FROM BACK-ARC BASIN TO BACK-ARC FORELAND BASIN—THE SEDIMENTARY BASIN AND TECTONIC EVOLUTION OF THE LATE CALEDONIAN—EARLY HERCYNIAN STAGES IN CORRIDOR AND NORTH QILIAN MTS

Qilian orogenic belt is a typical orogenic belt formed by polycyclic collisions between the North China plate and Qaidam microplate. Qilian ocean originated from the rift of the late Proterozoic Rodinia continent(Pangea\|850), evolved through rift basin and became an archipelagic ocean in the Caledonian stage. The Lower Proterozoic strata in Qilian area are mid\|high\|rank metamorphic rocks that constitute the metamorphic basement of the area. The “Huangyuan Movement" (in South Qilian and Central Qilian) and "Alashan Movement" (in North Qilian) in the latest Late Proterozoic formed a regional unconformity. The middle Proterozoic in the area are mudstones and carbonate rocks with stromatolites and ooids. The Qingbaikou System of the upper Proterozoic in the North Qilian and Corridor region is also mudstone and carbonate rock with stromatolites. The Qingbaikou System in Central Qilian is sandstones and mudstones. There are alkaline and tholeiite in the Sinian System in North Qilian and Corridor. The contact between Qingbaikou System and Sinian System is a regional unconformity (Quanji Movement). Qilian ocean began to rift away in Caledonian tectonic stage on the Pre\|Sinian basement.

STUDY ON SEDIMENTARY-TECTONIC EVOLUTION IN THE NORTH QAIDAM BASIN,QINGHAI PROVINCE

Jurassic deposition was extensively developed in the northern Qaidam basin.According to sequence stratigraphical analysis of outcrops,the Jurassic profile in the Dameigou area can be divided into 6 sequences.Sequences 1 and 4 consist of lowstand,water transgression and highstand systems tracts,and sequences 2,3 and 5 consist of lowstand and transgression systems tracts.However,sequence 6 only consists of a lowstand systems tract.The development of depositional sequences is controlled by lake level changes and basement faulting,which continued to be active in the Jurassic. The result of sedimentary－ tectonic evolution research indicates that the Qaidam Basin is a fault subsidence.This kind of basin framework determined that the coal－ forming environment would occur on the north side of the northern boundary fault of the Qaidam Basin and on the south side of the Lingjian fault, and the source rock would develop in the central subsidence belt between the two faults.

Tectonic evolution and source rocks development of the super oil-rich Bohai Bay Basin,East China

The Bohai Bay Basin,as a super oil-rich basin in the world,is characterized by cyclic evolution and complex regional tectonic stress field,and its lifecycle tectonic evolution controls the formation of regional source rocks.The main pre-Cenozoic stratigraphic system and lithological distribution are determined through geological mapping,and the dynamics of the pre-Cenozoic geotectonic evolution of the Bohai Bay Basin are investigated systematically using the newly acquired high-quality seismic data and the latest exploration results in the study area.The North China Craton where the Bohai Bay Basin is located in rests at the intersection of three tectonic domains:the Paleo-Asian Ocean,the Tethys Ocean,and the Pacific Ocean.It has experienced the alternation and superposition of tectonic cycles of different periods,directions and natures,and experienced five stages of the tectonic evolution and sedimentary building,i.e.Middle–Late Proterozoic continental rift trough,Early Paleozoic marginal-craton depression carbonate building,Late Paleozoic marine–continental transitional intracraton depression,Mesozoic intracontinental strike-slip–extensional tectonics,and Cenozoic intracontinental rifting.The cyclic evolution of the basin,especially the multi-stage compression,strike-slip and extensional tectonics processes in the Hercynian,Indosinian,Yanshan and Himalayan since the Late Paleozoic,controlled the development,reconstruction and preservation of several sets of high-quality source rocks,represented by the Late Paleozoic Carboniferous–Permian coal-measure source rocks and the Paleogene world-class extra-high-quality lacustrine source rocks,which provided an important guarantee for the hydrocarbon accumulation in the super oil-rich basin.

TECTONIC EVOLUTION OF THE EOCENE DROSH-VOLCANO-SEDIMENTARY BASIN IN NW-KOHISTAN ISLAND ARC TERRANE, HINDUKUSH, N. PAKISTAN

In NW Himalayas, the suture zone between the collided Indian and the Karakoram plates is occupied by crust of the Cretaceous Kohistan Island\|Arc Terrane [1] . Late Cretaceous (about 90Ma) accretion with the southern margin of the Karakoram Plate at the site of the Shyok Suture Zone turned Kohistan to become an Andean\|type margin. The Neotethys was completely subducted at the southern margin of Kohistan by Early Tertiary, leading to collision between Kohistan and continental crust of the Indian plate at the site of the Main mantle thrust.More than 80% of the Kohistan terrane comprises plutonic rocks of (1) ultramafic to gabbroic composition forming the basal crust of the intra\|oceanic stage of the island arc, and (2) tonalite\|granodiorite\|granite composition belong to the Kohistan Batholith occupying much of the intermediate to shallow crust of the terrane mostly intruded in the Andean\|type margin stage [2] . Both these stages of subduction\|related magmatism were associated with volcanic and sedimentary rocks formed in Late Cretaceous and Early Tertiary basins. This study addresses tectonic configuration of Early Tertiary Drosh basin exposed in NW parts of the Kohistan terrane, immediately to the south of the Shyok Suture Zone.

CENOZOIC TECTONIC EVOLUTION AND GEODYNAMICS OF KEKEXILI BASIN IN NORTHERN QINGHAI—XIZANG PLATEAU

Kekexili basin, located in Northern Qinghai—Xizang plateau, has an area of over 4000km\+2 and is the largest Paleogene land facies basin in the plateau. With NWW\|SEE trend, Kekexili basin extends along the north side of the Jinshajiang suture. Its sediments, Fenghuoshan group, formed in E 1—E 3, show a shape of wedge with big thickness in south and small thickness in north. There are four sedimentary facies; fan\|delta and alluvial facies that occur in south, lake and lake\|delta facies, which do in north, in this basin. The north\|dipping Jinshajiang normal faults on the south margin of the basin have controlled the developments of the basin. The S—N compression at the end of E3 strongly folded the basin strata and transformed Jinshajiang normal faults into thrusts. In N1, widespread denudation occurred in the whole plateau. During N 2—Q, Kekexili area uplifted along with the whole plateau, besides, the thrusts in the basin showed coherent activity. We propose a geodynamical model for explaining the basin development. In early E,India plate, due to its colliding Eurasia plate, stopped its ocean crust subduction northward, then the subducted ocean lithosphere breaking away made the south margin area, most possibly to the south of Jinshajiang suture, of Eurasia plate isostatically uplift, so the north\|dipping Jinshajiang suture acted as normal faults and controled the north basin development. In late E, the isostatic uplift finished, the basin also gradually terminated its development .At the end of E, Jinshajiang normal faults became thrusts and the basin strata were folded under the northward compression of India plate. In the N1, India plate started incontinental subduction, the lower crust and lower mantle lithosphere of Qinghai—Xizang area underwent more intensive compression and deformation than its upper crust, and the induced transversal expansion in the lower lithosphere uplifted the upper crust and decreased its horizontal stress, which conduced the upper crust undergo denudation. During N 2—Q, convective removal of the lower mantle lithosphere of Qinghai\|Xizang area led to rapid uplift of this area.

