『Abstract
Whether variations in the spatial distribution of erosion influence
the location, style, and magnitude of deformation within the Himalayan
orogen is a matter of debate. We report new 40Ar/39Ar
white mica and apatite fission-track (AFT) ages that measure the
vertical component of exhumation rates along an 〜120-km-wide NE-SW
transect spanning the greater Sutlej region of northwest India.
The 40Ar/39Ar data indicate that first the
High Himalayan Crystalline units cooled below their closing temperature
during the early to middle Miocene. Subsequently, Lesser Himalayan
Crystalline nappes cooled rapidly, indicating southward propagation
of the orogen during late Miocene to Pliocene time. The AFT data,
in contrast, imply synchronous exhumation of a NE-SW-oriented〜80×40
km region spanning both crystalline nappes during the Pliocene-Quaternary.
The locus of pronounced exhumation defined by the AFT data correlates
with a region of high precipitation, discharge, and sediment flux
rates during the Holocene. This correlation suggests that although
tectonic processes exerted the dominant control on the denudation
pattern before and until the middle Miocene; erosion may have
been the most important factor since the Pliocene.
Keywords: Himalaya; exhumation; erosion; uplift; geochronology』
Introduction
Geologic setting of the northwestern Himalaya
Thermochronological data
From diachronous to synchronous cooling of the Himalayan crystalline
core
Geodynamic implications and conclusions
Acknowledgments
References cited