气候变化领域集成服务门户(CCPortal): Shear Zone Development in Serpentinized Mantle: Implications for the Strength of Oceanic Transform Faults

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DOI	10.1029/2020JB020763
	Shear Zone Development in Serpentinized Mantle: Implications for the Strength of Oceanic Transform Faults
	Cox S.; Fagereng Å.; MacLeod C.J.
发表日期	2021
ISSN	21699313
卷号	126 期号:5
英文摘要	Oceanic transform faults display fewer and smaller-magnitude earthquakes than expected for their length. Several mechanisms have been inferred to explain this seismic slip deficit, including increased fault zone damage resulting in elevated fluid flow, and the alteration of olivine to serpentine. However, to date, these possible mechanisms are not supported by direct observation. We use micro to kilometer scale observations from an exhumed oceanic transform fault in the Troodos Ophiolite, Cyprus, to determine mineral-scale deformation mechanisms and infer likely controls on seismic behavior of serpentinized lithospheric mantle in active oceanic transform faults. We document a range of deformation fabrics including massive, scaly and phyllonitic serpentinite, attesting to mixed brittle-ductile deformation within serpentinite shear zones. The progressive development of a foliation, with cumulative strain, is an efficient weakening mechanism in scaly and phyllonitic serpentinite. Further weakening is promoted by a transition in the serpentine polytype from lizardite-dominated massive and scaly serpentinites to chrysotile-dominated phyllonitic serpentinite. The development of a foliation and polytype transition requires dissolution-precipitation processes. Discrete faults and fractures locally crosscut, but are also deformed by, foliated serpentinites. These brittle structures can be explained by local and transient elevated strain rates, and play a crucial role in strain localization by providing positive feedback for dissolution-precipitation by increasing permeability. We propose that the evolution in structure and deformation style documented within the serpentinized lithospheric mantle of the Southern Troodos Transform Fault Zone is a viable explanation for the dominantly creeping behavior and long-term weakness of oceanic transform faults. © 2021. The Authors.
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/187162
作者单位	School of Earth and Environmental Sciences, Cardiff University, Cardiff, United Kingdom
推荐引用方式 GB/T 7714	Cox S.,Fagereng Å.,MacLeod C.J.. Shear Zone Development in Serpentinized Mantle: Implications for the Strength of Oceanic Transform Faults[J],2021,126(5).
APA	Cox S.,Fagereng Å.,&MacLeod C.J..(2021).Shear Zone Development in Serpentinized Mantle: Implications for the Strength of Oceanic Transform Faults.Journal of Geophysical Research: Solid Earth,126(5).
MLA	Cox S.,et al."Shear Zone Development in Serpentinized Mantle: Implications for the Strength of Oceanic Transform Faults".Journal of Geophysical Research: Solid Earth 126.5(2021).