碩士 / 國立臺灣大學 / 海洋研究所 / 99 / The Huatung basin (HB), a 200 km cross sliver of seafloor, constitutes the westernmost frontier of the Philippine Sea Plate (PSP). Prior paleomagnetic analyses determined the age of the HB to be about 40 Ma, being tens of Ma younger than the adjacent west Philippine basin (WPB) across the Gagua ridge. However, an Ar-Ar dating for rocks dredged from the HB seafloor suggested an early-Cretaceous age (~125 Ma), thus reversing the age contrast with the WPB. Since then the controversy has remained. In this study, we selected from broadband seismic networks on Taiwan a rough linear array that points to the events in the Aleutian region, and investigated the amplitude variation of P waves along this array. The waves are defocused and focused traveling along the center and the bottom of the subducting slab, respectively, producing a low and high at the center and the far end of the linear array. We employed a 2D finite-difference waveform modeling and experimented with slab models with simple geometry and various ages. The older and thicker the slab, the more distant the high amplitudes appear. We compare observations with model results and found that the best-fit slab ages fall into 20-50 Ma. This suggests an Eocene age for the HB, in contradiction with the early-Cretaceous age proposed previously
| Identifer | oai:union.ndltd.org:TW/099NTU05279020 |
| Date | January 2011 |
| Creators | Yen-Hsiang Chang, 張硯香 |
| Contributors | , 郭本垣, 喬凌雲 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 35 |
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