Identification of the Middle Triassic Oceanic Crust of the Sumdo in the Tibet Plateau and Its Constraints on the Evolution of the Sumdo Paleo-Tethys Ocean

被引：11
|
作者：
Duan M. [1 ]
Xie C. [1 ,2 ]
Fan J. [1 ,2 ]
Wang B. [1 ]
Hao Y. [2 ]
机构：
[1] College of Earth Sciences, Jilin University, Changchun
[2] Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Natural Resources, Changchun
来源：
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | 2019年 / 44卷 / 07期
关键词：
Geochemistry; Green schist; Sumdo Paleo-Tethys Ocean; Zircon Hf isotope; Zircon U-Pb chronology;
D O I：
10.3799/dqkx.2019.100
中图分类号：
学科分类号：
摘要：
The Sumdo green schist is distributed in the Sumdo area in the segment of the Lhasa block. Because of the low level of research on its age and tectonic characteristics, it has seriously constrained our understanding of the evolution of the Sumdo Paleo-Tethys Ocean. Based on the detailed field geological survey, petrology, whole-rock geochemistry, LA-ICP-MS zircon U-Pb isotope and zircon Hf isotope analysis were carried out on the green schist. The zircon U-Pb age is approximately 232 Ma in the Sumdo green schist, which is the Middle Triassic, representing the protolith's crystallization of the green schist. The εHf(t) of zircons is 3.6 on average, showing the characteristics of a weakly depleted mantle. Petrology and geochemistry studies reveal that the protolith of green schist has characteristics of tholeiite, which appears as a flat curve in the chondrite-normalized REE patterns and primitive mantle-normalized trace element spidergrams, similar to N-MORB attributes. In all kinds of discriminative diagrams, they all fall into the N-MORB field, indicating that the protolith of Sumdo green schist may be an oceanic crust fragment from the Sumdo Paleo-Tethys Ocean. The identification of the Middle Triassic green schist in Sumdo indicates the Sumdo Paleo-Tethys Ocean may hold oceanic basin during the Middle Triassic. © 2019, Editorial Department of Earth Science. All right reserved.
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页码：2249 / 2264
页数：15
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