碩士 / 國立臺灣海洋大學 / 地球科學研究所 / 107 / In this study, we re-analyzed ocean-bottom seismometer (OBS) and multi-channel seismic (MCS) data collected along the southern profile of T1 with 18 OBSs and the northern profile of T2 with 12 OBSs shot from air guns, for imaging the transitional continental crust and the subducted slab across the northern South China Sea, Manila Trench, deformation front and accretionary prism in Bashi Strait off southern Taiwan, in 2009 TAIwan Integrated Geodynamics Research (TAIGER). First, the interfaces and the velocity of the initial model were built according to the MCS data and the tomographic model from the previous studies. Secondly, refracted and reflected arrivals propagating through the sedimentary and crustal structures were picked from OBS data. Finally, the travel times of refracted and reflected waves were used to invert the P-wave velocity and interface models with most of travel-time errors of each phase from each OBS data less than 0.1 s. We also converted from depth of the model interfaces to the zero-offset two-way time and superimposed the time horizons onto MCS sections to justify our models along T1 and T2 profiles. Along T1 profile, the maximum thickness of the accretionary prism east of the Manila Trench is about 12 km with large lateral variation of the P-wave velocity (3.5-4.5 km/s). Beneath the accretionary prism, large lateral variation of the P-wave velocity (4.7-6 km/s) in the middle crust due to subduction was also found. Lateral variation of P-wave velocity (6 km/s) in the middle crust along T2 profile is smoother than that along T1 profile, because subduction is active along T1 profile. Similarly, west of the Manila Trench along T1 and T2 profiles, the Moho is about 15 km depth so that the crust below the basins in the northern South China Sea is classified as the transitional continental crust. East of the Manila Trench, high P-wave velocity (~7.5 km/s) in the lower crust, due to underplating or mantle serpentinization, was imaged. We integrated the pseudo-3D interfaces of the crust from the P-wave velocity-interface models along T1, T2 and other 6 OBS profiles nearby. The pseudo-3D results show that thickness from the basement to the Moho is thinning (8 km thick) near the deformation front, possibly due to the failed rift in the northern South China Sea. Near the southern tip of Taiwan, thickness from the basement to the Moho is also less than 8 km due to collision near Taiwan.
| Identifer | oai:union.ndltd.org:TW/107NTOU5135005 |
| Date | January 2019 |
| Creators | Cho, Yu Hsiang, 卓鈺翔 |
| Contributors | Wang, Tan Kin, 王天楷 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 58 |
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