Constraints on the tectonic and landscape evolution of the Bhutan Himalaya from thermochronometry

Adams, B. A., Hodges, K. V., Whipple, K. X., Ehlers, T. A., van Soest, M. C. and Wartho, J.-A. (2015) Constraints on the tectonic and landscape evolution of the Bhutan Himalaya from thermochronometry Tectonics, 34 (6). pp. 1329-1347. DOI 10.1002/2015TC003853.

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Abstract

The observed geomorphology and calculated thermal histories of the Bhutan Himalaya provide
an excellent platform to test ideas regarding the influence of tectonics and climate on the evolution of a
convergentmountain range. However, little consensus has been reached regarding the late Cenozoic history of
the Bhutan Himalaya. Some researchers have argued that observed geologic relationships show slowing
deformation rates, such that the range is decaying from a geomorphic perspective, while others see the range
as growing and steepening. We suggest that a better understanding is possible through the integrated
interpretation of geomorphic and thermochronometric data from the comparison of predictions from models
of landscape evolution and thermal-kinematic models of orogenic systems. New thermochronometric data
throughout Bhutan aremost consistent with a significant decrease in erosion rates, from2 to 3 km/Ma down to
0.1–0.3 km/Ma, around 6–4Ma. We interpret this pattern as a decrease in rock uplift rates due to the activation
of contractional structures of the Shillong Plateau, an uplifted region approximately 100 km south of Bhutan.
However, low-relief, fluvial landscapes throughout the Bhutanese hinterland record a late pulse of surface uplift
likely due to a recent increase in rock uplift rates. Constraints from our youngest thermochronometers suggest
that this increase in rock uplift and surface uplift occurred within the last 1.75Ma. These results imply that
the dynamics of the Bhutan Himalaya and Shillong Plateau have been linked during the late Cenozoic, with
structural elements of both regions active in variable ways and times over that interval.

Document Type: Article
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
DOI etc.: 10.1002/2015TC003853
ISSN: 0278-7407
Date Deposited: 14 Jul 2015 07:43
Last Modified: 05 May 2017 12:49
URI: http://eprints.uni-kiel.de/id/eprint/29228

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