碩士 / 國立臺灣大學 / 海洋研究所 / 104 / The South China Sea (SCS) is an ideal place to examine the nature of continental rifting, breakup, and the onset of seafloor spreading. The SCS basin was formed by seafloor spreading from early Oligocene (~32Ma) to the middle Miocene (~15.5Ma),to know the crustal structures of the northern SCS continental margin may help us to understand the mechanism of the SCS rifting processes.
In this study, a total of 21 ocean bottom seismometer (OBS) records along 2 multichannel seismic reflection profiles are analyzed to investigate the upper crustal structure and crustal velocity profiles along this margin. There are two seismic profiles MCS840 and MCS883 which were collected by Ocean Research I are located in the northern continental margin of SCS, and they form a NW-SE trending line southeastern of the Dongsha island. This line starts from Dongsha rise, runs across the Chaoshan depression and south uplift area to the northern SCS East Sub-basin. To construct a more reliable structure model, we extract shallow velocity structure from the MCS profile data, to build an initial model to derive a 2D velocity model of the crustal structure with tomographic inversion technique using PROFIT code, then, we do forward modeling using RAYINVR to get a convincingly hybrid velocity model.
MCS840 seismic reflection profile shows that there are many high angle normal faults and some igneous bodies which have been dated at 1.23 MA. However, the igneous basement spread all over in profile MCS883, and the sediment strata above the basement are flat. OBS840 results show that the Moho depth decrease from north to south, and there exist a high velocity layer which is interpreted to be underplating material under the continent-ocean transition(COT). OBS883 shows a classic oceanic crustal structure with a crustal thickness about 9 km. Because of the basaltic magmatism, the basement velocity in OBS883 is higher than that of the OBS840.
| Identifer | oai:union.ndltd.org:TW/104NTU05279003 |
| Date | January 2016 |
| Creators | Hao Wang, 王晧 |
| Contributors | Char-Shine Liu, Tsui-Yu Chang, 劉家瑄, 張翠玉 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 94 |
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