameter that governs the structure and long-term stability of primordial dense piles in the lower mantle 43 . A low intrinsic (or chemical) density contrast between the primordial material and the surrounding regular mantle material (i.e., a small buoyancy ratio) favors rapid mixing, whereas a primordial base layer that is too intrinsically dense compared to the surroundings, is difficult to mix even after billion years 44 . Geodynamic simulations suggest that LLSVPs-like structures are more likely to form from the convective mixing of materials with a buoyancy ratio of 0.2–0.36, albeit this value is sensitive to other parameters such as the viscosity contrast between dense and ambient materials 43 , 45 . For the intrinsically light layer above around 2700-km depths, convective mixing with the surrounding materials brings up the density and completely erases the density anomaly for the majority (~ 86 vol%) of the light layer outside LLSVPs. Stoneley mode analysis suggests that LLSVPs are ~ 0.88% lighter at depths shallower than 2700 km 46 , coinciding with the scale of the light layer derived from the BMO and BECMO crystallization. If the shallow LLSVPs is intrinsically lighter, to generate the observed density anomaly, the remaining 14% of the primordial light layer may mix with the ambient mantle in a ratio of 3:1 by volume. On the other hand, if the shallow LLSVPs are intrinsically denser 21 and the apparent small density is due to thermal buoyancy, mixing with the dense base layer is required. The solidified BMO and BECMO are characterized by contrasting density profiles of the bottom dense layers. A well-known consequence of BMO crystallization is the long-term preservation of a thin layer of extremely enriched cumulates with high iron content (over 40 mol% of FeO), which is inconsistent with seismic constraints 44 . We find that a dense layer with a buoyancy ratio above 0.36 is around 135 km thick for the solidified BMO mantle, while efficiently decreasing to around 57 km for the BECMO mantle. Although this layer with a large buoyancy ratio for BECMO is still thicker than of ULVZs (10–40 km), it will likely be eroded with time as dense materials get entrained by mantle upwellings 47 . We note that the density profile of the solidified BECMO mantle (Fig. S5) is very similar to the initial setup of geodynamic modeling presented by ref. 14 , where a layer of materials from 40 to 200 km above the CMB with an intrinsic density 1.5% greater than the background mantle and the bottom 40 km of 15% denser, after billions of years of convective mixing, generates LLSVPs and ULVZs beneath the Coral Sea between Australia and New Zealand. Therefore, the addition of core exsolution is an effective means to reduce the Fe-content of the final-stage magma ocean cumulates 44 . The resulting density structure is well suited to generate LLSVPs and ULVZs. Si isotope composition The addition of core exsolutions affects the Si isotopic compositions of the deep Earth. Core fluid is depleted in heavy Si isotopes relative to the bulk silicate Earth (BSE) 48 – 51 . As a result, SiO 2 exsolved from the core has a light Si isotope composition with \(\:{\delta\:}{}^{30}{\text{S}\text{i}}_{SiO2}\:\) smaller than that of the BSE ( \(\:{\delta\:}{}^{30}{\text{S}\text{i}}_{\text{B}\text{S}\text{E}}\) = − 0.29 ± 0.07‰) 52 , 53 by about 0.11‰-0.35‰ (Supplementary Information; Fig. S6) 54 . SiO 2 exsolution, once dissolved into the BECMO, would bring down the \(\:{\delta\:}{}^{30}\text{S}\text{i}\) value of the magma ocean. The resulting Si isotope composition profile is shown in Fig. 3 . \(\:{\delta\:}{}^{30}\text{S}\text{i}\) of OIBs ( \(\:{\delta\:}{}^{30}{\text{S}\text{i}}_{\text{O}\text{I}\text{B}}\) = − 0.32 ± 0.09‰) exhibits large variability and on average is slightly more negative than \(\:{\delta\:}{}^{30}{\text{S}\text{i}}_{BSE}\) . Thermochemical convection calculations show that entrainment of pile materials into plumes typically does not exceeds ~ 12% 12, 55 . The strong negative Si isotopic anomaly at the lowermost mantle would be inevitably diluted by the ambient mantle. The observed variability of \(\:{\delta\:}{}^{30}{\text{S}\text{i}}_{BSE}\) can be generated by the sampling solidified at various depths of or by mixing with the ambient mantle in various proportions (Fig. 3 B). The strong negative \(\:{\delta\:}{}^{30}{\text{S}\text{i}}_{\text{O}\text{I}\text{B}}\) such as − 0.40 ± 0.07‰ in Iceland OIBs can only be generated with large fraction of the BECMO material, or by mixing with smaller amounts of scattered SiO 2 diapirs in the deep mantle 6 , 54 . Implications for lower mantle heterogeneities Many mechanisms have been proposed for generating deep and dense materials characteristic of LLSVPs 11 , 13 , 56 – 58 , among which the accumulation of recycled oceanic crust, primarily composed of MORBs, has received significant attention 11 , 59 – 62 . However, the seismic properties of MORBs in the deep mantle are subject to controversy 63 . While extrapolations based on low-pressure experiments suggest that MORBs may manifest as low-seismic-velocity anomalies in the lower mantle 64 , theoretical calculations have arrived at contradictory conclusions 65 . Geochemical evidence further challenges the notion that the deep edge of LLSVPs consists of MORBs, where OIBs are believed to sample. First, MORBs share the same Si isotope composition as the BSE, making it incapable of generating the light isotopic characteristics observed in some OIBs, despite the possibility of isotopically light altered oceanic crust 66 . Second, MORBs have been suggested to be chemically and isotopically too depleted to be the OIBs source materials 10 . MORBs are depleted of incompatible elements with small average La/Sm and Rb/Sr concentration ratios. Additionally, MORBs exhibit depleted isotopic compositions such as low 87 Sr/ 86 Sr, high 143 Nd/ 14 Nd, and high 176 Hf/ 177 Hf, which contrast the correlated trends observed in global OIBs. Consequently, the association between the subducted oceanic crust and LLSVPs remains uncertain. In contrast, the BECMO shares similar elemental abundances with the classic BMO, offering a promising explanation. BECMO, in contrast to the source mantle of MORBs, is enriched in incompatible elements and thus may host high La/Sm and Rb/Sr, high 87 Sr/ 86 Sr, low 143 Nd/ 14 Nd, and low 176 Hf/ 177 Hf ratios 13 , 67 . As such, BECMO, just like BMO, may serve as the hidden enriched reservoir to account for the terrestrial Hf-Nd mantle array 68 . The influx of SiO 2 exsolution from the core enriches the deep mantle derived from BECMO, aligning its compositional and mineralogical profiles with seismic observations and the geochemical signatures of OIBs. Furthermore, core exsolutions selectively deliver core signatures based on the solubility of corresponding elements, such as He and W. Highly siderophile elements are unlikely to be transferred by core exsolution to the mantle due to their insolubility in MgO and SiO 2 . Additionally, core exsolution may refractionate of He and Ne in the core fluid, resulting in an OIB-like 3 He/ 22 Ne signature in LLSVPs 27 , 69 . The crystallization of BECMO not only explains the formation of LLSVPs but also naturally gives rise to a thin layer of FeO-rich ferropericlase at the bottom, which could be the source of ULVZs 70 . In the region where BECMO is solidified, core exsolution may be entrained into the solid mantle, causing small-scale seismic scattering in the lower mantle 37 , 71 , 72 . As such, BECMO provides a unified mechanism that may account for both the seismic and geochemical heterogeneities observed in the deep Earth. By incorporating the influx of SiO 2 and MgO exsolution from the core and the selective delivery of core signatures, BECMO offers a comprehensive explanation for the complex relationships between LLSVPs, ULVZs, OIBs, and other deep Earth features, bridging gaps in our understanding of the deep mantle dynamics and the origins of these enigmatic phenomena. Declarations Data Availability The main data supporting the findings of this study are available within the paper and its supplementary information. Competing interests The authors declare no Competing Financial or Non-Financial Interests. Author contributions J.D. conceived and coordinated the entire project. Y.M. and J.D. performed calculations and modeling. J.D. wrote the first draft. All authors contributed to the discussion and revision of the manuscript. Acknowledgments J.D. acknowledge National Science Foundation EAR- 2242946. Z.D. expresses thanks for the funding from National Natural Science Foundation of China (no. 42150102) and from the Strategic Priority Research Program (B) of the Chinese Academy of Science (no. XDB18000000). Y.M. was supported by Stanback Postdoctoral Fellowship from Caltech Center for Comparative Planetary Evolution. References Garnero, E. J., McNamara, A. K. & Shim, S.-H. Continent-sized anomalous zones with low seismic velocity at the base of Earth's mantle. Nat Geosci 9, 481–489 (2016). https://doi.org:10.1038/ngeo2733 Trampert, J., Deschamps, F., Resovsky, J. & Yuen, D. Probabilistic Tomography Maps Chemical Heterogeneities Throughout the Lower Mantle. Science 306, 853–856 (2004). https://doi.org:doi:10.1126/science.1101996 Lau, H. C. P. et al. Tidal tomography constrains Earth’s deep-mantle buoyancy. Nature 551, 321 (2017). https://doi.org:10.1038/nature24452 Ni, S., Tan, E., Gurnis, M. & Helmberger, D. Sharp Sides to the African Superplume. Science 296, 1850–1852 (2002). https://doi.org:doi:10.1126/science.1070698 Hofmann, A. W. & Hart, S. R. An assessment of local and regional isotopic equilibrium in the mantle. Earth and Planetary Science Letters 38, 44–62 (1978). https://doi.org: https://doi.org/10.1016/0012-821X(78)90125-5 Pringle, E. A. et al. Silicon isotopes reveal recycled altered oceanic crust in the mantle sources of Ocean Island Basalts. Geochimica et Cosmochimica Acta 189, 282–295 (2016). https://doi.org: https://doi.org/10.1016/j.gca.2016.06.008 Deng, J. & Stixrude, L. Deep fractionation of Hf in a solidifying magma ocean and its implications for tungsten isotopic heterogeneities in the mantle. Earth and Planetary Science Letters 562, 116873 (2021). https://doi.org:10.1016/j.epsl.2021.116873 Mukhopadhyay, S. & Parai, R. Noble Gases: A Record of Earth's Evolution and Mantle Dynamics. Annual Review of Earth and Planetary Sciences 47, 389–419 (2019). https://doi.org:10.1146/annurev-earth-053018-060238 Mundl-Petermeier, A. et al. Anomalous 182 W in high 3 He/ 4 He Ocean Island Basalts: Fingerprints of Earth’s core? Geochimica et Cosmochimica Acta (2019). https://doi.org:10.1016/j.gca.2019.12.020 Niu, Y. Origin of the LLSVPs at the base of the mantle is a consequence of plate tectonics – A petrological and geochemical perspective. Geoscience Frontiers 9, 1265–1278 (2018). https://doi.org:https://doi.org/10.1016/j.gsf.2018.03.005 Tackley, P. J. Dynamics and evolution of the deep mantle resulting from thermal, chemical, phase and melting effects. Earth-Science Reviews 110, 1–25 (2012). https://doi.org: https://doi.org/10.1016/j.earscirev.2011.10.001 Deschamps, F., Kaminski, E. & Tackley, P. J. A deep mantle origin for the primitive signature of ocean island basalt. Nat Geosci 4, 879–882 (2011). https://doi.org:10.1038/ngeo1295 Labrosse, S., Hernlund, J. W. & Coltice, N. A crystallizing dense magma ocean at the base of the Earth’s mantle. Nature 450, 866–869 (2007). https://doi.org:10.1038/nature06355 Pachhai, S., Li, M., Thorne, M. S., Dettmer, J. & Tkalčić, H. Internal structure of ultralow-velocity zones consistent with origin from a basal magma ocean. Nat Geosci 15, 79–84 (2022). https://doi.org:10.1038/s41561-021-00871-5 Nomura, R. et al. Spin crossover and iron-rich silicate melt in the Earth’s deep mantle. Nature 473, 199–202 (2011). https://doi.org:10.1038/nature09940 Caracas, R., Hirose, K., Nomura, R. & Ballmer, M. D. Melt–crystal density crossover in a deep magma ocean. Earth and Planetary Science Letters 516, 202–211 (2019). https://doi.org:https://doi.org/10.1016/j.epsl.2019.03.031 