HR: 0830h
AN: T31F-0899    [PDF]
TI: Reorganization of Strain in Response to Erosional Forcing at Intermediate Scales: Puli Embayment, Western Taiwan
AU: * Upton, P
EM: phaedra.upton@maine.edu
AF: University of Maine, Department of Earth Sciences, Bryand Global Sciences Center, Orono, ME 04469
AU: Mueller, K J
EM: karl.mueller@colorado.edu
AF: University of Colorado, Department of Geological Sciences, 2200 Colorado Ave, Boulder, CO 80309
AU: Koons, P O
EM: peter.koons@maine.edu
AF: University of Maine, Department of Earth Sciences, Bryand Global Sciences Center, Orono, ME 04469
AU: Powell, L
AF: University of Colorado, Department of Geological Sciences, 2200 Colorado Ave, Boulder, CO 80309
AB: The Taiwan orogeny accommodates 82 mm of oblique convergence per year between the Philippine Sea and Eurasian plates and is situated in a region of very high rainfall, resulting in high rates of rock uplift and erosion. Studies in western Taiwan suggest that there is considerable along strike variation in late Quaternary erosion rates and in the modern distribution of strain along the western margin of the orogen. In the Puli Embayment, a 50 km wide, 1500 m deep depression within the Foothills belt, Hsueshan Range and Backbone Ranges of western Taiwan, lower elevation and enhanced exhumation are associated with a broad 50 km wide belt of active shortening hindward of the leading edge of the orogen. Localized high erosion rates have been shown to significantly influence the mechanical behavior of collisional mountain belts on timescales of 1-5 Ma where the wavelength of the erosional signal is on the order of the thickness of the brittle crust. Examples include the Southern Alps of New Zealand and the indentor corners, Nanga Parbat and Namche Bawa, of the Himalaya, where the geometry of the erosional signal is reflected in the topographic and petrological signal of the resultant mountain belt. The coincidence of enhanced exhumation, lower elevation and active deformation suggests that the Puli embayment is accommodating shortening and rock uplift in response to the reduction in mass. If so, it is occurring on shorter temporal and spatial scales than previously documented and may represent the early stages of river-induced thermal thinning leading to the formation of a structure on the scale of an anticlinorium. Western Taiwan provides an ideal setting in which to explore, on a sub-orogen scale, the implications of enhanced exhumation for the beginnings of reorganization of strain within an orogen at higher spatial and temporal frequency.
DE: 1206 Crustal movements--interplate (8155)
DE: 8020 Mechanics
DE: 8102 Continental contractional orogenic belts
DE: 8159 Rheology--crust and lithosphere
DE: 9320 Asia
SC: Tectonophysics [T]
MN: 2003 Fall Meeting