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Constructing the Eastern Margin of the Tibetan Plateau During the Late Triassic
Author(s) -
Zhan QiongYao,
Zhu DiCheng,
Wang Qing,
Cawood Peter A.,
Xie JinCheng,
Li ShiMin,
Wang Rui,
Zhang LiangLiang,
Zhao ZhiDan,
Deng Jun
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2018jb016353
Subject(s) - geology , magmatism , plateau (mathematics) , foreland basin , crust , mountain formation , tectonics , lithosphere , geochemistry , geomorphology , paleontology , mathematical analysis , mathematics
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.