Miyazaki, Y. & Korenaga, J. On the Timescale of Magma Ocean Solidification and Its Chemical Consequences: 2. Compositional Differentiation Under Crystal Accumulation and Matrix Compaction. Journal of Geophysical Research: Solid Earth 124, 3399–3419 (2019). https://doi.org:https://doi.org/10.1029/2018JB016928 Nakajima, M. & Stevenson, D. J. Melting and mixing states of the Earth's mantle after the Moon-forming impact. Earth and Planetary Science Letters 427, 286–295 (2015). https://doi.org:https://doi.org/10.1016/j.epsl.2015.06.023 Stixrude, L., Scipioni, R. & Desjarlais, M. P. A silicate dynamo in the early Earth. Nature Communications 11, 935 (2020). https://doi.org:10.1038/s41467-020-14773-4 Boukaré, C. E., Ricard, Y. & Fiquet, G. Thermodynamics of the MgO-FeO-SiO 2 system up to 140 GPa: Application to the crystallization of Earth's magma ocean. Journal of Geophysical Research: Solid Earth 120, 2015JB011929 (2015). https://doi.org:10.1002/2015JB011929 Deng, X. et al. Compositional and thermal state of the lower mantle from joint 3D inversion with seismic tomography and mineral elasticity. Proceedings of the National Academy of Sciences 120, e2220178120 (2023). https://doi.org:doi:10.1073/pnas.2220178120 Vilella, K. et al. Constraints on the composition and temperature of LLSVPs from seismic properties of lower mantle minerals. Earth and Planetary Science Letters 554, 116685 (2021). https://doi.org:https://doi.org/10.1016/j.epsl.2020.116685 O'Rourke, J. G., Korenaga, J. & Stevenson, D. J. Thermal evolution of Earth with magnesium precipitation in the core. Earth and Planetary Science Letters 458, 263–272 (2017). https://doi.org:https://doi.org/10.1016/j.epsl.2016.10.057 Badro, J., Siebert, J. & Nimmo, F. An early geodynamo driven by exsolution of mantle components from Earth’s core. Nature advance online publication (2016). https://doi.org:10.1038/nature18594 Du, Z. et al. Insufficient energy from MgO exsolution to power early geodynamo. Geophysical Research Letters, 11376–11381 (2017). https://doi.org:10.1002/2017GL075283 Hirose, K. et al. Crystallization of silicon dioxide and compositional evolution of the Earth’s core. Nature advance online publication (2017). https://doi.org:10.1038/nature21367 Deng, J. & Du, Z. Primordial helium extracted from the Earth’s core through magnesium oxide exsolution. Nat Geosci (2023). https://doi.org:10.1038/s41561-023-01182-7 Rizo, H. et al. 182 W evidence for core-mantle interaction in the source of mantle plumes. Geochemical Perspectives Letters 11, 6–11 (2019). https://doi.org:10.7185/geochemlet.1917 Trønnes, R. G. et al. Core formation, mantle differentiation and core-mantle interaction within Earth and the terrestrial planets. Tectonophysics 760, 165–198 (2019). https://doi.org: https://doi.org/10.1016/j.tecto.2018.10.021 Du, Z., Deng, J. & Lee, K. K. M. Experimental Constraints on Ferropericlase (Mg, Fe)O Melt Viscosity Up to 70 GPa. Geophysical Research Letters 44, 12,190 – 112,196 (2017). https://doi.org:10.1002/2017GL076177 Du, Z., Boujibar, A., Driscoll, P. & Fei, Y. Experimental Constraints on an MgO Exsolution-Driven Geodynamo. Geophysical Research Letters 46, 7379–7385 (2019). https://doi.org:0.1029/2019GL083017 Alfè, D. Melting Curve of MgO from First-Principles Simulations. Phys Rev Lett 94, 235701 (2005). https://doi.org:10.1103/PhysRevLett.94.235701 Du, Z. & Lee, K. K. M. High-pressure melting of MgO from (Mg,Fe)O solid solutions. Geophysical Research Letters 41, 8061–8066 (2014). https://doi.org:https://doi.org/10.1002/2014GL061954 Usui, Y. & Tsuchiya, T. Ab initio two-phase molecular dynamics on the melting curve of SiO 2 . Journal of Earth Science 21, 801–810 (2010). https://doi.org:10.1007/s12583-010-0126-9 González-Cataldo, F., Davis, S. & Gutiérrez, G. Melting curve of SiO 2 at multimegabar pressures: implications for gas giants and super-Earths. Scientific Reports 6, 26537 (2016). https://doi.org:10.1038/srep26537 Deng, J., Miyazaki, Y. & Lee, K. K. M. Implications for the melting phase relations in the MgO-FeO system at core-mantle boundary conditions. Journal of Geophysical Research: Solid Earth 124, 11 (2019). https://doi.org:10.1029/2018JB015499 Helffrich, G., Ballmer, M. D. & Hirose, K. Core-Exsolved SiO2 Dispersal in the Earth's Mantle. Journal of Geophysical Research: Solid Earth 123, 176–188 (2018). https://doi.org:https://doi.org/10.1002/2017JB014865 Davies, C. J., Pozzo, M., Gubbins, D. & Alfè, D. Transfer of oxygen to Earth's core from a long-lived magma ocean. Earth and Planetary Science Letters 538, 116208 (2020). https://doi.org:https://doi.org/10.1016/j.epsl.2020.116208 Mittal, T. et al. Precipitation of multiple light elements to power Earth's early dynamo. Earth and Planetary Science Letters 532, 116030 (2020). https://doi.org: https://doi.org/10.1016/j.epsl.2019.116030 Miyazaki, Y. & Korenaga, J. On the Timescale of Magma Ocean Solidification and Its Chemical Consequences: 1. Thermodynamic Database for Liquid at High Pressures. Journal of Geophysical Research: Solid Earth 124, 3382–3398 (2019). https://doi.org:https://doi.org/10.1029/2018JB016932 Andrault, D. et al. Solidus and liquidus profiles of chondritic mantle: Implication for melting of the Earth across its history. Earth and Planetary Science Letters 304, 251–259 (2011). https://doi.org:https://doi.org/10.1016/j.epsl.2011.02.006 Dziewonski, A. M. & Anderson, D. L. Preliminary reference Earth model. Physics of the Earth and Planetary Interiors 25, 297–356 (1981). https://doi.org:10.1016/0031-9201(81)90046-7 Li, Y., Deschamps, F. & Tackley, P. J. The stability and structure of primordial reservoirs in the lower mantle: insights from models of thermochemical convection in three-dimensional spherical geometry. Geophys J Int 199, 914–930 (2014). https://doi.org:10.1093/gji/ggu295 Ballmer, M. D., Lourenço, D. L., Hirose, K., Caracas, R. & Nomura, R. Reconciling magma-ocean crystallization models with the present-day structure of the Earth's mantle. Geochemistry, Geophysics, Geosystems 18, 2785–2806 (2017). https://doi.org:https://doi.org/10.1002/2017GC006917 Gülcher, A. J. P., Ballmer, M. D. & Tackley, P. J. Coupled dynamics and evolution of primordial and recycled heterogeneity in Earth's lower mantle. Solid Earth 12, 2087–2107 (2021). https://doi.org:10.5194/se-12-2087-2021 Koelemeijer, P., Deuss, A. & Ritsema, J. Density structure of Earth’s lowermost mantle from Stoneley mode splitting observations. Nature Communications 8, 15241 (2017). https://doi.org:10.1038/ncomms15241 McNamara, A. K. A review of large low shear velocity provinces and ultra low velocity zones. Tectonophysics 760, 199–220 (2019). https://doi.org:https://doi.org/ 10.1016/j.tecto.2018.04.015 Shahar, A. et al. High-temperature Si isotope fractionation between iron metal and silicate. Geochimica et Cosmochimica Acta 75, 7688–7697 (2011). https://doi.org : https://doi.org/10.1016/j.gca.2011.09.038 Hin, R. C., Fitoussi, C., Schmidt, M. W. & Bourdon, B. Experimental determination of the Si isotope fractionation factor between liquid metal and liquid silicate. Earth and Planetary Science Letters 387, 55–66 (2014). https://doi.org:https://doi.org/10.1016/j.epsl.2013.11.016 Moynier, F. et al. Metal-silicate silicon isotopic fractionation and the composition of the bulk Earth. Earth and Planetary Science Letters 549, 116468 (2020). https://doi.org: https://doi.org/10.1016/j.epsl.2020.116468 Ziegler, K., Young, E. D., Schauble, E. A. & Wasson, J. T. Metal–silicate silicon isotope fractionation in enstatite meteorites and constraints on Earth's core formation. Earth and Planetary Science Letters 295, 487–496 (2010). https://doi.org:https://doi.org/10.1016/j.epsl.2010.04.030 Fitoussi, C., Bourdon, B., Kleine, T., Oberli, F. & Reynolds, B. C. Si isotope systematics of meteorites and terrestrial peridotites: implications for Mg/Si fractionation in the solar nebula and for Si in the Earth's core. Earth and Planetary Science Letters 287, 77–85 (2009). https://doi.org:https://doi.org/10.1016/j.epsl.2009.07.038 Savage, P. S., Armytage, R. M. G., Georg, R. B. & Halliday, A. N. High temperature silicon isotope geochemistry. Lithos 190–191, 500–519 (2014). https://doi.org:https://doi.org/10.1016/j.lithos.2014.01.003 Helffrich, G., Shahar, A. & Hirose, K. Isotopic signature of core-derived SiO2. Am Mineral 103, 1161–1164 (2018). https://doi.org:10.2138/am-2018-6482CCBYNCND Williams, C. D., Li, M., McNamara, A. K., Garnero, E. J. & van Soest, M. C. Episodic entrainment of deep primordial mantle material into ocean island basalts. Nature Communications 6, 8937 (2015). https://doi.org:10.1038/ncomms9937 Wang, W. et al. Formation of large low shear velocity provinces through the decomposition of oxidized mantle. Nature Communications 12, 1911 (2021). https://doi.org:10.1038/s41467-021-22185-1 Ballmer, M. D., Schumacher, L., Lekic, V., Thomas, C. & Ito, G. Compositional layering within the large low shear-wave velocity provinces in the lower mantle. Geochemistry, Geophysics, Geosystems 17, 5056–5077 (2016). https://doi.org:https://doi.org/10.1002/2016GC006605 Lee, C.-T. A. et al. Upside-down differentiation and generation of a /`primordial/' lower mantle. Nature 463, 930–933 (2010). Christensen, U. R. & Hofmann, A. W. Segregation of subducted oceanic crust in the convecting mantle. Journal of Geophysical Research: Solid Earth 99, 19867–19884 (1994). https://doi.org:https://doi.org/10.1029/93JB03403 Li, M. & McNamara, A. K. Evolving morphology of crustal accumulations in Earth's lowermost mantle. Earth and Planetary Science Letters 577, 117265 (2022). https://doi.org: https://doi.org/10.1016/j.epsl.2021.117265 Panton, J., Davies, J. H. & Myhill, R. The Stability of Dense Oceanic Crust Near the Core-Mantle Boundary. Journal of Geophysical Research: Solid Earth 128, e2022JB025610 (2023). https://doi.org:https://doi.org/10.1029/2022JB025610 Mulyukova, E., Steinberger, B., Dabrowski, M. & Sobolev, S. V. Survival of LLSVPs for billions of years in a vigorously convecting mantle: Replenishment and destruction of chemical anomaly. Journal of Geophysical Research: Solid Earth 120, 3824–3847 (2015). https://doi.org:https://doi.org/10.1002/2014JB011688 Deschamps, F., Cobden, L. & Tackley, P. J. The primitive nature of large low shear-wave velocity provinces. Earth and Planetary Science Letters 349, 198–208 (2012). https://doi.org:10.1016/j.epsl.2012.07.012 Thomson, A. R. et al. Seismic velocities of CaSiO3 perovskite can explain LLSVPs in Earth’s lower mantle. Nature (2019). https://doi.org:10.1038/s41586-019-1483-x Wang, W. et al. Velocity and density characteristics of subducted oceanic crust and the origin of lower-mantle heterogeneities. Nature Communications 11, 64 (2020). https://doi.org:10.1038/s41467-019-13720-2 Yu, H.-M., Li, Y.-H., Gao, Y.-J., Huang, J. & Huang, F. Silicon isotopic compositions of altered oceanic crust: Implications for Si isotope heterogeneity in the mantle. Chem Geol 479, 1–9 (2018). https://doi.org:https://doi.org/10.1016/j.chemgeo.2017.12.013 Jackson, C. R. M., Ziegler, L. B., Zhang, H., Jackson, M. G. & Stegman, D. R. A geochemical evaluation of potential magma ocean dynamics using a parameterized model for perovskite crystallization. Earth and Planetary Science Letters 392, 154–165 (2014). https://doi.org:https://doi.org/10.1016/j.epsl.2014.01.028 Jones, R. E. et al. Origins of the terrestrial Hf-Nd mantle array: Evidence from a combined geodynamical-geochemical approach. Earth and Planetary Science Letters 518, 26–39 (2019). https://doi.org:https://doi.org/10.1016/j.epsl.2019.04.015 Li, Y., Vočadlo, L., Ballentine, C. & Brodholt, J. P. Primitive noble gases sampled from ocean island basalts cannot be from the Earth’s core. Nature Communications 13, 3770 (2022). https://doi.org:10.1038/s41467-022-31588-7 Wicks, J. K., Jackson, J. M. & Sturhahn, W. Very low sound velocities in iron-rich (Mg,Fe)O: Implications for the core-mantle boundary region. Geophysical Research Letters 37 (2010). https://doi.org:https://doi.org/10.1029/2010GL043689 Kaneshima, S. & Helffrich, G. Lower mantle scattering profiles and fabric below Pacific subduction zones. Earth and Planetary Science Letters 282, 234–239 (2009). https://doi.org: https://doi.org/10.1016/j.epsl.2009.03.024 Frost, D. A., Rost, S., Garnero, E. J. & Li, M. Seismic evidence for Earth's crusty deep mantle. Earth and Planetary Science Letters 470, 54–63 (2017). https://doi.org:https://doi.org/10.1016/j.epsl.2017.04.036 Lei, H. & He, J. Nucleation and Growth Kinetics of MgO in Molten Steel. Journal of Materials Science & Technology 28, 642–646 (2012). https://doi.org: https://doi.org/10.1016/S1005-0302(12)60110-8 Parks, G. A. Surface and interfacial free energies of quartz. Journal of Geophysical Research: Solid Earth 89, 3997–4008 (1984). https://doi.org: https://doi.org/10.1029/JB089iB06p03997 Klapczynski, V., Le Maux, D., Courtois, M., Bertrand, E. & Paillard, P. Surface tension measurements of liquid pure iron and 304L stainless steel under different gas mixtures. Journal of Molecular Liquids 350, 118558 (2022). https://doi.org:https://doi.org/10.1016/j.molliq.2022.118558 Li, Q., Xian, J.