塔东南坳陷侏罗系层序地层分析与油气前景

塔东南盆地发育侏罗系陆相煤系地层和白垩系红层,勘探程度低。为研究中生代地层的分布和对比,沉积特征及勘探方向,重点对侏罗系进行了露头层序地层学分析。建立了五个三级层序。层序1以正旋回的冲积扇或辫状河相为主,储集条件良好,层序2发育正旋回及反旋回的三角洲相,具有良好储集条件,上部有较好的生油岩,层序3为反旋回的三角洲相及湖相韵律层,是良好生油层和盖层,层序4为正旋回的河流相,层序5为正旋回的干旱气候下冲积扇相,可形成次生溶孔发育的良好储层。塔东南侏罗系分布广泛,有良好的油气前景,是重要的含油气层系。     

Geology and tectonic development of the continental margin north of Alaska

The continental margin north of Alaska, as interpreted from seismic reflection profiles, is of the Atlantic type and consists of three sectors of contrasting structure and stratigraphy. The Chukchi sector, on the west, is characterized by the deep late Mesozoic and Tertiary North Chukchi basin and the Chukchi Continental Borderland. The Barrow sector of central northern Alaska is characterized by the Barrow arch and a moderately thick continental terrace build of Albian to Tertiary clastic sediment. The terrace sedimentary prism is underlain by lower Paleozoic metasedimentary rocks. The Barter Island sector of northeastern Alaska and Yukon Territory is inferred to contain a very thick prism of Jurassic, Cretaceous and Tertiary marine and nonmarine clastic sediment. Its structure is dominated by a local deep Tertiary depocenter and two regional structural arches.We postulate that the distinguishing characteristics of the three sectors are inherited from the configuration of the rift that separated arctic Alaska from the Canadian Arctic Archipelago relative to old pre-rift highlands, which were clastic sediment sources. Where the rift lay relatively close to northern Alaska, in the Chukchi and Barter Island sectors, and locally separated Alaska from the old source terranes, thick late Mesozoic and Tertiary sedimentary prisms extend farther south beneath the continental shelf than in the intervening Barrow sector. The boundary between the Chukchi and Barrow sectors is relatively well defined by geophysical data, but the boundary between the Barrow and Barter Island sectors can only be inferred from the distribution and thickness of Jurassic and Cretaceous sedimentary rocks. These boundaries may be extensions of oceanic fracture zones related to the rifting that is postulated to have opened the Canada Basin, probably beginning during the Early Jurassic.     

右江盆地深水沉积层序地层学研究

以右江地区泥盆-三叠纪深水盆地相地层为研究对象,①详细讨论了深水浊流沉积的层序划分及特征,结果表明浊流沉积的层序界面特征明显,主要表现为界面不规则,LST期砂岩底面具大量侵蚀充填构造及塑性流动变形构造等,层序的体系域构成与浊积扇演化关系密切,即从低水位体系域→海侵体系域→高水位体系域的演化浊积扇经历了进积→退积→加积→进积演化过程;②详细讨论了深水硅泥质沉积的层序划分及特征,即可根据硅质岩、泥质岩 (包括粉砂岩 )相对含量变化及成因特征来识别层序及体系域组成特征。     

The geodynamic evolution of the South-Tethyan,margin in Zanskar,NW-Himalaya,as revealed by the Spongtang ophiolitic melanges

Abstract

— The composite nappe of the Spongtang ophiolite is thrust over Mesozoic and Cenozoic sediments of the North-Indian margin and shelf. The ophiolitic peridotiles tectonic-ally overlie a sedimentary melange, the detailed stratigraphy of which reveals the evolution of the South-Tethyan margin from its opening to its closure. The matrix of the melange is dated as Upper Campanian to Lower Eocene. Volcano-sedimentary olistoliths indicate carbonate platform sedimentation associated with alkaline lavas in the Permian, followed by more pelagic sedimentation of Upper Triassic and mid- Cretaceous age. They derived from external platforms near to the Indian shelf, but separated from it. Composite olistoliths of mid to late Cretaceous age, containing Permian elements, are found in the upper Cretaceous to lower Eocene wildflysch. Primary contacts of melange upon serpentinites indicates that the deeply eroded oceanic crust served partly as a substratum for the melange.     

