气候变化领域集成服务门户(CCPortal): Formation of Igneous Layering in the Lower Oceanic Crust From the Samail Ophiolite, Sultanate of Oman

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DOI	10.1029/2020JB019573
	Formation of Igneous Layering in the Lower Oceanic Crust From the Samail Ophiolite, Sultanate of Oman
	Mock D.; Neave D.A.; Müller S.; Garbe-Schönberg D.; Namur O.; Ildefonse B.; Koepke J.
发表日期	2021
ISSN	21699313
卷号	126 期号:1
英文摘要	As the largest and best exposed example of paleo fast-spreading oceanic crust on land, the Samail ophiolite in the Sultanate of Oman represents an ideal natural laboratory for investigating deep crustal processes at fast-spreading mid-ocean ridges. We studied two layered gabbro sequences from different stratigraphic depths: one from the middle of the plutonic crust showing decimeter-scale modal layering (i.e., varying phase proportions) with olivine abundances gradually decreasing from layer bases to tops (Wadi Somerah, Sumail block) and one located near the crust-mantle boundary showing millimeter-scale olivine-rich layers (Wadi Wariyah, Wadi Tayin block). Our multimethod approach of field, petrographic, geochemical, and microstructural observations focuses on documenting layered textures that are widely observed within the lower oceanic crust as well as understanding their formation mechanisms within the context of small scale crustal accretion processes beneath fast-spreading mid-ocean ridges. Results from the mid-crustal sequence indicate moderate cooling rates (Ca-in-olivine: log[dT/dt; °C yr−1] = −2.21 ± 0.7) and correlated variations in mineral compositions and microstructures. We infer that decimeter-scale layers in Wadi Somerah were deposited by density currents of crystal-laden magma within a sill environment that potentially experienced occasional magma replenishment. The millimeter layering in Wadi Wariyah is best explained by Ostwald ripening emphasizing initial heterogeneities possibly being provoked by cyclical nucleation of olivine through the competing effects of element diffusion and rapid cooling. Fast cooling is recorded for the crustal base (Ca-in-olivine: log[dT/dt; °C yr−1] = −1.19 ± 0.5, Mg-in-plagioclase: log[dT/dt; °C yr−1] = −1.35°C ± 0.6) demonstrating that heat locally can be lost very efficiently from the lowermost crust. ©2020. The Authors.
英文关键词	cooling rates; formation of layered gabbros; lower oceanic crust; Oman ophiolite
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/187429
作者单位	Institut für Mineralogie, Leibniz Universität Hannover, Hanover, Germany; Géosciences Montpellier, Université de Montpellier, CNRS, Université des Antilles, Montpellier, France; Department of Earth and Environmental Sciences, The University of Manchester, Manchester, United Kingdom; Institut für Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Kiel, Germany; Department of Earth and Environmental Sciences, KU Leuven, Leuven, KU, Belgium
推荐引用方式 GB/T 7714	Mock D.,Neave D.A.,Müller S.,et al. Formation of Igneous Layering in the Lower Oceanic Crust From the Samail Ophiolite, Sultanate of Oman[J],2021,126(1).
APA	Mock D..,Neave D.A..,Müller S..,Garbe-Schönberg D..,Namur O..,...&Koepke J..(2021).Formation of Igneous Layering in the Lower Oceanic Crust From the Samail Ophiolite, Sultanate of Oman.Journal of Geophysical Research: Solid Earth,126(1).
MLA	Mock D.,et al."Formation of Igneous Layering in the Lower Oceanic Crust From the Samail Ophiolite, Sultanate of Oman".Journal of Geophysical Research: Solid Earth 126.1(2021).