-W., Zhang, Y., Sun, T. & Vočadlo, L. Thermal Properties of Liquid Iron at Conditions of Planetary Cores. Journal of Geophysical Research: Planets 127, e2021JE007015 (2022). https://doi.org:https://doi.org/10.1029/2021JE007015 de Wijs, G. A. et al. The viscosity of liquid iron at the physical conditions of the Earth's core. Nature 392, 805–807 (1998). https://doi.org:10.1038/33905 Monteux, J., Qaddah, B. & Andrault, D. Conditions for segregation of a crystal-rich layer within a convective magma ocean. Journal of Geophysical Research: Planets 128 (2023). https://doi.org:https://doi.org/10.1029/2023JE007805 Stixrude, L. & Lithgow-Bertelloni, C. Thermodynamics of mantle minerals - II. Phase equilibria. Geophys J Int 184, 1180–1213 (2011). https://doi.org:10.1111/j.1365-246X.2010.04890.x Anderson, O. The power balance at the core–mantle boundary. Physics of the Earth and Planetary Interiors 131, 1–17 (2002). https://doi.org:10.1016/S0031-9201(02)00009-2 Chen, Y. & Zhang, Y. Olivine dissolution in basaltic melt. Geochimica et Cosmochimica Acta 72, 4756–4777 (2008). https://doi.org:https://doi.org/10.1016/j.gca.2008.07.014 Ghosh, D. B. & Karki, B. B. Transport properties of carbonated silicate melt at high pressure. Science Advances 3 (2017). https://doi.org:10.1126/sciadv.1701840 Stixrude, L., de Koker, N., Sun, N., Mookherjee, M. & Karki, B. B. Thermodynamics of silicate liquids in the deep Earth. Earth and Planetary Science Letters 278, 226–232 (2009). https://doi.org:https://doi.org/10.1016/j.epsl.2008.12.006 Abe, Y. in Evolution of the Earth and Planets 41–54 (1993). Solomatov, V. S., Olson, P. & Stevenson, D. J. Entrainment from a bed of particles by thermal convection. Earth and Planetary Science Letters 120, 387–393 (1993). https://doi.org: https://doi.org/10.1016/0012-821X(93)90252-5 Fiquet, G., Andrault, D., Itié, J. P., Gillet, P. & Richet, P. X-ray diffraction of periclase in a laser-heated diamond-anvil cell. Physics of the Earth and Planetary Interiors 95, 1–17 (1996). https://doi.org:https://doi.org/10.1016/0031-9201(95)03109-X Deschamps, F. & Cobden, L. Estimating core-mantle boundary temperature from seismic shear velocity and attenuation. Frontiers in Earth Science 10 (2022). https://doi.org:10.3389/feart.2022.1031507 Fischer, R. A. et al. High pressure metal–silicate partitioning of Ni, Co, V, Cr, Si, and O. Geochimica et Cosmochimica Acta 167, 177–194 (2015). https://doi.org:10.1016/j.gca.2015.06.026 Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryInformation.docx Cite Share Download PDF Status: Published Journal Publication published 12 Sep, 2025 Read the published version in Nature Geoscience → 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-3263305","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":323097586,"identity":"2e9fe762-a2d1-49b2-aa27-26731ae4af5f","order_by":0,"name":"JIE DENG","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7UlEQVRIiWNgGAWjYBACxmYgwQPE/OzNB4CUhAzxWiR7jiWAtPAQZxVImcGNHAMYGz9gbmc+wPCm4o5dw5kzn1/dqLHgYWA/fHQDfoexJTDOOfMsubG9d5t1zjGgw3jS0m7g18JjwMzbdjiZmefsNuMcNqAWCR4zAlr4PzDz/juczCaR88w45x9RWngYmHkbDtvxSOQwP85tI0oLm8HBOccOJ0jwHDNjzu2T4GEj5BfD/sMPH7ypOWxvf7z58eecb3Vy/OyHj+HX0sDAcABIJwJpNgmQCBs+5SAgD6XtgZj5AyHVo2AUjIJRMDIBAODGSFxbWVtKAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0001-5441-2797","institution":"Princeton University","correspondingAuthor":true,"prefix":"","firstName":"JIE","middleName":"","lastName":"DENG","suffix":""},{"id":323097587,"identity":"c382cc25-671d-4aa4-a26b-ef9ca74e7b6a","order_by":1,"name":"Yoshinori Miyazaki","email":"","orcid":"https://orcid.org/0000-0001-8325-8549","institution":"California Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Yoshinori","middleName":"","lastName":"Miyazaki","suffix":""},{"id":323097588,"identity":"d185954d-6d8b-42c6-b297-1e9ceddcc73b","order_by":2,"name":"Zhixue Du","email":"","orcid":"https://orcid.org/0000-0002-7716-2994","institution":"Guangzhou Institute of Geochemistry, Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Zhixue","middleName":"","lastName":"Du","suffix":""}],"badges":[],"createdAt":"2023-08-14 15:43:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3263305/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3263305/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41561-025-01797-y","type":"published","date":"2025-09-12T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":59963905,"identity":"ce58fe75-e59e-4307-ac64-55a025be2797","added_by":"auto","created_at":"2024-07-10 01:38:43","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":712874,"visible":true,"origin":"","legend":"\u003cp\u003eSchematics illustrating the formation and evolution of a basal exsolution contaminated magma ocean (BECMO). (A) Formation stage, with the percolation of Fe-rich melt towards the core-mantle boundary (CMB), leading to the formation of a deep BECMO of around 500-km. SiO\u003csub\u003e2\u003c/sub\u003e (yellow-green) and MgO (white) nanoparticles exsolve at the topmost outer core, upwelling into the overlying magma ocean and dissolving upon contact. (B) Growth stage, with the solid mantle layer expanding upward and downward. The BECMO increasingly enriches FeO through progressive fractional crystallization, while maintaining a nearly constant SiO\u003csub\u003e2\u003c/sub\u003e content due to the influx from the core. (C) Solidification stage, featuring complete solidification of the surface magma ocean and significant crystallization within the BECMO. Crystalized bridgmanite is increasingly FeO-rich towards the residual BECMO. In regions where the mantle remains partially molten, efficient exsolution flux into the magma ocean occurs. (D) Complete solidification stage, with the BECMO fully solidified and FeO-enriched ferropericlase formed at the bottom. Accumulation of core exsolution right below the CMB leads to the development of Rayleigh-Taylor instability, resulting in diapirs of meter-to-kilometer-sizes that are entrained into the solid mantle and concentrate at their respective natural buoyancy levels. The dense layers are swept by the convective currents and advected toward laterally convergent regions, forming LLSVPs and ULVZs. Areas filled with textures denote solid and otherwise liquid.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3263305/v1/f5b55d834fe5c60d86a4574f.png"},{"id":59963904,"identity":"33a868fa-b798-4968-8ff0-f4b02227e925","added_by":"auto","created_at":"2024-07-10 01:38:43","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":14847,"visible":true,"origin":"","legend":"\u003cp\u003eMineralogical and compositional profiles of solidified BMO (A, B) and BECMO (C, D). With the range of FeO content and SiO\u003csub\u003e2\u003c/sub\u003e content of the LLSVP shaded. (A, C) Mineralogical composition at each depth in wt%. Bridgmanite (brg) and ferropericlase (fp) are shown. (B, D) The fraction of MgO, FeO, and SiO\u003csub\u003e2\u003c/sub\u003e components in wt%.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3263305/v1/2baac873dfa830b198ec9398.png"},{"id":59963907,"identity":"d06898d7-b185-4d21-8f94-efa2ae6424db","added_by":"auto","created_at":"2024-07-10 01:38:43","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":159431,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3263305/v1/330238e60b8d9b9cba19f7f4.png"},{"id":91817639,"identity":"69f6a1a7-a3bf-4125-a963-fcf07d5faf0c","added_by":"auto","created_at":"2025-09-22 06:59:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1382439,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3263305/v1/89f942d7-b65f-4009-acb7-adedb7846b0c.pdf"},{"id":59964285,"identity":"4f9c1989-7887-4924-b633-1fa1cea3b7f8","added_by":"auto","created_at":"2024-07-10 01:46:43","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":445963,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-3263305/v1/e5ef2be5eccdef9e7cb7e943.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"\u003cp\u003eFormation of deep mantle heterogeneities through basal exsolution contaminated magma ocean\u003c/p\u003e","fulltext":[{"header":"One-Sentence Summary","content":"\u003cp\u003eA novel mechanism called\u0026nbsp;basal exsolution contaminated magma ocean\u0026nbsp;(BECMO) provides a unified mechanism\u0026nbsp;for the formation of deep mantle heterogeneities.\u003c/p\u003e"},{"header":"Main Text","content":"\u003cp\u003eEarth\u0026rsquo;s lower mantle, considered mostly homogeneous, harbors two prominent large low shear-wave velocity provinces (LLSVPs) positioned beneath the Pacific and Africa\u003csup\u003e1\u003c/sup\u003e. These LLSVPs exhibit mild reductions in P-wave (\u003cem\u003eV\u003c/em\u003e\u003csub\u003eP\u003c/sub\u003e) and S-wave (\u003cem\u003eV\u003c/em\u003es) velocities, and a comparable increase in bulk sound velocity (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u0026Phi;\u003c/sub\u003e), along with the decorrelation observed between \u003cem\u003eV\u003c/em\u003es and density anomalies in normal mode tomography\u003csup\u003e2\u003c/sup\u003e, the excess density in tidal tomography\u003csup\u003e3\u003c/sup\u003e, the presence of sharp margins\u003csup\u003e4\u003c/sup\u003e, and the occurrence of ultralow velocity zones (ULVZs) within or near the edges\u003csup\u003e1\u003c/sup\u003e. In addition, ocean island basalts (OIBs) that potentially sample the lowermost LLSVPs contain distinct isotope ratios compared with mid-ocean ridge basalts (MORBs) and other mantle reservoirs\u003csup\u003e5\u003c/sup\u003e. For major elements, Si of some OIBs is isotopically lighter than that of MORBs\u003csup\u003e6\u003c/sup\u003e. Anomalies in primordial and/or short-lived isotopic systematics of trace elements further indicate an early origin of the source of OIBs, and hence LLSVPs and ULVZs\u003csup\u003e7-10\u003c/sup\u003e. These characteristics collectively suggest the existence of primordial and intrinsically dense thermochemical piles enriched in iron and silicon\u003csup\u003e1,11\u003c/sup\u003e. Despite these observations, the origin of LLSVPs remains a topic of ongoing debate.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOne prominent mechanism proposed for generating primordial, deep, and dense materials characteristic of LLSVPs is the differentiation of a primordial basal magma ocean (BMO)\u003csup\u003e12-14\u003c/sup\u003e. Following the Moon-forming giant impact, extensive melting of Earth likely led to the formation of a BMO, wherein iron favored the liquid phase and subsequent crystallization generated negatively buoyant silicate melts\u003csup\u003e15-18\u003c/sup\u003e. The BMO holds significant intrigue, as it may not only produce heterogeneous seismic structures such as LLSVPs and ULVZs but also offer a compelling explanation for the ancient geodynamo\u003csup\u003e19\u003c/sup\u003e and the preservation of primordial geochemical signatures\u003csup\u003e7-9\u003c/sup\u003e. Phase equilibrium calculations suggest that the solidification of BMO quickly depletes the silicate melts of Si due to the crystallization of the first liquidus phase, bridgmanite, leading to a 1000-km bottom layer that contains approximately 20 wt% of ferropericlase\u003csup\u003e20\u003c/sup\u003e. However, this contrasts sharply with inferences drawn from seismic tomography which favor a low ferropericlase content of ~6-10 wt%\u0026nbsp;\u003csup\u003e21,22\u003c/sup\u003e. If LLSVPs originate from the BMO, a mechanism enriching Si content is required to replenish the crystallizing BMO and suppress the production of ferropericlase.