What controls the contrasting lithospheric structure beneath the western and central-eastern Tibetan plateau?
Abstract
The Tibetan plateau consists of several accreted terranes, e.g. Lhasa, Qiangtang and Songpan-Ganzi terranes, which have distinct geological histories and probably different thermal/mechanical properties. The heterogeneous multi-terrane structure of the overriding Tibetan lithosphere may strongly affect the geodynamic processes during the continental collision and plateau formation. We conducted systematic numerical models to explore how the multi-terrane structure of the overriding plate regulates the lithospheric deformation during the India-Asia collision. The model configurations are based on the structures and properties of the three major accreted terranes in the Tibetan plateau, in which the Lhasa and Qiangtang terranes are combined together as a unified strong terrane, while the Songpan-Ganzi terrane is regarded as a separate weak terrane. The model results reveal two distinct collision modes. In Mode I, the lithospheric mantles of both the strong and weak terranes in the Tibetan plate are completely detached, followed by the underthrusting of Indian lithosphere. In contrast, Mode II is characterized by partial or full preservation of the strong terrane between the double-sided subduction of the pro- and retro-plate. The model results further indicate that the collisional mode selection is strongly dependent on the width of the weak Songpan-Ganzi terrane; whereas the width of the strong Lhasa-Qiangtang terrane does not affect much. These two distinct continental collision modes are consistent with the deep structures of the western and central-eastern Tibetan plateau, respectively, and the first-order spatial-temporal distribution of the post-collisional magmatic rocks in the plateau.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.T43A0675L
- Keywords:
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- 3355 Regional modeling;
- ATMOSPHERIC PROCESSES;
- 8110 Continental tectonics: general;
- TECTONOPHYSICS;
- 8177 Tectonics and climatic interactions;
- TECTONOPHYSICS