塔中隆起下古生界断裂差异变形特征及控制机理

Differential Deformation Characteristics and Control Mechanism of Lower Paleozoic Fault in Tazhong Uplift

塔中隆起断裂差异分段、分期变形特征及其控制机理是学者们关注的重大问题,但一直以来缺乏较为详细的研究。本文在详细的地震解释基础上,分析了塔中隆起主要断裂的分段差异特征,甄别断裂活动期次,进一步探讨了塔中隆起断裂差异变形的控制机理。塔中逆冲断裂多具有分段差异变形特征,体现为沿断裂走向基底卷入和膏盐层滑脱型并存;加里东早期,塔中逆冲断裂在局部构造段存在伸展正断层的活动证据;加里东中期Ⅲ幕,NW向逆冲变形最为强烈,同时大规模发育以NE向走滑断裂;海西早期之后逆冲变形仅存在于部分断裂的局部构造分段。本文研究表明,塔中地区基底构造具有横向差异性,这可能是其下古生界差异变形特征的基础;此外,塔中隆起变形强度也存在分段差异性,其横向差异收缩作用是主要断裂变形差异和活动差异的主控因素,也可能是北东向走滑调节断裂的形成原因。

Differential deformation characteristics and its controlling mechanism of Tazhong Uplift has been amajor concern for Tarim petroleum geologists,but has been lacking for more detailed research.Based on3D seismic interpretation and fault activity identification,segmented and poly-phase differential fault movement and its controlling mechanism in the Lower Paleozoic of Tazhong uplift was discussed in this paper.The thrust faults in theTazhong area are characterized by segmental deformation,which is characterized by the coexistence of basement-involved type and capping-sliding type along the fault.During the Early Caledonian,there was evidence of extension faults in the local structural section of Tazhong thrust fault.In the Middle Caledonian,the NW-direction thrust deformation is the strongest.In the Early Hercynian,thrust deformation only existed in the local structural segmentation of the partial fault.The deformation pattern,deformation intensity and active period of the main thrust faults in the Tazhong uplift are obviously different from nearby structural segmentation.It is necessary to form an adjustment belt between the structural segments,which may be the reason for the formation of the NE strike-slip fault.The basal structure of the Tazhong has lateral differentiation,which may be the basis of the segmentation difference characteristics of the Lower Paleozoic.There are also deformation intensity segmented differences,which is the main control factor for deformation and activities differences,may also be reason for the formation of NE strike-slip.