從全新世沉積層序探討台南地區褶皺－逆衝斷層帶的構造特性

Abstract

為了了解台南地區的地下構造幾合型態及活動特性，重新進行了岩心紀錄及槽溝工作。由地層層序與古環境分析，估算此區地殼變動速率。研究結果顯示，台南台地的隆起受地下的台南斷層作用所造成，台南斷層為一朝東傾斜的逆衝斷層，斷層目前處於「鎖定」的狀態且斷層尖端未截切至地表淺層沉積層，但在長期變動下可能已經造成六雙層基盤的錯移。晚更新世以來，在台南斷層的作用下造成台南背斜，伴隨台南背斜的活動造成台南台地變動速率的變化，亦造成台南台地的全新世沉積層產生背斜的構造，台南台地背斜軸部的抬升速率為4.6 mm/yr，並向東與向西兩側遞減至0.6 mm/yr與0.2 mm/yr。後甲里斷層為一向西傾斜的盲斷層，只造成地表全新世沉積層產生褶皺，並在軸部產生數十公分的錯移。中洲台地的隆起因中洲斷層的活動所造成，中洲斷層亦為一向東傾斜的逆衝斷層，斷層目前處於「鎖定」的狀態。在長期變動下，應該已經造成六雙層基盤的錯移，且可能造成全新世沉積層的錯移。晚更新世以來，中洲斷層的作用造成中洲背斜，伴隨中洲背斜的活動使得中洲台地變動速率有不同的變化，亦造成中洲台地的全新世沉積層產生背斜的構造，中洲台地的抬升速率由1.2 mm/yr往東遞增至6.7 mm/yr。

In order to understanding Construct several shutting type attitudes and activity characteristics for the underground of the area of Tainan, have carried on noting down and trough ditch work of drill core again. One layer of preface and ancient environmental analysis, estimate the speed of the crust change of this district by the stratum. The result of study shows, the dislocated upwarping of the Tainan tableland is caused by underground Tainan fault function, Tainan fault that the east slope against thrust fault for one dynasty, state that fault in at present and fault peak the deposit layer to the earth's surface shallow layer to cut , but may already cause the moving by mistake of basement under changing for a long time. Since late Pleistocene, causing the Tainan anticline under the function of Tainan fault, it causes the change of the speed of Tainan tableland change follow Tainan anticlinal activity, it produces anticlinal structure that the ones that also cause the Tainan tableland brand-new to deposit on storey generation, the speed of lifting of the Tainan tableland anticlinal axle department as 4.6 mm/yr, and decrease progressively with both sides westwards to 0.6 mm/yr and 0.2 mm/yr eastwards.