The effect of antigorite dehydration on velocity structure and water migration in subduction zones  

作　　者：Huan Zeng Maining Ma Yongbing Li Jialei Zhang Hao Guan Xiao Li Key 

机构地区：[1]Laboratory of Earth System Numerical Modeling and Application,College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Geoscience Frontiers》2025年第1期335-345,共11页地学前缘(英文版)

基　　金：supported by the National Natural Science Foundation of China(Grant No.42174114,41674089).

摘　　要：The water migration in subduction zones,primarily driven by the phase transition in hydrous minerals,can give rise to hydrated regions with reduced velocity.A fundamental element in comprehending and deciphering these low-velocity zones revolves around acquiring insights into the stability and elasticity of relevant hydrous minerals.As one of the main water carriers in shallow areas,antigorite can dehydrate to form talc,forsterite,and fluid(talc-bearing peridotites)in deep areas of subduction zones,and then the talc thus serves as one of the minerals that can bring water to the deep Earth.Here,the elasticity of talc up to 24 GPa and forsterite up to 12 GPa are calculated by using the first principles method.The result supposes that the talc structure transforming from talc I to talc II is at a pressure between 6 GPa and 8 GPa,impacting the trend of elastic wave velocity in response to pressure.Furthermore,the elastic wave velocity of forsterite can be significantly affected by iron concentration.Meanwhile,a variation velocity model with antigorite consumption and talc content is set up for talc-bearing serpentinized peridotite based on the elastic properties of talc and forsterite in this study,and antigorite in Wang et al.(2022).The results of our model demonstrate a decrease in the low-velocity anomaly in subduction zones,particularly in deep regions or areas with higher initial serpentinization degrees.The results also suggest that the mode of antigorite dehydration can diminish the estimation of water content transported to depths of subduction zones,such as the Mariana Trench and Northern Japan subduction zones.The mode of antigorite dehydration thus provides a useful tool for constraining the composition,seismic velocity structure,and water migration in subduction zones.

关 键 词：TALC Antigorite dehydration Elastic properties Subduction zone First principles 

分 类 号：TQ3[化学工程]