HR: 0800h
AN: T11D-1299    [Abstracts]
TI: Terrace Development in Response to the Interference of two Active Structural Systems in Houli, central Taiwan
AU: * Lai, K
EM: d92224003@ntu.edu.tw
AF: Department of Geosciences National Taiwan University, No.1 sec 4 Roosevelt Road, Taipei, 106 Taiwan
AU: Chen, Y
EM: ygchen@ntu.edu.tw
AF: Department of Geosciences National Taiwan University, No.1 sec 4 Roosevelt Road, Taipei, 106 Taiwan
AU: Hung, J
EM: t260001@cc.ncu.edu.tw
AF: Department of Earth Sciences National Central University, No.300 Chungli Road, Chungli, 320 Taiwan
AU: Lin, Y N
EM: r92224104@ntu.edu.tw
AF: Department of Geosciences National Taiwan University, No.1 sec 4 Roosevelt Road, Taipei, 106 Taiwan
AB: The study area, Houli, is located between the frontal two thrust faults, Changhua (CH) and Sanyi, in the western wedge-tip of fold-and-thrust belt of Taiwan. Neotectonically it plays as transition role of Miaoli and Taichung two domains in the north and south respectively. The former one experienced a large earthquake over magnitude 7 in 1935 and also the latter one in 1999. Houli has long been well known not only the abundant terraces but also their deformation related to neotectonics. We recently remapped the geomorphic features by using the 40 m DEM and aerial photos to carefully analyze the subtle features and to realize the degree of the inferences given by different active structural systems. Besides the Tuntzuchiao fault produced by 1935 earthquake, there are two regional scale active structure systems, Tiechanshan (TCS) anticline and CH fault, have been reported in Houli. The TCS anticline is actually dominant in Miaoli area and plunges southward. Its axis orientation turns from NS to NE-SW when reaches Houli. The CH fault is believed as generated from Taichung area and migrated northward into the study area. According to our results, a number of tectonic scarps and warped surfaces in association with CH fault and its coupled back thrust reflect the CH fault system has been active since Pleistocene. On the other hand, the development of staircase terraces distributed ENE-WSW does not follow the growth of TCS anticline. Instead, it is in response to the growth of another smaller anticline, tentatively named as Yuehmei (YM) anticline that is developed parallel to TCS anticline. Looking at the relevant seismic profiles, YM anticline is a local drag-fold attached on the southern limb of TCS anticline and distributed merely in Houli area. Since not much geomorphic deformation associated with TCS anticline, it can be concluded that the growth of TCS anticline is much slower than YM anticline. It indicates that the development of YM anticline is probably to accommodate the shortening of Taichung neotectonic system.
DE: 8005 Folds and folding
DE: 8010 Fractures and faults
DE: 8107 Continental neotectonics
DE: 1824 Geomorphology (1625)
DE: 1242 Seismic deformations (7205)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting