Geological Society of America

T287 The Cenozoic Evolution of Tibet—How Do We Unify Seemingly Contradictory Evidence?

Wednesday, 7 November 2018
1:30 PM - 5:30 PM
Room 243

MIDDLE MIOCENE CLIMATE OPTIMUM RESULTS IN RAPID DOWNCUTTING OF THE MEKONG RIVER

Paper number: T287-14
Program: Technical Sessions
Time: 4:45 PM – 5:05 PM

Authors

Junsheng Nie Presenting Author
Lanzhou University, Lanzhou
Zhao Wang
Lanzhou University, Lanzhou
Gregory Ruetenik
SYRACUSE, NY
Kerry Gallagher
Rennes
Gregory Hoke
Syracuse University, Syracuse, NY
Carmala Garzione
University of Rochester, Rochester, NY
Daniel F. Stockli
Jackson School of Geosciences, University of Texas at Austin, Austin, TX
Thomas Stevens
Uppsala University, Villavägen
Martin Danisik
University of Waikato, Hamilton
Xiaofei HU
LANZHOU U, LANZHOU
Xiaofei HU
Lanzhou University, Lanzhou

Abstract

The timing of rapid kilometer-scale fluvial incision is widely used to infer the timing of uplift of plateaus. The Mekong River, which drains the eastern Qiangtang Terrane and southeastern Tibetan Plateau, is one of the 10 largest rivers in the world by water and sediment discharge. When the Mekong River was established is critical in understanding the elevation history of the Tibetan Plateau but is highly debated (ranging from >55 to <5 Ma). Here based on new low-temperature thermochronology data, we reveal a phase of rapid >700 m downward incision in the Mekong River during the middle Miocene, when the East Asian summer monsoon was intensified several-fold compared with the early Miocene. Using stream profile modeling, we demonstrate that such a middle Miocene increase in precipitation can produce the observed incision in the Mekong River. In the absence of an obvious tectonic contribution, this provides evidence for climatic control on kilometer-scale fluvial incision in the Tibetan Plateau.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-315266

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