| Summary: | 碩士 === 國立臺灣大學 === 地質學研究所 === 88 === By means of analyzing organic carbon concentrations and isotopic compositions of core sediments from Tsung-yeh, Ma-chou-hou, Ta-lun and Hsin-chuang, this study attempts to obtain the paleoecological, paleoenvironmental and paleoclimatic informations of Chianan plain in Taiwan since late Pleistocene. Moreover, such a study is advantageous to the stratigraphic correlations and explanations of local structural activities.
In general, the climate of Chianan Plain during Stage1 is warm and humid; however, there were local differences from north to south. Based on the isotopic data, the northern part of Chianan Plain was still a continental environment and dominated by C4 plants when the southern part was a shallow marine or lagoon formed by Holocene transgression and dominated by phytoplanktons. Subsequently, the entire plain has been evolved to be a terrestrial environment and associated with arid climate in Stage2. To the core bottom, due to the higher sea level of Stage5 the plain was inundated by sea-water.
The TIC data of the core sediments can be divided into two groups: around 0.5% and undetectable. This is another tool can accommodate it to 13C results to rapidly obtain the informations regarding environmental changes when it is considered with 13C results together.
This study confirmed that it is applicable in stratigraphic correlations by organic carbon isotope analysis. Likely the boundary between Stage4 and Stage5 defined by this method is concordant with that determined by long-term subsidence rate. Compared to cores with Wu-Ku core in Taipei basin, it can be concluded that the coastal environments in western Taiwan were strongly influenced by global sea level changes, although there are significant neotectonic differences.
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