十屋断陷盆地古构造坡折带特征及其对沉积体系的控制

The characteristics of underformed structural slope-break zone and its influnce on deposition system in Shiwu fault basin

十屋断陷位于松辽盆地东南隆起区的东南缘。根据古构造恢复结果,在十屋断陷的同裂谷阶段识别出主断裂坡折带和断阶坡折带。前者分布于断陷盆地的陡坡,受盆地的主断层控制;后者分布于断陷盆地的缓坡,受大致平行排列的次要断层控制。与断阶坡折带相比,主断裂坡折带为沉积作用提供了相对较大的可容纳空间,从而导致主断裂坡折带处的沉积作用以厚度大和砂岩体积分数高为特征。此外,主断裂坡折带在低水位期和湖侵期,控制了沉积体系类型,而在高水位期控制了沉积体系的规模。断阶坡折带导致沉积物厚度的变化明显。

Shiwu fault basin is located in the southeastern margin of southeast uplift area of Songliao Basin. According to the restore of paleostructure main fault slope-break zone and fault bench slop-break zone have been recognized.The former was developed along the steep slope of the fault basin and controlled by the main fault of the basin. The latter was developed along the gentle slope of the fault basin and controlled by secondary faults which were parallel each other. The main fault slop-break zone supplied relatively large accommodation space for the deposition compared with the fault bench slop-break zone, which resulted in relatively great thickness of the sediments and richness in sandstone. In addition, the main fault slop-break zone affected on the sedimentary system types during lower stand and lake transgression and on the sedimentary scale during high stand. The fault bench slop-break zone resulted in the sharp change of the sedimentary thickness.