台灣西南部地區的台南層紀錄了全新世以來的沉積現象及構造 運動，是一個研究古地震和全新世構造運動的絕佳地點。由於構造運 動活躍，有一些區域已經有明顯的褶皺現象。本研究蒐集了台灣西南 部許多重要的鑽探、槽溝和定年資料，並選取其中七孔鑽井進行磁感 率的量測，以利於進行地層對比，並綜合了相關的地形、地層與構造 分析，期望能夠了解台灣西南部地區台南層之分布及其構造之演化。 從地層分析得知，受到全球海水面變遷的影響，此研究區在鑽井 深度範圍內最少堆積了兩個層序的地層。除在基盤高區層序一直接與 基盤接觸外，其餘地點兩個層序間均有一層古土壤或是風化的岩屑， 代表一次陸相的環境。本研究利用台南井建立標準剖面，並將層序一 底部的假整合面界定為台南層底面，其C-14 年代約為18Ka。台南層 頂面則界定於林朝棨（1963）所定義之台南層頂面，其年代約為3Ka。 根據構造分析與地形剖面顯示，台南層底部地層之傾角比6 Ka 時間面及頂面為陡，反應出本研究區為一成長褶皺(growth fold)的構 造形態。並由各時間面所求得之上升速率，在現今的地形高區有逐漸 抬升的趨勢。在地形低區，曾文溪口及海岸地區皆有明顯的持續沉降 現象。高雄地區之上升速率，在18 Ka 附近顯示為抬升，而在6 Ka 則開始轉變為沉降。 台南層在本研究區域分布範圍相當廣闊，除了高雄地區已岀露地 表的更新世基盤外，其餘地區的鑽井岩心中皆可見到台南層的分布。 由相關研究瞭解，台南層向北可延伸至濁水溪沖積扇南緣。在屏東地 區，可能可以延伸進入屏東平原之西部。 The Tainan Formation underneath the Southwestern Plain of Taiwan is the best material for studying Holocene tectonics and Paleoearthquakes in the region. This study collect drill logs, trench maps, C-14 age data and related study results, and also apply the magnetic susceptibility measurement technique on several drill cores to help stratigraphic correlation analysis. We perform geomorphologic analysis, stratigraphic analysis and tectonic analysis and synthesize the results to clarify the stratigraphy and tectonic history of the Tainan Formation in the study area. Results from stratigraphic analysis reveals, this study area has at least deposited two sequences of sediments, which may be eustatic change related. This study define the bottom of the Tainan Formation at the bottom of the upper sequence, at where paleosol or weathering debris is commonly found. This study select the Tainan well core to present the standard column of the Tainan Formation. The C-14 age at the bottom is about 18Ka. We follow Lin(1963) to define top of the Tainan Formation. The C-14 age at the top is about 3Ka. According to profile analysis, the dip angle of strata at lower part of the Tainan Formation is steeper than that at upper part and top surface of the Tainan Formation. We interpret this phenomenon as growth fold in the study area. According to uplift rate calculation at different time planes, it tend to increasing positive uplift rate at present highland area. At low lands, like the Tsengwen-hsi river mouth and most coastal area, which show continues subsidence. In the Kaohsiung area, it shows uplift around 18 Ka, and then become subsidence since about 6 Ka. The distribution of the Tainan Formation is rather wide in Southwestern Plain of Taiwan. We can recognize the Tainan Formation in every core in the study area. According to related study, the Tainan Formation may extend northward to south of the Choshuihsi alluvium fan, and southeastward to west of Pingtung Plane.
