Presenter: Pei-Cheng Wu
Date: 2016/10/27
Abstract
Taiwan is located in a complex collision zone. In order to better understand the complicated structure beneath Taiwan, gravity studies, in addition to seismic and geological studies, provide useful geophysical information for studying shallow depths. Using the Bouguer anomaly map revised based on more accurate terrain data provided by the Taiwanese Digital Terrain Model compiled by the Taiwan Forestry Bureau to complete a 3-D gravity inversion of Taiwan, and it provides a more comprehensive and large-scale tectonic analysis. Following 3-D gravity inversion using the least squares method, author sliced horizontal and vertical profiles from the 3-D density model to visualize tectonic changes. The low Bouguer anomaly was caused by thick sediment and crust layers. The high-density layers are located in special tectonic areas such as the Peikang and Kuanying basement highs. The deepest Moho depth beneath the middle of the Central Range is 45–50 km. The high gradient changes of the eastern section of the Moho relief are shown by the complex mechanism of plate collision. The geometry of plate subduction is apparent in northeastern Taiwan, and the oceanic crust is observable under eastern Taiwan, showing arc-collision boundaries. This 3-D density model, when combined with updated gravity data and seismic tomography, offers better resolution for deep structures and serves as a physical property reference to better understand the tectonic structure beneath Taiwan.
Reference
Hsieh H.H. and H.Y. Yen (2016) Three-dimensional density structures of Taiwan and tectonic implications based on the analysis of gravity data. Journal of Asian Earth Sciences Volume 124, 1 July 2016,p. 247–259
Yen H.Y. and H.H. Hsieh (2010) A study on the compatibility of 3-D seismic velocity structures with gravity data of Taiwan. Terres. Atmos. Ocean. Sci., 21 (6) p. 897–904