Sediment characteristic analysis and discussion of environmental change since 16 ka - a case study at Sun-Moon Lake, Taiwan
| Autor: | Shih-Hung Liu, 劉時宏 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 This study focused on the lakes in mid-altitude area of Taiwan. In particular, we use several different proxies including both of physical and chemical characteristics to assessment possible environmental change and its distribution since late Pleistocene. In addition, we compared with archive data of Paleao-Environmental studies to enhance reliability of the interpretations. Furthermore, this study had supplemented with landforms and surface process as possible genesis and reactions to different environmental change trends. According to the methodology of limnology, this study sampling a core of lacustrine sediment and use physical and chemical analysis to detect characteristics of proxies and quantified for further interpolation. In 2012, this study had collected a 3.6 meter long sediment core vertically to the bottom of Sun-Moon Lake by piston corer which cooperated with Kobe Univ., Osaka City Univ., Kanazawa Univ. and cut into 2.5 cm for further analysis. This study collected a total of 152 samples. According to Carbon-14 dating, this study extrapolated different deposition rate in different intervals of the sediment core. In particular, this study aimed within the interval during 16ka until present. Time resolution of samples between the End of late Pleistocene and Holocene Optimum represents 300 years per sample, and thereafter decreased exponentially toward modern. In the interval of late Holocene to modern, each sample represents only 10 years. Laboratory analysis had been finished by physical and chemical analysis including grain size, grain density, dating, and chemical compositions for further interpretation in the hydrological laboratory in Kanazawa Univ. Our result showed a quantified data set of sediment characteristics to represents the environmental conditions and its changing trends. This study based on the data set for interpretations and discussion with archived data to generalized possible scenes since late Pleistocene. The results of this study had proposed different sub-stages by occurrence of parameters we had analysed. In particular, there are 5 stages since late Pleistocene to present. These stages include 1. the End of Pleistocene (16ka – 11.7ka), 2. Early Holocene (11.7ka – 6ka), 3. Holocene Optimum (6ka - 4ka), 4. 3ka event (3.5ka – 2.9ka) and 5. Late Holocene (2.9ka – 1930AD). In addition, these stages not only as a division of ages, but also defined differences in depositional environment and possible genesis and process acted on the scene. In addition, the further outcome of this study is related with palynology, sedimentology, and other related research results for integration. Preliminary results showed at least different scene of environmental change between each stage. In particular, some stages like long-term scale as millennial stages showed stable trends of environmental change. However, in some special case we can find significant rapid environmental change events are recorded by the quantity change of chemical components in the sediment. This study had proposed several catastrophic events, according to the result of radiocarbon dating, these events are shown in 9.7ka, 3ka, 2ka and 1ka. The most special case had revealed that according to radio-carbon dating, there had occurred a severe event around 3ka that brought massive sediments into the lake. It seems that Sun-Moon Lake’s sedimentation environment is affected during these stages and rapid events. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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