盆山转换与沉积地质记录——以楚雄前陆盆地分析为例

楚雄盆地位于扬子陆块的西南边缘,为一中生代周缘型前陆盆地。根据沉积相特征、层序地层结构和古地理演化的详细研究,结合古哀牢山造山带的构造演化,笔者认为楚雄盆地经历了从古生代被动大陆边缘沉积到中生代前陆盆地沉积的演化。前陆盆地演化的阶段性明显：晚三叠世卡尼期（云南驿组沉积期）和诺利早、中期（罗家大山组沉积期）为前陆复理石沉积;诺利晚期（花果山组沉积期）－古新世（赵家店组沉积期）为前陆磨拉石沉积。磨拉石     

Transects of the ancient and modern continental margins of eastern Canada

Rocks of the west flank of the northern Appalachian Orogen (miogeocline) record the history of the late Precambrian-early Paleozoic passive continental margin of Eastern North America. The ancient margin was destroyed by ophiolite obduction and arc collision during the Ordovician Taconic Orogeny. The present sinuous form of the miogeocline is interpreted to reflect ancient promontories and re-entrants of a previous orthogonal margin bounded by rifts and transforms.Four major terranes are recognized east of the miogeocline in Newfoundland and Nova Scotia. From west to east, these are the Dunnage, Gander, Avalon and Meguma. The Dunnage and Gander terranes were linked to the miogeocline during the Middle Ordovician Taconian Orogeny. The Avalon terrane arrived later, possibly during the mid-Paleozoic Acadian Orogeny. The Meguma terrane of southern Nova Scotia had docked with the Avalon terrane by Carboniferous time. The Dunnage terrane contains arc volcanics which lie above an ophiolitic substrate. The Gander terrane comprises a thick sequence of clastic sedimentary rocks, underlain by basement rocks with continental affinities. It has been interpreted as a continental margin, perhaps once on the eastern side of the Paleozoic Iapetus ocean. The Avalon terrane consists of belts of sedimentary and volcanic rocks which are probably underlain by Grenvillian basement. Its tectonic affinities are unclear. The Meguma terrane comprises a thick sequence of sediments, derived from the south-east. It is found only in southeastern Atlantic Canada. The boundaries between terranes are compressional in the west and steep, transcurrent faults in the east.The surface extent of the geological terranes is grossly correlative with deep structural zones, although no direct evidence exists for linking the two because most surface structures can be traced geophysically to only a few kilometres depth. A striking feature of the deep crustal structure is a lower, high velocity crustal layer beneath the Dunnage and Gander terranes.The modern margin of Atlantic Canada developed by rifting and by transform motion between adjacent continents. Stretching and thinning of the lithosphere, and the consequent production of basaltic magma that in places intrudes or underplates the thinned continental crust, are the most likely processes responsible for the evolution of the modern margin. These processes predict the observed deep sedimentary basins along the margin, the thinning of continental crust, and the high seismic velocities found within the ocean-continent transition zones.Rifting adjacent to Nova Scotia began in Late Triassic-Early Jurassic time between the present African and North American plates. These plate motions are also responsible for the major transform margin south of the Grand Banks. Separation between Iberia and the eastern Grand Banks occurred in mid-Cretaceous time, before the Late Cretaceous opening of the Labrador Sea. While the rifted segments of the margin exhibit deep sedimentary basins and thinned continental crust, the Grand Banks transform segment is characterized by a sharp transition zone and a relatively thin sediment cover. Numerous volcanic seamounts are built on the ocean crust adjacent to this transform segment.Mimicry of Paleozoic promontories and re-entrants by modern rift and transform margin segments, the location of Mesozoic sedimentary basins on ancestral Appalachian structures, and the reactivation and propagation of major Precambrian and Paleozoic structural boundaries during the latest phase of ocean opening attest to ancestral controls of the modern margins.The rift phase of both the ancient and modern passive margins is characterized by volcanism, mafic dike intrusion and by the development of basins filled with clastic sediments. The drift phase of both the ancient margin and the present Nova Scotia margin is marked by a change in sedimentary environment, such that carbonates replaced the rift phase clastic sediments. Two of the markers used to delineate the ancient ocean-continent transition zone; carbonate banks and steep gravity anomaly gradients, should be used with caution as the modern analogs of these markers may lie 100 km or more of this transition zone. Furthermore, it is naive to view the ancient transition as simple and narrow, for the modern margins exhibits complex transition zones between 30 and 300 km wide.In general, the evolution of the ancient and modern passive margins appear to be remarkably similar. Predictably, closing the present Atlantic will mimic the evolution of the Appalachian Orogen.     

