Origin of Late Silurian A-Type Granite in Wulonggou Area, East Kunlun Orogen: Zircon U-Pb Age, Geochemistry, Nd and Hf Isotopic Constraints

被引：16
作者：
Wang Y. [1 ,2 ]
Li Y. [1 ,3 ]
Wei J. [1 ,3 ]
Li H. [1 ]
Han Y. [4 ]
Zhou H. [1 ]
Huang X. [1 ]
Ke K. [1 ]
机构：
[1] Faculty of Earth Resources, China University of Geosciences, Wuhan
[2] Geological Exploration Institute of Liaoning Province, Dalian
[3] National Demonstration Center for Experimental Mineral Exploration Education, Wuhan
[4] Qinghai No. 1 Academy of Geology and Mineral Exploration, Ping'an
来源：
Li, Yanjun (liyanjun21023@163.com) | 2018年 / China University of Geosciences卷 / 43期
关键词：
A-type granite; East Kunlun orogen; Geochemistry; Late Silurian; Petrogenesis; Petrology; Post-collisional extensional setting;
D O I：
10.3799/dqkx.2018.717
中图分类号：
学科分类号：
摘要：
Late Silurian A-type granite is reported for the first time in the Wulonggou gold district, eastern segment of the Kunlun orogenic belt. This paper presents (1) laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb age for the Wulonggou A-type granite to determine precisely the time of the magmatism, (2) geochemical, Nd and Hf isotope data for the Wulonggou A-type granite to constrain the petrogenesis and tectonic setting. The LA-ICP-MS U-Pb analyses of zircon from the Wulonggou A-type granite yielded a weighted mean 206Pb/238U age of 420±3 Ma, indicating that it was emplaced in the Late Silurian. All rock samples are enriched in SiO2 (76.0%-78.4%), K2O (4.64%-5.22%) and Na2O (2.93%-3.25%), but with relatively low concentrations of FeOT (0.98%-1.45%), MgO (0.11%-0.22%) and CaO (0.27%-0.79%). Samples are also enriched in large ion lithophile elements (Rb, K, La) and light rare earth elements, but depleted in high field strength elements (Nb, P, Ti) and heavy rare earth elements with strong negative Eu anomalies (Eu/Eu*=0.09-0.12). The 104×Ga/Al ratios of the Wulonggou A-type granites vary from 3.09 to 3.15. Mineralogy and geochemistry of the rocks show an affinity with aluminous A-type granite. The εNd(t) values of whole-rock range from -2.5 to -2.2 with corresponding two-stage Nd model ages ranging from 1 339 to 1 365 Ma. The εHf(t) values of zircon vary from -2.8 to +2.1 and two-stage Hf model ages range from 1 269 to 1 583 Ma. The Nd and Hf isotopic data imply that different source materials have contributed to the magma genesis. Integrated geological, geochemical and isotopic data suggest that Wulonggou A-type granite is most likely generated via the mixture of asthenosphere-derived magma and the ancient crustal materials. The A-type granite was marked by A2 type and was formed in post-collisional extensional tectonic environment. In combination with the A-type granites such as those in the Helegangnaren and Binggou, it is concluded that the eastern Kunlun area had begun its post-orogenic extension stage since Late Silurian, and this stage continued at least about 34 Ma. © 2018, Editorial Department of Earth Science. All right reserved.
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页码：1219 / 1236
页数：17
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