塔里木盆地塔中隆起中北部地区断裂构造特征及演化

Structure and evolution of faults in central and northern parts of Tazhong Uplift,Tarim Basin

为系统揭示塔里木盆地塔中隆起中北部地区断裂构造特征及其成因演化,通过对该区大连片三维地震工区精细构造解析和相干体等分析,并结合区域动力背景,系统论述了该区的断裂构造类型、几何学特征、差异活动机制及其构造演化过程。研究结果表明,塔中隆起中北部发育了4类7期断裂构造,其中逆冲断裂和走滑断裂尤其发育。平面上北西向弧形逆冲断裂与北东向、北西向及南北向走滑断裂相互交切与耦合;垂向上断裂分层差异活动特征明显,下奥陶统及其以下地层,断裂发育数量多且以线形为主,中奥陶统-中下泥盆统多呈雁列式,上泥盆统-二叠系仅在塔中Ⅱ号断裂带、顺北5号断裂带西南端等地区发育少量断裂。研究区断裂活动受多期、多方向不同性质应力场所控制,经历了极其复杂的演化历史:加里东早期以塔中Ⅱ号断裂带等少量北倾正断层活动为主;加里东中期Ⅰ幕断裂活动强烈,表现为逆冲断裂与走滑断裂协同演化和相互耦合特征,走滑断裂对逆冲断裂的切割或限制作用明显;加里东中期Ⅲ幕断裂活动基本继承了加里东中期Ⅰ幕的构造格局,但在工区北部的顺北4号、5号等断裂带张扭性断裂活动特征显著;加里东晚期-海西早期,部分断裂发生继承性活动且张扭断裂发育范围进一步向南扩大;印支-燕山期,仅有少数断裂发生继承性活动;喜山期该区构造比较稳定,早期形成的复杂断裂构造进入深埋阶段。

[Objective]To reveal the structures and evolutionary patterns of faults in the central and northern parts of Tazhong Uplift,Tarim Basin,[Methods]this paper systematically discusses the types of fault structures,geometric characteristics,differential activity mechanisms,and tectonic evolution processes in this area by analysing detailed structural interpretations and coherent slices of combined large 3D seismic data along with the regional dynamic background.[Results]The results show that there are 4 types and 7 evolution stages of faults in the central and northern parts of Tazhong Uplift,among which thrust faults and strike-slip faults are particularly common.On the plane,NW arc thrust faults intersect with NE-,NW-and NS-striking strike-slip faults;vertically,the fault stratification and differential activity characteristics are obvious.In the Lower Ordovician and the belowing layers,faults developed in large numbers and were mainly linear in their trending directions.As for the Middle Ordovician-Middle and Lower Devonian layers,faults are mostly in the echelon type.In the Upper Devonian-Permian layers,a few faults developed in the TazhongⅡfault zone and the southwestern end of the Shunbei 5 fault zone.[Conclusion]The fault activity in the study area was controlled by stress sites exhibiting diverse properties across multiple phases and directions and experienced an extremely complex evolutionary history:In the Early Caledonian period,a small number of normal faults,such as the TazhongⅡfault zone,were mainly active;in the Middle CaledonianⅠperiod,the fault activity was very strong and was characterized by coevolution and mutual coupling of thrust faults and strike-slip faults.The strike-slip faults obviously cut or restricted the thrust faults.The fault activity of the Middle CaledonianⅢperiod basically inherited the tectonic framework of the Middle CaledonianⅠperiod,but the characteristics of transtensional fault activity in the Shunbei 4 and 5 fault zones are significant.From the Late Caledonian to Early Hercynian,some of the faults inherited activities with obvious transtensional characteristics.Conversely,in the Indochina-Yanshan period,only a few faults inherited activity,and the development area of transtensinal fault is further expanded to the south.During the Himalayan period,the tectonic movement of this area was relatively stable,and the complex fault structures that formed in the early stage transitioned into the deep burial stage.