塔河桑南地区T_7~4侵蚀面构造特征及演化研究

Structural Characteristics and Evolution of T_7~4 Erosion Surface in the Sangnan Region of Tahe

桑南地区位于阿克库勒凸起东南斜坡带,T_7~4侵蚀面是加里东中期Ⅰ幕运动形成的地质界面在地震剖面上的响应,是塔河地区中下奥陶统的顶界侵蚀面。通过现今构造及构造演化研究,认为研究区T_7~4侵蚀面在加里东中期具备单斜雏形;海西早期隆升幅度大,单斜构造形态基本定型;海西晚期-燕山期处于稳定抬升期,抬升强度南弱北强;喜山中期之后构造应力发生急剧变化,向北相对沉降更大,表现为南高北低。经历多次构造运动,研究区发育多期次、多组系、多方向的断裂系统。构造演化控制了岩溶储层的发育与分布,主要受不整合面、古地貌和断裂系统等因素的影响,研究区经历了加里东中、晚期、海西早期等3个时期岩溶作用,西北部主要受海西早期岩溶的控制,而中部及东南主要受加里东中期岩溶的控制。

Sangnan area is located in the southeast slope belt of Akekule uplift.T 7 4 erosion surface is the response of geological interface formed by the episode I of the middle Caledonian movement and the top erosion surface of Middle-Lower Ordovician in Tahe area.Based on the study of present tectonic and tectonic evolution,it is considered that the T 7 4 erosion surface has a monoclinic embryonic form in the middle Caledonian period in the study area.With the huge uplift in the early Hercynian,the monoclinic structure shape is basically finalized.Later,the tectonic uplift has a steady rate in the late Hercynian-Yanshanian period,and the uplift intensity is weak in the South and strong in the north.After the mid-Himalayan period,the tectonic stress changed dramatically,resulting in the relative subsidence to the North was larger.After so many tectonic movements,the study area developed multi-stage,multi-group and multi-direction fault systems.Structural evolution controls the development and distribution of karst reservoirs,which mainly affected by unconformity,palaeogeomorphology and fracture system.The study area has undergone three periods of karstification,the northwest area is mainly controlled by early Hercynian karst,while the middle and southeast area are mainly controlled by mid Caledonian karst.