摘要
环县西断层位于鄂尔多斯盆地天环坳陷中南部,为稳定克拉通地块内部的一条大断距正断层,探讨其几何学、运动学特征不仅可以为鄂尔多斯盆地早古生代盆地构造活动提供依据,也对后续探讨其与中央古隆起构造成因的关系具有重要意义。结合二维地震剖面、三维地震资料与钻井资料,刻画环县西断层几何学特征,以三维建模技术建立断面三维形态,利用平衡剖面恢复技术还原断层构造演化过程。研究认为,环县西断层为长约40.06 km、最大垂向断距约600 m、倾向西西北、走向北北东的高角度正断层。该断层切穿长城系、蓟县系、寒武系与奥陶系,具有平面分段、多期活动的特点。环县西断层由4条走向不同的断层连接而成。在寒武系沉积之前,环县西断层形成并活动;马四段沉积前,环县西断层继续活动,断层发育切穿马三段,下盘马三段剥蚀缺失;马五段沉积前,断层发育至马四段,下盘马四段遭受剥蚀;三叠系沉积前,断层再次发生小规模正断层活动,在上覆地层形成了三角剪切带;此后发生小规模构造反转,由伸展断层变为挤压断层,使上覆地层形成小规模背斜。环县西断层的形成是区域伸展背景下,基底薄弱带控制,多期构造叠加,后期局部反转共同作用的结果。
The Huanxian west fault is located in the central-southern part of the Tianhuan Depression in the Ordos Basin.As a large-throw normal fault within the stable cratonic block,investigating its geometric and kinematic characteristics can not only provide a basis for the tectonic activities of the Early Paleozoic basin in the Ordos Basin but also facilitate subsequent discussions on its genetic relationship with the central paleouplift.By integrating 2D seismic profiles,3D seismic data,and drilling data,the geometric characteristics of the Huanxian west fault are depicted,a 3D morphology of the fault plane is established using 3D modeling technology,and the tectonic evolution process of the fault is reconstructed via balanced cross-section restoration technology.The study suggests that the Huanxian west fault is a normal fault with a length of approximately 40.06 km,striking NNE,dipping WNW,and with a maximum throw of about 600 m.It cuts through the Changchengian System,Jixianian System,Cambrian System,and Ordovician System.The fault is characterized by planar segmentation and multi-stage activities:it is composed of four faults with different strikes;the Huanxian west fault formed and became active before the Cambrian deposition;it continued to be active before the deposition of the Ma 4 member,cutting through the Ma 5 member,with the Ma 3 member in the footwall suffering erosional absence;before the deposition of the Ma 5 member,the fault extended to the Ma 5 member,and the Ma 4 member in the footwall was eroded;before the Triassic deposition,the fault underwent another small-scale normal faulting activity,forming a triangular shear zone in the overlying strata.Later,a small-scale tectonic inversion occurred,transforming the extensional fault into a compressional fault,resulting in the formation of a small-scale anticline in the overlying strata.The formation of the Huanxian west fault is the result of the combined effects of the regional extensional setting,control of the basement weak zone,multi-stage tectonic superposition,and late-stage local inversion.
作者
刘昊
何登发
Liu Hao;He Dengfa(School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083)
出处
《地质科学》
北大核心
2025年第6期1633-1645,共13页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
新型油气勘探开发国家科技重大专项(编号:2025ZD1400201)
中国石油长庆油田公司科学研究与技术开发项目(编号:2024D1JC06-01)资助。
关键词
鄂尔多斯盆地
环县西断层
几何学与运动学
构造演化
三维构造模型
Ordos Basin
Huanxian west fault
Structural geometry and structural kinematics
Tectonic evolution
3D structural model
