【作者】 杨斌谊；

【导师】 刘池阳；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2004， 博士

【摘要】 焉耆盆地是位于南天山褶皱带上的一个中、新生代叠合盆地，处于塔里木、准噶尔及鄯善地块之间的特殊构造部位，经历了复杂的构造变动和强烈的后期改造，盆地地层剥蚀严重，研究其发育演化史难度颇大，致使对盆地属性及其发生、发展、衰退、消亡等过程的认识分歧较大。焉耆盆地自1993年投入全面勘探开发工作以来，已相继发现宝浪油田(1994)和本布图油田(1995)。随后的几年，盆地油气勘探效率逐年下降，主要在已发现的两个油田范围内获得少许储量。因而对盆地的发展演化尤其是中新生代演化历史的进一步系统研究，探讨侏罗纪盆地原型、盆地后期改造特征及对油气聚集的影响，无疑将对盆地的下一步油气勘探工作有所裨益。同样，该工作将对中国西部众多中小型类似盆地的构造研究及其油气勘探有积极的借鉴意义。 论文总体的研究思路是：以盆地研究的“整体、动态、综合”分析原则为指导，运用改造型盆地研究思路，突出改造过程的研究，采用与周邻类似盆地(库车坳陷、库米什盆地、尤尔都斯盆地)分析对比研究，探讨盆地属性及构造演化规律，进而探讨其对油气聚集的影响。 通过对焉耆盆地大地构造环境、侏罗纪沉积特征与演化、与周邻侏罗系对比、侏罗系剥蚀厚度与古沉积边界、平衡剖面与古构造恢复等研究认为，焉耆侏罗纪原型盆地性质为微拉张背景下的伸展断陷盆地。其形成的动力学机制为碰撞造山期后地壳冷却及应力松驰所导致的热塌陷沉降和伸展沉降的综合结果，可以归结为水平和垂向上两种地壳运动的结合。在上述研究基础上，认为焉耆盆地形成演化可分为，焉耆—库车前陆盆地阶段(T)、造山期后伸展盆地发育阶段(J)、挤压隆升剥蚀阶段(K)、区域(塌陷、伸展)沉降盆地阶段(E)和陆内破裂前陆盆地阶段(N+Q)等五个阶段。现今焉耆盆地属性为一典型的中生界残留盆地，在侏罗纪原型盆地的基础上经历了后期的燕山运动晚期及喜山运动中晚期的强烈改造，侏罗纪盆地伸展构造形态已很少保存，大多遭受强烈改造而显示为挤压性质，并最终形成焉耆盆地现今构造格局。 焉者盆地自中晚三叠世至早中侏罗世沉积相研究表明，侏罗纪时期盆地湖泊面积宽广，湖泊发育，其沉积演化与西北地区同时期诸盆地的沉积演化具良好的一致性，表现为一种准平原化作用下的较广泛沉积，与周邻地区的侏罗系应有更多的联系。 通过对焉耆侏罗纪盆地原始沉积范围的研究，认为侏罗纪原型盆地的古沉积边界远大于现今盆地侏罗系残留边界。碎屑含砾百分比、碎屑岩矿物成熟度指数和碎屑重矿物稳定系数研究表明。侏罗纪的主要时期盆地北部距物源区最近，水动力活跃，南部离物源区最远，水动力不活跃，沉积水体较为稳定。这表明侏罗纪焉耆盆地的北部边界较接近于现今侏罗系的北部边界，应该比现今侏罗系残留北界更靠北一些；而南部古沉积边界要较现今边界更靠南，应在库鲁克塔格地区以南，或包括库鲁克塔格地区。 与周邻侏罗系(库车坳陷、库米什盆地、尤尔都斯盆地)对比研究表明，焉耆盆地与库车地区和库米什地区侏罗纪时期应为相连通的统一盆地，库车地区于晚白垩世发生区域隆升，致使包括库车地区在内的整个焉耆—库车盆地缺失晚白垩世地层，焉耆—库车盆地发育中断，故盆地东界应为托克逊断裂附近，往西则应过霍拉山与库车地区相连。 平衡剖面研究结果表明。焉耆盆地侏罗纪时期整体处于弱伸展状态，盆地起伏不大，断裂不发育，发育有同沉积正断层，并沉积了中上侏罗统和下白垩统，于燕山运动晚期遭受强烈冲断隆升，造成盆地部分中侏罗统、上侏罗统剥蚀和下白垩统完全剥蚀，形成现今盆地的基本构造形态。原型盆地遭到破坏。博湖坳陷南部凹陷主要表现为强烈的隆升和冲断，形成了一系列冲断隆起带，而北部凹陷燕山运动晚期的作用强度较小，并伴随有一定的左行剪切活动，形成了一系列NW向和NNW向较宽缓构造带。对博湖坳陷构造变形的分析表明，盆地燕山运动晚期的改造作用其形成时间、构造幅度具有由南向北、由东向西逐渐变新、变小的趋势。 焉舍盆地喜山运动中晚期的改造作用相对较弱，主要表现在盆地早期形成的隆起边缘的冲断作用有所加强，而在中心部位则较弱。构造变形造成侏罗系与上覆第三系一同卷入褶皱，两个层系背斜高点、轴向一致，最终定型一系列NW向构造带，如宝浪苏木构造带和本布图构造带等。盆地于喜山期形成了一些新的构造圈闭，同时对燕山期形成的一些先期圈闭有一定的改造作用，或继承并最终定型，或遭受破坏。 通过对焉誉盆地烃源岩生烃史、流体包裹体测温、储层自生伊利石同位素测年、油藏饱和压力及构造运动等综合分析认为，盆地主要有两期油气成藏事件，第一期发生在侏罗纪末期，第二期发生在第三纪晚期。焉者盆地喜山运动中晚期的构造运动导致油气运移再分配，形成晚期再调整油藏，具有典型的“晚期调整”“晚期定型”、“晚期成藏”特征。 焉誉盆地圈闭形成演化可以分为三个主要阶段，即晚三叠世至侏罗纪末、侏罗纪末至早第三纪末和第三纪末至第四纪，圈闭整体捕获油气能力较差.唯有那些继承性发展良好并最终定型的圈闭构造，才能很好的捕获油气。盆地圈闭主要集中于?更多还原

