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Journal: |
Journal of Geophysical Research 2018 No.12
clicks:157 |
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Title:
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Author:
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Qiong-Yao Zhan1 , Di-Cheng Zhu1,2 , Qing Wang1 , Peter A. Cawood3 , Jin-Cheng Xie1 , Shi-Min Li1 , Rui Wang1 , Liang-Liang Zhang1 , Zhi-Dan Zhao1 , and Jun Deng |
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Adress: |
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Abstract:
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The steep eastern margin of the Tibetan Plateau is thought to have developed in the Cenozoic
by brittle crustal thickening or lower crustal flow related to India-Asia collision. However, our data indicate
that Late Triassic crustal shortening and voluminous magmatism contributed to crustal thickening and
topography of the region. Sr/Y ratios of intermediate to silicic magmatic rocks reflect mineral assemblages in
the magma source and can be used to constrain crustal thickness. The Sr/Y ratios from the Songpan-Ganzi
Fold Belt in the eastern Tibetan Plateau indicate that the eastern margin of the plateau achieved a crustal
thickness ranging from 44 ± 6 to 67 ± 9 km during ca. 220 to 190 Ma. An average elevation of 2,600 ± 300 m at
ca. 211 Ma is deduced based on average crustal thickness of 55 ± 2 km assuming Airy isostatic compensation.
The thickened crust and high topography of the eastern margin of the Tibetan Plateau during the Late
Triassic is supported by intense shortening and voluminous magmatism, contemporaneous Barrovian
metamorphism, and the development of a foreland basin. Our data indicate that the eastern margin of the
Tibetan Plateau was initially built during the Late Triassic, and this area has a long history of crustal thickening
and mountain building. |
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