中扬子晚二叠世沉积特征及古地理演化

通过剖面实测、岩相及沉积相分析,中扬子区晚二叠世主要发育碳酸盐岩开阔台地沉积、陆棚沉积及盆地沉积,吴家坪期以浅海相沉积为主,深水盆地范围较小,长兴期发育台地相及盆地相,深水盆地范围变大,研究区晚二叠世的沉积主要受南秦岭海活动控制和盆地演化影响,沉积分异在晚二叠世较发育.古地理演化表明,吴家坪期中扬子北缘为深水盆地沉积,...     

沉积盆地动力学与盆地流体成矿

沉积盆地实际上是地球动力学系统中一个巨大的动态化学反应器,其所处的地球动力学背景制约着它的边界条件、外部环境及其与外部环境的物质和能量交换。盆地内则是一个由固体无机,有机沉积物颗粒和盆地流体组成的多相反应体系,包括各种流-岩-烃及流-流反应、与有机质成熟演化有关的各种有机反应、在浅部还有细菌参与的生物化学反应。体系的上部边界不断有新沉积物颗粒和流体的加入,下部则有来自基底的流体或来自盆地边缘大气降水的加入循环,同时还有盆地的构造沉降和基底热能的交换,以及可能岩浆物质,能量的加入。沉积物的固结成岩和后生变化,以及其中储存的油气和金属矿床都是这个巨型化学反应器的一部分(并非全部)产物。因此,只有站在盆地动力学的高度,才可能从整体上去认识这些共存的复杂因素和作用过程的耦合关系,才可能从本质上理解有关矿床的形成机理和产出规律。     

Upper Silurian and Devonian pelagic deep-water radiolarian chert from the Khangai–Khentei belt of Central Mongolia: Evidence for Middle Paleozoic subduction–accretion activity in the Central Asian Orogenic Belt

Recent mapping projects undertaken in Central Mongolia have revealed the widespread occurrence of radiolarian chert within a Paleozoic accretionary complex. We present the results of the first detailed tectonostratigraphic and radiolarian biostratigraphic investigations of the Gorkhi Formation in the Khangai–Khentei belt of the Central Asian Orogenic Belt.The Gorkhi Formation consists of sandstone shale, alternating sandstone and shale of turbidite affinity and chert with small amounts of siliceous shale, basalt, limestone, and clast-bearing mudstone. Radiolarian chert that is completely devoid of terrigenous clastic material is commonly associated with underlying basalt (sedimentary contact) and with conformably overlying siliceous shale and turbidite deposits. The tectonic stacking of basalt–chert and chert–turbidite successions is the most remarkable structural feature of the formation.The recovery of moderately well-preserved radiolarians and conodonts from red chert led to the recognition of four radiolarian assemblages that have a combined age range from the latest Silurian (Pridolian) to the Late Devonian (Frasnian). No age control exists for the siliceous shale, shale, and sandstone, although they are considered to be latest Devonian or slightly younger on the basis of stratigraphic relationships with underlying chert.The Gorkhi Formation has previously been interpreted as a thick sedimentary basin deposit overlying an unexposed Archean–Neoproterozoic basement; however, the stratigraphy within individual tectonic slices clearly corresponds to that of an ocean plate stratigraphy of an accretionary complex generated by the trenchward movement of an oceanic plate. From the lowermost to uppermost units, the stratigraphy comprises ocean floor basalt, pelagic deep-water radiolarian chert, hemipelagic siliceous shale, and terrigenous turbidite deposits. The biostratigraphic data obtained in the present study provide corroborating evidence for the existence of an extensive deep-water ocean that enabled the continuous sedimentation of pelagic chert over a period of nearly 50 million years. These data, together with structural data characterized by tectonic repetition of the stratigraphy, indicate that these rocks formed as an accretionary wedge along an active continental margin, possibly that of the Angara Craton. The mid-oceanic chert was probably deposited in the Northern Hemisphere portion of the Paleo–Pacific Ocean that faced the Angara Craton and the North China–Tarim blocks. Thus, we propose that subduction–accretion processes along the Paleo–Pacific rim played an important role in the accretionary growth of the active continental margin of the Angara Craton, directly influencing the evolution of the Central Asian Orogenic Belt.     

