Between 1999 and 2002 our group accomplished a projects founded by the Austrian Science Foundation (FWF) in the Himalayas. Focus is to constrain timing and amount of Pliocene-Pleistocene exhumation and to relate the exhumation processes to tectonics and erosion.
The ability to deduce exhumation mechanisms from thermochronological data is hampered by the fact that assumptions on the thermal state of the lithosphere have to be made. Additional argumentation is generally required to discriminate between erosion-controlled and tectonically induced exhumation. This problem can be overcome by studying the spatial distribution of zircon and apatite (U-Th)/He and fission track data. In this work the variation of four different low temperature isotopic systems generating age trends along a sampling line is used to infer mechanisms of Quaternary exhumation in the Central High Himalayan Metamorphic Belt. Observed zircon age trends with southwards increasing cooling ages (from 0.5 to 1.7 Ma) are attributed to tectonically induced exhumation. The uniform apatite cooling ages clustered c. 0.5 Ma are attributed to erosion.
View of the study area with Nanda Devi Mountain in the background
(U-Th)/He and FT ages for Tethian Himalayas (TH), Higher Himalayas (HH), Lesser Himalayan Metamorphics (LHM) and Lesser Himalayan Sediments (LHS). Lines give trend of cooling ages for HH and LHM.
For further papers see publications
Timing and mechanisms of Central Himalayan exhumation: discriminating between
tectonic and erosion processes. Ana-Voica Bojar, Harald Fritz, Stefan Nicolescu,
Martin Bregar and Ravi P. Gupta.- Terra Nova, 17, 427–433, 2005, doi: