HR: 15:10h
AN: H33F-07    [Abstracts]
TI: Interpreting Thermochronometric Data in Fold-and-Thrust Belts: An Example From Taiwan
AU: * Lock, J
EM: janelock@ess.washington.edu
AF: University of Washington, Dept. Earth and Space Sciences, Seattle, WA 98195 United States
AU: Willett, S
EM: swillett@u.washington.edu
AF: University of Washington, Dept. Earth and Space Sciences, Seattle, WA 98195 United States
AB: At the scale of individual structures, fold-and-thrust belts are transient. They evolve as material is accreted and new faults become active. Each fault may be active for a very short time and material will experience a very different thermal and kinematic exhumation depending on its location. Even if the orogen as a whole has reached a regional stationary thermal field, individual low-T thermochronometric ages reflect spatially and temporally variable cooling rates. These rates respond to the development of local structures. Faults and folds produce differential motion and thus advect heat producing variable thermal fields and paths through the thermal field. To infer cooling histories and interpret low-temperature thermochronometric data in fold-and-thrust belts, we present the results of a combined forward structural and 2-dimensional finite-element thermo-kinematic model. We use our modeling technique to interpret new apatite fission track and U-Th/He ages from samples collected in the Taiwan western foothills fold-and-thrust belt. These ages show a complex pattern of reset, partially reset, and unreset ages that vary with structural and stratigraphic position. We interpret this pattern in terms of differential motion on structures, which we build into our model. The ages provide constraint on both timing and geometry of structures.
DE: 1140 Thermochronology
DE: 8107 Continental neotectonics (8002)
DE: 8108 Continental tectonics: compressional
DE: 8175 Tectonics and landscape evolution
SC: Hydrology [H]
MN: Fall Meeting 2005