Outward growth of the Tibetan Plateau across the Cenozoic (Invited)
Abstract
The surface uplift history of the Tibetan Plateau (TP) offers a key testing ground for evaluating models of collisional tectonics and holds important implications for processes ranging from global cooling to the onset of the Asian monsoon. Various models have been proposed to reveal the surface uplift history of the TP, but remain controversial. We evaluate these models using data from structural geology, magmatism, exhumation, and paleoaltimetry studies. Structural analyses indicate that the thrust belts, which spread from the central TP toward its surrounding margins, accommodated most of the India-Asia convergence, and facilitated the crustal shortening and thickening in the central TP. The Eocene adakitic rocks located in the Qiangtang and the Lhasa blocks likely generated by partial melting of an eclogitic source. The ultrapotassic and potassic rocks in the Qiangtang block are of Paleogene age (50-30 Ma), whereas those both in the Qiangtang and Lhasa blocks are Late Oligocene and Early Miocene (26-8 Ma). Low-temperature thermochronologic ages in the central TP are older than 40-35 Ma, whereas those in the margins are younger than 20 Ma (mostly Late Miocene, and Pliocene/Pleistocene in age). Independent paleoaltimetry estimates suggest that the Lhasa and Qiangtang terranes attained their current elevations during the Eocene, most likely due to the initial collision between India and Tibet, whereas the Hoxil basin area to the north and Himalayas to the south were still low, even under sea level in the latter case. We argue for an inside-out growth pattern for the Tibetan Plateau. The TP grew southward and northward from a nucleus of high topography and is likely to continue expanding along the Mazar Tagh fault to the northwest, the Kuantai Shan-Hei Shan-Longshou Shan to the northeast, the Longquan Shan to the east and the Shillong plateau to the south in the future.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.T34A..04W
- Keywords:
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- 8100 TECTONOPHYSICS