气候变化领域集成服务门户(CCPortal): Hydration of a Mantle Shear Zone Beyond Serpentine Stability: A Possible Link to Microseismicity Along Ultraslow Spreading Ridges?

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DOI	10.1029/2020JB019509
	Hydration of a Mantle Shear Zone Beyond Serpentine Stability: A Possible Link to Microseismicity Along Ultraslow Spreading Ridges?
	Vieira Duarte J.F.; Kaczmarek M.-A.; Vonlanthen P.; Putlitz B.; Müntener O.
发表日期	2020
ISSN	21699313
卷号	125 期号:10
英文摘要	Hydration of the oceanic mantle is a fundamental process of the global water cycle promoting chemical and volumetric changes and facilitating mantle exhumation along detachment faults. At which depth these processes occur and how fluids circulate along ductile mantle shear zones are, however, less well constrained. Here we present field, chemical, and microstructural evidence of hydration processes of peridotite mylonites within an upper mantle shear zone from an Alpine ophiolite (Lanzo massif, Italy). Mylonitic and ultramylonitic areas of the anastomosing shear zone are enriched in Cl-bearing amphibole. Electron backscatter diffraction (EBSD) data indicate the activation of the (100)[001] amphibole slip system arguing for synkinematic growth and deformation at temperatures consistent with Mg-hornblende stability between 800°C and 850°C. High Cl contents in amphibole (0.15–0.61 wt%) as well as oxygen isotope data (δ18Owhole-rock between 4.4‰ and 4.7‰) indicate accumulation and focusing of seawater-derived fluid in mylonitic and ultramylonitic domains. Such hydration processes are consistent with strain partitioning between water-poor (less deformed) and water-rich (intensely deformed) layers, consistent with changes in olivine and pyroxene crystallographic preferred orientations (CPOs). Our results support recent geophysical data from ultraslow spreading mid-ocean ridge systems that fluids might penetrate beyond the stability of serpentine to depth between 6 and 15 km. Such peridotite shear zones act as fluid pathways for long-lived detachment faults or oceanic transform faults, along which upper mantle rocks are exhumed to the seafloor. Fracturing and fluid flow along such peridotite shear zones might be recorded by deep microseismicity along ultraslow spreading ridges. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	amphibole; hydration; Lanzo; mantle shear zone; microseismicity; Western Alps
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/187566
作者单位	Institute of Earth Sciences, UNIL-Mouline, University of Lausanne, Lausanne, Switzerland; Institute of Geological Sciences, University of Bern, Bern, Switzerland; Géosciences Environnement Toulouse (GET), CNRS-CNES-IRD-Université de Toulouse III, Observatoire Midi Pyrénées, Toulouse, France
推荐引用方式 GB/T 7714	Vieira Duarte J.F.,Kaczmarek M.-A.,Vonlanthen P.,et al. Hydration of a Mantle Shear Zone Beyond Serpentine Stability: A Possible Link to Microseismicity Along Ultraslow Spreading Ridges?[J],2020,125(10).
APA	Vieira Duarte J.F.,Kaczmarek M.-A.,Vonlanthen P.,Putlitz B.,&Müntener O..(2020).Hydration of a Mantle Shear Zone Beyond Serpentine Stability: A Possible Link to Microseismicity Along Ultraslow Spreading Ridges?.Journal of Geophysical Research: Solid Earth,125(10).
MLA	Vieira Duarte J.F.,et al."Hydration of a Mantle Shear Zone Beyond Serpentine Stability: A Possible Link to Microseismicity Along Ultraslow Spreading Ridges?".Journal of Geophysical Research: Solid Earth 125.10(2020).