摘要：
近年来,龙门山褶皱冲断带是国内外专家学者研究复杂构造地质的天然实验室.通过野外地质调查和精细地震构造解释,利用最新最的油气勘探地球物理资料,通过选取龙门山北段、中段、南段与构造走向基本垂直的成像效果较好具有代表性的区域地震大剖面3条,借助Geo—sec二维平衡剖面构造恢复技术,对龙门山褶皱冲断带的构造发育及其演化过程进行分析.通过对各段构造发育及断裂演化史进行深入剖析,总结出7种构造发育样式以及北、中、南段构造组合特征.通过对比北、中、南段构造发育及演化特征,证实龙门山褶皱冲断带是由多期构造运动叠加形成的复式构造,具体表现为基底卷入推覆冲断、盖层滑脱叠瓦状推覆冲断、逆冲双重构造等多种构造样式.印支运动早期以前,主要以拉张环境为主,缓慢隆升;印支晚期以后,以挤压环境为主,逆冲推覆快速隆升,至喜马拉雅运动时期定型.在此基础上,综合石油地质综合评价,结合各段区域内已发现气田的构造特征,对有利油气构造样式进行了预测,指出其中的被动断弯与断展背斜构造、顶板双重构造、背冲构造是油气勘探的有利构造样式.%Objectives:In recent years,the Longmenshan fold—thrust belt is a natural laboratory for domestic and foreign experts and scholars to study complex geological structures.Through the field geological survey,fine seismic structure interpretation,the latest advanced imaging data are used,selecting three typical lines of the Longmenshan northern,middle and southern sections,which is basically vertical toward the strike.With the aid of Geo-sec 2D balanced cross-section technique,the tectonic development and evolution of the Longmenshan fold—thrust belt are analyzed.Through the deeply analysis of the tectonic development and the evolution history of faults,the author have summarized seven tectonic development style and tectonic feature patterns of the northern,middle and southern sections.Methods:This paper carries out research with seismic profile,geological outcrops and balanced cross-section comprehensive analysis and previous research results.Results:Through the in-depth analysis of the tectonic development and the evolution history of faults,the authors have summarized 7 tectonic development patterns and tectonic features of the northern,middle and south sections.By comparing the tectonic development and evolution characteristics of the northern,middle and southern sections,it is confirmed that the Longmenshan fold—thrust belt is a multi-stage structure formed by superposition of multi-stage tectonic movements.The results show that the basement is involved-thrusting,Thrusting thrust,passive roof duplex and other structural styles.Before the early Indo—China movement,the stress environmental mainly was extensional environment,slowly uplifted;and lately was the compressional environment,rapid thrusting uplift and till the Himalayaorogeny period stereotype.Conclusions:On the basis of constructed style analysis,combining the comprehensive evaluation of the petroleum geology and the structural characteristics of gas fields found in the nearby sections,the structural styles of the favorable oil and gas are predicted.The passive fault-bend and fault-propagation folds,passive roof duplex,back thrusts are favorable structural styles of oil and gas exploration.