【Abstract】 Yanqi basin is a Mesozoic and Cenozoic superposed basin in the southern Tianshan folded belt. It locates in the special structural spot among Tarim, Jugger and Shanshan Block and experiences so complexed structure changes and extremely later reformation that the strata in basin eroded strongly and it is rather difficult to realize the evolution. There exist much difference in the basin attribute and the development of bearing, developing, declining and disappearing. Since 1993’s full-scale exploration in Yanqi basin, there has found Baolang oilfield and Benbutu oilfield. The exploration rate has slowed down year after year in the following years. Little reserve has been got around these two oilfields. Recently the basin has been in its grown exploration stage that it is in dire need of seek for new target. Therefore it is significant to further petroleum exploration, sysmaticly researching on the basin’s development, especially Mesozoic and Cenozoic evolution history, discussing the Jurassic basin prototype, late reformation features and its influence on petroleum accumulation. The work will insolubly be good example to structural research and petroleum exploration of many likely basins in western china.The thesis is directed by the rule of united, dynamic and integration, uses the thought of reformed basins and projects the reformation courses. It contrasts the basin with surrounding likely basins such as Kuche depression, Kumishi basin and You’erdusi basin in order to discuss the basin attribute, structural evolution rules and their influence on petroleum accumulation.Yanqi basin in Jurassic is an extended and faulted basin in the weak extensional background through research on the tectonic environment, sedimentary features and its evolution, contrast with neighboring Jurassic, eroded thickness and paleo-despositional boundary, profile of equilibrium and recovered paleostructures. The area of Yanqi, Kuche and Kumi should be a connected and united basin and deposit in stable circumstance in this period. The dynamic mechanism could be the synthetical result of heat sink and extensive subsidence caused by the crustal cooling and stress relaxation after collisional orogenic epoch. It can also be thought as the combination of the two crustal movements in horizontal and vertical direction. Based on the above research, the evolution of Yanqi basin could be divided into five stages which are Triassic foreland basin stage in Yanqi-Kuche area, Jurassic extensive basin stage after the orogenic epoch, Cretaceous uplift and erosion stage by compression, Eogene regional subsidence stage cause by breakdown and extension, in-land broken foreland basin stage in Neocene and Quaternary. The present Yanqi basin is a typical Mesozoic residual basin which suffered strong reformation in late Yanshan movement and mid-late Himalayan movement on the Jurassic base. The extensive structure in Jurassic basin keeps little and perfumes compression features by so intensive remold that today’s framework developed finally.The sedimentary research on mid-late Triassic and early-mid Jurassic basin shows that lakes are abundant with broad width at the stage, whose sedimental evolution has well correlated with that of the other basins in northwest region in the same period andhas much relation with adjacent areas. The sedimentation in Jurassic is rather broader with peneplane feature.Through analysizing the Jurassic original sedimentary range in Yanqi basin, it is considered that the paleo-boundary in Jurassic is broader than the present residual boundary. The ratio of conglomerate to clastic, mineral maturation index and heavy mineral stability factor in clastic rock all indicate that the north of the basin is nearer to the provenance than the south so that the hydrodynamism of the north is more active than the south and the water in the south is rather stable. From the above it concludes that the Jurassic boundary in the north is near the present and is in the far north than the residual boundary and that the paleodeposition boundary of更多还原