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

Tremblay, M. M. , Fox, M., Schmidt, J. L., Tripathy-Lang, A., Wielicki, M. M., Harrison, T. M., Zeitler, P. K. and Shuster, D. L. (2015) Erosion in southern Tibet shut down at ∼10 Ma due to enhanced rock uplift within the Himalaya. Proceedings of the National Academy of Sciences of the United States of America, 112(39), pp. 12030-12035. (doi: 10.1073/pnas.1515652112) (PMID:26371325) (PMCID:PMC4593086)

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.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Tremblay, Dr Marissa
• Authors: Tremblay, M. M., Fox, M., Schmidt, J. L., Tripathy-Lang, A., Wielicki, M. M., Harrison, T. M., Zeitler, P. K., and Shuster, D. L.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Proceedings of the National Academy of Sciences of the United States of America
• Publisher: National Academy of Sciences
• ISSN: 0027-8424
• ISSN (Online): 1091-6490
• Published Online: 07 August 2015