HR: 11:35h
AN: T32C-06 [Abstracts]
TI: Erosion or Channel Flow? What controlls the Development of the Himalayan Orogen?
AU: * Thiede, R C
EM: thiede@geo.uni-potsdam.de
AF: Universitt Potsdam, Institut fr Geowissenschaften, Postfach 60 15 53
, Potsdam, 14415
Germany
AU: Ehlers, T A
EM: tehlers@umich.edu
AF: University of Michigan, Geological Sciences, 2534 C.C. Little Building, 425 E. University Ave.
, Ann Arbor, MI 48109-1
United States
AU: Bookhagen, B
EM: bodo@crustal.ucsb.edu
AF: UC Santa Barbara, Institute for Crustal Studies, 1140 Girvetz Hall, Santa Barbara, CA 93106
United States
AU: Strecker, M R
EM: strecker@geo.uni-potsdam.de
AF: Universitt Potsdam, Institut fr Geowissenschaften, Postfach 60 15 53
, Potsdam, 14415
Germany
AB:
The role of coupling between erosion and tectonics focused on the southern front of the High Himalaya remains controversial.
Geological field data and models favour a midcrustal channel flow that today has been exhumed and exposed by denudation since
Miocene time. But what controls the development of the Himalayan Orogen? Is the spatial distribution of erosion influencing
the location, style and magnitude of the deformation or alternatively is the orogen formation driven by orogen internal
processes such as continuous extrusion of a mid-crustal channel?
40Ar/39Ar white mica and apatite fission track (AFT) ages constrain exhumation paths along an approximately 120-km-wide NE-SW
transect spanning the greater Sutlej region of the northwest-Himalaya, India. The 40Ar/39Ar data indicates that first the
High Himalayan Crystalline units were exhumed in early to middle Miocene (about 19-15 Ma). Subsequently, southward
propagating Lesser Himalayan Crystalline nappes were rapidly exhumed during late Miocene to Pliocene time (7-4 Ma). The AFT
data, in contrast, imply synchronous exhumation of an elliptically shaped, NE-SW-oriented about 80 x 40 km region spanning
both crystalline nappes during the Pliocene to Quaternary time (<2 Ma). The locus of pronounced exhumation defined by the
AFT data correlates with a region of high relief, precipitation, discharge, and sediment flux rates. This correlation
suggests that, while tectonic processes as the mid-crustal channel flow may have exerted the dominant control on the pattern
of denudation before and until the middle Miocene; however surface processes have been the most important factor controlling
both pattern of denudation and deformation since the Pliocene time.
DE: 1140 Thermochronology
DE: 8175 Tectonics and landscape evolution
SC: Tectonophysics [T]
MN: Fall Meeting 2005