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Geophysical Research Letters

Formation mechanism of steep convergent intracontinental margins: Insights from numerical modeling

Authors

  • Lin Chen,

    Corresponding author
    1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
    2. Institute of Geophysics, Swiss Federal Institute of Technology (ETH-Zurich), Zurich, Switzerland
    • Corresponding author: L. Chen, State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences. Beitucheng West Road No. 19, Chaoyang District, Beijing 100029, China. (chenlin@mail.iggcas.ac.cn)

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  • Taras V. Gerya,

    1. Institute of Geophysics, Swiss Federal Institute of Technology (ETH-Zurich), Zurich, Switzerland
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  • Zhong-Jie Zhang,

    1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
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  • Alan Aitken,

    1. Centre for Exploration Targeting, The University of Western Australia, Crawley, WA, Australia
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  • Zhong-Hai Li,

    1. State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China
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  • Xiao-Feng Liang

    1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
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Abstract

[1] The margins surrounding the Tibetan Plateau show some diversity in topographic gradient. The most striking example is the eastern Tibetan margin bordered by the Longmen Shan range, which is characterized by a remarkably steep topography transition between eastern Tibet and the Sichuan Basin. There is significant uncertainty over whether this margin was formed by crustal shortening or lower-crustal flow. To investigate the formation mechanism of steep convergent intracontinental margins, we conducted petrological-thermomechanical numerical simulations based on the lithospheric structure and thermal state of the eastern Tibetan margin. Our numerical experiments demonstrate that a very steep topographic gradient, such as the eastern Tibetan margin, is an inherent characteristic of convergence between a hot and weak lithosphere with thick crust and a cold and strong lithosphere with thin crust. Although lower-crustal flow has potentially contributed to the crustal thickness difference between the two convergent blocks, it is not a prerequisite for the growth of steep convergent intracontinental margin. Rather, the topography at the margin can be explained by a near isostatic response to crustal thickening resulting from shortening.

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