Earthquake-related Tectonic Deformation of Soft-sediments and Its Constraints on Basin Tectonic Evolution

The authors introduced two kinds of newly found soft-sediment deformation-synsedimentary extension structure and syn-sedimentary compression structure, and discuss their origins and constraints on basin tectonic evolution. One representative of the syn-sedimentary extension structure is syn-sedimentary boudinage structure, while the typical example of the syn-sedimentary compression structure is compression sand pillows or compression wrinkles. The former shows NW-SE-trendlng contemporaneous extension events related to earthquakes in the rift basin near a famous Fe-Nb-REE deposit in northern China during the Early Paleozoic （or Mesoproterozoic as proposed by some researches）, while the latter indicates NE-SW-trending contemporaneous compression activities related to earthquakes in the Middle Triassic in the Nanpanjiang remnant basin covering south Guizhou, northwestern Guangxi and eastern Yunnan in southwestern China. The syn-sedimentary boudinage structure was found in an earthquake slump block in the lower part of the Early Paleozoic Sailinhudong Group, 20 km to the southeast of Bayan Obo, Inner Mongolia, north of China. The slump block is composed of two kinds of very thin layers-pale-gray micrite （microcrystalline limestone） of 1-2 cm thick interbedded with gray muddy micrite layers with the similar thickness. Almost every thin muddy micrite layer was cut into imbricate blocks or boudins by abundant tiny contemporaneous faults, while the interbedded micrite remain in continuity. Boudins form as a response to layer-parallel extension （and/or layer-perpendicular flattening） of stiff layers enveloped top and bottom by mechanically soft layers. In this case, the imbricate blocks cut by the tiny contemporaneous faults are the result of abrupt horizontal extension of the crust in the SE-NW direction accompanied with earthquakes. Thus, the rock block is, in fact, a kind of seismites. The syn-sedimentary boudins indicate that there was at least a strong earthquake belt on the southeast side of the basin during the early stage of the Sailinhudong Group. This may be a good constraint on the tectonic evolution of the Bayan Obo area during the Early Paleozoic time. The syn-sedimentary compression structure was found in the Middle Triassic flysch in the Nanpanjiang Basin. The typical structures are compression sand pillows and compression wrinkles. Both of them were found on the bottoms of sand units and the top surface of the underlying mud units. In other words, the structures were found only in the interfaces between the graded sand layer and the underlying mud layer of the flysch. A deformation experiment with dough was conducted, showing that the tectonic deformation must have been instantaneous one accompanied by earthquakes. The compression sand pillows or wrinkles showed uniform directions along the bottoms of the sand layer in the flysch, revealing contemporaneous horizontal compression during the time between deposition and diagenesis of the related beds. The Nanpanjiang Basin was affected, in general, with SSW-NNE compression during the Middle Triassic, according to the syn-sedimentary compression structure. The two kinds of syn-sedimentary tectonic deformation also indicate that the related basins belong to a rift basin and a remnant basin, respectively, in the model of Wilson Cycle.

Extensional structures of the Nan'an Basin in the rifting tip of the South China Sea: Implication for tectonic evolution of the southwestern continental margin

Nan'an Basin is a giant hydrocarbon basin,but its tectonic division scheme and associated fault systems has not been well understood.Based on newly acquired seismic data from the southwestern margin of the South China Sea,this study analyzed the structural units,tectonic feature and geodynamics of the sedimentary basin.The new data suggests that the Nan0 an Basin is a rift basin oriented in the NE-SW direction,rather than a pull-apart basin induced by strike-slip faults along the western margin.The basin is a continuation of the rifts in the southwest South China Sea since the late Cretaceous.It continued rifting until the middle Miocene,even though oceanic crust occurred in the Southwest Subbasin.However,it had no transfer surface at the end of spreading,where it was characterized by a late middle Miocene unconformity(reflector T3).The Nan'an Basin can be divided into eight structural units by a series of NE-striking faults.This study provides evidences to confirm the relative importance and interplay between regional strike-slips and orthogonal displacement during basin development and deformation.The NE-SW-striking dominant rift basin indicates that the geodynamic drivers of tectonic evolution in the western margin of the South China Sea did not have a large strike-slip mechanism.Therefore,we conclude that a large strike-slip fault system did not exist in the western margin of the South China Sea.

