金湖凹陷铜城断层构造特征与成因分析

依据高精度三维地震资料与前人对金湖凹陷乃至苏北盆地构造的分析成果,在构造理论指导下应用构造解析方法,对铜城断层构造特征与成因进行研究。结果表明:铜城断层近SN延伸,断面具"丝带效应",其东、西两盘诸断层发育规模、活动性和剖面样式有所差异,铜城断层与两盘断层不具成因上的"世代关系",但具有构造分区作用;区域应力和先存构造是影响铜城断层形成与演化的主要因素;古新世—早始新世NW—SE向伸展作用时,铜城断层为具有调节作用的变换断层,并不受郯庐断裂的走滑作用影响,中始新世近SN向伸展作用下,又叠加以主动走滑性质,断层规模扩大,渐新世至早中新世近EW向挤压应力造成南段断面倒转而呈"逆断层"特征;铜城断层形成于伸展环境,在挤压环境中受到局部改造,具有走滑性质、多期活动、逐次发育特征。

Structural characteristics and genetic analysis of Tongcheng fault in Jinhu sag

Using the high-precision 3D seismic data, and based on the previous results of structural analysis of Jinhu sag and Subei Basin, this paper analyzed the structural features and discussed the genesis of the Tongcheng fault. The results show that the Tongcheng fault strikes SN, and its fault-plane has the feature of "Ribbon Effect ". The scale, activity and section structure pattern of the faults in the west side are different from the east side. The Tongcheng fault has no genetic relationship with the faults on its both sides, but it may have played a role in structural dividing. The regional stress and pre-structure has important influence on the fault ''s evolution. During Paleocene to early Eocene, the Tongcheng fault formed and was controlled by NW-SE extension. The fault was a transfer fault which played a role in the structural accommodating, but wasn ''t affected by the strike-slip Tan-lu fault in this stage. In Eocene the Tongcheng fault grew and owned property of active strike-slip, controlled by the near SN extension. During Oligocene to early Miocene, the south plane of the fault reversed and the fault became a reverse fault caused with near EW compression. The Tongcheng fault began to form in extensional environment, and experienced local modification in compressional environment. In summary the fault is featured as strike-slip, multi-periodic activities and varying fault nature at different structural stage.