【作者】 汤济广；

【导师】 梅廉夫；

【作者基本信息】 中国地质大学 ， 能源地质工程， 2007， 博士

【摘要】 沉积盆地是地壳的基本构造单元之一，其演化受地球动力学所制约。受地球深部热一构造体制变化，岩石圈表层的板块在地质历史过程中反复分离和汇聚，同时拼合后发生多阶段陆内俯冲作用，地壳运动表现为多阶段性和多旋回性。受多旋回地壳运动的动力学机制控制，盆地的演化有着复杂的构造体制转换和频繁的旋回性，制约了盆地的形成环境、沉降机制、沉积充填。中国中西部含油气盆地的演化多经历多个成盆期，油气资源丰富，而由于大陆构造的多样性、复杂性和分层性，对盆地变革过程中构造变形机制、演化及动力学过程的探讨已超出经典的“二维”板块构造理论，而需从“三维”的新思维上去认识。因此对多旋回叠加改造型盆地的构造演化研究不仅具有重要的实际意义，同时对盆地发育演化过程中构造体制转换的探讨亦有着重要的大陆动力学意义。柴达木盆地位于青藏高原东北缘，大地构造位置处于亚洲中轴构造域和特提斯—喜马拉雅构造域的结合部位，为阿尔金山、祁连山和昆仑山所围限，中、新生代有着复杂的成盆机制和构造演化过程。柴达木盆地北缘西段为盆地侏罗系含油气系统的分布区，油气资源丰富，中、新生代以来的成盆作用主要与阿尔金山和祁连山相关。受周缘造山带的多旋回造山运动，柴达木盆地北缘西段中、新生代以来有着多期成盆作用和复杂的构造演化，从而导致了盆地的复杂构造变形，制约了烃源岩的分布和演化、生储盖组合的形成、圈闭的形成和分布、油气的成藏与改造过程，也决定了研究区油气的多期次聚集、改造与重建，因此使得油气形成和分布复杂。尽管围绕油气勘探工作在研究区开展了许多地质研究，但由于受盆地复杂的结构构造所制约，许多认识到目前为止还没有统一，如成盆动力学机制、构造演化过程、成藏富集规律等。对于多旋回叠加改造型盆地，构造演化是控制油气成藏的主导因素，直接制约着油气形成、运聚成藏及改造、保存，即对该类盆地的成藏研究需以构造为先导，通过构造的研究以带动对成藏规律的认识。针对柴达木盆地北缘西段成藏研究中主要的问题，论文基于多旋回叠加改造型盆地的成盆和成藏理论，通过野外地质调查、地震剖面的解释、岩石组构分析、物源分析、EsR测年和裂变径迹热年代学分析以及典型油气藏成藏期次和形成过程的剖析，在柴达木盆地北缘西段的盆地结构、成盆机制与演化、构造演化对成藏的控制作用及油气分布规律等方面取得了以下新的成果和认识：1、平面上，将柴达木盆地北缘西段划分为赛什腾—绿梁山隆起、赛昆坳陷和马海隆起等三个一级构造单元，且基于变形强度和变形运动学特征，在一级构造单元的基础上划分出10个二级构造单元。研究区的构造变形具分带、分段和分层的特点，沿着南祁连山构造作用方向，可分为逆冲推覆构造带、逆冲断褶构造带和滑脱拆离构造带；垂直于构造作用方向，沿马仙断裂将分为东西两个构造段；纵向上，根据卷入地层变形样式的不同分为上、下两个构造形变层。并基于构造样式的分类原则并结合构造变形特征，将研究区构造样式分为山前基底逆冲、山前断层褶皱、下形变层基底逆冲、扭动构造和上形变层逆冲—褶皱组合和深浅层断裂组合等六类。2、NE—SW向和SE—NW向两条剖面共21个样品的磷灰石裂变径迹热年代学的研究表明，裂变径迹年龄大于地层年龄的样品揭示了母岩物源区存在多次构造热事件，其对应的时间分别为52～57 Ma、106～110 Ma、133.3～161.9 Ma和208.9Ma，其中208.9Ma的年龄值为阿尔金山隆升的体现，而其它三个年龄段直接体现了南祁连山的隆升。在裂变径迹年龄小于地层年龄的样晶中，样品的年龄集中于三个年龄段：12Ma、50～63 Ma和89～118Ma，反映了研究区的三次构造热事件。综合全部磷灰石裂变径迹热年代学数据可知，柴达木盆地北缘西段在中、新生代存在四期隆起事件，其时间为晚侏罗世—白垩纪、古新世、渐新世和中新世，而周缘造山带在晚三叠世还存在一期隆起。结合研究区构造变形特征可知，晚侏罗世—白垩纪主要为一种单纯的隆升作用，古新世和中新世的构造事件主体为隆升，断裂褶皱作用不明显，而渐新世以及O和C同位素所揭示的上新世—第四纪则是柴达木盆地北缘西段发生强烈断裂褶皱的两个时期。3、野外地质调查表明，柴达木北缘西段节理、断裂及裂缝中充填物具有方解石→石英→(石膏、沥青)的充填时序，其时间分别为晚侏罗世—白垩纪、古新世—渐新世、上新世，显示多期构造活动。研究区古近系与上侏罗统角度不整合、古近系与白垩系平行不整合和白垩系与侏罗系平行不整合接触，反映晚侏罗世—白垩纪存在差异隆升过程。岩石组构分析显示，侏罗纪和白垩纪时期构造运动处于相对较强烈时期，也是构造变形持续时间较长时期；白垩纪以后一直到始新世时期构造运动强度呈现减弱趋势，而渐新世时期构造运动又呈现有增强的趋势；中新世又呈现构造运动减弱趋势。4、通过古水流和重矿物综合研究，并结合磷灰石裂变径迹热年代学和盆地构造变形分析，认为柴达木盆地北缘西段为受阿尔金山和南祁连山非同步或非同性质造山运动共同作用的中、新生代盆地，其阿尔金山和南祁连山有着多个造山运动旋回。多旋回的造山运动促使了多期成盆作用，基于多期原型盆地在空间上的叠加、后期构造运动对早期盆地的改造作用，在此提出了多旋回叠加改造型盆地的概念，认为：①印支期受秦岭—祁连海槽的关闭和祁连山的逆冲挤压作用，原型盆地为前陆盆地；②早燕山期受地壳均衡垂向调整作用形成局部伸展环境，形成断陷与坳陷；③晚燕山期由于新特提斯洋的打开，形成挤压作用下的坳陷型盆地；④早喜马拉雅期，在印度板块与欧亚板块碰撞作用下，阿尔金山和南祁连山复活，共同作用形成走滑—前陆型盆地；⑤晚喜马拉雅期青藏高原再次隆升和扩展，走滑—前陆型盆地进一步发展。5、根据柴达木盆地北缘西段中、新生代盆山关系，将盆地构造演化分为三个构造旋回，四个亚构造旋回。印支构造旋回以逆冲推覆、隆升剥蚀为主要特征；早燕山亚旋回为拉张作用，造成局部小型断陷发育；晚燕山亚旋回以差异隆升为主要特征，同时还伴有弱的逆冲作用；早喜马拉雅亚旋回为逆冲推覆、断裂褶皱和扭动构造作用：晚喜马拉雅亚旋回的构造演化方式与早喜马拉雅亚旋回相似，但构造作用更为强烈。6、多旋回叠加改造型盆地油气成藏与构造演化相响应，构造演化对油气成藏起着建造和改造作用。综合柴达木盆地北缘西段中、新生代构造演化与油气成藏特征，认为燕山期和早喜马拉雅期构造演化对成藏起着建造作用，晚喜马拉雅期构造作用则为建造—改造作用。燕山期的建造作用表现为促进了生烃洼陷的发育、形成了有利于油气聚集的古隆起和油气侧向运移的不整合面输导通道；早喜马拉雅期的建造作用为加速了烃源岩的热演化和生排烃作用、形成构造圈闭和断裂输导体系；晚喜马拉雅期为建造与改造并存，改造作用方式为油藏抬升和断裂活动，针对侏罗系和古近系油气藏，使其具有多期成藏，晚期调整的成藏模式，建造作用对象为新近系油气藏，构造作用促进了构造圈闭和断裂输导体系的发育，具有断裂输导，晚期成藏的成藏特征。7、根据构造演化和典型油气藏的解剖，认为柴达木盆地北缘西段的油气成藏受控于为有效烃源岩的分布和有效的输导体系。受地壳垂向均衡调整所控制，研究区发育多个生烃洼陷，处于生烃洼陷周缘的构造将易于捕获油气，且各洼陷烃源岩的发育规模控制着周缘油气藏规模大小，而烃源岩的成熟度则制约着油气相态的分布。研究区绝大多数油气藏与烃源岩区都具有一定的空间距离，油气都是通过烃源岩中排出沿一定的输导体系经过一定距离的运移、聚集到圈闭中而成藏，由断裂、不整合面和砂岩输导层所组成的网络状输导运移体系，对油气起着垂向和侧向运移作用，而输导体系的输导能力直接关系到油气运聚成藏。8、在多旋回叠加改造型盆地中，构造演化控制着盆地油气分布，而这种控制作用具体体现在对生烃洼陷分布、烃源岩热演化过程、有效封闭体系规模、输导体系形成和构造圈闭发育等方面的制约上。综合构造演化特征，认为柴达木北缘西段中、新生代多旋回叠加改造型盆地的油气分布存在三方面规律：烃源岩的分布及成烃演化控制着油气藏的分布和相态；晚燕山期古隆起和早喜马拉雅期发育的构造是深层油气运移的有利指向；深、浅层断裂共同组成的有效输导体系控制着新近系油气成藏更多还原

