Exploring the Variability of Late Cenozoic Exhumation Rates across the Himalayan Rain Shadow.

Schultz, M., Hodges, K., Jolliff, B., van Soest, M. and Wartho, J.-A. (2015) Exploring the Variability of Late Cenozoic Exhumation Rates across the Himalayan Rain Shadow. [Poster] In: AGU Fall Meeting 2015. , 14.-18.12.2015, San Francisco, USA .

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The Himalayan ranges of South Asia form one of the world's starkest rain shadows. Data from the NASA - Japan Aerospace Exploration Agency Tropical Rainfall Measurement Mission (TRMM) suggest that precipitation in the central Himalaya drops from more than four meters per year along the southern flanks of the Higher Himalaya (falling mostly as rain during the summer monsoon) to about half a meter per year north of the range crest on the southern Tibetan Plateau. While a correlation between modern precipitation and erosion seems intuitive, important questions remain regarding how far backward in time the correlation might extend. Previous investigations of the relationships between precipitation patterns and thermochronologic cooling dates south of the Himalayan range crest have yielded discrepant results, partly due to the fact that many were conducted along deep trans-Himalayan gorges that serve to channel monsoon storms locally northward, sometimes obscuring broader trends. We are addressing this problem through the comparative studies of bedrock exhumation on million-year timescales north and south of the range crest in transects that are not along major trans-Himalayan gorges. In this presentation, we review a developing (U-Th)/He dataset for metamorphic and intrusive igneous samples of the Greater Himalayan sequence from the north side of the Himalaya at the approximate longitude of Mount Everest (Qomolangma). Results thus far include Middle Miocene (U-Th)/He zircon and apatite dates that are one to two orders of magnitude older than Pliocene-Pleistocene dates typically obtained on similar units from the southern flank of the Himalaya. If this trend continues, and if planned studies south of Everest in 2014 yield very young cooling ages as expected, the simplest explanation is that the modern correlation between monsoon precipitation and erosion rates extends at least as far back as the Miocene Epoch.

Document Type: Conference or Workshop Item (Poster)
Additional Information: Abstract # T33A-2932
Keywords: Late Cenozoic Exhumation Rates; Himalayan; Rain Shadow
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Date Deposited: 16 Nov 2015 13:31
Last Modified: 16 Nov 2015 13:31
URI: http://oceanrep.geomar.de/id/eprint/30202

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