Sedimentary elements,evolutions and controlling factors of the Miocene channel system:a case study of the deep-water Taranaki Basin in New Zealand

Deep-water channel systems are important petroleum reservoirs,and many have been discovered worldwide.Understanding deep-water channel sedimentary elements and evolution is helpful for deep-sea petroleum exploration and development.Based on high-resolution 3D seismic data,the Miocene channel system in the deep-water Taranaki Basin,New Zealand,was analyzed by using seismic interpretation techniques such as interlayer attribute extraction and strata slicing.The channel system was divided into five composite channels(CC-I to CC-V)according to four secondary level channel boundaries,and sedimentary elements such as channels,slump deposits,inner levees,mass transport deposits,and hemipelagic drape deposits were identified in the channel system.The morphological characteristics of several composite channels exhibited stark variances,and the overall morphology of the composite channels changed from relatively straight to highly sinuous to relatively straight.The evolution of the composite channels involved a gradual and repeated process of erosion and filling,and the composite channels could be divided into three evolutionary stages:initial erosion-filling,later erosion-filling(multistage),and channel abandonment.The middle Miocene channel system may have formed as a consequence of combined regional tectonic activity and global climatic change,and its intricate morphological alterations may have been influenced by the channel's ability to self-regulate and gravity flow properties.When studying the sedimentary evolution of a large-scale deep-water channel system in the Taranaki Basin during the Oligocene-Miocene,which transitioned from a passive margin to plate convergence,it can be understood how tectonic activity affected the channel and can also provide a theoretical reference for the evolution of the deepwater channels in areas with similar tectonic conversion environments around the world.

Sedimentary characteristics and processes of the Paleogene Dainan Formation in the Gaoyou Depression, North Jiangsu Basin, eastern China

In this paper,the type,vertical evolution,and distribution pattern of sedimentary facies of the Paleogene Dainan Formation in the Gaoyou Depression of the North Jiangsu Basin are studied in detail.Results show that fan delta,delta,nearshore subaqueous fan,and lacustrine facies developed during the Dainan Formation period and their distribution pattern was mainly controlled by tectonics and paleogeography.The fan delta and nearshore subaqueous fan facies predominantly occur in the southern steep slope region where fault-induced subsidence is thought to have created substantial accommodation,whereas the delta facies are distributed on the northern gentle slope which is thought to have experienced less subsidence.Finally,the lacustrine facies is shown to have developed in the center of the depression,as well as on the flanks of the fan delta,delta,and nearshore subaqueous fan facies.Vertically,the Dainan Formation represents an integrated transgressiveregressive cycle,with the E2d1being the transgressive sequence and the E2d2being the regressive sequence.This distribution model of sedimentary facies plays an important role in predicting favorable reservoir belts for the Dainan Formation in the Gaoyou Depression and similar areas.In the Gaoyou Depression,sandstones of the subaqueous distributary channels in the fan delta and the subaqueous branch channels in the delta are characterized by physical properties favorable for reservoir formation.

Sedimentary fill history of the Huicheng Basin in the West Qinling Mountains and associated constraints on Mesozoic intracontinental tectonic evolution

