Geochemical characteristics of sandstones from the Xikang Group in Jiajika area, western Sichuan, and their constraints on provenance and tectonic setting

被引：0
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作者：
Zhou X. [1 ,2 ,3 ]
Zhou Y. [1 ,2 ,3 ]
Tan H. [1 ,2 ,3 ]
Yue X. [1 ,2 ,3 ]
机构：
[1] Institute of Multipurpose Utilization of Mineral Resources, Chinese Academy of Geological Sciences, Chengdu
[2] Technology Innovation Center of Rare Earth Resources Application, China Geological Survey, Chengdu
[3] Research Center of Multipurpose Utilization of Metal Mineral Resources of China Geological Survey, Chengdu
来源：
Dizhi Xuebao/Acta Geologica Sinica | 2022年 / 96卷 / 04期
关键词：
Geochemistry; Jiajika area; Provenance; Songpan-Garzi orogenic belt; Tectonic setting; Xikang Group;
D O I：
10.19762/j.cnki.dizhixuebao.2021215
中图分类号：
学科分类号：
摘要：
In the middle part of the Songpan-Ganzi orogenic belt, there is a set of turbidity rocks of the Xikang Group, which is a set of sedimentary shale with huge thickness about 2000~3000 meters, and is characterized by deep-subdeep sea fan deposits. Based on the analytical content of major elements, trace elements and grain size analysis from the Xikang Group's sandstones, the tectonic settings and provenance were studied. The results show that major elements SiO2, CaO, MgO, Al2O3, Fe2O3, K2O, Na2O and MnO from the Zhuwo, the Xinduqiao and the Lianghekou Formations of the Xikang Group are different from each other, but the overall content is comparable to that of the continental crust. The sandstones have a consistent REE pattern, enrichment of LREE relative to HREE, with LREE/HREE of 6.26~18.07 (averaging 10.38), (La/Yb)N of 6.64~33.66 (averaging 13.27) and δEu of 0.37~0.91 (averaging 0.67). Index of the chemical variation (ICV) of 1.40~5.23, with an average of 2.43, indicating that the sandstone is the first sediment against the background of tectonic activity which is obviously controlled by source rocks, and reflect a chemical weathering environment of cold and dry climate. Furthermore, the Th/U values of 2.80~9.40 (with an average of 5.32) and chemical index alteration (CIA) of 50.32~86.93 (with an average of 62.80) reflect that it has undergone a weak weathering that might have strengthened in the later period (the sedimentary period of the Lianghekou Formation) due to the stability of regional structure. The discriminatory plots of provenance and the tectonic discrimination diagrams reflect that the provenance is mainly from the quartz-feldspathic provenance area, which is dominated by the active continental margin tectonic environment and has a strong background of tectonic activity. © 2022, Science Press. All right reserved.
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页码：1380 / 1396
页数：16
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