气候变化领域集成服务门户(CCPortal): Serpentinization, Carbonation, and Metasomatism of Ultramafic Sequences in the Northern Apennine Ophiolite (NW Italy)

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DOI	10.1029/2020JB020619
	Serpentinization, Carbonation, and Metasomatism of Ultramafic Sequences in the Northern Apennine Ophiolite (NW Italy)
	Schwarzenbach E.M.; Vogel M.; Früh-Green G.L.; Boschi C.
发表日期	2021
ISSN	21699313
卷号	126 期号:5
英文摘要	Fluid-rock interaction in ultramafic rocks considerably affects the chemical and isotopic composition of the oceanic lithosphere. We present a geochemical and petrological study of serpentinites and ophicalcites of the Northern Apennine ophiolite, Italy. This ophiolite sequence represents fragments of Jurassic oceanic lithosphere that have been denuded by low angle detachment faults, exposing peridotites on the ocean floor and triggering hydrothermal alteration. Seawater circulation is documented by (Jurassic) seawater-like 87Sr/86Sr values and δ13C values of 1.1–3.0‰ in carbonate veins of the ophicalcites. Bulk rock ophicalcites have low 87Sr/86Sr values of 0.70489–0.70599, elevated SiO2 contents, and talc druses filling calcite veins that record Si-metasomatism. In contrast, underlying serpentinites have 87Sr/86Sr values above Jurassic seawater values. Bulk rock δD and δ18O values of ophicalcites and serpentinites suggest interaction with an evolved seawater-derived and/or magmatic fluid. These chemical signatures result from a complex history of serpentinization, carbonation, and metasomatism. Multiphase water-rock interaction includes infiltration of basement-derived fluids during initial mantle upwelling within an opening ocean basin, followed by localized high-temperature fluid infiltration, extensive seawater circulation resulting in carbonation, and oxidation near the seawater-exposed surface, and finally, fluid-rock interaction with overlying mafic lithologies leading to Si-metasomatism. The studied sequence represents an excellent example of the evolution from serpentinite to ophicalcite during continuous uplift and exposure of ultramafic rocks on the seafloor and documents the complex hydrothermal evolution of ultramafic rocks associated with this process. The extensive chemical transformation of mantle peridotites likely has an impact on geochemical cycles and subduction zone processes. © 2021. The Authors.
英文关键词	Carbonation; isotope signatures; Northern Apennine ophiolite; peridotites; serpentinization; Si-metasomatism
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/187112
作者单位	Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany; Department of Earth Sciences, ETH Zürich, Zürich, Switzerland; Institute of Geosciences and Earth Resources - CNR Pisa, Pisa, Italy
推荐引用方式 GB/T 7714	Schwarzenbach E.M.,Vogel M.,Früh-Green G.L.,et al. Serpentinization, Carbonation, and Metasomatism of Ultramafic Sequences in the Northern Apennine Ophiolite (NW Italy)[J],2021,126(5).
APA	Schwarzenbach E.M.,Vogel M.,Früh-Green G.L.,&Boschi C..(2021).Serpentinization, Carbonation, and Metasomatism of Ultramafic Sequences in the Northern Apennine Ophiolite (NW Italy).Journal of Geophysical Research: Solid Earth,126(5).
MLA	Schwarzenbach E.M.,et al."Serpentinization, Carbonation, and Metasomatism of Ultramafic Sequences in the Northern Apennine Ophiolite (NW Italy)".Journal of Geophysical Research: Solid Earth 126.5(2021).