楚雄中生代前陆盆地的构造沉降史研究

云南楚雄盆地位于场子陆块的西南边缘,为一典型的中生代周缘前陆盆地,盆地演化阶段明显,晚三叠世为前陆早期复理石沉积,侏罗纪则为前陆晚期磨拉石沉积。对盆地构造沉降史研究后笔者认为：①晚三叠世复理石沉积盆地构造沉降幅度巨大,沉降与沉积中心位于盆地最西部,紧邻古哀牢山造山带,沉积体呈形楔形展布;③侏罗纪磨拉石沉积盆地构造沉降和沉积中心以及前缘隆起向内陆方向迁移明显;③中生代构造快速沉降的沉积体的楔形展布表     

层序地层学方法及其在陆相湖盆研究中的应用

针对中国中、新生代陆相湖盆的特征,从沉积盆地的构造和边缘背景对海相层序地层的影响出发,讨论了湖水面相对变化、沉积物供给、气候等对湖相层序地层的控制作用,明确指出两种背景条件具有本质差异,海相层序地层学方法不能简单套用于内陆盆地分析。     

Temperate carbonate platform drowning linked to Miocene oceanographic events: Maiella platform margin, Italy

Carbonate platform drownings are frequent, often synchronous global occurrences, yet explanations for these world-wide events remain unsatisfactory. In the Central Apennines, Lower and Middle Miocene carbonate rocks deposited on a 'temperate' ramp in the Maiella platform margin record two episodes of platform drowning followed by hemipelagic sedimentation, dated as latest Oligocene–Aquitanian (26–23 M a) and as Burdigalian–Langhian (20–16 Ma). A high-resolution stratigraphy, based on strontium- isotopes, allows us to correlate key phases of platform evolution with events recorded in deep water ocean sediments. This paper suggests that high weathering rates and nutrient input in the Mediterranean during the early and middle Miocene –possibly linked to the uplift of the Tibetan region – set the preconditions for platform drowning, which were ultimately caused by rapid eustatic sea-level rises.     

海拉尔盆地乌尔逊-贝尔凹陷构造演化对油气成藏的控制作用

从成盆、成源、成烃和成藏4个方面对海拉尔盆地乌尔逊-贝尔凹陷各构造演化阶段的石油地质意义进行了分析。海拉尔盆地成盆的动力机制是中蒙边界区中生代推覆构造形成后的晚造山期伸展垮塌作用,为典型的被动裂陷盆地。乌尔逊-贝尔凹陷形成演化经历了5个时期：山间残留阶段、被动裂陷阶段、主动裂陷阶段、断坳转化阶段和坳陷阶段。被动裂陷阶段沉积物震荡式沉积形成南一段中部砂泥互层的优质烃源岩,主动裂陷阶段盆地强烈裂陷,窄而深的断陷结构控制盆地南一段上部有效源岩分布,断坳转化阶段盆地快速沉降促进烃源岩熟化,伊敏组沉积晚期烃源岩大量排烃控制形成早期原生油藏,伊敏组末期盆地反转,部分油藏受活动断裂破坏调整到大磨拐河组形成次生油藏。不同演化阶段形成多种类型的隆起带,构成有利的油气聚集区带,控制了不同含油气系统油气聚集。     

Sedimentationsabläufe im Atlas-Golf (Kreide Küstenbecken Marokko)

