A Major Out of Sequence Fault in Central Range and Its Implication to Mountain Building Process of Taiwan Orogenic Belt

Abstract:

A Major Out of Sequence Fault in Central Range and Its Implication to Mountain Building Process of Taiwan Orogenic Belt

Yuan-Hsi Lee¹, Wei Lo², Wei-Hau Wang¹, Tim-Byrne ³, Ruey-Juen Rau ⁴

1. Department of Earth and Environmental Sciences, National Chung Cheng

University, Taiwan, R.O.C.

2. Department of Materials and Mineral Resources Engineering, Taipei, National Taipei University of Technology, Taiwan, R.O.C.

3. Center for Integrative Geosciences, University of Connecticut, Storrs, CT, USA

4. Department of Earth Science, National Chen-Kung University, Taiwan, R.O.C.

Taiwan mountain belt results from collision between Eurasia continental crust and Philippine Sea plate that result in exposing the metamorphic complex with high exhumation rate in eastern Central Range of Taiwan orogenic belt. In this study we combine with field survey, zircon fission track (ZFT), metamorphic grade, and tomography data to identify there exists a major out of sequence fault (MOSF) in eastern Central Range of Taiwan orogenic belt. This MOSF extends from north to south of eastern central Range with several segments and the total length is more than 250 km. The ZFT shows total annealing age of ca.1-3 Ma on the hanging wall and partial annealing ages on the foot wall. The seismicity data indicates the MOSF is still active from central to southern central Range.

We consider that the MOSF is related with crustal channel flow in depth. To the western side of crustal flow it shows thrusting mechanism associated with MOSF and the normal faults (or normal shearing zone) develop in eastern side of the crustal channel flow. This crustal channel flow is also related with exposing the metamorphic complex in Central Range that is important mechanism for the mountain building process of Taiwan orogenic belt.