Zircon U-Pb Chronology and Geochemistry of the Wuliji Intrusions in the Northern Alxa Block:Constraints on the Tectonic Evolution of the Southern Altaids

被引：0
|
作者：
Zhang S. [1 ,2 ]
He Z. [2 ]
Zhao P. [3 ]
Hu E. [4 ]
Wang Y. [4 ]
Zhou Y. [4 ]
机构：
[1] School of Earth Science and Resources, China University of Geosciences, Beijing
[2] Inner Mongolia Mining Development Co., Ltd., Huhhot
[3] Shanxi Mineral Resources and Geological Survey, Xi'an
[4] Faculty of Earth Resources, China University of Geosciences, Wuhan
来源：
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | 2021年 / 46卷 / 01期
关键词：
Crust-mantle interaction; Geochemistry; Paleo-Asian Ocean; Permo-Carboniferous; Post-collision; Wuliji intrusions;
D O I：
10.3799/dqkx.2019.259
中图分类号：
学科分类号：
摘要：
The northern Alxa block is the key area for studying the closing of the Paleo-Asian Ocean, whereas the Permo-Carboniferous igneous in this area have been rarely investigated, leading to the time and way of the closing of the Paleo-Asian Ocean can not be unified directly, and more importantly, restricting a deeper insight into the tectonic evolution of the central southern Altaids in late Paleozoic.In this paper, we carried out a systematic study of the petrography, whole rock geochemistry, zircon U-Pb dating for the Wuliji intrusions, which are located in the Shalazhashan structural belt that spreading between the Engewusu fault belt and Badanjilin fault belt.Our results demonstrated that the Wuliji intrusions are mainly composed of granodiorite and granite, the weighted average ages of two samples from granodiorite are 266.00±1.00 Ma(MSWD=0.69), 267.76±0.97 Ma(MSWD=0.26), and the weighted average ages of three samples from granite are 254.57±0.99 Ma(MSWD=0.79), 253.70±1.70 Ma(MSWD=2.50), 252.50±2.90 Ma(MSWD=4.70). The SiO2 contents of the granodiorite are between 64.13%-67.17%, while the granite are between 68.08%-75.29%, the Na2O+K2O contents of the granodiorite are between 6.40%-7.00%, while the granite are between 7.09%-7.94%, both are I-type granites with medium degree of differentiation. They are depleted in Nb, Ta, P, Ti and HREEs, but relatively enriched in K, Zr, Hf and LREEs, the total content rations of LREE and HREE are between 6.49-17.45 and the fractionation of the HREEs is obvious. The (La/Yb)N values of granodiorite are between 6.21-8.80, while the granite are between 9.21-22.06. Geochemistry shows that the two stages intrusions were resulted from crust-mantle interaction with the crust as the major magmatic source and the separate crystallization, fluid metasomatism. The geological, elemental and isotopic evidences show that the Paleo-Asian Ocean maybe closed in Pre-Permian, and the Alxa was in-board evolution since Permian, the Wuliji area was under the transformation phase from regional syn-orogenic squeeze to post-orogenic extension or post-collision extension phase. © 2021, Editorial Department of Earth Science. All right reserved.
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页码：101 / 121
页数：20
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