The Geological Institute of Bonn University since 1975 investigates in connection with DSDP/IPOD the Cretaceous of the Atlantic coastal basin in south-western Morocco. 30 main stratigraphic sections and numerous auxiliary ones were taken along several traverses, running along distances of 150 to 200 km in west-east direction. The recognized epicontinental facies-pattern along the traverse of the southern High Atlas mountain range depicts clearly, that we cut here the critical region of intertonguing marine, fine-clastic-carbonaceous sediments and continental detritic deposits. The littoral zone successively progrades with three major transgressions (Neocomian, Upper Aptian, Turonian) towards the African Continent. Sedimentation processes, stratigraphy, paleomagnetics, geochemistry, sedimentology and paleogeography are investigated, taking selected horizons on one hand and complete stratigraphic columns on the other. A new sedimentation model reflecting transgression and regression events in the Cretaceous “Atlas Gulf” show some probabilities of eustatic sea-level changes. There are similarities between the Atlas Gulf and other coastal basins on both sides of the Atlantic Ocean. There are certain relations between the sedimentary record of the proand regrading littoral zone on the continent and in the nearby deep sea deposits. There is an exciting coincidence between the stratigraphie succession of the downwarping Atlas Gulf and the sedimentary cover of the interior of Africa, especially the Mesozoic Sahara Basin.     

The structure of the guinean continental margin: Implications for the connection between the central and the south atlantic oceans

The results of a recent geological-geophysical survey, conducted off Guinea, are combined with previous data to establish a preliminary stratigraphy and provide a structural sketch of this portion of the West African continental margin. Three sectors are distinguished:

A northwestern portion of the margin comprises a wide and deeply submerged plateau — the Guinean Marginal Plateau underlain by a thick sedimentary sequence and facing westward toward the Gambia Abyssal Plain. Scismic stratigraphy and structures show clear analogies to the Jurassic margins of the central Atlantic. Including the presence of a Cretaceous paleoslope covered by Cenozoic deposits.

A southern area of the margin comprises a series of aligned (W-E trending), acoustic basement features extending along the slope and bounding the Guinean Plateau to the south. These features, basement ridges and volcanic piles are related to a fracture zone system also documented by magnetic anomalies and gravity data. The bordering deep Sierra Leone abyssal plain, also dissected by E-W-trending oceanic fracture zones, contains a sedimentary cover apparently not older than middle Cretaceous.

Between both sectors and between two NW-SE trending scarps lies an intermediate area. The seismic profiles show that here, the margin is dissected by faults creating a series of asymmetric horst and graben features progressively narrowing towards the S-E and covered by untectonized (but partly eroded) Upper Cretaceous to Cenozoic sediments.

The overall structure of the Guinean Margin is interpreted as the result of two major events. During a first phase the margin was created at the southern extremity of the central Jurassic Atlantic and developed like other comparable margins. During a s econd phase (beginning in Early Cretaceous times) the margin was progressively submitted to the opening of the equatorial South Atlantic. This process gave rise to the margin of the southern Guinean plateau (locally injected by volcanics) and generated the tectonic features of the intermediate zone. This protion may thus represent a part of the rifted Jurassic margin discordantly dissected by the oblique opening of the south Atlantic in the area. The oceanic crust of the central and south Atlantic were definitively connected only during Late Albian times as indicated by the end of the tectonic activity and the early Upper Cretaceous unconformity.     

Structure of the European continental margin between Portugal and Ireland, from seismic data

The continental margin reviewed in this paper corresponds in almost all its parts to a Hercynian platform which was more or less structured during the Mesozoic and Cenozoic in association with the formation of the Atlantic Ocean.

In the areas above water and the continental shelves, this Hercynian platform either has a thin sedimentary covering (Galicia, Armorica, West Ireland, Porcupine Bank) or, on the contrary, has been extensively depressed by distension movements accompanied with the formation of thick Mesozoic and Cenozoic basins connected with the oceanic domain (West Portugal, Basco-Cantabrian zone, Adour Basin, Parentis Basin, Western Approaches Basin, North Celtic Sea Basin, Porcupine Seabight Basin). In addition, the Early Cenozoic Pyrenean-Alpine compression movements had repercussions on the structure of the north Spanish margin.