\u003c/p\u003e\n\u003cp\u003eRecently, oxide exsolutions such as MgO and SiO\u003csub\u003e2\u003c/sub\u003e have been proposed as a new form of mass flux from the core into the mantle\u003csup\u003e23-26\u003c/sup\u003e. Core exsolutions deliver distinctive core-like geochemical signatures and may serve as the source materials for\u0026nbsp;OIBs\u003csup\u003e27,28\u003c/sup\u003e. However, the interaction between these oxides and the BMO has not been systematically explored\u003csup\u003e29\u003c/sup\u003e. Here, we study the crystallization of basal exsolution contaminated magma ocean (BECMO), where synchronous BMO solidification and core exsolution occur (Fig. 1). Our results demonstrate that the continuous supply of core exsolutions significantly inhibits the crystallization of ferropericlase within the BECMO, particularly at the late stage.\u0026nbsp;Core exsolutions also reduces Fe contents of the final-stage MO cumulates which may serve as the source material to generate the LLSVPs and ULVZs by convective mixing. In the region where BECMO is solidified, core exsolution may be entrained in the solid mantle as diapirs, causing small-scale seismic scattering in the deep mantle. Geochemically, BECMO materials may possess both the BMO-like signature with enriched trace elements and core-like signature such as enrichment in primordial \u003csup\u003e3\u003c/sup\u003eHe and depletion in \u003csup\u003e182\u003c/sup\u003eW\u0026nbsp;\u003csup\u003e27\u003c/sup\u003e. The solidified mantle from the BECMO and the SiO\u003csub\u003e2\u003c/sub\u003e-rich diapirs entrained also inherits the light Si isotope signature from core and thus may represent a potential source material for OIBs.\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e\n\u003ch2\u003eTransfer and dissolution of core exsolution\u003c/h2\u003e\n\u003cp\u003eSeveral studies have proposed that as Earth cools, light elements such as Mg\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e, Si, and O \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e become saturated in the core and precipitate in the forms of SiO\u003csub\u003e2\u003c/sub\u003e and MgO. The high melting points of MgO and SiO\u003csub\u003e2\u003c/sub\u003e, i.e., around 8000 K and 6000 K at the core-mantle boundary (CMB), respectively \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e, indicate that these precipitates occur as crystalline solids. Although trace elements like iron may slightly lower their melting points\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e, their concentrations are not significant\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e. In this study, we focus on the exsolution of MgO and SiO\u003csub\u003e2\u003c/sub\u003e from the core at the CMB as crystalline particles.\u003c/p\u003e\n\u003cp\u003eBoth SiO\u003csub\u003e2\u003c/sub\u003e and MgO are buoyant in the lowermost mantle (Fig. S1). Due to the large density contrast with the core fluid, the exsolved particles can only grow to nanometer sizes before sedimenting towards the topmost outer core (Supplementary Information). The fate of these core exsolutions largely depends on the state of the overlying mantle. If the mantle is in a solid state, the significant rheological contrast between the exsolution and solid silicate causes the exsolved particles to accumulate as a layer at the CMB. Rayleigh-Taylor instability then develops, leading to the formation of diapirs that rise through the mantle for thousands of kilometers until they reach a neutral buoyancy depth (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eConversely, if the overlying mantle is in a liquid state, as in the case of a BMO, the core exsolutions float into the magma ocean and dissolve immediately (Fig. S2; Supplementary Information). As a result, the cooling core continuously supplies MgO and SiO\u003csub\u003e2\u003c/sub\u003e to the crystalizing magma ocean. In our model, we assume that only Mg, Si, and O precipitate out of the core and do not consider the reverse diffusion of elements\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. We follow ref.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e to assume that light elements dissolved into the core form a stably stratified layer below the CMB, which resists mixing with the rest of the core fluid.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003eSolidification of the basal exsolution contaminated magma ocean\u003c/h2\u003e\n\u003cp\u003eWe model the solidification and differentiation of a BMO and a BECMO using the self-consistent thermodynamic model of ref.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e with a simplified pyrolitic bulk composition (42.2 wt%, FeO: 8.7 wt%, and SiO\u003csub\u003e2\u003c/sub\u003e: 49.1 wt%). For both cases, we assume that a BMO of a\u0026thinsp;~\u0026thinsp;500 km thickness is initially formed as a result of melt-solid density crossover\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e (Supplementary Information). The preferential partitioning of iron into the melt phase makes it heavier than the coexisting solid at pressures greater than ~\u0026thinsp;80 GPa, and percolation would extract iron-rich melt from the mushy layer and transport it towards the CMB (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). We calculate the amount and composition of newly formed crystals within the BMO, as the temperature of the CMB decreases from 5000 K to ~\u0026thinsp;3700 K at which both BMO and BECMO completely solidify. Crystals are considered to form a fractionated layer at the top of BMO, and the BMO thickness decreases with time. The major difference between BECMO and BMO is that, for the former, MgO and SiO\u003csub\u003e2\u003c/sub\u003e solids exsolved from the core are continuously dissolved into the magma ocean.\u003c/p\u003e\n\u003cp\u003eWithout the addition of exsolutions, the fractionation within the BMO creates a deep layer extremely enriched in FeO in the lowermost 200 km (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). This is due to the sequestration of the liquidus mineral, Mg-rich bridgmanite into the solidified mantle, and thus the enrichment of FeO correlates with the depletion of SiO\u003csub\u003e2\u003c/sub\u003e, leading to the formation of a thick bottom layer composed of mostly FeO. Fe-rich ferropericlase significantly reduces \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u0026Phi;\u003c/sub\u003e and thus cannot generate the observed the anti-correlation of \u003cem\u003eV\u003c/em\u003es and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u0026Phi;\u003c/sub\u003e. The general trend of variation of element concentration with depth is consistent with another thermodynamic calculation\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. Such an outcome is always expected as long as a small iron partitioning coefficient between bridgmanite and melt is adopted in a thermodynamic model, which, however, is not the case for ref.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e. We note that an early study\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e predicts an even stronger enrichment of FeO at the CMB than in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. The difference arises because we assume that some amounts of Fe-rich melt are trapped within the fractionated layer due to a relatively low effective percolation efficiency (Fig. S3; Supplementary Information).\u003c/p\u003e\n\u003cp\u003eThe addition of the exsolutions significantly changes the composition and mineralogy of the lowermost mantle, with minimal effects on the shallow part (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). This is expected as the magma ocean is voluminous initially and the effects of exsolution dissolution are diluted. Since the SiO\u003csub\u003e2\u003c/sub\u003e yield is much larger than the MgO yield (Supplementary Information), the compositional response of the magma ocean is dominated by SiO\u003csub\u003e2\u003c/sub\u003e addition. SiO\u003csub\u003e2\u003c/sub\u003e consumed due to the crystallization of bridgmanite is replenished by the exsolution, resulting in a nearly constant molar fraction of SiO\u003csub\u003e2\u003c/sub\u003e for most depths in the solidified mantle at pressures smaller than approximately 132 GPa. Note overall the SiO\u003csub\u003e2\u003c/sub\u003e content of the residual liquid still decrease with time as the consumption of SiO\u003csub\u003e2\u003c/sub\u003e due to bridgmanite crystallization exceeds the rate of SiO\u003csub\u003e2\u003c/sub\u003e assimilation (Fig. S4). Nevertheless, the addition of core exsolution significantly delay the depletion of SiO\u003csub\u003e2\u003c/sub\u003e component to the state where ferropericlase is the liquidus phase\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. Consequently, silicate phases dominate most depths, with ferropericlase concentrated towards the very bottom of the mantle. As a result, the solidification of the BECMO can simultaneously explain the SiO\u003csub\u003e2\u003c/sub\u003e and FeO enrichment in the LLSVPs as well as the Fe-rich and dense ultralow-velocity zones in the base of the mantle, as inferred from the tomography models \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. We note that the amount of MgO and SiO\u003csub\u003e2\u003c/sub\u003e added to the mantle by exsolution could be as large as ~\u0026thinsp;10\u003csup\u003e23\u003c/sup\u003e kg (Supplementary Information), which is a few percent of the present-day mantle mass. This large amount of exsolution leads to an increase in the CMB pressure by over 5 GPa and, equivalently a recession of the CMB of over 70 km, diluting the effect of FeO concentration near the lowermost layer.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eDensity of solidified BECMO and its long-term stability\u003c/h3\u003e\n\u003cp\u003eWe further compare the density of the solidified mantles of the two fractionated models as well as the unfractionated mantle of the same bulk composition (Fig. S5). As expected, the unfractionated mantle closely mimics that of the PREM\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e. Mantles crystallized from BMO and BECMO share nearly identical densities for most of the depths except for the lowermost\u0026thinsp;~\u0026thinsp;200 km. Both solidified BMO and BECMO mantles are around 1.3% less dense than the unfractionated mantle at depths shallower than around 2700 km. Such a small difference is generated by considering a relatively large melt retention during magma ocean solidification (Supplementary Information). The sharp increase in densities for both BMO and BECMO mantles below around 2700 km depth is a result of the accumulation of Fe-rich ferropericlase or magnesiow\u0026uuml;stite. Due to the suppressed production of ferropericlase in BECMO, the bottom dense layer of the BECMO mantle is significantly thinner, and the maximum density is less extreme than that of BMO (Fig. S4).