Abstract

The formation of the Tibetan plateau during the India-Asia collision remains an outstanding issue. Proposed models mostly focus on the different styles of Tibetan crustal deformation, yet these do not readily explain the observed variation of deformation and deep structures along the collisional zone. Here we use three-dimensional numerical models to evaluate the effects of crustal rheology on the formation of the Himalayan-Tibetan orogenic system. During convergence, a weaker Asian crust allows strain far north within the upper plate, where a wide continental plateau forms behind the orogeny. In contrast, a stronger Asian crust suppresses the plateau formation, while the orogeny accommodates most of the shortening. The stronger Asian lithosphere is also forced beneath the Indian lithosphere, forming a reversed-polarity underthrusting. Our results demonstrate that the observed variations in lithosphere deformation and structures along the India-Asia collision zone are primarily controlled by the strength heterogeneity of the Asian continental crust.

Highlights

  • The formation of the Tibetan plateau during the India-Asia collision remains an outstanding issue

  • The debate on the plateau formation mechanisms is further reflected in the complex seismic and magnetotelluric structures found beneath the Tibetan plateau along the whole convergent margin[8,9,10,11,12]

  • The inferred lateral variation of crustal strength strongly correlates with the present-day deformation, with a narrow plateau adjacent to the Tarim Basin and a broader plateau to the east (Fig. 1a). This suggests that east-west variations in the strength of the Asian plates might have played a dominant role for the development of the observed heterogeneous structure of the whole HimalayanTibetan system

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Summary

Introduction

The formation of the Tibetan plateau during the India-Asia collision remains an outstanding issue. The net lithospheric strength must have varied largely along this margin[22] Some of these heterogeneities might be preserved in the present-day structure of the lithosphere, such as the Tarim Basin, which is a rigid crustal block compared to the surrounding crust[23], and the inferred weaker crust in the southern and central Tibet[24,25,26]. The inferred lateral variation of crustal strength strongly correlates with the present-day deformation, with a narrow plateau adjacent to the Tarim Basin and a broader plateau to the east (Fig. 1a) This suggests that east-west variations in the strength of the Asian plates might have played a dominant role for the development of the observed heterogeneous structure of the whole HimalayanTibetan system. Our models suggest that the lateral variations observed in the lithosphere deformation and structures along the India-Asia collision zone are controlled by the strength heterogeneity of the Asian continental crust

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Results
Conclusion

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