台南、高雄及屏東地區，位於台灣西南部的南端，由於大部分位於平原區，故許多構造線被沖積層所覆蓋，必須藉由重力及震測才能大略知道其所在位置。另外，在嘉南地區有緊密的構造線及頻繁的地震，而往南到本研究之區域構造線逐漸減少並消失，所以本研究在此區域由北而南繪製四條剖面，來瞭解南北構造上的變化，並研究主要斷層之層位落差情形，來分析本地區的斷層是否有位移轉換的關係。 本研究主要利用中油的地表地質調查、震測及鉆井等資料，並參考相關的地球物理研究報告，將資料投影至剖面上，以轉折法及平衡剖面的原理來繪製地下深部的構造。並根據地質圖上斷層上下盤之層位，以縱向層位落差圖來分析沿斷層走向層位變化的情形。 本研究的結果如下： 1.基底滑離面的深度約在海平面以下約九至十二公里處，在旗山斷層以西，此滑離面為長枝坑層底部，而在屏東平原地區，可能達到更老的地層。 2.屏東平原地區之地下構造型態與旗山斷層以西可能不太相同，且根據地層對比顯示在屏東背斜的西側可能有斷層存在。 3.龍船斷層及古亭坑斷層及所形成的褶皺作用，本研究推斷為斷層擴展褶皺，並沿著軸部的弱帶切穿而出露地表。 4.根據層位落差圖顯示，此地區的斷層是存在位移轉換的關係，同時在北邊由斷層移位所累積的地殼收縮量，在南邊則以褶皺的方式來取代。 GPS data in southwestern Taiwan show that horizontal velocity increases from north toward south. The crustal movement is thus inferred to be more active in the south. However, outcropped faults and folds become less toward south in the Tainan-Kaohsiung area based on the geological map. In addition, earthquake activity does not reflect the active crustal movement. Therefore, a change of deformation mechanism from north to south occurred in the study area. In this study, we apply the kink method and balanced cross-section to construct four sections from the Lungchuan to Fengshan area using surface, well log, and seismic data in Tainan, Kaoshiung and Pingtung area. Our goals are to understand the subsurface structure and to document the relationship between faults and folds. Furthermore, we use stratigraphic separation diagrams to study stratigraphic separation along major faults in this area. Results of the study indicate that : (1)In the western Chishan fault, the basal decollement lies probably in the base of Changchihkeng Formation or the older strata. The depth to detachment is about 9 to 12 km below the sea level. However, in the Pingtung plain, the basal decollement should be placed below the Changchihkeng Formation. (2)A different structural style occurred across the western and eastern Chishan fault. (3)The folds in front of the Lungchuan and Gutingkeng faults are interpreted to be fold-propagation fold, and these two faults crop out the surface along the fold axis. (4)Stratigraphic separation diagrams indicate that displacement transfer occur in this area, where crustal shortening is achieved by thrusting in the north whereas folding in the south.
