成果归属作者：

朱弟成 ; 莫宣学 ; 赵志丹

成果归属机构：

地球科学与资源学院

作者：

Zhu, Di-Cheng ; Zhao, Zihi-Dan ; Niu, Yaoling ; Mo, Xuan-Xue ; Chung, Sun-Lin ; Hou, Zeng-Qian ; Wang, Li-Quan ; Wu, Fu-Yuan

单位：

China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China;China Univ Geosci, Sch Earth Sci & Resources, Beijing 100083, Peoples R China;Univ Durham, Dept Earth Sci, Durham DH1 3LE, England;Lanzhou Univ, Sch Earth Sci, Lanzhou 730000, Peoples R China;Natl Taiwan Univ, Dept Geosci, Taipei 106, Taiwan;Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China;Chengdu Inst Geol & Mineral Resources, Chengdu 610082, Peoples R China;Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China

关键词：

zircon U-Pb dating and Hf isotope; Mesozoic-early Tertiary magmatic rocks; lithospheric architecture; tectonomagmatic evolution; Lhasa Terrane; Tibet

摘要：

The Lhasa Terrane in southern Tibet has long been accepted as the last geological block accreted to Eurasia before its collision with the northward drifting Indian continent in the Cenozoic, but its lithospheric architecture, drift and growth histories and the nature of its northern suture with Eurasia via the Qiangtang Terrane remain enigmatic. Using zircon in situ U-Pb and Lu-Hf isotopic and bulk-rock geochemical data of Mesozoic-Early Tertiary magmatic rocks sampled along four north-south traverses across the Lhasa Terrane, we show that the Lhasa Terrane has ancient basement rocks of Proterozoic and Archean ages (up to 2870 Ma) in its centre with younger and juvenile crust (Phanerozoic) accreted towards its both northern and southern edges. This finding proves that the central Lhasa subterrane was once a microcontinent. This continent has survived from its long journey across the Paleo-Tethyan Ocean basins and has grown at the edges through magmatism resulting from oceanic lithosphere subduction towards beneath it during its journey and subsequent collisions with the Qiangtang Terrane to the north and with the Indian continent to the south. Zircon Hf isotope data indicate significant mantle source contributions to the generation of these granitoid rocks (e.g., similar to 50-90%, 0-70%, and 30-100% to the Mesozoic magmatism in the southern, central, and northern Lhasa subterranes, respectively). We suggest that much of the Mesozoic magmatism in the Lhasa Terrane may be associated with the southward Bangong-Nujiang Tethyan seafloor subduction beneath the Lhasa Terrane, which likely began in the Middle Permian (or earlier) and ceased in the late Early Cretaceous, and that the significant changes of zircon epsilon(Hf)(t) at similar to 113 and similar to 52 Ma record tectonomagmatic activities as a result of slab break-off and related mantle melting events following the Qiangtang-Lhasa amalgamation and India-Lhasa amalgamation, respectively. These results manifest the efficacy of zircons as a chronometer (U-Pb dating) and a geochemical tracer (Hf isotopes) in understanding the origin and histories of lithospheric plates and in revealing the tectonic evolution of old orogenies in the context of plate tectonics. (C) 2010 Elsevier B.V. All rights reserved.

基金：

Chinese National Natural Science Foundation [40830317, 40973026, 40873023]; National Key Project for Basic Research of China [2011CB403102, 2009CB421002, 2006CB701402]; New Century Excellent Talents in University [NCET-10-0711]; Chinese 111 Project [B07011]; Chinese Geological Survey [1212010610104]; Leverhulme Trust

语种：

英文

DOI：

10.1016/j.epsl.2010.11.005

来源：

EARTH AND PLANETARY SCIENCE LETTERS,2011(1-2):241-255.

出版日期：

2011-01-03

提交日期：

2017-12-14

引用参考：

Zhu, Di-Cheng; Zhao, Zihi-Dan; Niu, Yaoling; Mo, Xuan-Xue; Chung, Sun-Lin; Hou, Zeng-Qian; Wang, Li-Quan; Wu, Fu-Yuan. The Lhasa Terrane: Record of a microcontinent and its histories of drift and growth[J]. EARTH AND PLANETARY SCIENCE LETTERS,2011(1-2):241-255.