【Abstract】 The basin is one of the basic structural units developed on the continental lithosphericsurface, which evolution is controlled by the earth geodynamic mechanism. Because of thetransformation of the earth’s heat and tectonic system, the plate, lies on the lithosphere surface, diverged and converge time after time, and happen multistage intracontinental subduction aftercollision, then, the lithospheric movement has the characteristic of multistage and multicycle. Forthe control of multicycle crustal movement, the basin evolution underwent complicated tectonicsystem transform and showed frequent cyclicity, and the developmental environment, sedimentation mechanism and fill mode frequently changed in the cause of evolution. The basin, which have abundant hydrocarbon resources in the West China, have many original basin phasesin Mesozoic-Cenozoic, but due to multiformity, complexity and delamination of the continentalstructure, the study about tectonized mechanism, evolution and dynamic course in the process oforiginal basin’s transform is beyond classical two-dimension plate tectonic theory, it need newtheory to support the research on the bases of three-dimension. Consequently, it not only hasimportant practicability to study the tectonic evolution to the multicycle superimposedreformation basin, and it is helpful to develop continental geodynarnics in the research of thetectonic system transform in the basin evolution.Qaidam basin lies in the northeast margin of Qinghai-Tibet Plateau, and located in theconjoint zone of Asian structural domain and Thetys-Himalayan one in the geotectonic situation, and surrounded by Altyn Mountain, Qilian Mountain and Kunlan Mountain, so its evolution hascomplicated geodynamic mechanism and reformation characteristic in Mesozoic-Cenozoic. Thewest of Northern Qaidam basin is the distributed area of Jurassic petroleum system, and hasabundant hydrocarbon resources. The basin formation processes correlates mainly with AltynMountain and Qilian Mountain in Mesozoic-Cenozoic. Because of multicycle orogenicmovement of periphery orogene, The west of Northern Qaidam basin has multiple phase basinformation and complicated tectonic evolution, and to lead the intricate tectonic reformation, control the distribution and evolvement of source rock, the form of source-reservoir-capcombination, the development and distribution of trap, hydrocarbon accumulation and reformation, and restrict the petroleum multiphase migration, accumulation, reformation andreconstruct, therefore, the distribution of oil and gas in the strata is very complicated. With thegeologic researches had been doing connected with oil exploratory, however, was restrained bythe target of the project, and there are so many cognitions need to unify and so many geologicproblems need to do further research, such as, basin formation dynamic mechanism, tectonicevolution, the distribution regularity of petroleum reservoir etc. In multicycle superimposedreformation basin, tectonic evolution is the ruling factor to control hydrocarbon accumulation, itdirectly restrict hydrocarbon generation, migration, accumulation, reconstruction andpreservation, so