苏北盆地高邮凹陷断层演化规律研究

Study on faults evolution in Gaoyou Fault Depression of Subei Basin

依据断层所切层位,将高邮凹陷内断层分为3种类型:I型至少切割中、下构造层;II型切割中、上构造层;III型切割下构造层。凹陷不同部位断层组合形式具有明显差异,凹陷边界断层主要以铲式扇为特征,内部以次级地堑、地垒式低幅度凸起和箕状半地堑等为特征。不同时期断层的活动性和构造样式是凹陷构造演化的反映:泰州组—阜一段沉积时期,凹陷向NNW方向坳陷伸展,断层规模和数量较小;阜二段—阜四段沉积时期继承前期伸展方向断陷伸展,凹陷南部边界断层开始强烈活动;戴南组—三垛组沉积时期,逐渐转化为NNW—SSE方向双向伸展断陷活动阶段;盐城组沉积以来,进入整体坳陷阶段,大规模断裂活动基本停止。

According to the cut positions, faults in Gaoyou fault depression are classified into 3 types, including type Ⅰ cutting at least the middle and lower.structural layers, type Ⅱ cutting middle and upper structural layers and type Ⅲ cutting the lower structural layers. The fault configurations at different positions of the fault depression differ from each other. Faults at the fault depression boundary are featured by shovel shape and the inner ones are featured by sub-graben, horst bulge and half-graben figures. The activity and structural configurations of the faults at different periods would reflect the evolution of the fault depression, during the sedimentation period of Taizhou Formation-Fu Section Ⅰ, the fault depression strikes to the NNW direction and extends to the downwarp, but the scale and amount of the faults are small. During the sedimentation period of Fu Section Ⅱ-Fu Section Ⅳ, the extension continued towards the same direction, and the faults at the southern boundary of the fault depression takes on violent actions. During the sedimentation period of Dainan Formation-Sanduo Formation, the extension continued simultaneously towards 2 directions, NNW and SSE. Since the sedimentation of Yancheng Formation, general downwarp period comes and large scale fault activities stop.