DOI: 10.1038/s41561-021-00756-7
论文题名: Dry metastable olivine and slab deformation in a wet subducting slab
作者: Ishii T. ; Ohtani E.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2021
卷: 14, 期: 7 起始页码: 526
结束页码: 530
语种: 英语
英文关键词: crustal deformation
; dehydration
; hydration
; magnesium
; olivine
; reaction kinetics
; silicate
; slab
; subduction
; transformation
; wadsleyite
英文摘要: A widely accepted explanation for deep-focus earthquakes is that they are caused by the delayed transformation kinetics of dry olivine, which would seem to require dry subducting slabs. However, many geochemical and geophysical observations and mineral physics data indicate that water is present within both hydrous and nominally anhydrous minerals, implying hydrated subducting slabs. The presence of metastable olivine in wet slabs is therefore paradoxical, and the hydration state of the slabs remains an open question. Here, we report results of water-partitioning experiments between olivine, wadsleyite and a major dense hydrous magnesium silicate in slabs, hydrous phase A, under water-undersaturated conditions. We show that olivine and wadsleyite coexisting with hydrous phase A are kinetically dry and contain less than 1 ppm and approximately 300 ppm water, respectively. Our results suggest that olivine and wadsleyite show dry transformation kinetics even in wet slabs. It is therefore possible that olivine transformation as a cause of deep-focus earthquakes and large slab deformation creating stagnant slabs could occur in the water-undersaturated wet slabs. These processes could be caused jointly by dehydration of hydrous minerals and the subsequent rapid phase transformation when the dehydration starts at lower temperatures than the phase transformation. © 2021, The Author(s), under exclusive licence to Springer Nature Limited. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/169768
Appears in Collections: 气候变化与战略
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作者单位: Center for High Pressure Science and Technology Advanced Research, Beijing, China; Bayerisches Geoinstitut, University of Bayreuth, Bayreuth, Germany; Department of Earth Sciences, Graduate School of Science, Tohoku University, Aoba, Sendai, Japan
Recommended Citation:
Ishii T.,Ohtani E.. Dry metastable olivine and slab deformation in a wet subducting slab[J]. Nature Geoscience,2021-01-01,14(7)