碩士 / 國立臺灣大學 / 海洋研究所 / 101 / Morphology and crustal type are annoying problems in continental margin off northeastern South China Sea . Typical passive continental margin includes land extended continental shelf, steep continental slope, continental rise and deep sea basins, they divide by morphology and the slope gradient variation Morphology in Passive margin northeastern South China Sea is different with typical passive continental margin, shelf break is usually occurs at 200 meters depth, at the continental margin northeastern South China Sea presents at deeper part. In continental slope, the gradient is slow than surrounding areas and the range is wider. Continental rise and deep sea basin is higher than other place, and it appear many ups and downs, so the passive continental margin northeastern South China Sea is a special area.
In this study, a new data set have 11 lines, 2,853 km reflection seismic data to survey structural characteristics and distribution east of Dongsha region, to explain the morphology controlling by structure. The basement uplifted at the edge of lower shelf and landward basin created by basement rifting. Sediment accumulated in the basin and become a flat lower shelf. Under the continental slope, rifted basin induced by basement subsiding and it made the slope gradient becoming slowly. There were a regional volcanic activity at the continental slope south of Dongsha region, and the activity could be dating at 1.23 millions ago. Oceanic basin in study area, the basement depth is higher than other region''s basins, we suppose the high morphology in the basin was caused by igneous activity and titled blocks activity on the basement.
Northeastern South China Sea was supposed that have continental-oceanic transition zone crust(COT), the structure characteristics in the transition zone have some igneous activities in the thinned continental crust, and it also have a high velocity zone at the lower crust. But according to different geophysical surveys, the crustal type distributions are not the same. This study suggests that the transition zone in the northern South China Sea contains the area between the basement where subsides rapidly to the typical oceanic crust. In our study area, we suppose that the crustal type is thinned continental crust according to titled blocks movement pattern at the basement of deep ocean basin. Therefore, this study suggests that the continental-oceanic transition zone distribution is similar to the version publish by Wang et al. (2006).
| Identifer | oai:union.ndltd.org:TW/101NTU05279034 |
| Date | January 2013 |
| Creators | Chung-Lin Hsieh, 謝宗霖 |
| Contributors | Char-Shine Liu, 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 | 87 |
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