碩士 / 國立臺灣海洋大學 / 應用地球物理研究所 / 93 / Taiwan is located in the boundary between the Eurasian and Philippine Sea plates. Due to different collision subduction, two arc-trench systems in different direction were occurred. One is the Luzon arc-trench system in N-S direction; the other the Ryukyu arc-trench system in E-W direction. The Okinawa Trough is a back-arc basin which was formed by an extension in the Eurasian plate, and the tectonic setting in this area has a series of normalfault systems and igneous activitives. According to previous studies, we know that Southernmost Part of Okinawa Trough (SPOT) have evolved at least two main tensional phases of extension, the first phase probably happened in early Pleistocene and struck in NE-SW direction; and the second phase occurred during late Pleistocene and Holocene changed to E-W.
In this study, we have compiled the seismic data collected by old R/V Chiu-Lien, Ocean Research No.I, and French R/V l'Atalante to re-map the fault systems in the SPOT area. We integrated the seismic profiles with the corrected bathymetry data to relocate these faults. Our results show these normal fault systems has three main groups, respectively N45°E、N60°E and N80°E. We find the N45°E faults lacated in the northern area of Taiwan, that most of N60°E faults are located in the northern and southern slope of SPOT and continental shelf to the northern Taiwan. The N80°E faults are found in the center area of SPOT. Compare with the faults and a new topographic map, we find a lot of faults around the canyons, such as the North-Mienhua, Mienhuy, and Keelung canyons. We suggest that the origin of these canyons are probably due to the tectonic forces. The canyon is a weak area, and is eroded much fast than the surrounding continental shelf. Processing through a series of erosional processes, the canyon becomes what looks like today. We find a lot of graben structures located in the center of SPOT. This area is the extensional axis of SPOT. We also find many possible igneous bodies in the seismic profiles, some of them are the intrusions and the others penetrate the seabed and form the submarine volcanoes. We have found at least 68 volcanoes in the SPOT area. The interactions of submarine volcanoes, canyons, and fault grabens demonstrate an active tectonic activities in the study area..
| Identifer | oai:union.ndltd.org:TW/093NTOU5502003 |
| Date | January 2005 |
| Creators | Yi-Huan Huang, 黃怡煥 |
| Contributors | Chao-Shing Lee, 李昭興 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 67 |
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