Stability and physical properties of brucite at high pressures and temperatures:Implication for Earth’s deep water cycle  

作　　者：Ningyu Sun Xinyang Li Luo Li Qingchun Zhang Yingxin Yu Zhu Mao Cijin Zhou Dongzhou Zhang 

机构地区：[1]Deep Space Exploration Laboratory/School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,PR China [2]State Key Laboratory of Superhard Materials,Jilin University,Changchun 130012,PR China [3]CAS Center for Excellence in Comparative Planetology,University of Science and Technology of China,Hefei 230026,Anhui,PR China [4]Center for Advanced Radiation Sources,University of Chicago,Chicago,IL 60637,USA

出　　处：《Geoscience Frontiers》2025年第1期407-415,共9页地学前缘(英文版)

基　　金：supported by National Key R&D Program of China(2018YFA0702703);National Natural Science Foundation of China(42002036);the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB18000000);the Fundamental Research Funds for the Central Universities(WK2080000144,WK2080000189);supported by the National Science Foundation-Earth Sciences(EAR-1128799);Department of Energy-GeoSciences(DE-FG02-94ER14466);supported by DOE-BES,under Contract No.DE-AC02-06CH11357;BL15U1 of Shanghai Synchrotron Radiation Facility(proposal 2019-SSRF-PT-011379).

摘　　要：Brucite is a common hydrous mineral on Earth and may contribute to the deep water cycle of the Earth,but its stability and structure under mantle conditions remain uncertain.In this study,we investigated the stability of brucite up to 60 GPa at 800 K and 45 GPa at 1850 K.Within the experiment P-T conditions,no theoretically predicted new phase was observed,and brucite remained in the Pm1 structure.With the determined thermal EoS of brucite and the elastic parameters of mantle minerals,we modeled the velocity and density profile of subducted hydrous harzburgite in the top lower mantle,assuming that the water was stored in brucite and phase D.Based on the modelling,1 wt.%water will reduce the velocity and density of harzburgite by~5%and~2%,respectively,yet whether the water is stored in brucite or phase D has weak influence on both density and velocity.With a water content up to 2.4 wt.%,the density of hydrous harzburgite could be reduced to 2.2(2)%-2.8(2)%lower than the surrounding mantle,while the VP and VS of hydrous harzburgite are still 0.3(1)%-0.7(1)%and 0.7(2)%-1.8(2)%higher than that of the normal mantle.Thus,the low-density hydrous harzburgite may slow down the subducting of slab,despite being a high-velocity body in seismic observations.

关 键 词：BRUCITE Phase stability High pressure-temperature Subducted slabs Hydrous harzburgite 

分 类 号：P58[天文地球—岩石学]