气候变化领域集成服务门户(CCPortal): The nature of the interface between basalts and serpentinized mantle in oceanic domains: Insights from a geological section in the Alps

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DOI	10.1016/j.tecto.2020.228646
	The nature of the interface between basalts and serpentinized mantle in oceanic domains: Insights from a geological section in the Alps
	Coltat R.; Branquet Y.; Gautier P.; Boulvais P.; Manatschal G.
发表日期	2020
ISSN	00401951
卷号	797
英文摘要	The association of mafic extrusive rocks and serpentinized mantle rocks is a common feature encountered in numerous ultra-distal magma-poor rifted margins as well as in (ultra)slow-spreading oceanic settings where detachment faulting and mantle exhumation occur. Although seismic imaging and high-resolution TOBI radar allow imaging this association, the nature of this interface is poorly understood (e.g. nonconformity vs. tectonic channelized vs. diffuse fluid flow along the interface). The timing between magmatism and active detachment faulting is often poorly constrained and it remains difficult to decipher if mafic extrusives are pre-, syn- or post-exhumation of mantle rocks at the seafloor. In this study, we characterize the nature of this interface from a section of a Jurassic ultra-distal margin preserved in the Platta nappe, SE Swiss Alps. We show that the basalt-serpentinized mantle contact does neither correspond to an Alpine thrust system, nor to a nonconformity or a detachment plane exhuming mantle rocks from underneath already emplaced basalts. Rather, the basalt-serpentinite interface corresponds to a weak decoupling level formed by conjugate low-angle normal faults onto which conjugate high-angle normal faults branch. These structures are diagnostic of co-axial extensional tectonics occurring during and after emplacement of basalts over a formerly exhumed serpentinized mantle. Carbonate extensional and shear veins and foliated ophicalcites formed during this Jurassic extensional event. Their distribution across and along the basalt-serpentinite interface demonstrates that this decoupling interface was a high-permeability layer that channelized high fluid flow responsible for the widespread hydrothermal alteration. A positive feedback between fluid flow and extensional deformation is proposed. © 2020 Elsevier B.V.
关键词	Alpine ophiolites Basalt-serpentinite interface Extensional tectonics Fluid-assisted deformation Ophicalcites Ultra-distal magma-poor rifted margin
英文关键词	Basalt; Clay alteration; Faulting; Magnesite; Radar imaging; Detachment faulting; Extensional deformation; Extensional tectonics; Geological section; High permeability; High resolution; Hydrothermal alterations; Seismic imaging; Flow of fluids; basalt; deformation; exhumation; extensional tectonics; faulting; hydrothermal alteration; magma; mantle structure; nappe; normal fault; ophiolite; serpentine; Alps
语种	英语
来源期刊	Tectonophysics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/207734
作者单位	Univ Rennes, CNRS, Géosciences Rennes – UMR 6118, Rennes, F-35000, France; Institut des Sciences de la Terre d'Orléans, UMR 7327, Université d'Orléans, Orléans, France; Institut de Physique du Globe de Strasbourg, EOST-CNRS UMR 7516, Université de Strasbourg, Strasbourg, France
推荐引用方式 GB/T 7714	Coltat R.,Branquet Y.,Gautier P.,et al. The nature of the interface between basalts and serpentinized mantle in oceanic domains: Insights from a geological section in the Alps[J],2020,797.
APA	Coltat R.,Branquet Y.,Gautier P.,Boulvais P.,&Manatschal G..(2020).The nature of the interface between basalts and serpentinized mantle in oceanic domains: Insights from a geological section in the Alps.Tectonophysics,797.
MLA	Coltat R.,et al."The nature of the interface between basalts and serpentinized mantle in oceanic domains: Insights from a geological section in the Alps".Tectonophysics 797(2020).