Direct dating of the Sinongduo thrust system in southern Tibet: immediate response to India-Asia collision

ABSTRACT

The Tibetan Plateau is a product of the continental collision between the Indian and Asian plates along the Indus-Yarlung suture zone that started in the early Cenozoic. This collision initially produced stress at the collisional boundary and later propagated with time on both the Indian plate and Asian plate. Many studies have reported tectonic deformation in the Himalayas representing the immediate response of continental collision on the Indian side near the collisional boundary. However, there have been only few studies on the early Cenozoic shortening structures in the Lhasa block that forms the southernmost part of the Asian plate. In this study, we performed Ar/Ar geochronology of syntectonic muscovite from the Sinongduo thrust system in the central Lhasa block. The results show that the Sinongduo thrust system was active in the Early Eocene. We interpret the Sinongduo thrust system as an immediate response to the India-Asia collision in the Lhasa block. This study reconciles the early Cenozoic India-Asia collision with the lack of tectonic response in the Lhasa block.

KEYWORDS:

• Crustal deformation
• AR/AR geochronology
• fault dating
• India-Asia collision
• Lhasa block

Highlights

• The Sinongduo thrust system was active during the Early Eocene.

• Crustal shortening and thickening occurred in the Lhasa block during the early Cenozoic.

• The Sinongduo thrust system represents a tectonic response to the onset of India-Asia collision in the Lhasa block.

Acknowledgments

This work was funded by the National Natural Science Foundation of China (grants 41772075 and 42072313), the Deep Resources Exploration and Mining, the National Key R&D Program of China (grants 2018YFC0604101 and 2018YFC0604105) and the Geological Survey Program of China (DD20190167). The authors would like to thank Prof. Renaud Soucy La Roche, An Yin, Delores Robinson, and an anonymous reviewer for their insightful and constructive comments that considerably helped to improve this manuscript. We also thank Dr. Linglin Zhong for his assistance in improving our work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

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Additional information

Funding

This work was supported by the National Natural Science Foundation of China [41772075, 42072313]; Deep Resources Exploration and Mining, the National Key R&D Program of China [2018YFC0604101, 2018YFC0604105]; Geological Survey Program of China [DD20190167].