气候变化领域集成服务门户(CCPortal): Oxygen isotopes in ophicalcites: an ever-lasting controversy?

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DOI	10.1007/s00531-020-01934-5
	Oxygen isotopes in ophicalcites: an ever-lasting controversy?
	Bernoulli D.; Weissert H.
发表日期	2020
ISSN	14373254
英文摘要	Tectono-sedimentary breccias, known as ophicalcites, overlie serpentinised peridotites at a Jurassic ocean–continent transition along the Penninic-Austroalpine transition in the Eastern Alps of Switzerland. Deformation of the exhumed mantle rocks and breccia formation occurred under decreasing temperatures and along low-angle detachment faults exposing the mantle rocks at the sea floor and was coupled with hydrothermal activity and carbonation of the serpentinites at shallow depth and/or at the sea floor. Carbon isotopes in the ophicalcites persistently show marine values; however, the interpretation of oxygen-isotope values remained controversial: are they related to Jurassic hydrothermal activity or do they reflect Alpine metamorphic overprint? Here we discuss recent interpretations that relate oxygen isotope values measured in ophicalcites exclusively to Jurassic hydrothermal activity; to this end we use data that we earlier obtained along a north–south profile across Graubünden (eastern Switzerland). We revisited the sites of controversial interpretation along a north–south profile in eastern Switzerland. Along this profile, oxygen isotope values in ophicalcites and overlying pelagic sediments, up to 25 my younger than the ophicalcites, show identical values and become systematically lower with increasing Alpine metamorphism; they strongly deviate from values in ophicalcites and pelagic sediments measured along the Mid-Atlantic Ridge or ancient Atlantic ocean-continent transitions as e.g. in the Iberia–Newfoundland transect. The oxygen-isotope values measured in Alpine ophicarbonates thus reflect isotopic resetting during the Alpine orogeny, related to fluid-rock interaction during regional metamorphism. Hydrothermal processes that accompanied the formation of ophicalcites are not disputed; however, they cannot be traced by oxygen isotope geochemistry. © 2020, The Author(s).
英文关键词	Alps; Graubünden; Jurassic; Ocean–continent transition; Ophicalcite; Oxygen-isotopes
语种	英语
来源期刊	International Journal of Earth Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/147754
作者单位	Department of Earth Sciences, Swiss Federal Institute of Technology (ETH), Zürich, 8092, Switzerland
推荐引用方式 GB/T 7714	Bernoulli D.,Weissert H.. Oxygen isotopes in ophicalcites: an ever-lasting controversy?[J],2020.
APA	Bernoulli D.,&Weissert H..(2020).Oxygen isotopes in ophicalcites: an ever-lasting controversy?.International Journal of Earth Sciences.
MLA	Bernoulli D.,et al."Oxygen isotopes in ophicalcites: an ever-lasting controversy?".International Journal of Earth Sciences (2020).