A structural study of the Hukou and Hsinchu areas Northwestern Taiwan
Bally, Albert W.
Master of Arts
Northwestern Taiwan, which includes the Kuanyin, Hukou and Hsinchu areas, was initially a part of the continental shelf of the mainland China coast. The Neogene sediments were deposited m gently east-dipping basement in a stable shelf type environment. The sedimentary sequence shows a regional tilt as well as a thickening of strata towards the southeast, the location of the former ocean. The structures which make up the Hukou and Hsinchu areas are located in the frontal edge of the western foothills range. The structure is dominated by simple-step thrust faults. Frequently, the upthrown blocks of the faults are folded and form the typical asymmetrical folds with steeper north/northwest limbs (e.g. the Hukou and Chingtsaohu Anticlines). A possible solution to the structure of western Taiwan is a progressive change from a simple-step thrust fault in the north to more imbricated faults in the foothills to the southeast. This is similiar to the type of imbrication found in the Canadian Rocky Mountain. Based on the assumption of the oblique plate convergence in the Taiwan area, a model with more westerly substructural involvement of pre-Miocene rocks provides a more conservative estimate of the possible amount of the plate shortening in Taiwan than do previously published studies based on the fault-bend folding model.