From the structural standpoint, the main features of the margin are linked both to the deep indentation of the Bay of Biscay and to the existence of more or less collapsed blocks prolonging the continental domain. These blocks are visible either in the topography (Porto and Vigo seamounts, Galicia Banks, Asturian marginal shelf, Porcupine Bank) or solely by seismic reflection (Trevelyan Escarpment). Thick marginal sedimentary basins exist at the foot of the slope.     

Geology of the Dolomites

The Dolomites region is a spectacularly exposed portion of the Southern Alps, a northern Italian chain derived from the comparatively gentle deformation of the Tethyan passive continental margin of Adria. The regionhad an active Permo-Jurassic tectono-magmatic evolu-tion, leading from Permian magmatism, through a Mid-die Triassic episode offast subsidence and volcanism, to the Jurassic oceanic break-up. Although the sedimentary succession ranges in age from Middle Permian to Creta-ceous, the geological landscape is largely dominated by the majestic Triassic carbonates, making the area a clas-sical one for the early Mesozoic stratigraphy. Particu-larly noteworthy are the Anisian to Carnian carbonate platforms, recording an evolution from regional muddy banks to isolated high-relief builduos. The hlline of the various basins and the development of a last generation of regional peritidal platform followed. The carbonate platforms of the Dolomites bear witness to a remarkable set of changes in the carbonate production and to signif-icant palaeoclimatic fluctuations,from arid to moist con-difions and vice versa; a great range of margin and slope depositional styles is therefore recorded. Alpine tectonic shortening strongly affected the area, with a first Eocenede formation, followed by later Neogene overthrusting and strike-slip movements.     

珠江口盆地荔湾凹陷珠江组关键地质界面SB21的识别及地质意义

荔湾凹陷是珠江口盆地最南部的一个超深水凹陷,其结构特点、沉积过程研究是认识被动陆缘演化的重要内容.运用地震地层学方法,基于高分辨率2D/3D地震资料的沉积追踪与对比,一个特征明显且全区可追踪的地质界面——SB21界面被识别出.该界面上下揭示出多种沉积现象:北部剥蚀区、中北部的沉积物过路区、中南部冲沟和沉积物波叠置区、南部的沉积物堆积区.推测这种沉积样式的多样性与发生在23.8 Ma前后的白云运动有密切关系,该构造运动造成荔湾凹陷的差异性沉降,主要表现为荔湾凹陷中南部的快速沉降,导致凹陷北部及中东部的相对抬升.该期构造运动使原有的沉积平衡发生改变,造成沉积物的再分配,沉积物从北部剥蚀区经过路区向中南部堆积区运移.自东向西发育的冲沟,推测与该时期差异沉降导致中东部近南北走向的相对隆起与西侧沉降区的差异沉降,以及有来自凹陷东北角的物源叠加作用有关.SB21界面的沉积反射特征研究,揭示了洋陆边界复杂多变的沉积过程及其驱动机制,对我们认识更大区域的构造沉积过程具有一定的帮助.      

从前陆盆地充填地层分析盆山耦合关系

根据前陆盆地充填地层分析盆地和造山带的耦合关系，研究区域包括四川中生代前陆盆地和鄂尔多斯中生代前陆盆地。研究表明，前陆盆地和造山带具有较好的耦合关系。前陆盆地充填沉积物特征是造山带形成演化和盆地沉降的响应。向上变粗的沉积序列以及地层不整合盆地方向的迁移反映了造山带向前陆不断隆升的演化过程，前陆盆地沉积物的岩石学特征反映了双物源供给和造山带的剥蚀。层序地层的体系域构成和地层堆积方式主要受控于前陆盆地沉降速度的变化。     

甘孜-理塘构造带泥盆系的深水沉积

甘孜－理塘构造带由大面积为三叠系地层覆盖而难以对其下覆的地层进行研究,导致了了们对甘孜－理塘构造带的构造演化认识产生很大分歧。通过对劳改皮沉积混杂岩体的地层学、生物学,沉积学和岩石化学等方面的研究,认为甘孜－理塘构造带三叠系盖层之下可能存在大面积的泥盆系、甚至上古生界的深水沉积。进而得出甘孜－理塘洋的演化历史应该向前推移到早泥盆世,而不是通常所说的晚二叠世,同时指出,沉积混杂岩是研究隐伏基底的重要