The Qinling Orogenic Belt is divided commonly by the Fengxian-Taibai strike-slip shear zone and the Huicheng Basin into the East and West Qinling mountains, which show significant geological differences after the Indosinian orogeny. The Fengxian-Taibai fault zone and the Meso-Cenozoic Huicheng Basin, situated at the boundary of the East and West Qinling, provide a natural laboratory for tectonic analysis and sedimentological study of intracontinental tectonic evolution of the Qin- ling Orogenic Belt. In order to explain the dynamic development of the Huicheng Basin and elucidate its post-orogenic tecton- ic evolution at the junction of the East and West Qinling, we studied the geometry and kinematics of fault zones between the blocks of West Qinling, as well as the sedimentary fill history of the Huicheng Basin. First, we found that after the collisional orogeny in the Late Triassic, post-orogenic extensional collapse occurred in the Early and Middle Jurassic within the Qinling Orogenic Belt, resulting in a series of rift basins. Second, in the Late Jurassic and Early Cretaceous, a NE-SW compressive stress field caused large-scale sinistral strike-slip faults in the Qinling Orogenic Belt, causing intracontinental escape tectonics at the junction of the East and West Qinling, including eastward finite escape of the East Qinling micro-plate and southwest lateral escape of the Bikou Terrane. Meanwhile, the strike-slip-related Early Cretaceous sedimentary basin was formed with a fight-order echelon arrangement in sinistral shear zones along the southern margin of the Huicheng fault. Overall during the Mesozoic, the Huicheng Basin and surrounding areas experienced four tectonic evolutionary stages, including extensional rift basin development in the Early and Middle Jurassic, intense compressive uplift in the Late Jurassic, formation of a strike-slip extensional basin in the Early Cretaceous, and compressive uplift in the Late Cretaceous.

A seismic model for crustal structure in North China Craton

We present a digital crustal model in North China Craton(NCC). The construction of crustal model is based on digitization of original seismic sounding profiles, and new results of three-dimensional structure images of receiver functions. The crustal model includes seismic velocity and thickness of crustal layers. The depths to Moho indicate a thinning crust ~30 km in the east areas and a general westward deepening to more than 40 km in the west. The P wave velocity varies from 2.0 to 5.6 km/s in the sedimentary cover,from 5.8 to 6.4 km/s in the upper crust, and from 6.5 to 7.0 km/s in the lower crust. By analyzing regional trends in crustal structure and links to tectonic evolution illustrated by typical profiles, we conclude that:(1) The delimited area by the shallowing Moho in the eastern NCC represents the spatial range of the craton destruction. The present structure of the eastern NCC crust retains the tectonic information about craton destruction by extension and magmatism;(2) The tectonic activities of the craton destruction have modified the crustal structure of the convergence boundaries at the northern and southern margin of the NCC;(3) The Ordos terrene may represent a relatively stable tectonic feature in the NCC, but with the tectonic remnant of the continental collision during the assembly of the NCC in the north-east area and the response to the lateral expansion of the Tibetan Plateau during the Cenozoic in the south-west.

滨里海盆地东缘北特鲁瓦油田石炭系层序地层与沉积演化特征

根据三维地震、测井及钻井取心等资料,结合Vail的层序划分方案,在滨里海盆地东缘北特鲁瓦油田石炭系碳酸盐岩台地内识别出7个地震层序界面及7个钻井层序界面,并将KT-Ⅰ油层组划分为3个半三级层序,KT-Ⅱ油层组划分为3个三级层序。纵向上层序格架内沉积环境由开阔台地、局限台地至蒸发台地演化。根据研究区层序格架内的古地貌恢复及沉积演化研究,将研究区古地貌—沉积演化划分为3个阶段:台地初始隆坳分异期(SQ2-SQ3层序)、差异抬升与沉积分异定型期(SQ4层序)及继承发育期(SQ5-SQ7层序)。进一步分析认为,层序格架控制下的隆坳格局分异控制了白云岩亚类在平面上的分布,低部位以泥晶云岩—膏盐岩组合和泥晶云岩—泥晶灰岩组合为主,主要为潟湖相沉积;而高部位则以泥粉晶云岩、细粉晶云岩和残余颗粒泥晶云岩为主,发育云坪相及云化颗粒滩相沉积。结果表明,区内KT-Ⅰ油层组沉积期并非前人认为的西高东低剥蚀后沉降充填,而是继承性差异沉降的结果,古地理格局总体具有“东台西槽、北高南低”特征,其始终控制着有利相带和优质储集层的发育展布。这一认识对滨里海地区油气勘探开发战略选区具有重要的指导作用。

