红旗凹陷典型构造变形特征及物理模拟

红旗凹陷是经历了多期建造与改造的叠合盆地,现今难以见到原型盆地的面貌,导致断裂体系的形成机制复杂,在建造期、改造期断裂系统的发育机制,断裂系统之间的迁就、利用、切割改造关系尚不清楚。因此其构造演化及形成机制至今仍然存在较大的分歧。基于相似性原理,首次在研究区运用构造物理模拟实验方法,对凹陷北西边界红西断层控制作用下的伸展和挤压形成的构造样式及演化规律进行研究,以再现动力学演化过程,并取得了与实际地质情况较高的吻合度。结果表明,凹陷受到间歇性的伸展和挤压力的影响,共经历了断陷期(塔木兰沟组-南屯组一段)、断坳转换期(南屯组二段-伊敏组)和坳陷期(青元岗组)三个构造演化阶段。在变形过程中,内部形成的调节断层发育具有期次性,断陷期的发育的断层终止在南屯组一段顶面,断坳转换期发育的断层终止在伊敏组顶面。可见凹陷的构造样式主要受犁式控陷断层和区域伸展、挤压作用的共同影响。

Deformation Characteristics and Physical Simulation of Typical Structures in Hongqi Sag

Hongqi Sag was a superimposed basin that had experienced multi-stage construction and transformation. Nowadays, it was difficult to saw the appearance of the prototype basin, which led to the complex formation mechanism of the fault system. How the fault system developed in the construction and transformation period, and how the relationship between the fault system was transferred, utilized, cut and transformed were not clear. Therefore, the structural evolution and formation mechanism are still quite different. On the basis of previous studies and based on the principle of similarity, the structural pattern and evolution law of extensional and compressional structures under the control of Hongxi fault on the northwest boundary of the sag were studied for the first time in the study area by using the method of structural physical simulation experiment, so as to reproduced the dynamic evolution process and achieved a high degree of coincidence with the actual geological situation. The results show that under the influence of intermittent extension and extrusion, the sag has experienced three tectonic evolution stages: faulted period(Tamulangou Formation to Nantun Formation 1), fault depression transition period(Nantun Formation 2 to Yimin Formation) and depression period(Qingyuangang Formation). In the process of deformation, the development of internal regulating faults is of periodicity. The developed faults in the faulted period end at the top of Nantun Formation 1, and the developed faults in the fault depression transition period end at the top of Yimin formation. It can be seen that the structural style of the sag is mainly affected by the plough controlled fault and regional extension and extrusion.