<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml"><p>Optically Stimulated Luminescence (OSL) of quartz, with closure temperatures of 30–35°C in conjunction with Apatite Fission Track (AFT; closure temp. ∼120°C) and 40Ar-39Ar (biotite closure temperature ∼350°C), were used to obtain cooling ages from Higher Himalayan crystalline rocks of Western Arunachal Himalaya (WAH). Cooling age data based on OSL, AFT and Ar-Ar thermochronology provide inference on the exhumation — erosion history for three different time intervals over million to thousand year scale.</p><p>Steady-state exhumation of ∼0.5 mm/yr was observed during Miocene (>7.2 Ma) till Early Pleistocene (1.8 Ma). Onset of Pleistocene glacial/interglacial conditions from ∼1.8 Ma formed glaciated valleys and rapid erosion with rivers incising deep valleys along their course. Erosion enables midcrustal partial melts to move beneath the weak zone in the valley and causes an erosion-induced tectonic uplift. This resulted in a rapid increase in exhumation rate. The OSL thermochronology results suggest increased erosion over ∼21 ka period from Late Pleistocene (2.5 mm/yr) to Early Holocene (5.5 mm/yr) and these are to be contrasted with pre 1.8 Ma erosion rate of 0.5 mm/yr. Enhanced erosion in the later stage coincides with the periods of deglaciation during Marine Isotope Stages (MIS) 1 and 2. The results of the present study suggest that in the present setting OSL thermochronology informed on the short-term climatic effect on landscape evolution and techniques like the AFT and 40Ar-39Ar provided longer-term exhumation histories.</p></abstract>

Optically Stimulated Luminescence (OSL) of quartz, with closure temperatures of 30–35°C in conjunction with Apatite Fission Track (AFT; closure temp. ∼120°C) and 40Ar-39Ar (biotite closure temperature ∼350°C), were used to obtain cooling ages from Higher Himalayan crystalline rocks of Western Arunachal Himalaya (WAH). Cooling age data based on OSL, AFT and Ar-Ar thermochronology provide inference on the exhumation — erosion history for three different time intervals over million to thousand year scale.Steady-state exhumation of ∼0.5 mm/yr was observed during Miocene (>7.2 Ma) till Early Pleistocene (1.8 Ma). Onset of Pleistocene glacial/interglacial conditions from ∼1.8 Ma formed glaciated valleys and rapid erosion with rivers incising deep valleys along their course. Erosion enables midcrustal partial melts to move beneath the weak zone in the valley and causes an erosion-induced tectonic uplift. This resulted in a rapid increase in exhumation rate. The OSL thermochronology results suggest increased erosion over ∼21 ka period from Late Pleistocene (2.5 mm/yr) to Early Holocene (5.5 mm/yr) and these are to be contrasted with pre 1.8 Ma erosion rate of 0.5 mm/yr. Enhanced erosion in the later stage coincides with the periods of deglaciation during Marine Isotope Stages (MIS) 1 and 2. The results of the present study suggest that in the present setting OSL thermochronology informed on the short-term climatic effect on landscape evolution and techniques like the AFT and 40Ar-39Ar provided longer-term exhumation histories.

Rapid denudation of Higher Himalaya during late Pliestocence, evidence from OSL thermochronology

Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai, India, 400076

Geosciences Division, Physical Research Laboratory, Navrangpura, Ahmedabad, India, 380009

Geochronometria

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Optically Stimulated Luminescence (OSL) of quartz, with closure temperatures of 30–35°C in conjunction with Apatite Fission Track (AFT; closure temp. ∼120°C)...

Rapid denudation of Higher Himalaya during late Pliestocence, evidence from OSL thermochronology

Published Online: Sep 27, 2013

Page range: 304 - 310

DOI: https://doi.org/10.2478/s13386-013-0124-7

Keywords
OSL thermochronology, apatite fission track, 40Ar-39Ar thermochronology, Eastern Himalaya, erosion, denudation

© 2013 Silesian University of Technology, Gliwice, Poland

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Rapid denudation of Higher Himalaya during late Pliestocence, evidence from OSL thermochronology

Published Online: Sep 27, 2013

Page range: 304 - 310

DOI: https://doi.org/10.2478/s13386-013-0124-7

KeywordsOSL thermochronology, apatite fission track, 40Ar-39Ar thermochronology, Eastern Himalaya, erosion, denudation

© 2013 Silesian University of Technology, Gliwice, Poland

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
OSL thermochronology, apatite fission track, 40Ar-39Ar thermochronology, Eastern Himalaya, erosion, denudation