Insights into the pattern of the southernmost Longitudinal Valley Fault : Implications from geodetic data analysis and geomorphic evidences
Speaker: Szu-Hua Wang
Abstract
The 150 km long, NNE-trending Longitudinal Valley, situated between the Central Range and the Coastal Range, has generally been considered as the suture zone of the Eurasian and Philippine Sea plates in eastern Taiwan. The Longitudinal Valley Fault (LVF), running along the eastern edge of the valley, is one of the most active structures of the orogenic belt. Previous studies indicated a rapid shortening of approximately 30 mm/yr across the LVF, consuming a large portion of the converging rate (82 mm/yr) between the two plates. Since the southern tip of the Longitudinal Valley seems to represent the starting point of collision, numerous studies had been carried out in this area for better understanding of the colliding history. Geodetic data analysis revealed strain partitioning developed in this region, based on measurements between 1983 and 1990, using the Taitung trilateration network. In addition, detailed geomorphic analyses of fluvial terraces give good agreement with the results obtained from geodetic data analysis. According to the results, two individual faults were delineated, bounding the Late Quaternary Peinanshan Conglomerate: a thrust fault to the west and a strike-slip fault to the east. A model was then proposed to illustrate the tectonic evolution of the Peinanshan area.
Reference
Lee, J.-C., J. Angelier, H.-T. Chu, S.-B. Yu, and J.-C. Hu, 1998. Plate-boundary strain partitioning along the sinistral collision suture of the Philippine and Eurasian plates: Analysis of geodetic data and geological observation in southeastern Taiwan, Tectonics, 17, 859 – 871.
Shyu, J. B. H., K. Sieh, Y.-G. Chen, R. Y. Chuang, Y. Wang, and L.-H. Chung, 2008. Geomorphology of the southernmost Longitudinal Valley fault: Implications for evolution of the active suture of eastern Taiwan, Tectonics, 27, TC1019, doi:10.1029/2006TC002060.