塔里木盆地顺北西部地区火成岩侵入体发育特征及其与断裂耦合关系

Igneous rock intrusions in the western Shunbei area,Tarim Basin:Characteristics and coupling relationships with faults

塔里木盆地顺北西部地区火成岩侵入体分布广泛,对地层和含油气系统改造作用明显,但该地区火成岩侵入体发育特征及其与深部走滑断裂带之间的耦合关系并不十分清楚。基于顺北西部地区最新二维和三维地震资料,精细刻画了火成岩侵入体形态特征,划分了火成岩侵入体不同类型及组合关系,判别了火成岩侵入体发育期次,确定了火成岩侵入体与深部走滑断裂耦合关系。结果表明:(1)顺北西部地区火成岩侵入体具有“一”字形、舌形、碟形以及半碟形几种形态类型。(2)单一侵入岩床通过相接、相连及错断组合形成岩床复合体。(3)火成岩侵入体主要分布于中-下奥陶统顶面至中-下泥盆统顶面之间,侵入岩床活动类型包括单期单层、单期多层和多期多层3类。(4)不整合面和断裂作为岩浆侵入的通道,控制了火成岩侵入体发育数量和规模,导致研究区南部和北部侵入作用存在明显差异。(5)研究区北部深部走滑断裂作为岩浆主要侵入通道,纵向侵入作用较强;南部岩浆以不整合面为主要侵入通道,横向侵入作用更强。

Igneous rock intrusions are extensively distributed in the western Shunbei area,Tarim Basin,playing a significant role in transforming stratigraphic architecture and petroliferous systems.However,there is a lack of clear understanding of their characteristics and coupling relationships with deep strike-slip fault zones.Using the latest 2D and 3D seismic data of the area,we present a fine-scale characterization of their morphological features,categorizing their types and combinations.Furthermore,we identify their developmental stages and define their coupling relationships with deep strike-slip faults.The results show that the igneous rock intrusions in the western Shunbei area exhibit multiple morphotypes,including stratum-concordant,tongue-,saucer-,and half-saucer-shaped intrusions.Individual intrusive sheets can combine to form sill complexes through processes of conjunction,connection,and faultinduced dislocation.The igneous intrusions in the Shunbei area predominantly occur between the tops of the MiddleLower Ordovician and the Middle-Lower Devonian,with the activity types of intrusive sheets being categorized into single-stage and single-layer,single-stage and multi-layer,and multi-stage and multiple-layer types.Unconformities and faults,acting as magma conduits,dictate the quantity and scale of the igneous rock intrusions,leading to notable disparities in igneous rock intrusions between the southern and northern parts of the study area.Specifically,the northern part of the study area featuring the deep strike-slip faults serving as primary magma conduits,exhibits intense vertical magma intrusion.In contrast,the southern part featuring unconformities acting as magma conduits,shows stronger horizontal magma intrusion.