\u003c/p\u003e\n\u003cp\u003eDensity is the most important parameter that governs the structure and long-term stability of primordial dense piles in the lower mantle\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. A low intrinsic (or chemical) density contrast between the primordial material and the surrounding regular mantle material (i.e., a small buoyancy ratio) favors rapid mixing, whereas a primordial base layer that is too intrinsically dense compared to the surroundings, is difficult to mix even after billion years\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e. Geodynamic simulations suggest that LLSVPs-like structures are more likely to form from the convective mixing of materials with a buoyancy ratio of 0.2\u0026ndash;0.36, albeit this value is sensitive to other parameters such as the viscosity contrast between dense and ambient materials\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eFor the intrinsically light layer above around 2700-km depths, convective mixing with the surrounding materials brings up the density and completely erases the density anomaly for the majority (~\u0026thinsp;86 vol%) of the light layer outside LLSVPs. Stoneley mode analysis suggests that LLSVPs are ~\u0026thinsp;0.88% lighter at depths shallower than 2700 km\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e, coinciding with the scale of the light layer derived from the BMO and BECMO crystallization. If the shallow LLSVPs is intrinsically lighter, to generate the observed density anomaly, the remaining 14% of the primordial light layer may mix with the ambient mantle in a ratio of 3:1 by volume. On the other hand, if the shallow LLSVPs are intrinsically denser\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e and the apparent small density is due to thermal buoyancy, mixing with the dense base layer is required.\u003c/p\u003e\n\u003cp\u003eThe solidified BMO and BECMO are characterized by contrasting density profiles of the bottom dense layers. A well-known consequence of BMO crystallization is the long-term preservation of a thin layer of extremely enriched cumulates with high iron content (over 40 mol% of FeO), which is inconsistent with seismic constraints\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e. We find that a dense layer with a buoyancy ratio above 0.36 is around 135 km thick for the solidified BMO mantle, while efficiently decreasing to around 57 km for the BECMO mantle. Although this layer with a large buoyancy ratio for BECMO is still thicker than of ULVZs (10\u0026ndash;40 km), it will likely be eroded with time as dense materials get entrained by mantle upwellings\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eWe note that the density profile of the solidified BECMO mantle (Fig. S5) is very similar to the initial setup of geodynamic modeling presented by ref.\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, where a layer of materials from 40 to 200 km above the CMB with an intrinsic density 1.5% greater than the background mantle and the bottom 40 km of 15% denser, after billions of years of convective mixing, generates LLSVPs and ULVZs beneath the Coral Sea between Australia and New Zealand. Therefore, the addition of core exsolution is an effective means to reduce the Fe-content of the final-stage magma ocean cumulates\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e. The resulting density structure is well suited to generate LLSVPs and ULVZs.\u003c/p\u003e\n\u003ch3\u003eSi isotope composition\u003c/h3\u003e\n\u003cp\u003eThe addition of core exsolutions affects the Si isotopic compositions of the deep Earth. Core fluid is depleted in heavy Si isotopes relative to the bulk silicate Earth (BSE)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e48\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e. As a result, SiO\u003csub\u003e2\u003c/sub\u003e exsolved from the core has a light Si isotope composition with \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\delta\\:}{}^{30}{\\text{S}\\text{i}}_{SiO2}\\:\\)\u003c/span\u003e\u003c/span\u003esmaller than that of the BSE (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\delta\\:}{}^{30}{\\text{S}\\text{i}}_{\\text{B}\\text{S}\\text{E}}\\)\u003c/span\u003e\u003c/span\u003e= \u0026minus;\u0026thinsp;0.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u0026permil;) \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e by about 0.11\u0026permil;-0.35\u0026permil; (Supplementary Information; Fig. S6) \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e. SiO\u003csub\u003e2\u003c/sub\u003e exsolution, once dissolved into the BECMO, would bring down the \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\delta\\:}{}^{30}\\text{S}\\text{i}\\)\u003c/span\u003e\u003c/span\u003e value of the magma ocean. The resulting Si isotope composition profile is shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e. \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\delta\\:}{}^{30}\\text{S}\\text{i}\\)\u003c/span\u003e\u003c/span\u003e of OIBs (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\delta\\:}{}^{30}{\\text{S}\\text{i}}_{\\text{O}\\text{I}\\text{B}}\\)\u003c/span\u003e\u003c/span\u003e= \u0026minus;\u0026thinsp;0.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u0026permil;) exhibits large variability and on average is slightly more negative than \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\delta\\:}{}^{30}{\\text{S}\\text{i}}_{BSE}\\)\u003c/span\u003e\u003c/span\u003e. Thermochemical convection calculations show that entrainment of pile materials into plumes typically does not exceeds\u0026thinsp;~\u0026thinsp;12% \u003csup\u003e12,\u003cspan class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e. The strong negative Si isotopic anomaly at the lowermost mantle would be inevitably diluted by the ambient mantle. The observed variability of \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\delta\\:}{}^{30}{\\text{S}\\text{i}}_{BSE}\\)\u003c/span\u003e\u003c/span\u003e can be generated by the sampling solidified at various depths of or by mixing with the ambient mantle in various proportions (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eB). The strong negative \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\delta\\:}{}^{30}{\\text{S}\\text{i}}_{\\text{O}\\text{I}\\text{B}}\\)\u003c/span\u003e\u003c/span\u003e such as \u0026minus;\u0026thinsp;0.40\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u0026permil; in Iceland OIBs can only be generated with large fraction of the BECMO material, or by mixing with smaller amounts of scattered SiO\u003csub\u003e2\u003c/sub\u003e diapirs in the deep mantle\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n\u003ch3\u003eImplications for lower mantle heterogeneities\u003c/h3\u003e\n\u003cp\u003eMany mechanisms have been proposed for generating deep and dense materials characteristic of LLSVPs \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e56\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e58\u003c/span\u003e\u003c/sup\u003e, among which the accumulation of recycled oceanic crust, primarily composed of MORBs, has received significant attention\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e59\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e62\u003c/span\u003e\u003c/sup\u003e. However, the seismic properties of MORBs in the deep mantle are subject to controversy\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e63\u003c/span\u003e\u003c/sup\u003e. While extrapolations based on low-pressure experiments suggest that MORBs may manifest as low-seismic-velocity anomalies in the lower mantle \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e64\u003c/span\u003e\u003c/sup\u003e, theoretical calculations have arrived at contradictory conclusions\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e65\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eGeochemical evidence further challenges the notion that the deep edge of LLSVPs consists of MORBs, where OIBs are believed to sample. First, MORBs share the same Si isotope composition as the BSE, making it incapable of generating the light isotopic characteristics observed in some OIBs, despite the possibility of isotopically light altered oceanic crust\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e66\u003c/span\u003e\u003c/sup\u003e. Second, MORBs have been suggested to be chemically and isotopically too depleted to be the OIBs source materials\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. MORBs are depleted of incompatible elements with small average La/Sm and Rb/Sr concentration ratios. Additionally, MORBs exhibit depleted isotopic compositions such as low \u003csup\u003e87\u003c/sup\u003eSr/\u003csup\u003e86\u003c/sup\u003eSr, high \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e14\u003c/sup\u003eNd, and high \u003csup\u003e176\u003c/sup\u003eHf/\u003csup\u003e177\u003c/sup\u003eHf, which contrast the correlated trends observed in global OIBs. Consequently, the association between the subducted oceanic crust and LLSVPs remains uncertain.\u003c/p\u003e\n\u003cp\u003eIn contrast, the BECMO shares similar elemental abundances with the classic BMO, offering a promising explanation. BECMO, in contrast to the source mantle of MORBs, is enriched in incompatible elements and thus may host high La/Sm and Rb/Sr, high \u003csup\u003e87\u003c/sup\u003eSr/\u003csup\u003e86\u003c/sup\u003eSr, low \u003csup\u003e143\u003c/sup\u003eNd/\u003csup\u003e14\u003c/sup\u003eNd, and low \u003csup\u003e176\u003c/sup\u003eHf/\u003csup\u003e177\u003c/sup\u003eHf ratios\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e67\u003c/span\u003e\u003c/sup\u003e. As such, BECMO, just like BMO, may serve as the hidden enriched reservoir to account for the terrestrial Hf-Nd mantle array\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e68\u003c/span\u003e\u003c/sup\u003e. The influx of SiO\u003csub\u003e2\u003c/sub\u003e exsolution from the core enriches the deep mantle derived from BECMO, aligning its compositional and mineralogical profiles with seismic observations and the geochemical signatures of OIBs. Furthermore, core exsolutions selectively deliver core signatures based on the solubility of corresponding elements, such as He and W. Highly siderophile elements are unlikely to be transferred by core exsolution to the mantle due to their insolubility in MgO and SiO\u003csub\u003e2\u003c/sub\u003e. Additionally, core exsolution may refractionate of He and Ne in the core fluid, resulting in an OIB-like \u003csup\u003e3\u003c/sup\u003eHe/\u003csup\u003e22\u003c/sup\u003eNe signature in LLSVPs\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e69\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe crystallization of BECMO not only explains the formation of LLSVPs but also naturally gives rise to a thin layer of FeO-rich ferropericlase at the bottom, which could be the source of ULVZs \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e70\u003c/span\u003e\u003c/sup\u003e. In the region where BECMO is solidified, core exsolution may be entrained into the solid mantle, causing small-scale seismic scattering in the lower mantle\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e71\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e72\u003c/span\u003e\u003c/sup\u003e. As such, BECMO provides a unified mechanism that may account for both the seismic and geochemical heterogeneities observed in the deep Earth. By incorporating the influx of SiO\u003csub\u003e2\u003c/sub\u003e and MgO exsolution from the core and the selective delivery of core signatures, BECMO offers a comprehensive explanation for the complex relationships between LLSVPs, ULVZs, OIBs, and other deep Earth features, bridging gaps in our understanding of the deep mantle dynamics and the origins of these enigmatic phenomena.\u003c/p\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u0026nbsp;\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe main data supporting the findings of this study are available within the paper and its supplementary information.\u0026nbsp;\u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare no Competing Financial or Non-Financial Interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor contributions\u003c/h2\u003e \u003cp\u003eJ.D. conceived and coordinated the entire project. Y.M. and J.D. performed calculations and modeling. J.D. wrote the first draft. All authors contributed to the discussion and revision of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eJ.D. acknowledge National Science Foundation EAR- 2242946. Z.D. expresses thanks for the funding from National Natural Science Foundation of China (no. 42150102) and from the Strategic Priority Research Program (B) of the Chinese Academy of Science (no. XDB18000000). Y.M. was supported by Stanback Postdoctoral Fellowship from Caltech Center for Comparative Planetary Evolution.