北非地区构造演化与含油气盆地形成

北非地区古生代位于冈瓦纳大陆北缘,经历古生代冈瓦纳和中新生代特提斯2大裂谷—拗陷—前陆盆地演化旋回,是世界范围内重要的油气富集区之一。基于公开地质资料和油气勘探数据的综合分析,指出北非地区含油气盆地存在克拉通叠加拗陷、裂谷和被动陆缘3种盆地类型,盆地演化经历冈瓦纳期和特提斯期2大成盆旋回,明确了区域构造演化对含油气盆地类型、盆地结构和生储盖发育规律的控制作用。受全球板块构造演化影响,北非地区经历了5期构造演化阶段:(1)晚元古代—早寒武世基底拼合和裂谷发育阶段;(2)寒武纪—早石炭世克拉通内拗陷发育阶段;(3)晚石炭世—早二叠世海西造山阶段;(4)晚二叠世—早白垩世裂谷盆地发育阶段;(5)晚白垩世—现今阿尔卑斯造山阶段。以海西造山作用为标志,形成古生代冈瓦纳期成盆旋回和中新生代特提斯期成盆旋回。北非西部盆地演化以古生代冈瓦纳期旋回占主导,在霍加尔地盾周边形成克拉通拗陷叠加盆地;东部盆地演化以中新生代特提斯旋回占主导,形成中新生代裂谷盆地和被动陆缘盆地。受盆地发育特征控制,西部克拉通拗陷叠加盆地烃源岩以志留系、泥盆系泥岩为主,储集层包括古生界和三叠系,区域盖层为志留系页岩和上三叠统—下侏罗统蒸发岩;东部裂谷盆地烃源岩以白垩系、古近系、新近系为主,储集层包括裂谷前古生界和裂谷期中生界、新生界,区域盖层为中新生代裂谷晚期蒸发岩。总的来看,北非地区差异构造演化控制了其含油气盆地形成机制差异和源储盖发育规律。

The Cenozoic sedimentary environment and sedimentary filling evolution of Wan'an Basin in the western South China Sea

As one of the basins with extremely abundant oil and gas resources in South China Sea,the Wan'an Basin has attracted great attention from domestic and international geologists and hydrocarbon explorers.Currently,the sequence stratigraphic framework,distribution of sedimentary systems and sedimentary filling evolution of the Wan'an Basin are still not clear,consequently,it bring some difficulties for hydrocarbon exploration.Based on the palaeobios,well drilling,well logging,and seismic and other data,the sequence stratigraphic framework of the Wan'an Basin is established,and the sequence interfaces of T100,T60,T50,T40 and T30 in this study are identified.On this basis,the sedimentary environment and sedimentary filling evolution of the Wan'an Basin are systematically analyzed.The results show that the basin had experienced three tectonic evolution periods since Cenozoic,i.e.,the OligoceneeEarly Miocene extensional fault-depression period,Middle Miocene strike-slip reformation period and Late Miocene eQuaternary regional depression period.Thereinto,the provenance in the extensional faultdepression period(OligoceneeEarly Miocene)was mainly from the western uplift of the basin,where the deltaeshore-shallow lacustrineebathylimnetic sedimentary system during Early Oligocene and delta elittoral-neritic sedimentary system during Late OligoceneeEarly Miocene were developed respectively.The provenance during the strike-slip reformation period(Middle Miocene)was still mainly from the western uplift of the basin,where the deltaelittoral-neriticecarbonate platform sedimentary system was developed,and the carbonate platform began to develop abundantly.The provenance during the regional depression period(Late MioceneeQuaternary)is mainly supplied by input of the western distal large rivers,the deltaelittoral-shallow seaecarbonate platformebathyal sea sedimentary system was developed in the Late Miocene,and the shelf-margin deltaecontinental slopeebathyal sea sedimentary system was developed during Pliocene-Quaternary.Therefore,the Wan'an Basin has a favorable hydrocarbon resource potential.

