南堡凹陷老爷庙地区构造-沉积分析

Tectono-Sedimentary Analysis of Laoyemiao Region in Nanpu Depression

利用构造-沉积分析方法,探讨南堡凹陷老爷庙横向背斜对东营组扇三角洲沉积体系的控制作用.通过对西南庄边界断层和老爷庙背斜的几何学解剖,确定老爷庙背斜为西南庄断层断面弯曲控制的横向背斜.该背斜从沙河街组一段沉积期开始发育,馆陶组沉积期叠加了NE向的走滑断层.含砾率统计发现,含砾率高值均分布在横向背斜转折端、横向背斜和边界断层交汇控制了主水系的入口,提供长距离输沙路径.从井-震结合剖面和古地貌图识别出横向背斜发育时期的上、下坡折位置.扇三角洲平原受上坡折控制,发育在背斜转折端;下坡折控制扇三角洲前缘和前扇三角洲的分界.边界断层控制的横向背斜在沉积盆地内普遍发育.横向背斜控制长距离输沙和相分配模式对砂体预测具有重要的意义.

The aim of this paper is to test a new approach-tectono-sedimention analysis to gain insights into the controls of Laoyemiao transverse fold on the fan delta of Dongying Formation. By investigating the features of basin-bounding master fault （Xi＇nanzhuang fault） and fold geometry in Laoyemiao region, we have determined that Laoyemiao fold is essentially a transverse fold produced by Xi ＇ nanzhuang fault flexural. The fold with axes trending NW-SE was developed in sedimentary period of the 1st Member of Shahejie Fro. , and superimposed by Miocene NE trending strike-slip faults. Calculation of gravel content shows that the high values zone basically coincides with the hinge, which in turn reveals that the joint of the transverse fold and Xi＇nanzhuang fault is the main drainage entry, and fold hinge provides major sediment long distance transportation pathway. From logging, seismic data and paleogeomorphology, the upper and lower slope break of transverse fold are identified. The sedimentary facies interpretation shows that they are consistent with the delimits of fan-delta plain and front, fan-delta front and pro-fan delta respectively. It can be proved that transverse fold constrains the facies distribution. Transverse folds caused by basin-bounding master fault are widely developed in sedimentary basins. The established model of sediment transportation for long distance and facies distribution of transverse fold is significant for favorable sandbodies prediction.