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGarnero, E. J., McNamara, A. K. \u0026amp; Shim, S.-H. Continent-sized anomalous zones with low seismic velocity at the base of Earth's mantle. Nat Geosci 9, 481\u0026ndash;489 (2016). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/ngeo2733\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/ngeo2733\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTrampert, J., Deschamps, F., Resovsky, J. \u0026amp; Yuen, D. Probabilistic Tomography Maps Chemical Heterogeneities Throughout the Lower Mantle. Science 306, 853\u0026ndash;856 (2004). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:doi:10.1126/science.1101996\u003c/span\u003e\u003cspan address=\"https://doi.org:doi:10.1126/science.1101996\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLau, H. C. P. \u003cem\u003eet al.\u003c/em\u003e Tidal tomography constrains Earth\u0026rsquo;s deep-mantle buoyancy. Nature 551, 321 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/nature24452\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/nature24452\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNi, S., Tan, E., Gurnis, M. \u0026amp; Helmberger, D. Sharp Sides to the African Superplume. Science 296, 1850\u0026ndash;1852 (2002). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:doi:10.1126/science.1070698\u003c/span\u003e\u003cspan address=\"https://doi.org:doi:10.1126/science.1070698\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHofmann, A. W. \u0026amp; Hart, S. R. An assessment of local and regional isotopic equilibrium in the mantle. Earth and Planetary Science Letters 38, 44\u0026ndash;62 (1978). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0012-821X(78)90125-5\u003c/span\u003e\u003cspan address=\"10.1016/0012-821X(78)90125-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePringle, E. A. \u003cem\u003eet al.\u003c/em\u003e Silicon isotopes reveal recycled altered oceanic crust in the mantle sources of Ocean Island Basalts. Geochimica et Cosmochimica Acta 189, 282\u0026ndash;295 (2016). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gca.2016.06.008\u003c/span\u003e\u003cspan address=\"10.1016/j.gca.2016.06.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDeng, J. \u0026amp; Stixrude, L. Deep fractionation of Hf in a solidifying magma ocean and its implications for tungsten isotopic heterogeneities in the mantle. Earth and Planetary Science Letters 562, 116873 (2021). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.epsl.2021.116873\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2021.116873\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMukhopadhyay, S. \u0026amp; Parai, R. Noble Gases: A Record of Earth's Evolution and Mantle Dynamics. Annual Review of Earth and Planetary Sciences 47, 389\u0026ndash;419 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1146/annurev-earth-053018-060238\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1146/annurev-earth-053018-060238\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMundl-Petermeier, A. \u003cem\u003eet al.\u003c/em\u003e Anomalous \u003csup\u003e182\u003c/sup\u003eW in high \u003csup\u003e3\u003c/sup\u003eHe/\u003csup\u003e4\u003c/sup\u003eHe Ocean Island Basalts: Fingerprints of Earth\u0026rsquo;s core? Geochimica et Cosmochimica Acta (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.gca.2019.12.020\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.gca.2019.12.020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNiu, Y. Origin of the LLSVPs at the base of the mantle is a consequence of plate tectonics \u0026ndash; A petrological and geochemical perspective. Geoscience Frontiers 9, 1265\u0026ndash;1278 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.gsf.2018.03.005\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.gsf.2018.03.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTackley, P. J. Dynamics and evolution of the deep mantle resulting from thermal, chemical, phase and melting effects. Earth-Science Reviews 110, 1\u0026ndash;25 (2012). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.earscirev.2011.10.001\u003c/span\u003e\u003cspan address=\"10.1016/j.earscirev.2011.10.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDeschamps, F., Kaminski, E. \u0026amp; Tackley, P. J. A deep mantle origin for the primitive signature of ocean island basalt. Nat Geosci 4, 879\u0026ndash;882 (2011). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/ngeo1295\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/ngeo1295\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLabrosse, S., Hernlund, J. W. \u0026amp; Coltice, N. A crystallizing dense magma ocean at the base of the Earth\u0026rsquo;s mantle. Nature 450, 866\u0026ndash;869 (2007). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/nature06355\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/nature06355\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePachhai, S., Li, M., Thorne, M. S., Dettmer, J. \u0026amp; Tkalčić, H. Internal structure of ultralow-velocity zones consistent with origin from a basal magma ocean. Nat Geosci 15, 79\u0026ndash;84 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41561-021-00871-5\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/s41561-021-00871-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNomura, R. \u003cem\u003eet al.\u003c/em\u003e Spin crossover and iron-rich silicate melt in the Earth\u0026rsquo;s deep mantle. Nature 473, 199\u0026ndash;202 (2011). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/nature09940\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/nature09940\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCaracas, R., Hirose, K., Nomura, R. \u0026amp; Ballmer, M. D. Melt\u0026ndash;crystal density crossover in a deep magma ocean. Earth and Planetary Science Letters 516, 202\u0026ndash;211 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2019.03.031\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2019.03.031\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMiyazaki, Y. \u0026amp; Korenaga, J. On the Timescale of Magma Ocean Solidification and Its Chemical Consequences: 2. Compositional Differentiation Under Crystal Accumulation and Matrix Compaction. Journal of Geophysical Research: Solid Earth 124, 3399\u0026ndash;3419 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1029/2018JB016928\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1029/2018JB016928\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakajima, M. \u0026amp; Stevenson, D. J. Melting and mixing states of the Earth's mantle after the Moon-forming impact. Earth and Planetary Science Letters 427, 286\u0026ndash;295 (2015). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2015.06.023\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2015.06.023\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStixrude, L., Scipioni, R. \u0026amp; Desjarlais, M. P. A silicate dynamo in the early Earth. Nature Communications 11, 935 (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41467-020-14773-4\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/s41467-020-14773-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoukar\u0026eacute;, C. E., Ricard, Y. \u0026amp; Fiquet, G. Thermodynamics of the MgO-FeO-SiO\u003csub\u003e2\u003c/sub\u003e system up to 140 GPa: Application to the crystallization of Earth's magma ocean. Journal of Geophysical Research: Solid Earth 120, 2015JB011929 (2015). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/2015JB011929\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1002/2015JB011929\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDeng, X. \u003cem\u003eet al.\u003c/em\u003e Compositional and thermal state of the lower mantle from joint 3D inversion with seismic tomography and mineral elasticity. \u003cem\u003eProceedings of the National Academy of Sciences\u003c/em\u003e 120, e2220178120 (2023). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:doi:10.1073/pnas.2220178120\u003c/span\u003e\u003cspan address=\"https://doi.org:doi:10.1073/pnas.2220178120\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVilella, K. \u003cem\u003eet al.\u003c/em\u003e Constraints on the composition and temperature of LLSVPs from seismic properties of lower mantle minerals. Earth and Planetary Science Letters 554, 116685 (2021). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2020.116685\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2020.116685\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eO'Rourke, J. G., Korenaga, J. \u0026amp; Stevenson, D. J. Thermal evolution of Earth with magnesium precipitation in the core. Earth and Planetary Science Letters 458, 263\u0026ndash;272 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2016.10.057\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2016.10.057\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBadro, J., Siebert, J. \u0026amp; Nimmo, F. An early geodynamo driven by exsolution of mantle components from Earth\u0026rsquo;s core. Nature advance online publication (2016). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/nature18594\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/nature18594\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDu, Z. \u003cem\u003eet al.\u003c/em\u003e Insufficient energy from MgO exsolution to power early geodynamo. Geophysical Research Letters, 11376\u0026ndash;11381 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/2017GL075283\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1002/2017GL075283\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHirose, K. \u003cem\u003eet al.\u003c/em\u003e Crystallization of silicon dioxide and compositional evolution of the Earth\u0026rsquo;s core. Nature advance online publication (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/nature21367\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/nature21367\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDeng, J. \u0026amp; Du, Z. Primordial helium extracted from the Earth\u0026rsquo;s core through magnesium oxide exsolution. Nat Geosci (2023). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41561-023-01182-7\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/s41561-023-01182-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRizo, H. \u003cem\u003eet al.\u003c/em\u003e \u003csup\u003e182\u003c/sup\u003eW evidence for core-mantle interaction in the source of mantle plumes. Geochemical Perspectives Letters 11, 6\u0026ndash;11 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.7185/geochemlet.1917\u003c/span\u003e\u003cspan address=\"https://doi.org:10.7185/geochemlet.1917\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTr\u0026oslash;nnes, R. G. \u003cem\u003eet al.\u003c/em\u003e Core formation, mantle differentiation and core-mantle interaction within Earth and the terrestrial planets. Tectonophysics 760, 165\u0026ndash;198 (2019). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.tecto.2018.10.021\u003c/span\u003e\u003cspan address=\"10.1016/j.tecto.2018.10.021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDu, Z., Deng, J. \u0026amp; Lee, K. K. M. Experimental Constraints on Ferropericlase (Mg, Fe)O Melt Viscosity Up to 70 GPa. Geophysical Research Letters 44, 12,190\u0026thinsp;\u0026ndash;\u0026thinsp;112,196 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1002/2017GL076177\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1002/2017GL076177\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDu, Z., Boujibar, A., Driscoll, P. \u0026amp; Fei, Y. Experimental Constraints on an MgO Exsolution-Driven Geodynamo. \u003cem\u003eGeophysical Research Letters\u003c/em\u003e 46, 7379\u0026ndash;7385 (2019). https://doi.org:0.1029/2019GL083017\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlf\u0026egrave;, D. Melting Curve of MgO from First-Principles Simulations. Phys Rev Lett 94, 235701 (2005). