气候变化领域集成服务门户(CCPortal): Petrological characteristics of the Neoproterozoic Ess ophiolite mantle section; Arabian Shield; Saudi Arabia: a mineral chemistry perspective

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DOI	10.1007/s00531-019-01799-3
	Petrological characteristics of the Neoproterozoic Ess ophiolite mantle section; Arabian Shield; Saudi Arabia: a mineral chemistry perspective
	Gahlan H.A.; Azer M.K.; Asimow P.D.; Mubarak H.S.; Al-Kahtany K.M.
发表日期	2020
ISSN	14373254
起始页码	239
结束页码	251
卷号	109 期号:1
英文摘要	The Ess ophiolite, one of the most important ophiolitic massifs of the Arabian Shield, consists of a lower succession of serpentinized mantle rocks overlain by an ultramafic cumulate sequence, layered and isotropic gabbros, sheeted dykes, pillow lavas and pelagic sediments. The Ess mantle section is composed mainly of serpentinized peridotites with chromitite pods, dunite, wehrlite and pyroxenite. Extensive metasomatism and alteration has transformed the ultramafic rocks to talc-carbonates, magnesite deposits and listvenite, especially along shear zones and fault planes. Nevertheless, relics of primary chromian spinel, olivine and pyroxenes are observed. Both primary and metamorphic olivines can be recognized in dunite; the latter is marked by very high forsterite content (97–98), low NiO content (< 0.2 wt%) and wide variations in MnO content (0.03–1.3 wt%). The mesh and bastite textures of the serpentine suggest that protoliths were mainly harzburgite with minor dunite. Some fresh cores of Cr-spinel are rimmed by ferritchromite and Cr-magnetite, indicating prograde metamorphism at lower amphibolite facies under oxidizing conditions. The high Cr# (> 0.6) and low TiO2 content (< 0.14 wt%) of fresh Cr-spinel and the high forsterite (0.90–0.93) and NiO contents (0.4–0.5 wt%) of fresh olivine are all consistent with residual mantle rocks that experienced high degrees of partial melt extraction. Orthopyroxene and clinopyroxene in the Ess peridotites have low CaO, Al2O3 and TiO2 contents resembling those typically found in depleted harzburgites from fore-arcs. Consequently, we propose that the Ess mantle peridotites formed in a forearc setting during subduction initiation that developed as a result of northwest subduction due to the convergence between East and West Gondwana, leading eventually to closure of the Mozambique Ocean during the Pan-African orogeny. © 2019, Geologische Vereinigung e.V. (GV).
英文关键词	Arabian shield; Ess ophiolite; Fore-arc; Serpentinized peridotite; Supra-subduction zone
语种	英语
scopus关键词	forearc basin; mantle source; metasomatism; mineralogy; ophiolite; peridotite; petrology; Proterozoic; serpentinite; subduction zone; Arabian Shield
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/147730
作者单位	Department of Geology and Geophysics, King Saud University, Riyadh, 11451, Saudi Arabia; Geology Department, Assiut University, Assiut, 71516, Egypt; Geological Sciences Department, National Research Centre, Cairo, Egypt; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States; Seismic Studies Center, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
推荐引用方式 GB/T 7714	Gahlan H.A.,Azer M.K.,Asimow P.D.,et al. Petrological characteristics of the Neoproterozoic Ess ophiolite mantle section; Arabian Shield; Saudi Arabia: a mineral chemistry perspective[J],2020,109(1).
APA	Gahlan H.A.,Azer M.K.,Asimow P.D.,Mubarak H.S.,&Al-Kahtany K.M..(2020).Petrological characteristics of the Neoproterozoic Ess ophiolite mantle section; Arabian Shield; Saudi Arabia: a mineral chemistry perspective.International Journal of Earth Sciences,109(1).
MLA	Gahlan H.A.,et al."Petrological characteristics of the Neoproterozoic Ess ophiolite mantle section; Arabian Shield; Saudi Arabia: a mineral chemistry perspective".International Journal of Earth Sciences 109.1(2020).