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DOI	10.2138/am-2022-8392
	Microchemistry and magnesium isotope composition of the Purang ophiolitic chromitites (SW Tibet): New genetic inferences
	Xiong, Fahui; Zoheir, Basem; Robinson, Paul T. T.; Wirth, Richard; Xu, Xiangzhen; Qiu, Tian; Sun, Yi
发表日期	2023
ISSN	0003-004X
EISSN	1945-3027
起始页码	1117
结束页码	1131
卷号	108 期号:6
英文摘要	New petrographic and microanalytical studies of mineral inclusions in the Purang ophiolitic chromitites (SW Tibet) are used to scrutinize the evolution of the associated Cretaceous sub-oceanic lithospheric mantle section. Silicate inclusions in the chromite grains include composite and single-phase orthopyroxene, clinopyroxene, amphibole, and uvarovite. Most inclusions are sub-rounded or globular, whereas a few inclusions exhibit cubic/octahedral crystal morphologies. The latter are randomly distributed in the large chromite grains, though discrete aggregates are consistently confined to the grain centers. Abundant micrometer-scale, clinopyroxene inclusions are topotaxially aligned along crystallographic planes. Less-abundant sulfide, wustite, apatite, and uvarovite inclusions are observed in some samples.The trace element geochemistry of the Purang chromitite evoke parental MORB- and boninitelike melts, consistent with the supra-subduction zone setting. The d(26)Mg values of the high-Cr and high-Al chromitites range from -0.25 to -0.29 parts per thousand and -0.05 to -0.32 parts per thousand, respectively. The associated harzburgite has nearly overlapping d(26)Mg values of -0.13 to -0.37 parts per thousand, but pyroxenite sills show distinct d(26)Mg values (-0.61 to -0.67 parts per thousand). The variable Mg isotope signatures, combined with abundant exotic, ultrahigh-pressure and super reduced (UHP-SuR) mineral inclusions in the chromite grains, suggest that recycling and recrystallization under different mantle conditions played an important role in the genesis and evolution of these rocks. Furthermore, discrete silicate, sulfide, and metal alloy inclusions in the Purang chromitites are comparable to those reported in other Tethyan ophiolites, and collectively suggest a common geodynamic evolution.
关键词	Purang ophiolite SW Tibet UHP-SuR mineral inclusions high-Cr and high-Al chromitites deep mantle recycling SSZ processes
英文关键词	THETFORD MINES OPHIOLITE; ZANGBO SUTURE ZONE; RAY-IZ OPHIOLITE; PODIFORM CHROMITITES; LUOBUSA OPHIOLITE; OCEANIC LITHOSPHERE; TRACE-ELEMENTS; UPPER-MANTLE; HIGH-CR; ORIGIN
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
WOS记录号	WOS:001000325200010
来源期刊	AMERICAN MINERALOGIST
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/282893
作者单位	China Geological Survey; Institute of Geology, Chinese Academy of Geological Sciences; Chinese Academy of Geological Sciences; Southern Marine Science & Engineering Guangdong Laboratory; Southern Marine Science & Engineering Guangdong Laboratory (Guangzhou); Egyptian Knowledge Bank (EKB); Benha University; University of Kiel; Helmholtz Association; Helmholtz-Center Potsdam GFZ German Research Center for Geosciences; China University of Geosciences - Beijing
推荐引用方式 GB/T 7714	Xiong, Fahui,Zoheir, Basem,Robinson, Paul T. T.,et al. Microchemistry and magnesium isotope composition of the Purang ophiolitic chromitites (SW Tibet): New genetic inferences[J],2023,108(6).
APA	Xiong, Fahui.,Zoheir, Basem.,Robinson, Paul T. T..,Wirth, Richard.,Xu, Xiangzhen.,...&Sun, Yi.(2023).Microchemistry and magnesium isotope composition of the Purang ophiolitic chromitites (SW Tibet): New genetic inferences.AMERICAN MINERALOGIST,108(6).
MLA	Xiong, Fahui,et al."Microchemistry and magnesium isotope composition of the Purang ophiolitic chromitites (SW Tibet): New genetic inferences".AMERICAN MINERALOGIST 108.6(2023).