ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    走滑断裂的生长地层识别与应用:以塔里木盆地西北缘皮羌断裂为例

    Identification and Application of Growth Strata Associated with Strike-Slip Faults: Example from the Piqiang Fault in the Northwestern Margin of the Tarim Basin

    • 摘要: 生长地层是指构造变形过程中沉积的地层,其年龄可用于限定构造变形发生的时间。通过生长地层分析约束构造活动的发生时限已在挤压和伸展构造发育区得到了广泛应用,然而与走滑断裂相关的生长地层分析案例尚鲜见报道。笔者通过野外地质调查、遥感影像分析和地震剖面解释等手段与方法,厘定塔里木盆地西北缘皮羌断裂的几何样式和构造属性;基于地层的平面特征,确定与该断裂构造活动同期的生长地层,并据此限定皮羌断裂的活动时间。研究结果表明,地表标志层的左旋错断、断层面发育的近水平擦痕和近竖直阶步、断层迹线的线性特征及地震剖面上的正花状构造特征指示皮羌断裂为左行走滑断裂。在平面上,中新统(N1)及以下地层的厚度在皮羌断裂西侧向斜的同一翼保持稳定,地层的曲率也基本协调;而上新统(N2)与下伏地层则呈角度不整合接触,且上新统—早更新统(N2-Q11)地层的厚度越靠近皮羌断裂越薄,且随着地层时代变新,地层的平面曲率逐渐变小,表明上新统至早更新统(N2-Q11)地层是与皮羌断裂强烈走滑活动相关的生长地层。这一认识与基于地震剖面的生长地层分析结果一致。研究成果不仅有助于深入理解皮羌断裂的构造演化过程,还可为走滑断裂构造背景下生长地层的识别与应用提供新思路。

       

      Abstract: Growth strata, which are deposited during tectonic deformation, serve as vital markers for dating the timing of such deformation events. While the utilization of growth strata analysis to constrain the timing of tectonic activities is well-established in regions characterized by compressional and extensional tectonics, its application to strike-slip faults remains largely unexplored. This study employs a comprehensive methodology integrating field geological investigations, remote sensing image analysis, and seismic profile interpretation to elucidate the geometric patterns and structural attributes of the Piqiang Fault located at the northwestern margin of the Tarim Basin. By identifying syntectonic growth strata through their map-view characteristics, we aim to determine the active period of the Piqiang Fault. The results show that the Piqiang Fault exhibits characteristics of a sinistral strike-slip fault, evidenced by left-lateral dislocation of surface marker beds, nearly horizontal scratches and vertical steps on the fault plane, the linear fault trace, and the positive flower structural style in seismic profiles. Notably, the strata of N1 and older intervals maintain consistent thicknesses and curvatures within the same limb of the syncline to the west of the Piqiang fault. In contrast, the N2 strata display an angular unconformity with the underlying strata. Furthermore, from N2 to Q11, strata thicknesses decrease progressively towards the Piqiang Fault, accompanied by a reduction in map-view curvatures with decreasing stratigraphic age. These observations collectively suggest that the strata from N2 to Q11 represent growth strata associated with intense strike-slip activity along the Piqiang Fault. This interpretation is corroborated by growth strata analysis from seismic profile data. Our findings not only contribute to a deeper understanding of tectonic evolution of the Piqiang Fault, but also provide novel insights into the identification and application of growth strata in the context of strike-slip faulting.

       

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