碩士 / 國立中央大學 / 地球科學學系 / 107 / As a major pathway of the sediment transportation to deep sea, submarine canyon plays an important role on the source-to-sink, terrestrial-to-marine dispersal system. Kaoping submarine canyon (KPSC) is located on southwestern offshore Taiwan. It originates from the Kaoping River (KPR) mouth through the Kaoping shelf and slope then merges to the northeastern Manila Trench. Because of the dramatic climate change in the southern Taiwan (e.g. strong typhoon triggers flooding or moonson), huge amount of highly concentrated sediments carried by KPR into KPSC may develop turbidity current or hyperpycnal flow in the canyon head. Aithough previous studies using traditional reflective seismic and bathymetry to understand the morphology and structures in KPSC region, and they indicated that slope failures is caused by turbidity current and formed U-shaped valley in the upper canyon. Due to limitation of the seismic source (i.e. central frequency is 50 Hz), near seafloor sedimentary seqences cannot be revealed. We rather used alternative and high resolution marine geophysical exploration method, sparker reflective seismic method in this study. Twenty seismic sections were acquired and analyzed across and prepenticular to the uppermost Kaoping submarine canyon in particular focusing on the area of turbidity current occorence. The results show that five basic standard seismic stratigraphic sequences were identified : (1) Lowstand System Tract (LST); (2) Transgreesive System Tract (TST); (3) Highstand System Tract (HST); (4) Last Glacial Maximun (LGM) uncomformity and (5) Mud diapirism. The LST is characterized high amplitude, continuous and propagating toward to sea, the TST is also high amplitude, continuous but parallel to the seafloor. The LGM is high amplitude and continuous as an angular uncomformity beteen LST and TST. The HST is instead lowest amplitude and dis-continuous amongst the study area. Furthermore, about 40 meters and U-shaped depression was identified in the southern bank of the canyon with respect to the northern bank, HST was gone with thin LST in the southern bank, which indicates a strong and continuous erosion occurred in the south. We suggested that may be the result of canyon overbanking flow erosion. In addition, mud diapirsim also caued slope failure and seafloor depression in the south. The deposits of the slope failure may be one of the sources on turbidity current.
| Identifer | oai:union.ndltd.org:TW/107NCU05134019 |
| Date | January 2019 |
| Creators | Chung-Lin Tsai, 蔡仲霖 |
| Contributors | Yi-Ching Yeh, 葉一慶 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 136 |
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