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1103/PhysRevLett.94.235701\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1103/PhysRevLett.94.235701\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDu, Z. \u0026amp; Lee, K. K. M. High-pressure melting of MgO from (Mg,Fe)O solid solutions. Geophysical Research Letters 41, 8061\u0026ndash;8066 (2014). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/2014GL061954\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1002/2014GL061954\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUsui, Y. \u0026amp; Tsuchiya, T. Ab initio two-phase molecular dynamics on the melting curve of SiO\u003csub\u003e2\u003c/sub\u003e. Journal of Earth Science 21, 801\u0026ndash;810 (2010). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1007/s12583-010-0126-9\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1007/s12583-010-0126-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGonz\u0026aacute;lez-Cataldo, F., Davis, S. \u0026amp; Guti\u0026eacute;rrez, G. Melting curve of SiO\u003csub\u003e2\u003c/sub\u003e at multimegabar pressures: implications for gas giants and super-Earths. Scientific Reports 6, 26537 (2016). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/srep26537\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/srep26537\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDeng, J., Miyazaki, Y. \u0026amp; Lee, K. K. M. Implications for the melting phase relations in the MgO-FeO system at core-mantle boundary conditions. Journal of Geophysical Research: Solid Earth 124, 11 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1029/2018JB015499\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1029/2018JB015499\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHelffrich, G., Ballmer, M. D. \u0026amp; Hirose, K. Core-Exsolved SiO2 Dispersal in the Earth's Mantle. Journal of Geophysical Research: Solid Earth 123, 176\u0026ndash;188 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/2017JB014865\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1002/2017JB014865\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDavies, C. J., Pozzo, M., Gubbins, D. \u0026amp; Alf\u0026egrave;, D. Transfer of oxygen to Earth's core from a long-lived magma ocean. Earth and Planetary Science Letters 538, 116208 (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2020.116208\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2020.116208\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMittal, T. \u003cem\u003eet al.\u003c/em\u003e Precipitation of multiple light elements to power Earth's early dynamo. Earth and Planetary Science Letters 532, 116030 (2020). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.epsl.2019.116030\u003c/span\u003e\u003cspan address=\"10.1016/j.epsl.2019.116030\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMiyazaki, Y. \u0026amp; Korenaga, J. On the Timescale of Magma Ocean Solidification and Its Chemical Consequences: 1. Thermodynamic Database for Liquid at High Pressures. Journal of Geophysical Research: Solid Earth 124, 3382\u0026ndash;3398 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1029/2018JB016932\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1029/2018JB016932\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAndrault, D. \u003cem\u003eet al.\u003c/em\u003e Solidus and liquidus profiles of chondritic mantle: Implication for melting of the Earth across its history. Earth and Planetary Science Letters 304, 251\u0026ndash;259 (2011). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2011.02.006\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2011.02.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDziewonski, A. M. \u0026amp; Anderson, D. L. Preliminary reference Earth model. Physics of the Earth and Planetary Interiors 25, 297\u0026ndash;356 (1981). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/0031-9201(81)90046-7\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/0031-9201(81)90046-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi, Y., Deschamps, F. \u0026amp; Tackley, P. J. The stability and structure of primordial reservoirs in the lower mantle: insights from models of thermochemical convection in three-dimensional spherical geometry. Geophys J Int 199, 914\u0026ndash;930 (2014). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1093/gji/ggu295\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1093/gji/ggu295\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBallmer, M. D., Louren\u0026ccedil;o, D. L., Hirose, K., Caracas, R. \u0026amp; Nomura, R. Reconciling magma-ocean crystallization models with the present-day structure of the Earth's mantle. Geochemistry, Geophysics, Geosystems 18, 2785\u0026ndash;2806 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/2017GC006917\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1002/2017GC006917\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eG\u0026uuml;lcher, A. J. P., Ballmer, M. D. \u0026amp; Tackley, P. J. Coupled dynamics and evolution of primordial and recycled heterogeneity in Earth's lower mantle. Solid Earth 12, 2087\u0026ndash;2107 (2021). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.5194/se-12-2087-2021\u003c/span\u003e\u003cspan address=\"https://doi.org:10.5194/se-12-2087-2021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKoelemeijer, P., Deuss, A. \u0026amp; Ritsema, J. Density structure of Earth\u0026rsquo;s lowermost mantle from Stoneley mode splitting observations. Nature Communications 8, 15241 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/ncomms15241\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/ncomms15241\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcNamara, A. K. A review of large low shear velocity provinces and ultra low velocity zones. Tectonophysics 760, 199\u0026ndash;220 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/\u003c/span\u003e\u003cspan address=\"https://doi.org:https://doi.org/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.tecto.2018.04.015\u003c/span\u003e\u003cspan address=\"10.1016/j.tecto.2018.04.015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShahar, A. \u003cem\u003eet al.\u003c/em\u003e High-temperature Si isotope fractionation between iron metal and silicate. Geochimica et Cosmochimica Acta 75, 7688\u0026ndash;7697 (2011). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org\u003c/span\u003e\u003cspan address=\"https://doi.org\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.gca.2011.09.038\u003c/span\u003e\u003cspan address=\"10.1016/j.gca.2011.09.038\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHin, R. C., Fitoussi, C., Schmidt, M. W. \u0026amp; Bourdon, B. Experimental determination of the Si isotope fractionation factor between liquid metal and liquid silicate. Earth and Planetary Science Letters 387, 55\u0026ndash;66 (2014). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2013.11.016\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2013.11.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoynier, F. \u003cem\u003eet al.\u003c/em\u003e Metal-silicate silicon isotopic fractionation and the composition of the bulk Earth. Earth and Planetary Science Letters 549, 116468 (2020). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.epsl.2020.116468\u003c/span\u003e\u003cspan address=\"10.1016/j.epsl.2020.116468\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZiegler, K., Young, E. D., Schauble, E. A. \u0026amp; Wasson, J. T. Metal\u0026ndash;silicate silicon isotope fractionation in enstatite meteorites and constraints on Earth's core formation. Earth and Planetary Science Letters 295, 487\u0026ndash;496 (2010). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2010.04.030\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2010.04.030\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFitoussi, C., Bourdon, B., Kleine, T., Oberli, F. \u0026amp; Reynolds, B. C. Si isotope systematics of meteorites and terrestrial peridotites: implications for Mg/Si fractionation in the solar nebula and for Si in the Earth's core. Earth and Planetary Science Letters 287, 77\u0026ndash;85 (2009). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2009.07.038\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2009.07.038\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSavage, P. S., Armytage, R. M. G., Georg, R. B. \u0026amp; Halliday, A. N. High temperature silicon isotope geochemistry. Lithos 190\u0026ndash;191, 500\u0026ndash;519 (2014). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.lithos.2014.01.003\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.lithos.2014.01.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHelffrich, G., Shahar, A. \u0026amp; Hirose, K. Isotopic signature of core-derived SiO2. Am Mineral 103, 1161\u0026ndash;1164 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.2138/am-2018-6482CCBYNCND\u003c/span\u003e\u003cspan address=\"https://doi.org:10.2138/am-2018-6482CCBYNCND\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWilliams, C. D., Li, M., McNamara, A. K., Garnero, E. J. \u0026amp; van Soest, M. C. Episodic entrainment of deep primordial mantle material into ocean island basalts. Nature Communications 6, 8937 (2015). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/ncomms9937\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/ncomms9937\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, W. \u003cem\u003eet al.\u003c/em\u003e Formation of large low shear velocity provinces through the decomposition of oxidized mantle. \u003cem\u003eNature Communications\u003c/em\u003e 12, 1911 (2021). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41467-021-22185-1\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/s41467-021-22185-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBallmer, M. D., Schumacher, L., Lekic, V., Thomas, C. \u0026amp; Ito, G. Compositional layering within the large low shear-wave velocity provinces in the lower mantle. Geochemistry, Geophysics, Geosystems 17, 5056\u0026ndash;5077 (2016). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/2016GC006605\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1002/2016GC006605\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee, C.-T. A. \u003cem\u003eet al.\u003c/em\u003e Upside-down differentiation and generation of a /`primordial/' lower mantle. Nature 463, 930\u0026ndash;933 (2010).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChristensen, U. R. \u0026amp; Hofmann, A. W. Segregation of subducted oceanic crust in the convecting mantle. Journal of Geophysical Research: Solid Earth 99, 19867\u0026ndash;19884 (1994). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1029/93JB03403\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1029/93JB03403\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi, M. \u0026amp; McNamara, A. K. Evolving morphology of crustal accumulations in Earth's lowermost mantle. Earth and Planetary Science Letters 577, 117265 (2022). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.epsl.2021.117265\u003c/span\u003e\u003cspan address=\"10.1016/j.epsl.2021.117265\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePanton, J., Davies, J. H. \u0026amp; Myhill, R. The Stability of Dense Oceanic Crust Near the Core-Mantle Boundary. \u003cem\u003eJournal of Geophysical Research: Solid Earth\u003c/em\u003e 128, e2022JB025610 (2023). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1029/2022JB025610\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1029/2022JB025610\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMulyukova, E., Steinberger, B., Dabrowski, M. \u0026amp; Sobolev, S. V. Survival of LLSVPs for billions of years in a vigorously convecting mantle: Replenishment and destruction of chemical anomaly. Journal of Geophysical Research: Solid Earth 120, 3824\u0026ndash;3847 (2015). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1002/2014JB011688\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1002/2014JB011688\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDeschamps, F., Cobden, L. \u0026amp; Tackley, P. J. The primitive nature of large low shear-wave velocity provinces. Earth and Planetary Science Letters 349, 198\u0026ndash;208 (2012). