Geochemistry, detrital zircon geochronology and Hf isotope of the clastic rocks in southern Tibet: implications for the Jurassic-Cretaceous tectonic evolution of the Lhasa terrane

Wei, Youqing; Zhao, Zhidan; Niu, Yaoling; Zhu, Di-Cheng; DePaolo, Donald J.; Jing, Tianjing; Liu, Dong; Guan, Qi; Sheikh, Lawangin

Abstract

In order to reconstruct tectonic evolution history of the southern margin of Asia (i.e., Lhasa terrane) before the India-Asia collision, here we present a comprehensive study on the clastic rocks in the southern Lhasa terrane with new perspectives from sedimentary geochemistry, detrital zircon geochronology and Hf isotope. Clasts from the Jurassic-Early Cretaceous sedimentary sequences (i.e., Yeba and Chumulong Formations) display high compositional maturity and experienced moderate to high degree of chemical weathering, whereas those from the late Early-Late Cretaceous sequences (Ngamring and Shexing Formations) are characterized by low compositional maturity with insignificant chemical weathering. Our results lead to a coherent scenario for the evolution history of the Lhasa terrane. During the Early-Middle Jurassic (∼192-168Ma), the Lhasa terrane was speculated to be an isolated geological block. The Yeba Formation is best understood as being deposited in a back-arc basin induced by northward subduction of the Neo-Tethys ocean with sediments coming from the interiors of the Lhasa terrane. The Middle Jurassic-Early Cretaceous Lhasa-Qiangtang collision resulted in the formation of a composite foreland basin with southward-flowing rivers carrying clastic materials from the uplifted northern Lhasa and/or Qiangtang terranes. During the late Early-Late Cretaceous (∼104-72Ma), the Gangdese magmatic arc was uplifted rapidly above the sea level, forming turbidites (Ngamring Formation) in the Xigaze forearc basin and fluvial red beds (Shexing Formation) on the retro-arc side. At the end of Late Cretaceous, the Lhasa terrane was likely to have been uplifted to high elevation forming an Andean-type margin resembling the modern South America before the India-Asia collision.

Citation

Wei, Y., Zhao, Z., Niu, Y., Zhu, D., DePaolo, D. J., Jing, T., …Sheikh, L. (2020). Geochemistry, detrital zircon geochronology and Hf isotope of the clastic rocks in southern Tibet: implications for the Jurassic-Cretaceous tectonic evolution of the Lhasa terrane. Gondwana Research, 78, 41-57. https://doi.org/10.1016/j.gr.2019.08.014

• Journal Article Type: Article
• Acceptance Date: Aug 25, 2019
• Online Publication Date: Oct 5, 2019
• Publication Date: Feb 28, 2020
• Deposit Date: Oct 8, 2019
• Publicly Available Date: Oct 5, 2020
• Journal: Gondwana Research
• Print ISSN: 1342-937X
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 78
• Pages: 41-57
• DOI: https://doi.org/10.1016/j.gr.2019.08.014
• Public URL: https://durham-repository.worktribe.com/output/1288869