廊固凹陷沙四晚期构造应力场模拟及低级序断层预测

在了解区域构造背景、分析断层活动特征及构造演化特征的基础上,对廊固凹陷沙四晚期构造应力场进行数值模拟,并对低级序断层发育进行预测。研究结果表明,研究区在沙四晚期活动的主要断层包括大兴断层、半截河断层等6条,牛北斜坡构造带与河西务构造带在该时期隆起明显,综合分析可知该时期最小主应力方向为SE144°—NW324°;低级序断层发育受最小主应力、剪应力等的影响,最小主应力和最大主应力与最小主应力的差值控制断层的优势发育区,平面剪应力控制断层走向,该区主要发育北北东—北东走向的断层;剖面剪应力在大部分区域为左旋,表明断层视倾向以北西向为主。

NUMERICAL SIMULATION OF STRUCTURAL STRESS FIELD IN THE LATE SEDIMENTARY PERIOD OF Es4 AND PREDICTION OF THE LOWER-ORDER FAULTS IN LANGGU SAG

On the basis of the research of structural background, fault activity and structural evolution, the method of numerical simulation of structural stress was applied to simulate the stress distribution in the late sedimentary period of Es₄ in Langgu sag, and the development of the lower-order faults could be predicted. The research showed that the active faults in the late sedimentary period of Es₄ were Daxing fault, Banjiehe fault and so on. Niubei slope belt and Hexiwu structural belt were uplift obviously during this period. The comprehensive analysis indicated that the direction of the minimum principal stress was SE144°-NW324°, the development of the lower-order faults were mainly influenced by the minimum principal stress and the shear stress, et al. The minimum principal stress and the difference between principal stresses (the maximum and minimum principal stress) controlled the advantage area of the fault development. The plane shear stress controlled the fault strike, and its most faults in this area were NNE-NE. The profile shear stress controlled the dip direction, in the main part of this area the profile shear stress was sinistral shear stress, which showed that the dip direction of the most faults was NW.