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.epsl.2012.07.012\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2012.07.012\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThomson, A. R. \u003cem\u003eet al.\u003c/em\u003e Seismic velocities of CaSiO3 perovskite can explain LLSVPs in Earth\u0026rsquo;s lower mantle. Nature (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41586-019-1483-x\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/s41586-019-1483-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, W. \u003cem\u003eet al.\u003c/em\u003e Velocity and density characteristics of subducted oceanic crust and the origin of lower-mantle heterogeneities. Nature Communications 11, 64 (2020). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41467-019-13720-2\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/s41467-019-13720-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYu, H.-M., Li, Y.-H., Gao, Y.-J., Huang, J. \u0026amp; Huang, F. Silicon isotopic compositions of altered oceanic crust: Implications for Si isotope heterogeneity in the mantle. Chem Geol 479, 1\u0026ndash;9 (2018). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.chemgeo.2017.12.013\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.chemgeo.2017.12.013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJackson, C. R. M., Ziegler, L. B., Zhang, H., Jackson, M. G. \u0026amp; Stegman, D. R. A geochemical evaluation of potential magma ocean dynamics using a parameterized model for perovskite crystallization. Earth and Planetary Science Letters 392, 154\u0026ndash;165 (2014). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2014.01.028\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2014.01.028\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJones, R. E. \u003cem\u003eet al.\u003c/em\u003e Origins of the terrestrial Hf-Nd mantle array: Evidence from a combined geodynamical-geochemical approach. Earth and Planetary Science Letters 518, 26\u0026ndash;39 (2019). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2019.04.015\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2019.04.015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi, Y., Vočadlo, L., Ballentine, C. \u0026amp; Brodholt, J. P. Primitive noble gases sampled from ocean island basalts cannot be from the Earth\u0026rsquo;s core. Nature Communications 13, 3770 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/s41467-022-31588-7\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/s41467-022-31588-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWicks, J. K., Jackson, J. M. \u0026amp; Sturhahn, W. Very low sound velocities in iron-rich (Mg,Fe)O: Implications for the core-mantle boundary region. Geophysical Research Letters 37 (2010). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1029/2010GL043689\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1029/2010GL043689\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaneshima, S. \u0026amp; Helffrich, G. Lower mantle scattering profiles and fabric below Pacific subduction zones. Earth and Planetary Science Letters 282, 234\u0026ndash;239 (2009). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.epsl.2009.03.024\u003c/span\u003e\u003cspan address=\"10.1016/j.epsl.2009.03.024\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFrost, D. A., Rost, S., Garnero, E. J. \u0026amp; Li, M. Seismic evidence for Earth's crusty deep mantle. Earth and Planetary Science Letters 470, 54\u0026ndash;63 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2017.04.036\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2017.04.036\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLei, H. \u0026amp; He, J. Nucleation and Growth Kinetics of MgO in Molten Steel. Journal of Materials Science \u0026amp; Technology 28, 642\u0026ndash;646 (2012). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S1005-0302(12)60110-8\u003c/span\u003e\u003cspan address=\"10.1016/S1005-0302(12)60110-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParks, G. A. Surface and interfacial free energies of quartz. Journal of Geophysical Research: Solid Earth 89, 3997\u0026ndash;4008 (1984). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1029/JB089iB06p03997\u003c/span\u003e\u003cspan address=\"10.1029/JB089iB06p03997\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKlapczynski, V., Le Maux, D., Courtois, M., Bertrand, E. \u0026amp; Paillard, P. Surface tension measurements of liquid pure iron and 304L stainless steel under different gas mixtures. Journal of Molecular Liquids 350, 118558 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.molliq.2022.118558\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.molliq.2022.118558\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi, Q., Xian, J.-W., Zhang, Y., Sun, T. \u0026amp; Vočadlo, L. Thermal Properties of Liquid Iron at Conditions of Planetary Cores. \u003cem\u003eJournal of Geophysical Research: Planets\u003c/em\u003e 127, e2021JE007015 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1029/2021JE007015\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1029/2021JE007015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Wijs, G. A. \u003cem\u003eet al.\u003c/em\u003e The viscosity of liquid iron at the physical conditions of the Earth's core. Nature 392, 805\u0026ndash;807 (1998). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1038/33905\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1038/33905\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMonteux, J., Qaddah, B. \u0026amp; Andrault, D. Conditions for segregation of a crystal-rich layer within a convective magma ocean. Journal of Geophysical Research: Planets 128 (2023). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1029/2023JE007805\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1029/2023JE007805\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStixrude, L. \u0026amp; Lithgow-Bertelloni, C. Thermodynamics of mantle minerals - II. Phase equilibria. Geophys J Int 184, 1180\u0026ndash;1213 (2011). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1111/j.1365-246X.2010.04890.x\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1111/j.1365-246X.2010.04890.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnderson, O. The power balance at the core\u0026ndash;mantle boundary. Physics of the Earth and Planetary Interiors 131, 1\u0026ndash;17 (2002). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/S0031-9201(02)00009-2\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/S0031-9201(02)00009-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen, Y. \u0026amp; Zhang, Y. Olivine dissolution in basaltic melt. Geochimica et Cosmochimica Acta 72, 4756\u0026ndash;4777 (2008). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.gca.2008.07.014\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.gca.2008.07.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGhosh, D. B. \u0026amp; Karki, B. B. Transport properties of carbonated silicate melt at high pressure. Science Advances 3 (2017). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1126/sciadv.1701840\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1126/sciadv.1701840\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStixrude, L., de Koker, N., Sun, N., Mookherjee, M. \u0026amp; Karki, B. B. Thermodynamics of silicate liquids in the deep Earth. Earth and Planetary Science Letters 278, 226\u0026ndash;232 (2009). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/j.epsl.2008.12.006\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.epsl.2008.12.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbe, Y. in \u003cem\u003eEvolution of the Earth and Planets\u003c/em\u003e 41\u0026ndash;54 (1993).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSolomatov, V. S., Olson, P. \u0026amp; Stevenson, D. J. Entrainment from a bed of particles by thermal convection. Earth and Planetary Science Letters 120, 387\u0026ndash;393 (1993). https://doi.org:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0012-821X(93)90252-5\u003c/span\u003e\u003cspan address=\"10.1016/0012-821X(93)90252-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFiquet, G., Andrault, D., Iti\u0026eacute;, J. P., Gillet, P. \u0026amp; Richet, P. X-ray diffraction of periclase in a laser-heated diamond-anvil cell. Physics of the Earth and Planetary Interiors 95, 1\u0026ndash;17 (1996). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:https://doi.org/10.1016/0031-9201(95)03109-X\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/0031-9201(95)03109-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDeschamps, F. \u0026amp; Cobden, L. Estimating core-mantle boundary temperature from seismic shear velocity and attenuation. Frontiers in Earth Science 10 (2022). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.3389/feart.2022.1031507\u003c/span\u003e\u003cspan address=\"https://doi.org:10.3389/feart.2022.1031507\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFischer, R. A. \u003cem\u003eet al.\u003c/em\u003e High pressure metal\u0026ndash;silicate partitioning of Ni, Co, V, Cr, Si, and O. Geochimica et Cosmochimica Acta 167, 177\u0026ndash;194 (2015). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org:10.1016/j.gca.2015.06.026\u003c/span\u003e\u003cspan address=\"https://doi.org:10.1016/j.gca.2015.06.026\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-3263305/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3263305/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eEarth’s mantle harbors two large low shear-wave velocity provinces (LLSVPs) with patches of ultra-low velocity zones (ULVZs) distributed in the bottom. These structures exhibit distinct seismic and geochemical signatures compared to the surrounding mantle. Yet, their origin remains enigmatic. One proposed explanation is the differentiation of an early basal magma ocean (BMO). However, the presence of an excessively thick layer of iron-rich ferropericlase in the crystallized BMO conflicts with seismic tomography. Here, we investigate the crystallization of a BMO continuously contaminated by oxide exsolutions from the core, termed BECMO, and find significant suppression of ferropericlase crystallization and consequently a mineralogical profile consistent with LLSVPs and ULVZs. In addition, diapirs of core exsolution entrained into the solid mantle may cause small-scale scattering. The BECMO inherits the light silicon isotope composition from the core and exhibits trace element enrichments, suggesting its potential role as a source material for ocean island basalts potentially sampling the lowermost LLSVPs, pointing to a unified mechanism for forming deep mantle heterogeneities.\u003c/p\u003e","manuscriptTitle":"Formation of deep mantle heterogeneities through basal exsolution contaminated magma ocean","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-10 01:38:39","doi":"10.21203/rs.3.rs-3263305/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-geoscience","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"ngeo","sideBox":"Learn more about [Nature Geoscience](http://www.nature.com/ngeo/)","snPcode":"","submissionUrl":"","title":"Nature Geoscience","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Research","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"9ad6d243-5af2-4205-b0fe-95906dfa1cf3","owner":[],"postedDate":"July 10th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-22T06:48:35+00:00","versionOfRecord":{"articleIdentity":"rs-3263305","link":"https://doi.org/10.1038/s41561-025-01797-y","journal":{"identity":"nature-geoscience","isVorOnly":false,"title":"Nature Geoscience"},"publishedOn":"2025-09-12 04:00:00","publishedOnDateReadable":"September 12th, 2025"},"versionCreatedAt":"2024-07-10 01:38:39","video":"","vorDoi":"10.1038/s41561-025-01797-y","vorDoiUrl":"https://doi.org/10.1038/s41561-025-01797-y","workflowStages":[]},"version":"v1","identity":"rs-3263305","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3263305","identity":"rs-3263305","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}