HR: 0800h
AN: T51A-0320    [Abstracts]
TI: Inversion Accompanying Arc Collision in the Taiwan Orogen
AU: * Rodriguez, F A
EM: ferrodriguez@tamu.edu
AF: Texas A&M University, Department of Geology and Geophysics, Center for Tectonophysics 151 M.T. Halbouty Building, Geology & Geophysics, TAMU, College Station, Tx 77843-3115,
AU: Wiltschko, D V
EM: d.wiltschko@tamu.edu
AF: Texas A&M University, Department of Geology and Geophysics, Center for Tectonophysics 151 M.T. Halbouty Building, Geology & Geophysics, TAMU, College Station, Tx 77843-3115,
AB: A kinematic model for the Western Foothills fold and thrust belt (WFFTB) of southern Taiwan based on serial balanced sections shows that inversion of pre-existing normal fault basins is common. The basal fault is interpreted to follow both stratigraphic horizons and pre-existing normal faults. The estimated aggregate shortening of the easternmost fault of the WFFTB is about 40 km. Restoration of the WFFTB structures places the Eurasian margin at one time at least as far east as the present position of the Coast Range. A regional structure, the sub-Yuching anticline, explains the uplift of the Yuching and Tignpinglin synclines above their regional level. This structure is on-line with the interpreted continuation of the Manila trench beneath Taiwan. There is not a strict forward-breaking thrust sequence in southern Taiwan. The Tachieshan, Schuangtung and Pinghchi faults first moved before deposition of the Cholan Fm between 6 and 3.3 Ma. These faults were reactivated at 1.5 Ma continuing until today. The most western thrust sheets contain structures closely associated with the Peikang high, implying that the structures are either formed by inversion of faults of the Peikang high or new thrust faults whose ramps are located on pre-existing normal faults. While inversion has not been described in either the on- land or offshore accretionary prism portion of the Taiwan orogen, we propose that the collision portion should be best viewed as a series of inverted structures built upon pre-existing Neogene basins. The province of inversion follows the Eurasian margin and may not yet have propagated offshore.
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8000 STRUCTURAL GEOLOGY
DE: 8005 Folds and folding
DE: 8102 Continental contractional orogenic belts and inversion tectonics
DE: 8104 Continental margins: convergent
SC: Tectonophysics [T]
MN: 2007 Fall Meeting