HR: 1340h
AN: T53A-0470    [Abstracts]
TI: Field Evidence of Active Uplift in the Central Bhutan Himalaya
AU: * Tobgay, T
EM: ttobgay@utep.edu
AF: University of Texas at El Paso, 500 W. University Blvd., El Paso, TX 79968 United States
AU: Hurtado, J M
EM: jhurtado@utep.edu
AF: University of Texas at El Paso, 500 W. University Blvd., El Paso, TX 79968 United States
AB: The Bhutan Himalaya is distinguished by an east-west trending anomalously flat swath of topography bounded by abrupt physiographic transitions (PT2a and PT2b) to the north and south, respectively. These physiographic transitions manifest themselves as prominent knickpoints on the longitudinal profiles of major rivers in Bhutan. Analyses of longitudinal profiles of rivers using a bedrock incision model indicate discrete zones of steep channels adjacent to the physiographic transitions. Mapping of bedrock geology shows that these knickpoints do not mark lithologic contacts, and therefore, patterns in channel response may not reflect differential erosion. In addition, climatic factors, such as precipitation, are spatially invariant in Bhutan. Thus, the morphology of rivers in Bhutan at the physiographic transitions may reflect spatial gradients in tectonic uplift. Kinematic analysis of brittle faults and shear zones indicate potentially recent deformation with thrust sense and normal sense movement along PT2a and PT2b, respectively. Surveys of fluvial terraces show deformation of Quaternary deposits and provide direct evidence for local and regional tectonic uplift. The age of the organic material within the terraces obtained by 14C method will place constraints on the age of the terraces and the rate of Quaternary deformation in the region.
DE: 9320 Asia
DE: 8010 Fractures and faults
DE: 8102 Continental contractional orogenic belts
DE: 8107 Continental neotectonics
DE: 1824 Geomorphology (1625)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting