Paleostress and Fold Analysis of the Chimei Fault, Coastal Range, eastern Taiwan
Date Issued
2014
Date
2014
Author(s)
Kuo, Szu-Ting
Abstract
The Chimei Fault, which thrusts the Tuluanshan Formation over the Paliwan Formation, is the only major fault cutting across the entire Coastal Range. Though previously regarded as a reverse fault with strike-slip component, paleostress analysis has not yet been focused on the Chimei Fault. In order to reconstruct the structural evolution of the Chimei Fault, this study first describes the structure features of the fault rock as illustrated by the excellent exposures along the Hsiukuluan River, and then analysis of fault-slip data and folds are carried out.
Fault rock along the exposure indicates more complicated features toward the Chimei Fault plane. This study thus divides the fault damage zone into four structural domains based on reported fracture density data. In the hanging wall, Domain I and Domain II are dominated by strike-slip faults that filled by mineral veins, showing strike-slip movement with NE-SW compression. In the footwall, Domain III and Domain IV are separated by the P fault, dominated by ductile and brittle structures, respectively. Domain III, indicating N-S compression that determined by fold axial planes and axes, consists of asymmetric folds and active deformation structures deformed under insufficiently consolidated condition. Domain IV is crosscut by brittle faults, showing NW-SE compression.
The fault slip data within these domains are divided into three sets. The first set, recorded in the Domain I and Domain II, is deemed to related to thermal events of the Tuluanshan Formation and fracture prior to the formation of the footwall since mineral-vein intrusions are confined to the hanging wall. The second set, shown in the Domain III, is demonstrated by the initial deformation of the footwall before the fault rock becomes completely consolidated, followed by the third set that recorded in the Domian IV until the footwall is uplifted to the shallower brittle regime. The second and the third set illustrate the deformation of the Chimei Fault, constructing a two-stage evolution: (1) N-S compression with reverse component; (2) NW-SE compression with reverse component.
Subjects
斷層帶
破壞帶
古應力
海岸山脈
Type
thesis
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