浅层地震勘探资料揭示汤东断裂特征

The Characteristics of the Tangdong Fault Revealed by Shallow Seismic Survey

汤东断裂是汤阴地堑的东界断裂,也是太行山山前一条重要的隐伏活动断裂。为了查明汤东断裂的产状、性质及其浅部构造特征,跨断裂开展了高分辨率浅层地震剖面探测,获得了高信噪比的浅层地震反射波叠加剖面。本文根据浅层地震剖面结果并结合研究区地质资料和已有深地震探测成果,对汤东断裂的浅部构造特征进行了分析和讨论。结果表明:汤东断裂为1条走向NNE、倾向NWW的铲型正断层,其浅部表现为由2—3条断层组成的Y字形构造,并错断了埋深约30—50m第四纪地层,断裂向下延伸至上地壳底部,属晚第四纪以来的隐伏活动断裂。汤东断裂两侧新生代沉积差异明显,断裂上升盘内黄隆起一侧,新生代沉积层较薄,其底界埋深约480m,下降盘汤阴地堑一侧,沉积了巨厚的新生代地层。研究结果为确定汤东断裂位置、评价断裂的活动性提供了基础资料。

The Tangdong fault is the eastern border fault of the Tangying graben and is an important buried active fault in the front of Taihang mountain. To investigate the occurrences, properties and shallow tectonic features of the Tangdong fault, we completed high resolution shallow seismic profiles with crossing the fault and obtain the shallow seismic reflection stacked profiles which have higher signal-noise ratio. Based on the results and combined it with the geological date and deep seismic explored result, we analyzed and discussed the shallow structures features of Tangdong fault. Our results show that the Tangdong fault is a NNE trending and NWW dipping spade shaped normal fault. In the shallow position the Tangdong fault show ＂Y＂ structure which consist of 2 to 3 faults. The Tangdong fault disrupts 30-50m Quaternary strata in shallow part, and extends to bottom of upper crust in deep part. Therefore it is a buffed active faults in the late Quaternary period. There exists remarkble difference in Cenozoic strata on both sides of the fault. The Cenozoic strata is thin on the side of Neihuang uplift of the fault upthrown block, and its bottom buries in about 480m. The Cenozoic strata is thick on the side of Tangying graben of the fault downthrown block. In this study, the location of Tangdong fault was determined, and the evaluation of the fault activity was provided.