碩士 / 國立彰化師範大學 / 生物學系 / 93 / Banda Sea located in the West Pacific Warm Pool (WPWP) is a marginal sea in the low latitude of the Southern Hemisphere, and play an important role of heat and moisture sources to the global climatic and oceanic environments on regional and global scales. The piston core MD012380 (5°45.64’S, 126°54.25’E), 3990 cm in length, was retrieved from the central continental shelves of the Banda Sea during IMAGES VII cruise in 2001. The age model was determined by radiocarbon, oxygen isotope and paleomagnetic data and recovered from the last 824 ka to present. In general, fossil diatoms are good indicators for paleoceanography and provide us to understand a variety of environmental conditions. The core MD012380 was examined for the changes of fossil diatom abundance and species relative abundance of diatom which were based on taxonomy and morphology. The absolute diatom abundance (ADA) of this sediment core ranged from 3 to 52×106 valves/g DW and the relative abundance of Chaetoceros spp., upwelling indicator species, ranged from 9 to 50%. The changes of the upwelling indicated species showed high in the glacial period and low in the interglacial period. It was evident to reveal the stronger upwelling conditions in the glacial period. The fluctuation of opal content in this core was similar to ADA, but some anomalous peaks of opal content could not reflect high ADA during 98-92, 86-82, 78-74, 64-60 and 35-28 ka. The high relative abundance of giant diatom, Ethmodiscus rex, could be accounted for those peaks. The fluctuated pattern of the ADA was not consisted with the relative abundance pattern of Chaetoceros spp. and could not be indicated as the productivity in the Banda Sea. Diatom temperature index (Td index) applied in high latitude area of the Northern Hemisphere was successfully indicated the relative changes of the past sea water temperature in the Banda Sea and firstly performed success in the Southern Hemisphere equator area. According to the fossil diatom assemblage during the last 400 kyrs, the results of factor analysis showed Factor 1 scores pattern was similar with the relative abundance of Chaetoceros spp., Factor 2 scores pattern was similar with the Td index and Factor 3 scores pattern was similar with the relative abundance of the salinity group diatom. Hence, we assumed that Factor 1 could reflect the fluctuation of upwelling condition, Factor 2 could reflect the sea water temperature and Factor 3 could reflect the fluctuation of the salinity condition in the Banda Sea. The relative abundance pattern of the freshwater diatom in the core MD012380 showed high in the interglacial period and low in the glacial period, but it increased abruptly during the late glacials and reduced largely during the late interglacials. These scenarios showed the precipitation fluctuation changed earlier than the temperature fluctuation in the Banda Sea.
| Identifer | oai:union.ndltd.org:TW/093NCUE5112008 |
| Date | January 2005 |
| Creators | LIAO Chung-Ching, 廖中靖 |
| Contributors | WANG Wei-Lung, 王瑋龍 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 86 |
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