气候变化领域集成服务门户(CCPortal): Late Devonian postcollisional magmatism in the ultrahighpressure metamorphic belt, Xitieshan terrane, NW China

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DOI	10.1130/B31772.1
	Late Devonian postcollisional magmatism in the ultrahighpressure metamorphic belt, Xitieshan terrane, NW China
	Zhao Z.; Wei J.; Santosh M.; Liang S.; Fu L.; Zhao S.; Li H.
发表日期	2018
ISSN	167606
起始页码	999
结束页码	1016
卷号	130 期号:2021-05-06
英文摘要	Postcollisional magmatism in the North Qaidam ultrahigh-pressure metamorphic belt provides important information on crustal reworking, crust-mantle interaction, and related geodynamic processes. Here, we report zircon U-Pb ages and Hf isotopic compositions, as well as whole-rock major- and trace-element and Sr-Nd isotopic compositions for a suite of gabbros and granitoids from the Xitieshan terrane in the North Qaidam ultrahigh-pressure metamorphic belt. These rocks formed concurrently at ca. 372 Ma (Late Devonian), ~50 m.y. after the continental collision between the Qaidam and Qilian blocks. The gabbro samples have low- to medium-K tholeiitic composition, with high FeOT and TiO2 contents. They are enriched in large ion lithophile elements, and depleted in Nb and Ta, similar to the lithospheric mantle source, which is also indicated by their Zr/Nb, La/Nb, and Nb/Ta values. In addition, these rocks have relatively enriched isotopic signatures compared to mid-ocean ridge basalt. This implies that the mantle source may have been metasomatized by subduction-related melts, which is further confirmed by the signatures of trace elements. The coeval felsic rocks are high-K calc-alkaline, slightly peraluminous I-type granites. They are characterized by high light rare earth element/heavy rare earth element ratios, with a negative Eu anomaly, strong depletion in Ba, Sr, and high field strength elements (e.g., Nb, Ta, Ti, and P), and enrichment in Rb, Th, U, and Pb, resembling the upper continental crust. The Sr-Nd-Hf isotopic signatures of these granitoids, however, show remarkable differences from upper continental crust-derived melts and North Qaidam basements, but they are generally consistent with previously emplaced syncollisional granite in the Xitieshan terrane. Therefore, the granitoids are best interpreted as the products of melting of the syncollisional granite. Meanwhile, the involvement of coeval mantle-derived melts is suggested by the relatively depleted isotopic signatures and mafic magmatic enclaves hosted by the granitoids. Additionally, some of the inherited zircons in the granitoids display negative εHf(t) values and Paleoproterozoic depleted mantle model ages (TDM2), suggesting that the source also involved ancient crustal materials. Based on the temporal and spatial associations of the gabbro-granitoid suite, in conjunction with their petrogenetic features, we propose a geodynamic model involving convective removal of the lithosphere and resultant asthenospheric upwelling to explain the crustal reworking, crust-mantle interaction, and related postcollisional geodynamic processes in the North Qaidam ultrahigh- pressure metamorphic belt. © 2017 Geological Society of America.
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/185024
作者单位	Faculty of Earth Resources, China University of Geosciences, Wuhan, 430074, China; Department of Geology and Geological Engineering, Colorado School of Mines, Golden, CO 80401, United States; Centre for Tectonics, Exploration and Resources, Department of Earth Sciences, University of Adelaide, Adelaide, SA 5005, Australia; School of Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China; School of Geosciences, Yangtze University, Wuhan, 430100, China
推荐引用方式 GB/T 7714	Zhao Z.,Wei J.,Santosh M.,et al. Late Devonian postcollisional magmatism in the ultrahighpressure metamorphic belt, Xitieshan terrane, NW China[J],2018,130(2021-05-06).
APA	Zhao Z..,Wei J..,Santosh M..,Liang S..,Fu L..,...&Li H..(2018).Late Devonian postcollisional magmatism in the ultrahighpressure metamorphic belt, Xitieshan terrane, NW China.Bulletin of the Geological Society of America,130(2021-05-06).
MLA	Zhao Z.,et al."Late Devonian postcollisional magmatism in the ultrahighpressure metamorphic belt, Xitieshan terrane, NW China".Bulletin of the Geological Society of America 130.2021-05-06(2018).