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Erosion in southern Tibet shut down at ∼10 Ma due to enhanced rock uplift within the Himalaya

Erosion in southern Tibet shut down at ∼10 Ma due to enhanced rock uplift within the Himalaya

Authors :
M. M. Wielicki
Alka Tripathy-Lang
David L. Shuster
Jennifer Schmidt
Matthew Fox
T. Mark Harrison
Peter K. Zeitler
Marissa M. Tremblay
Source :
Proceedings of the National Academy of Sciences. 112:12030-12035
Publication Year :
2015
Publisher :
Proceedings of the National Academy of Sciences, 2015.

Abstract

Exhumation of the southern Tibetan plateau margin reflects interplay between surface and lithospheric dynamics within the Himalaya-Tibet orogen. We report thermochronometric data from a 1.2-km elevation transect within granitoids of the eastern Lhasa terrane, southern Tibet, which indicate rapid exhumation exceeding 1 km/Ma from 17-16 to 12-11 Ma followed by very slow exhumation to the present. We hypothesize that these changes in exhumation occurred in response to changes in the loci and rate of rock uplift and the resulting southward shift of the main topographic and drainage divides from within the Lhasa terrane to their current positions within the Himalaya. At ∼17 Ma, steep erosive drainage networks would have flowed across the Himalaya and greater amounts of moisture would have advected into the Lhasa terrane to drive large-scale erosional exhumation. As convergence thickened and widened the Himalaya, the orographic barrier to precipitation in southern Tibet terrane would have strengthened. Previously documented midcrustal duplexing around 10 Ma generated a zone of high rock uplift within the Himalaya. We use numerical simulations as a conceptual tool to highlight how a zone of high rock uplift could have defeated transverse drainage networks, resulting in substantial drainage reorganization. When combined with a strengthening orographic barrier to precipitation, this drainage reorganization would have driven the sharp reduction in exhumation rate we observe in southern Tibet.

Details

ISSN :
10916490 and 00278424
Volume :
112
Database :
OpenAIRE
Journal :
Proceedings of the National Academy of Sciences
Accession number :
edsair.doi.dedup.....dc3dc2600261c2ae025f9d8af3727532
Full Text :
https://doi.org/10.1073/pnas.1515652112