塔里木盆地顺南地区18号走滑断裂带的构造几何学特征及成因机制

毛丹凤; 何登发; 陈槚俊; 田方磊

doi:10.3799/dqkx.2023.065

地球科学 ›› 2023, Vol. 48 ›› Issue (06) : 2151 -2167. DOI: 10.3799/dqkx.2023.065

塔里木盆地顺南地区18号走滑断裂带的构造几何学特征及成因机制

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Geometry Characteristics and Genesis of No.18 Strike-Slip Faults in Shunnan Area, Tarim Basin, SW China

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摘要

为深化塔里木盆地小滑移距走滑断裂的几何学特征及成因机制认识，利用最新三维地震与井资料，详细解剖顺南地区18号走滑断裂带构造特征，讨论成因机制.该断裂带纵横比1∶10，且中间长、上下短；在平面上发育双重构造、马尾扇、左阶与右阶雁列等构造样式，在剖面上发育花状、地堑等构造样式；断层性质各异，断距差异大，断层间以软连接为主，硬连接次之；断裂带在不同构造层的分段特征具有继承性与差异性，在平面的不同位置纵向构造样式组合差异大.受先存断裂、地层能干性差异、多期次不同走滑活动的影响，断裂带在早寒武世末期已初步形成，在晚奥陶世早期与末期分别发生右行、左行走滑活动，此期间南部与北部的活动强度较弱，对应的马尾扇、走滑双重构造逐渐定型，中部走滑活动较强，且在上奥陶统能干性频繁变化处发育似花状构造；志留世末-早石炭世前在断裂带北部发生较强的左行走滑活动，促进断层的侧向硬连接，晚石炭世末期在断裂带中部发生较弱的右行走滑活动，促进似花状构造的继续发育，且此2次走滑活动在能干性相对较弱的碎屑岩地层形成雁列.

Abstract

In order to deepen the understanding of geometric characteristics and genetic mechanism of strike-slip faults with small displacement in Tarim basin, the characteristics of the No. 18 strike-slip faults in Shunnan area in detail were studied. Using the latest 3D seismic data and well data, it discusses its genetic mechanism. The aspect ratio of the faults is about 1∶10, and the faults are the longest in the middle in vertical direction; the faults have features such as duplex structures, horsetail fans, left and right echelons on the map, and such as flower structural styles and graben on seismic profiles; the fault properties and throw are different, and the linkage of faults is soft-link, followed by hard-link; the segmentation characteristics of the faults in different structural layers have inheritance and difference, and there are great differences in the combination of longitudinal structural styles in different positions on the map. Affected by early faults, the deformability of different strata and the different strike-slip activities in different periods, the faults had preliminary formed in the late of the Early Cambrian. The faults experienced successively right and left-lateral strike-slip activities in the Late Ordovician, and the activities were the strongest on the middle of map and the flower structure was formed where the strata physics changes frequently in the Upper Ordovician; respectively the horsetail in the southern and strike-slip double structure in the northern were gradually formed during this period. The northern faults experienced intense left-lateral strike-slip activity between the Late Silurian and the Early Carboniferous, and it promoted the lateral hard-link of faults. The middle faults experienced weak right-lateral strike-slip activity during the Late Carboniferous, and it promoted the formation of flower structures. The echelons were formed in the clastic rock with poweless deformability.