塔里木盆地雅克拉断凸周缘阳霞组沉积相

塔里木盆地北部雅克拉断凸周缘侏罗系是重要的油气勘探层位,主要发育断凸为物源的近源冲积扇-扇三角洲沉积体系,但该模式难以解释雅克拉断凸南部侏罗系大规模砂体发育的原因。在雅克拉断凸构造演化分析的基础上,利用地震、岩心、储集层等资料,开展沉积相特征的综合分析,确定雅克拉断凸周缘侏罗系阳霞组沉积相空间分布规律。雅克拉断凸在侏罗系沉积期整体具有西高东低的特征,西部受剥蚀,东部在阳霞组沉积晚期为准平原化状态,其沉积体系主要包括2部分:一部分为雅克拉断凸西部物源,形成大量沿断凸呈裙边分布的近源扇三角洲沉积体系;另一部分为南天山物源,在雅克拉断凸东部形成了自北向南延伸的浅水辫状河三角洲沉积体系。从储集层特征上看,扇三角洲沉积体系岩性较粗,主要为砾岩和含砾中—粗砂岩,结构成熟度和成分成熟度低,物性差;辫状河三角洲沉积体系岩性主要为含砾中—细砂岩,搬运距离长,结构成熟度和成分成熟度较高,物性较好。阳霞凹陷东部地区阳霞组可能成为有利的勘探目标区。

渤海湾超级油盆构造演化及其烃源岩发育

综合运用渤海湾盆地新采集的高品质地震剖面以及最新的勘探成果资料,通过对各主要层系的地层分布、构造和古地理格局的分析,系统开展渤海湾盆地大地构造演化的动力学研究。结果表明,渤海湾盆地所处的华北克拉通位于古亚洲洋、特提斯洋和太平洋等3大构造体系域的交接地带,经历了不同期次、不同方向、不同性质构造旋回的交替叠加,主要经历5期盆地构造演化与沉积建造阶段,即中新元古代大陆裂陷槽、早古生代克拉通边缘坳陷碳酸盐岩建造、晚古生代海陆过渡相克拉通内坳陷、中生代陆内走滑-伸展构造和新生代陆内裂陷阶段。盆地的多旋回演化,特别是晚古生代以来所经历的海西、印支、燕山和喜马拉雅等多期挤压、走滑和伸展构造活动,控制了多套优质烃源岩发育、改造和保存,尤以上古生界石炭系—二叠系煤系烃源岩以及古近系世界级特优质湖相烃源岩最为重要,为超级富油气盆地的成藏提供了重要的烃源保障。

松辽盆地北部青山口组富烃页岩形成环境与成因

通过古地温、古地貌、沉积环境定量恢复及地质事件综合研究,分析青山口组富烃页岩形成环境及成因。结果表明,松辽盆地青山口组富烃页岩R_(o)介于0.75%~1.60%,游离烃含量高,介于(4~12)mg/g,形成于古地温梯度(50~70)℃/km的高温热盆背景;在拉伸大地动力学及热沉降背景下形成了正断层密集断裂带控制的页岩层系,两凹一凸的古地貌为页岩形成演化提供富集场所;湖相温湿气候及岩浆热液为藻类繁殖成为厚层富烃页岩发育奠定物质基础;缺氧的半深湖—深湖还原—强还原环境有利于有机质埋藏。综合分析表明,构造、湖相沉积与古地温耦合作用奠定了富烃页岩的构造背景和热动力条件,温湿气候、缺氧环境及火山热液带来的营养物质是富烃页岩形成的重要原因。

