气候变化领域集成服务门户(CCPortal): Deformation of Antigorite and Its Geological Implications

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DOI	10.1029/2021JB021650
	Deformation of Antigorite and Its Geological Implications
	Shao T.; Zhou Y.; Song M.; Ma X.; Zhang L.; Yao W.; Dang J.; Li J.
发表日期	2021
ISSN	21699313
卷号	126 期号:6
英文摘要	The deformation model of antigorite and its relationship to intermediate-depth earthquakes are still controversial. Here, we conducted deformation experiments on foliated iron-poor antigorite at confining pressures of 1,100–1,500 MPa, temperatures of 400–600°C, and axial displacement rates of 3.75 × 10−6–7.24 × 10−4 mm/s using a solid-medium Griggs-type apparatus. As the temperature and/or pressure increases, the stress exponent decreases, and all samples show stable fault slip. Microstructural observations show ductile behavior indicated by kinking and bending of the originally straight foliation, and brittle characteristics, such as Riedel shear, comminution, and microcracking. Therefore, antigorite deformation is controlled by a semibrittle regime. Antigorite decomposed to forsterite and enstatite in samples sheared at temperatures ≥550°C but not in samples triaxially compressed at 600°C. This observation, combined with phase boundary information, implies that the deformation geometry (e.g., triaxial compression or shear) may change the phase stability of antigorite. Following dehydration, samples still show stable fault slip, indicating that dehydration does not directly trigger earthquakes. In cold subduction zones, fine-grained antigorite in the core of the shear zone likely induces seismic activity by producing water and talc (or a talc-like phase) in the process of shear friction because such phases within the fault zone may reduce the rate dependence, thereby inducing unstable slip. The comparison of the semibrittle strengths of antigorite and dunite and the weak strain rate dependence of stress suggest that a thin antigorite layer immediately above the subducting slab is not sufficient to cause significant decoupling between the slab and the mantle wedge. © 2021. American Geophysical Union. All Rights Reserved.
英文关键词	Antigorite; deformation geometry; earthquakes; semibrittle flow; slab-mantle wedge decoupling; subduction zones
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187074
作者单位	State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China; State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing, China; CAS Center for Excellence in Deep Earth Science, Guangzhou, China
推荐引用方式 GB/T 7714	Shao T.,Zhou Y.,Song M.,et al. Deformation of Antigorite and Its Geological Implications[J],2021,126(6).
APA	Shao T..,Zhou Y..,Song M..,Ma X..,Zhang L..,...&Li J..(2021).Deformation of Antigorite and Its Geological Implications.Journal of Geophysical Research: Solid Earth,126(6).
MLA	Shao T.,et al."Deformation of Antigorite and Its Geological Implications".Journal of Geophysical Research: Solid Earth 126.6(2021).