鄂尔多斯盆地北部断裂分析

Analysis of the faults in the northern Ordos Basin, Northwest China

长期以来 ,多数研究者认为鄂尔多斯盆地为稳定的克拉通盆地 ,盆地内部不发育断裂。但近年在新采集、处理的地震剖面上陆续发现了盆地北部存在着断距约 40～ 2 40m的断层 ,总体上看 ,从天环向斜北部到苏里格庙、乌审召、东胜一带为北东向断裂多发带。这些断层以断开奥陶系风化壳、太原组和山西组煤层等地震反射层波组为主 ,通常组成单向逆冲断层、对冲断凹型、背冲断垒型和先逆后正反转型等几种断层类型。这些断层是鄂尔多斯盆地在燕山运动中、晚期受到周边构造单元强烈挤压所形成的 ,也是由克拉通盆地向前陆盆地转化的伴生产物。图 1参

The Ordos basin has been being thought as a stable craton basin for a long time by many Chinese researchers, in which none of the faults were developed yet. Hovewer, the recent studies of seismic profiles and processed data show that some of the faults with a fault throw ranging from 40m to 240m developed in the northern part of the Ordos Basin. Overeally, the area from Tianhuanbei to Suligemiao, Wushenzao to reach Dongsheng are the location with many faults developed in NS direction, where the faults cut off Ordovician weathered crust and Coals of Taiyuan and Shanxi Formation (in age of Permian), that mainly composted of the group of reflect wave. The faults usually formed simple thrust fault, ramp faults, back thrust faults and reverse faults. The faults were formed by the extremely extruded near the rim or edge of Ordos Basin in the middle and later Yanshan movement, and they are also the by products of the transformation of foreland basin.