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DOI	10.1016/j.oregeorev.2022.105283
	Geochemical constraints on the multistage evolution of the Yilashan ophiolite, central Tibet
	Xu, Xiang Zhen; Xiong, Fahui; Zoheir, Basem; Yan, Jinyu; Zhang, Boyang; Zhang, Ran; Yang, Jingsui
发表日期	2023
ISSN	0169-1368
EISSN	1872-7360
卷号	153
英文摘要	The Yilashan ophiolite in the southern part of the central Bangong-Nujiang suture zone comprises variably deformed harzburgite, dunite, and less abundant gabbro and pyroxenite pods and crosscutting veins. Cr-spinels in podiform chromitite bodies are characterized by high Cr# (64.3-74.3), high Mg# (58.2-67.5), and consistently low contents of TiO2 (<= 0.12 wt%). Primary melt calculations designate parental boninitic magmas with Al2O3(liquid) contents of 11.67-13.49 wt%, and (FeO/MgO)liquid values of 0.92-1.12. Whole-rock geochemical data of fresh pyroxenite samples are characterized by negative K, Ta, Nb and Zr anomalies, no Eu anomaly, and chondrite-normalized REE patterns comparable to the N-MORB melts. The gabbro samples, in contrast, are high-K calc-alkaline, with elevated contents of LILE (Rb, K, Th) and depleted HFSE (i.e., Nb, Ta, P, Ti), consistent with subduction-related magmas. The fractionated chondrite-normalized REE patterns, high LREE/HREE values, and negative Eu anomalies of these gabbroic rocks are similar to the island arc basalts. Pyroxenite shows high PPGE/IPGE values, variable Pd/Ir (55.7-316.7), and left-leaning primitive mantle-normalized PGE pattern, whereas massive chromitite is enriched in IPGE relative to PPGE. The PGE patterns of pyroxenite and chromitite, though distinct, depict significant fractionation and partial melting in their formation. The elevated contents of PPGEs in pyroxenite suggest derivation from sulfur-saturated magmas as chromitite crystallization scavenged the compatible IPGEs from the parental melt. This assumption is supported by clinopyroxene in pyroxenite with variable Al2O3 contents and variable Cr2O3 contents (0.32 to 0.73 wt%). For the fractionated gabbro unit, zircons yielding a concordia U-Pb age of 162.8 +/- 3.0 Ma and widely variable epsilon Hf(t) values (-9.2 to +12.0) suggest formation from heterogenous or reworked source materials during a Middle Jurassic subduction increment in the Neo-Tethyan Ocean.
关键词	Yilashan ophiolite High-Cr chromitites MORB and boninitic magmas Mantle partial melting Reworking and subduction zone processes
英文关键词	THETFORD MINES OPHIOLITE; PLATINUM-GROUP ELEMENTS; BANGONG-NUJIANG SUTURE; U-PB GEOCHRONOLOGY; ISOTOPIC CONSTRAINTS; PODIFORM CHROMITITES; LUOBUSA OPHIOLITE; UPPER-MANTLE; TECTONIC IMPLICATIONS; CHROMIAN SPINEL
WOS研究方向	Geology ; Mineralogy ; Mining & Mineral Processing
WOS记录号	WOS:000925186800001
来源期刊	ORE GEOLOGY REVIEWS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/283400
作者单位	Ministry of Natural Resources of the People's Republic of China; China Geological Survey; Chinese Academy of Geological Sciences; Institute of Geology, 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
推荐引用方式 GB/T 7714	Xu, Xiang Zhen,Xiong, Fahui,Zoheir, Basem,et al. Geochemical constraints on the multistage evolution of the Yilashan ophiolite, central Tibet[J],2023,153.
APA	Xu, Xiang Zhen.,Xiong, Fahui.,Zoheir, Basem.,Yan, Jinyu.,Zhang, Boyang.,...&Yang, Jingsui.(2023).Geochemical constraints on the multistage evolution of the Yilashan ophiolite, central Tibet.ORE GEOLOGY REVIEWS,153.
MLA	Xu, Xiang Zhen,et al."Geochemical constraints on the multistage evolution of the Yilashan ophiolite, central Tibet".ORE GEOLOGY REVIEWS 153(2023).