the research of hydrocarbon accumulation to the basin must make certain thetectonic evolution above all, and the understand to the distribution regularity of petroleumaccumulation must base on the study to structure. Aim at this main problem in the study ofhydrocarbon accumulation in the west of Northern Qaidam basin, bases on the theory of basinformation and petroleum accumulation, the paper carded the field geologic investigation, theexplanation of seismic profile, analysis of sediment provenance, ESR dating and fission trackthermchronoiogy analysis, analyzing the typical petroleum reservoir forming period and process.Throughout above analysis, this paper acquired some new achievements on basin structure, basinformation mechanism and evolution, the control about tectonic evolution to hydrocarbonaccumulation and the contribution regularity of petroleum reservoir.1、The west of Northern Qaidam basin could be divided three stair structural units:Saishiteng-Lvliangshan uplift, Kunsai depression and Mahal uplift, and according to deformationintensity and kinematics, ten secondary structural units are divided on the basis of stair ones. Thestudy area structure is characterized by segmentation along the strike, zonation in the dipdirection and structural layer vertically. Along the deformation direction of Southern QilianMountain, three structural zones are compartmentalized, from north toward south, thethrust-overthrust structural zone, the fault-fold structural zone and the decollement-detachmentstructural zone. The study are divided two structural segmentations fault from west from east byMaxian. According to the difference of structural deformation style, two tectonic deformationlayers can be sure vertically. On the basis of classify principle of structural style and thecharacteristic of tectonic evolution, there are five structural styles in the study area, such aspiedmont basement thrust, piedmont fault-fold, basement thrust of upper deformation layer, shearstructure and thrust-fold of lower deformation layer etc.2、Apatite fission track dating evidences from 21 samples, which distributed in two crosssections of NE-SW direction and SE-NW direction in the study area, shows that the sampleswhich fission track ages are older than their respective strata ages reflect the provenance ages ofthese apatite, the time of tectonothermal episodes is 52～57 Ma、106～110 Ma、133.3～161.9 Maand 205.9Ma. In the dating, the time of 208.9Ma shows the uplift of Altyn Mountain, other showthe uplift of Southern Qilian Mountain. The samples which fission track ages are younger thantheir respective strata ages shows that the maximum burial temperatures for these samplesexceeded the total annealing temperatures of the fission tracks, and reflect three tectonothermalepisodes which happened in 12Ma、50～63 Ma and 89～118Ma respectively. The dating show that there are four uplift phases which corresponding period is late Jurassic-Cretaceous,Paleocene, Oligocene and Miocene in the west of Northern Qaidam basin, but the peripheralorogen have also a uplift phase in later Triassic. Combined with the characteristic of structuralreformation, it is clear that the reformation mode is only uplift in late Jurassic- Cretaceous, upliftmainly and fault-folding weakly in