碩士 / 國立臺灣大學 / 海洋研究所 / 98 / The South China Sea (SCS) is a marginal sea offshore Southeast Asia which can be divided into three portions, the northern continental margin, the central oceanic basin and the southern continental margin. The northernmost SCS abuts the Southeastern Asia continental margin and is contiguous to the Taiwan accretionary wedge in the northeast. Based on latest marine magnetic studies, seafloor spreading of the northeastern SCS took place about 37 Ma, associated with magnetic anomalies C15 to C17 and suggesting that northernmost SCS is the oldest oceanic crust of the SCS.
By analysis new deep seismic reflection profiles collected by the R/V Marcus G. Langseth during the 2009 TAIGER survey and together with previously published seismic sections, we have mapped many structures in the northeastern South China Sea continental margin where normal faults, igneous bodies, and slope basins are prevailing. Taking Formosa Ridge (118°E or so) for a boundary, morphology of the northeastern SCS continental margin shows distinctive variation. From wide and gentle dipping continental slope to the west of 118°E because of the most igneous activities in the region around south of Dongsha Island, to steeply dipping and narrow continental slope near Taiwan.
Different basement patterns are observed in different areas of the northeastern SCS due to the multiple phases of igneous activities. We can also approximately define some deep strong Moho deflections on MGL0905-10. Beneath the continental slope, there lies unusually thickened crust which may be formed during the SCS spreading period through underplating process and later magmatic events. A regional maximum of crustal thickness is located around Dongsha Island area. There are at least four events of igneous activities in the northernmost SCS continental margin, and our study indeed shows that multiple volcanic activities have a great influence on the Cenozoic evolution of this region.
| Identifer | oai:union.ndltd.org:TW/098NTU05279033 |
| Date | January 2010 |
| Creators | I-Ting Chang, 張怡婷 |
| Contributors | 劉家瑄 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 74 |
Page generated in 0.007 seconds