鄂尔多斯盆地基底断裂及其现代活动性

对鄂尔多斯盆地基底断裂特征及其活动性作了总结、归纳与分析。结果表明,鄂尔多斯盆地不仅是一个四周被活动断裂或深大断裂围限的块体,其内部还存在大量规模不等的基底断裂,并具有明显的分区特征。盆地内基底断裂带可分成4组:几乎贯穿整个盆地的华池—米脂—大同北东向断裂带;盆地北部的多条东西向断裂带和中部的定边—绥德、南部的庆阳—富县—宜川等东西向断裂带;中部发育的定边—吴起、乌审旗—榆林北西向断裂带与盆地东西两侧的近南北向巨型断裂带。鄂尔多斯盆地内存在的现代构造地貌以及普遍发育的雁行状、X共轭状节理等现象,是新构造运动的直接表现;盆地内存在的深部流体活动信息、现代地球化学景观特征以及众多的小地震、微地震活动及其与基底构造的密切关系,反映了这些断裂的现代活动性。

Basement Faults and Their Recent Activity in Ordos Basin

The features of basement faults and their activities in Ordos Basin are summarized and analyzed. The study shows that the Ordos Basin is not only a single block surrounded by active faults or deep fracture zone reported before, but a basin with a large numbers of obviously region-related basement faults in the interior. The basement faults can divided into four groups in the basin, that is, the NE-trending Huachi-Mizhi-Datong fault zone penetrated almost the basin, the EW-trending faults several faults of the northern part, Dingbian-Suide fault zone in the central part and Qinyang-Fuxian-Yichuan fault zone in the south part, the NW-trending Dingbian-Wuqi fault zone and Wushenqi-Yulin fault zone and the SN-trending fault zone at its eastern and western sides. Modern tectonic geomorphology, all-pervading echelon and X-shaped conjugate joints are direct exhibition of neotectonic movement in the basin. Existing deep fluid information, modern landscape geochemistry features, multitudinous minor-moderate earthquake and micro-earthquakes indicate the recent activity of the faults.