Paleocene and Miocene, fault-folding consumingly inOligocene and Pliocene-Quaternary which is supported by the isotopes of O and C.3、The field investigation indicated that the filler in joint, fault and fracture has the fillsequence: calcite→, quartz→(gypsum, bitumen) in the west of Northern Qaidam basin, and themineral fill corresponding period is Late Jurassic-Cretaceous, Palaeocene-Oligocene andPliocene which indicates multiple phase tectonic movement. There are the angle disconformitybetween Eogene and Upper Jurassic, nonangular unconformity between Eogene and Cretaceous,and between Cretaceous and Jurassic in the study area, then, the formation relation reflect that thecharacteristic of tectonic evolution is differential uplift in Late Jurassic-Cretaceous. The analysisquartz c-axis fabricshow show Jurassic-Cretaceous is the tectonic violence activity period, andtectonic deformation endurance long-lasting period, Cretaceous-Eogene tectonic activitybecome reducible, and Oligocene violence activity again, Miocene reducible.4、Based on the comprehensive research of palaeocurrent and heavy mineral, and combineapatite fission track dating and basin tectonic deformation analysis, we consider the west ofNorthern Qaidam basin is a Mesozoic-Cenozoic basin which is controlled by the conjunctaction of Altyn Mountain and Qilian Mountain which underwent several multicycle orogeny.Multicyclic orogeny led to multiphase basin formation, consequently, based on multiphaseoriginal basin superimposition in space and later stage tectonic activity to early original basin,the concept of multicycle superimposed reformation basin is proposed, consider that:①becauseof the close of Qinling-Qilian ocean trough and the thrust of Qilian Mountain, the original basinis foreland basin in Indo-Chinese epoch;②Early Yanshan epoch, controlled by vertical balancedadjust of crust, the fault depression and depression form in local extendible environment;③Dueto the new Tethyan’s open in Late Yanshan epoch, the feeble compressional environment form,the original basin is depression;④Early Himalayan epoch, owing to the collision between Indiablock and Eurasia block, Altyn Mountain and Southern Qilian Mountain revive, Joint actionleads to strike slip-foreland basin formation.⑤Tibet highland epoch uplift and expand again,strike slip-foreland basin further forms in Late Himalayan.5、According to Mesozoic-Cenozoic basin-mountain system in the west of Northern Qaidambasin, the tectonic evolution could be divided into three cycle, four subcycle. Indosinian cycle ischaracterized by thrust-overthrusting and uplifting-erosion. Early Yanshanian subcycle representextension tectonics and develops miniature fault depression. Late Yanshanian subcycle ischaracterized by differential uplifting attend by mildly thrusting. Early Himalayan subcyclemainly take place thrust-overthrusting, fault-folding and strike-sliding. The tectonic evolutioncharacter of Late Himalayan subcycle is the same as Early Himalayan, but become stronger.6、In multicycle superimposed reformation basin, hydrocarbon accumulation responds totectonic evolution, the latter play the role of building and reconstructing for reservoirs. According to the analysis of tectonic evolution and hydrocarbon accumulation in the west