華江高地是否存在？

Abstract

本研究採用淺層反射震測法調查台北盆地第三紀基盤構造，經四年來，累積約100條測線記錄，並配合鑽井資料，已大致可描繪出第三紀基盤形貌。台北盆地之基盤以崁腳斷層之延線為界，劃分為西北-東南兩半，西北半部基盤可深達400公尺，主要朝向新莊斷層方向變深。東南半部基盤受到古新店溪切割，在台北市區底下較深，向兩側麓山帶逐漸變淺。利用板橋、中和、萬華一帶密集的震測測線，即與地調所板橋退輔會井資料比對，可追蹤此一地區之地層，結果顯示華江高地並不存在。

After the fourth phase of Taipei basin project, we have accomplished more than 100 reflec-tion seismic lines and with which the Tertiary basement as well as the Quaternary layers could be mapped over most areas of the basin. The results indicate that the basins Tertiary basement can be separated into two parts along a line extended from Kanchiao fault. The northwestern part is found as deepest as 400 m and the deepest places are along the western border near Hsinchuang fauIt. The southeastern part has its deep bottom shaped by ancient Hsientein river under the present Taipei city. The basement regularly becomes shallow toward the hillside. There is a basement rise, called Huajianng High (proposed by Wang Lee, 1978) . depicted on the Taipei basin basement contour mapin the past. In this study, we use the seismic profiles collected at Panchiao, Chungho, and Wanhwa areas to check this strange Huajianng High base-ment anomaly. The results provide strong evidences not to support the existence of such a base?ment bottom high. Due to its odd direction of distribution against the surrounding geological structure, Huajianng High seems need to be re-evaluated. We would like to suggest to drill a deepborehole at Youth Park near the center of Huajianng High to clearify this problem.