渤海湾盆地辽中凹陷北部东营组沉积体系发育演化与构造古地貌的控制作用

根据地震和钻、测井资料,识别渤海湾盆地东北部辽中凹陷北部东营组中下段地震相和岩相组合类型,揭示沉积体系的发育演化规律;拉平古水平面,恢复东营组沉积时期构造古地貌,探讨构造古地貌对沉积体系发育演化的控制作用。结果表明:辽中凹陷北部东营组中下段可识别6种地震相与9种岩相组合类型,发育辫状河三角洲、曲流河三角洲、湖底扇以及碎屑湖泊等沉积,北部由辫状河三角洲演变为双向供源的曲流河三角洲-湖底扇,中南部早期发育小型辫状河三角洲并逐渐消亡,南部小型辫状河三角洲逐渐向北推进;东营组中下段沉积期研究区整体南高北低,可划分辽东凸起和辽中凹陷2个隆坳单元,进一步识别断裂陡坡带、缓坡断阶带、缓坡带、古沟谷等构造古地貌单元;研究区发育的沉积体系类型及规模与古坡折坡度、凹陷沉降中心位置、古沟谷规模密切相关,沉积体系的分布演化是盆地隆坳格局、坡折地貌形态、古沟谷发育位置与物源供给方向共同作用的结果。该结果对研究区油气勘探有利砂体预测具有指导意义。

粤东河源盆地的深部构造、沉积序列与盆地演化

粤东河源盆地是东南沿海规模较大的晚中生代—新生代陆相盆地之一,发育有较为完整的晚白垩世—新近纪地层。研究该盆地的深部构造、控盆断裂、沉积序列和盆地的形成发展,对于认识东南沿海晚中生代—新近纪的大地构造演化有重要意义。通过对野外地质调查、地球物理反射剖面和约两千米的地质科学钻探等数据资料的综合研究,查明了河源盆地为中生代—新生代沉积断陷盆地,地层结构清晰,沉积基底为早古生代地层,并建立了该盆地晚白垩世—新近纪的三阶段沉积序列;该盆地发育渐新世的火山岩,揭示了控盆边界断裂及内部构造发育特征,暗示了原型盆地的破坏发生于晚新生代:即盆地南北两侧紫金—博罗逆冲断层和河源断裂带在晚古近纪—新近纪强烈地改造了原型盆地;基于以上认识,初步恢复了河源盆地的形成演化历史,构建了河源盆地沉积序列-构造演化模式。

鄂尔多斯盆地奥陶系马家沟组一段—三段构造沉积演化及其油气地质意义

基于测井、岩心、薄片、地球化学分析,重建鄂尔多斯盆地奥陶系马家沟组一段—三段(简称马一段—马三段)构造-岩相古地理格局,探讨构造沉积演变特征及其油气地质意义。研究表明:①马家沟组底部稳定发育一套穿时的、高自然伽马值段、边缘相泥质白云岩,分布于怀远运动期构造不整合面之上,具有与早奥陶世弗洛期全球海侵可对比的δ13C正漂移特征;②奥陶系马一段—马二段沉积期全球海平面上升、古陆淹没为水下隆起,形成一隆两坳构造格局,中央隆起首次接受沉积;随后马三段沉积期盆外俯冲挤压、盆内隆坳分异,乌审旗—靖边凸起活化;③构造格局演变对沉积古环境产生显著影响,马一段沉积期向西超覆,东部坳陷内海侵封隔形成大规模盐质蒸发潟湖;马二段沉积期持续海侵并沟通广海,环东部坳陷发育大规模颗粒滩,晚期干化收缩形成小规模蒸发潟湖;马三段沉积期受高地封隔影响,向东侧水体渐次分异分别形成云膏质和盐质蒸发潟湖,同时颗粒滩环凹沿高地展布;④马家沟组底部发育烃源岩,马二段和马三段滩相储层环坡展布,源储配置良好,有利于天然气成藏,具有一定勘探潜力。