| Summary: | 碩士 === 國立成功大學 === 地球科學系 === 107 === In northwestern Taiwan, the Talu sandstone has long been a popular research topic due to its potential to be an oil and gas reservoir. The previous studies proposed that the Talu sandstone was deposited in the deltaic environment, also called the Talu Delta, and yet regional correlations of sandstone layers in the delta sequences are different among these previous studies. This study proposed the evolution of the Talu Delta base on the method of parasequence analysis. Then the sea-level fluctuation history during the deposition of the Talu Delta was also established. Parasequence units and their correspondent ancient sedimentary environments were interpreted based on well logs and cutting data. Twelve parasequence units with coarsening-upward facies were identified and grouped into four parasequence sets corresponding to distinct stacking patterns. They are, from bottom to top, progradation, aggradation, retrogradation to aggradation and back to progradation. The main vertical variation of sedimentary environments was the cycle of prodelta and delta front. The sea-level fluctuation during the Talu Delta deposition contains three cycles, including the first longer period cycle from rise to fall and the two following shorter period cycles. According to the variation of the accommodation rate, we also defined four distinct stacking patterns. Their mode in evolution is consistent to the results of parasequence analysis.
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