气候变化领域集成服务门户(CCPortal): Coexisting High-Al and High-Cr Chromitites in the Dingqing Ophiolite (SE Tibet): Inferences to Compositional Heterogeneity in the Tethyan Upper Mantle

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DOI	10.3390/min13091234
	Coexisting High-Al and High-Cr Chromitites in the Dingqing Ophiolite (SE Tibet): Inferences to Compositional Heterogeneity in the Tethyan Upper Mantle
	Zhang, Boyang; Zoheir, Basem; Zhang, Chenjie; Mu, Xiaoping; Xu, Xiangzhen; Qiu, Tian; Xiong, Fahui
发表日期	2023
EISSN	2075-163X
卷号	13 期号:9
英文摘要	The Dingqing ophiolite represents a significant allochthonous ophiolite nappe in the eastern segment of the Bangong-Nujiang suture zone in southeastern Tibet. The microanalytical data of associated podiform chromitites classify them into two distinct varieties: high-Al and high-Cr. The coexistence of both high-Cr and high-Al chromitites in the Dingqing ophiolite suggests a complex or multistage evolutionary history of the host rocks. New petrological and geochemical analyses are used herein to unravel the interrelationships between the chromitite ores and host rocks and assess the mechanism of formation. The Dingqing ophiolitic nappe is made up mainly of harzburgite, dunite, and less abundant pyroxenite and gabbro. Several small lens-shaped bodies of chromitite ore are mostly confined to the harzburgite rocks, with ore textures varying from massive to sparsely disseminated chromite. In addition to magnesiochromite, the orebodies contain minor amounts of olivine, amphibole, and serpentine. The textural relationships provide compelling evidence of plastic deformation and partial melting of the associated peridotites. Detailed examination of the Cr-spinel grains reveals a wide range of composition, spanning from high-Al (Cr# = 3.18-59.5) to high-Cr (Cr# 60.3-87.32). The abundances of the platinum-group element (PGE) in chromitites are significantly variable (93 to 274 ppb). Formation of the Dingqing peridotites most likely took place in a mid-ocean ridge (MOR) setting, and subsequent modifications by supra-subduction zone (SSZ) melts resulted in heterogenous or mixed geochemical characteristics of these rocks. Chemistry of the spinel-olivine-clinopyroxene assemblage demonstrates multiple stages of partial melting of the source mantle rocks, including an early phase of restricted partial melting (similar to 20%-30%) and a later phase of extensive partial melting (>40%). The formation of the high-Al chromitite type was associated with the early phase (constrained melting), whereas extensive partial melting in the late stages likely led to the accumulation of high-Cr podiform chromitite bodies.
关键词	Dingqing ophiolite Bangong-Nujiang suture zone high-Al chromitite high-Cr chromitite partial melting multistage evolution
英文关键词	NUJIANG SUTURE ZONE; MELT-ROCK REACTION; PLATINUM-GROUP; LUOBUSA OPHIOLITE; PODIFORM CHROMITITES; RICH CHROMITITES; CHROMIAN SPINEL; OMAN OPHIOLITE; PERIDOTITES; GEOCHEMISTRY
WOS研究方向	Geochemistry & Geophysics ; Mineralogy ; Mining & Mineral Processing
WOS记录号	WOS:001077271600001
来源期刊	MINERALS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/283350
作者单位	China Geological Survey; Chinese Academy of Geological Sciences; Institute of Geology, Chinese Academy of Geological Sciences; Ministry of Natural Resources of the People's Republic of China; Egyptian Knowledge Bank (EKB); Benha University; University of Kiel
推荐引用方式 GB/T 7714	Zhang, Boyang,Zoheir, Basem,Zhang, Chenjie,et al. Coexisting High-Al and High-Cr Chromitites in the Dingqing Ophiolite (SE Tibet): Inferences to Compositional Heterogeneity in the Tethyan Upper Mantle[J],2023,13(9).
APA	Zhang, Boyang.,Zoheir, Basem.,Zhang, Chenjie.,Mu, Xiaoping.,Xu, Xiangzhen.,...&Xiong, Fahui.(2023).Coexisting High-Al and High-Cr Chromitites in the Dingqing Ophiolite (SE Tibet): Inferences to Compositional Heterogeneity in the Tethyan Upper Mantle.MINERALS,13(9).
MLA	Zhang, Boyang,et al."Coexisting High-Al and High-Cr Chromitites in the Dingqing Ophiolite (SE Tibet): Inferences to Compositional Heterogeneity in the Tethyan Upper Mantle".MINERALS 13.9(2023).