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DOI	10.1130/B35225.1
	Petrogenesis of Late Triassic high-Mg diorites and associated granitoids with implications for Paleo-Tethys evolution in the northeast Tibetan Plateau
	Tan J.; Wei J.H.; Zhao S.Q.; Li Y.J.; Liu Y.; Liu X.Y.; Zhang F.; Gan J.R.; Wang Z.H.
发表日期	2020
ISSN	167606
起始页码	955
结束页码	976
卷号	132 期号:2021-05-06
英文摘要	Recent research on Paleo-Tethys tectonics has identified a huge late Paleozoic to Mesozoic igneous belt that extends more than 2500 km in the northeast Tibetan Plateau. However, the magma genesis and evolution in this belt remains a subject of considerable debate. This paper presents a combination of zircon U-Pb ages, mineral compositions, major and trace element concentrations, and Sr-Nd-Hf isotopic data for the plutons across the Zhiduo arc belt that marks the site connecting different tectonic-magmatic units. The studied rocks from one quartz diorite, two granodiorite plutons, and their mafic enclaves define a continuous compositional evolution varying from high- to medium-K calc-alkaline gabbroic diorite to granodiorite. Laser ablation--inductively coupled plasma--mass spectroscopy U-Pb analyses of zircons from these three plutonic suites and one mafic enclave yield Late Triassic ages of 222--217 Ma, establishing that the mafic and felsic magmas were nearly coeval. All these rocks are featured by zoned hornblende and plagioclase with Mg- and Ca-rich mantles or oscillatory change in compositions. They exhibit high and variable MgO (up to 4.88--5.66 wt%), Cr, and Ni contents except that one granitoid pluton (Dangjiangrong) possesses high Co (up to 145.0 ppm). They are characterized by subduction-type trace element patterns, with prominent positive Rb, Th, Pb, and K anomalies and negative Ba, Nb, P, and Ti. Together with continuous and heterogeneous Sr-, Nd-, and zircon Hf-isotopic compositions, it suggests that these Late Triassic high-Mg diorites and associated granitoids were generated through magma mixing and fractional crystallization accompanied by chemical exchange. Taking into account the magmatic record from nearby regions, we suggest that double-sided subduction and rollback of the subducting Paleo-Tethys oceanic slab is the main mechanism to generate geochemically-varied magmatism in the northeast Tibetan Plateau, and eventually close the Paleo-Tethys Ocean during much of the Late Triassic.© 2020 Geological Society of America. All rights reserved.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184777
作者单位	School of Earth Resources, China University of Geosciences, Wuhan, 430074, China; School of Geosciences, Yangtze University, Wuhan, 430100, China; Camborne School of Mines, University of Exeter, Penryn, Cornwall TR10 9FE, United Kingdom
推荐引用方式 GB/T 7714	Tan J.,Wei J.H.,Zhao S.Q.,et al. Petrogenesis of Late Triassic high-Mg diorites and associated granitoids with implications for Paleo-Tethys evolution in the northeast Tibetan Plateau[J],2020,132(2021-05-06).
APA	Tan J..,Wei J.H..,Zhao S.Q..,Li Y.J..,Liu Y..,...&Wang Z.H..(2020).Petrogenesis of Late Triassic high-Mg diorites and associated granitoids with implications for Paleo-Tethys evolution in the northeast Tibetan Plateau.Bulletin of the Geological Society of America,132(2021-05-06).
MLA	Tan J.,et al."Petrogenesis of Late Triassic high-Mg diorites and associated granitoids with implications for Paleo-Tethys evolution in the northeast Tibetan Plateau".Bulletin of the Geological Society of America 132.2021-05-06(2020).