of NorthernQaidam basin, The author consider that the tectonic evolution effect constructively on reservoirformation in Yanshan epoch and early Himalayan epoch, and acting as construct-reconstructingin late Himalayan epoch. The constructing of Yanshan epoch behaves as promoting the formationof hydrocarbon-generation sag, coming into being paleo-uplift which is propitious tohydrocarbon accumulating, and making for unconformity transporting pathway for petroleumlateral migration. The constructing of Himalayan represent as accelerating hydrothermalevolution of source rock and generation-expulsion of hydrocarbon, forming structural trap andfault transporting pathway. Construction and reconstruction take place synchronously in LateHimalayan. The reconstructing is characteristic of reservoir uplifting and faulting. As to Jurassicand Paleogene hydrocarbon accumulation, it shows that multi-stage formation and late-stageadjustment for hydrocarbon accumulation. The constructing act on Neogene hydrocarbonaccumulation figure as promoting the formation of structural trap and fault transportingpathway, and characterize by fault transporting and late-stage accumulation of hydrocarbon.7、Based on the evolution of tectonic and analysis of typical reservoirs, consider that thereservoirs are controlled by distribution of effective hydrocarbon source rock and effectivesystems of transmission in the west of Northren Qaidam basin. It is controlled by verticalbalanced adjust of crust, there are several hydrocarbon generating depressions in the region ofstudy, then, the trap may apt to capture hydrocarbon in margin of hydrocarbon generatingdepression, and the scale of hydrocarbon source rock controls the scale of surrounding reservoirs,at the same time, the maturity of hydrocarbon source rock control the distribution of phase ofhydrocarbon. In study area, there is always definite distance between reservoir and hydrocarbonsource region, so the petroleum blow off from hydrocarbon source rock, migrate through somesystems of transmission and accumulate in traps to form reservoirs. The net systems oftransmission which compose of faults, unconformity and transmission layer of sandstone play asignificant role to vertical and lateral migration of petroleum. The transmission capability ofsystems of transmission restrict the migration, accumulation, and forming reservoirs directly.8、In multicycle superimposed reformation basin, the tectonic evolution controls thedistribution of hydrocarbon, and the controlling is embodied as restraint to the distribution ofhydrocarbon generating depression, the thermal evolution of source rock, the scale of effectivesealed systems, the formation of transmission systems, and the development of structural traps.Combined tectonic evolution, consider that the distribution of hydrocarbon has three regularpattern in the west of Northern Qaidam basin: the distribution of source rock and the hydrocarbongenerating evolution control the distribution and phase of reservoirs, palaeohigh of later Yanshanperiod and the structure which developed in Himalayan period are the region to which deeppetroleum apt to migrate, the effective systems of transmission which compose of deep andshallow faults control the formation of reservoirs in Neogene.更多还原