Anomalous elasticity of talc at high pressures:Implications for subduction systems

作     者：Ye Peng Mainak Mookherjee Andreas Hermann Geeth Manthilake David Mainprice Ye Peng;Mainak Mookherjee;Andreas Hermann;Geeth Manthilake;David Mainprice

作者机构：Earth Materials LaboratoryDepartment of EarthOceanand Atmospheric SciencesFlorida State UniversityTallahasseeFL 32306USA Centre for Science at Extreme Conditions and SUPASchool of Physics and AstronomyThe University of EdinburghEdinburgh EH93FDUK Laboratoire Magmas et Volcans CNRSIRDOPGCUniversitéClermont Auvergne63000 Clermont-FerrandFrance Geosciences MontpellierUMR CNRS 5243Universitéde MontpellierMontpellier 34095France 

出 版 物：《Geoscience Frontiers》 (地学前缘（英文版）)

年 卷 期：2022年第13卷第4期

页      面：34-47页

核心收录：

学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

基　　金：supported by the US National Science Foundation grant EAR 1763215 and EAR 1753125 XSEDE facilities(GEO170003) the High-Performance Computing,Research Computing Center,Florida State University the UK’s National Supercomputer Service through the UK CarParrinello Consortium(EPSRC Grant No.EP/P022561/1)and project ID d56"Planetary Interiors" funding from the INSU-CNRS the French Government Laboratory of Excellence initiative n°ANR-10-LABX-0006,the Région Auvergne the European Regional Development Fund(Cler Volc contribution number 530) 

主　　题：Talc Elasticity Seismic anisotropy Hydrous minerals Subduction zone 

摘      要：Talc is a layered hydrous silicate mineral that plays a vital role in transporting water into Earth’s interior and is crucial for explaining geophysical observations in subduction zone *** this study,we explored the structure,equation of state,and elasticity of both triclinic and monoclinic talc under high pressures up to 18 GPa using first principles simulations based on density functional theory corrected for dispersive *** results indicate that principal components of the full elastic constant tensor C_(11) and C_(22),shear components C_(66),and several off-diagonal components show anomalous pressure *** non-monotonic pressure dependence of elastic constant components is likely related to the structural changes and is often manifested in a polytypic transition from a low-pressure polytype talc-I to a high-pressure polytype talc-Ⅱ.The polytypic transition of talc occurs at pressures within its thermodynamic ***,the bulk and shear elastic moduli show no anomalous *** study also shows that talc has low velocity,extremely high anisotropy,and anomalously high V_(P)/V_(S) ratio,thus making it a potential candidate mineral phase that could readily explain unusually high V_(P)/V_(S) ratio and large shear wave splitting delays as observed from seismological studies in many subduction systems.