气候变化领域集成服务门户(CCPortal): Electrical conductivity of omphacite and garnet indicates limited deep water recycling by crust subduction

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DOI	10.1016/j.epsl.2021.116784
	Electrical conductivity of omphacite and garnet indicates limited deep water recycling by crust subduction
	Liu H.; Zhang K.; Ingrin J.; Yang X.
发表日期	2021
ISSN	0012821X
卷号	559
英文摘要	It is usually stated that oceanic crust recycling at subduction zones introduces large quantities of water into Earth's interior. However, it remains clouded how much water is recycled to the deep mantle. This is largely due to the challenge in directly sampling, and analyzing the water content of, a deep subducting crust. The subducting crust below ∼30 km depth is dominated by omphacite and garnet in eclogite-facies rocks. Here we have determined the electrical conductivity of omphacite and garnet in representative subduction-related eclogites, each with varying contents of Fe and H2O that are key in electrical conduction. Considering the measured conductivity, the eclogite chemistry by geochemical investigations and the highly resistive property of subducting crusts by geophysical surveys, we demonstrate that, at 70-120 km depths in the subducting crust, the H2O contents of omphacite and garnet are strikingly small, with the maximum value being <400 and <80 ppm in the former and latter, respectively. The very small water contents indicate extremely water-poor conditions, or very low water activity, during the eclogite-facies metamorphism and in the system. This further implies the absence of appreciated amounts of hydrous phases such as amphibole and chlorite in the matrix, because of the strong ability of omphacite and garnet in hosting water as documented in natural samples. We suggest that the recycling of water to the deep mantle by oceanic crust subduction is probably very limited. The results are important for modeling the conductivity of subducting slabs and understanding the deep water circulation. © 2021 Elsevier B.V.
关键词	crust subduction deep water recycling electrical conductivity experimental studies omphacite and garnet
英文关键词	Electric conductivity; Garnets; Geochemical surveys; Metamorphic rocks; Earth's interior; Electrical conduction; Electrical conductivity; Geochemical investigations; Geophysical surveys; Hydrous phasis; Subducting slabs; Subduction zones; Water recycling; crustal structure; deep water; electrical conductivity; experimental study; garnet; omphacite; subduction
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203192
作者单位	State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, 210023, China; Univ. Lille, CNRS, INRAE, ENSCL, UMR 8207, UMET, Unité Matériaux et Transformations, Lille, F59000, France
推荐引用方式 GB/T 7714	Liu H.,Zhang K.,Ingrin J.,et al. Electrical conductivity of omphacite and garnet indicates limited deep water recycling by crust subduction[J],2021,559.
APA	Liu H.,Zhang K.,Ingrin J.,&Yang X..(2021).Electrical conductivity of omphacite and garnet indicates limited deep water recycling by crust subduction.Earth and Planetary Science Letters,559.
MLA	Liu H.,et al."Electrical conductivity of omphacite and garnet indicates limited deep water recycling by crust subduction".Earth and Planetary Science Letters 559(2021).