盆地周边地质调查是研究盆地构造演化的一种重要补充手段，露头区断层活动规律可以直观分析盆地内观察不到的断层性质。本文主要研究了磁村断层的野外地质特征及其对沉积的控制，并类比了沉积盆地内的断层对沉积的控制。研究发现磁村断裂带内地质现象丰富，发现有擦痕、阶步、碎裂灰岩、牵引褶皱、石香肠构造、菱形构造等，其中石香肠构造和菱形构造受控于岩性及断裂带内局部应力场变化，与其他证据共同指示磁村断层为一条右旋伸展-走滑断层。在此基础上分析了磁村断层走滑活动模式及对沉积扇体的控制，并针对断层走滑活动的沉积响应，在沉积盆地内找到了多处伸展-走滑型断层和走滑-伸展型断层控沉积的沉积迁移现象，且发现了走滑伸展作用产生的斜歪扇背斜现象。这种控制作用使沉积砂体沿断层走向展布，进而控制油气成藏和分布。综合分析认为，磁村断层形成于晚中生代以来鲁西地块的张扭性应力场，是鲁西隆起不同块体差异伸展所致，起调节不同块体应变的作用。%Field observation around a basin is an important way to understand tectonic evolution of the basin. Moreover, the geological characteristics of the outcrops could be applied to the faults which are not directly observed in the basin. This paper focuses on the geological characteristics of the Cicun Fault in the western Shandong Uplift and its effect on the deposition. Furthermore, an analogy between the outcrop and the basin in regarding of the sedimentary responses to the fault activity is conducted. There are a variety of strike-slipping-related geological characteristics in the fault zone, such as scratches, steps, limestone cataclasites, drag folds, two types of boudins, “rhombic structure”. What’s more, the boudinage and “rhombic structure” are controlled by the lithological changes and local change of tectonic stress field. The linear structure, together with other evidence indicates that the Cicun Faults is a right-lateral normal strike-slip fault. The activity model of the Cicun Fault and its sedimentary responses are summarized. The Cicun Fault is also characterized by several imbricate sedimentary facies along the obliquely-slipping faults in Jiyang Depression, as well as the inclined fan-folds. Consequently, the sand bodies distributing along the strike controlled the formation of oil reservoir. Based on the comprehensively study, the results indicate that the Cicun Fault developed under the trans-extension at the Late Mesozoic, and it was resulted from the adjustment of the differential extension between the sub-blocks in the western Shandong Uplift.
展开▼
