Structural evolution of the Feda Graben area – A new model

The pre-Cretaceous basin evolution of the Feda Graben area in the vicinity of the Norwegian-Danish basin has been reconstructed utilizing geological and structural interpretation. The analysis reveals that the basin was faulted at its borders prior to the salt deposition in the Late Permian. Salt movement was initiated in Late Triassic and thick Triassic and Lower Jurassic pods were deposited in the graben area due to this movement. Salt pillows were developing along the Feda Graben bordering faults until Middle Jurassic when the pillows were collapsed. Salt diapirs within the study area preferentially occupy the crest of the Feda Graben and their occurrence is controlled by the underlying faulted topography. The diapirs were fed by salt from the central and southern parts of the basin and were developed by different processes i.e. upbuilding, downbuilding. Various raft structures were developed in the graben area hanging wall while some uplift occurred in the footwall during Mesozoic rifting. The Feda Graben area experienced rifting from Late Jurassic to Early Cretaceous. The most pronounced subsidence episode related with this rifting in the Feda Graben area took place along the eastern bounding Gert Fault. The Mesozoic rifting event is marked by a major unconformity on the seismic sections throughout the study area. Furthermore, the region experienced basin inversion in Late Cretaceous. The effects of inversion are more pronounced in the western part and along the Gert Fault. The inversion phenomenon can be properly understood only when considered together with the geometry of the Late Jurassic half-graben. Due to some inconsistencies in the previously proposed models for the development of the Feda Graben, a new conceptual model has been constructed.     

Structural differences between the western and eastern Qiongdongnan Basin: evidence of Indochina block extrusion and South China Sea seafloor spreading

Located at the intersection between a NW-trending slip system and NE-trending rift system in the northern South China Sea, the Qiongdongnan Basin provides key clues for us to understand the proposed extrusion of the Indochina Block along with Red River Fault Zone and extensional margins. In this paper we for the first time systematically reveal the striking structural differences between the western and eastern sector of the Qiongdongnan Basin. Influenced by the NW-trending slip faults, the western Qiongdongnan Basin developed E–W-trending faults, and was subsequently inverted at 30–21 Ma. The eastern sector was dominated by faults with NE orientation before 30 Ma, and thereafter with various orientations from NE, to EW and NW during the period 30–21 Ma; rifting display composite symmetric graben instead of the composite half graben or asymmetric graben in the west. The deep and thermal structures in turn are invoked to account for such deformation differences. The lithosphere of the eastern Qiongdongnan Basin is very hot and thinned because of mantle upwelling and heating, composite symmetric grabens formed and the faults varied with the basal plate boundary. However, the Southern and Northern Uplift area and middle of the central depression is located on normal lithosphere and formed half grabens or simple grabens. The lithosphere in the western sector is transitional from very hot to normal. Eventually, the Paleogene tectonic development of the Qiongdongnan Basin may be summarized into three stages with dominating influences, the retreat of the West Pacific subduction zone (44–36 Ma), slow Indochina block extrusion together with slab-pull of the Proto-South China Sea (36–30 Ma), rapid Indochina block extrusion together with the South China Sea seafloor spreading (30–21 Ma).     

Structural geology of the Huldra Field, northern North Sea—a major tilted fault block at the eastern edge of the Horda Platform

The Huldra fault block is a rotated major fault block on the east margin of the Viking Graben in the northern North Sea. Unlike the rest of the Horda Platform area, the Jurassic section in the Huldra fault block was rotated more than 20° during slip on the listric Huldra fault, which forms a low-angle detachment beneath the Huldra fault block. The fault block is interpreted as resulting from marginal collapse of the Horda Platform after relief along the eastern margin of the Viking Graben built up in early parts of the middle to late Jurassic rifting history. The collapse resulted in NW directed transport of the Huldra fault block, consistent with a previously postulated change in extension direction from W–E to NW–SE toward the end of the Jurassic period. Minor faults within the Hulrda fault block are consistent with E–W extension and thus may have formed early during the late Jurassic rifting phase. Nevertheless, the crest (Huldra Field) seems surprisingly intact, considering its proximity to a major fault zone. Deformation bands studied from core material are non-cataclastic and concentrated in zones. Evidence for smearing along a cored fault surface indicates that minor subseismic faults may be sealing. Production data from the field indicate good communication between most wells, suggesting that the subseismic faults and deformation band zones that are present in the reservoir have relatively small influence on the flow of gas in the reservoir.     

Slide block (?) of Jurassic sandstone and submarine channels in the basal Upper Cretaceous of the Viking Graben: Norwegian North Sea

Seismic-facies analysis of a seismically-anomalous sequence of mid-Cretaceous (Cenomanian-Turonian) basin fill in Lease Block 34/8, Viking Graben, Norwegian North Sea, reveals a possible slide block (?) composed of Jurassic-age Brent Group strata that apparently detached from the adjacent structural high (34/8 structure) and slid downslope onto Lower Cretaceous sediments in the Viking Graben floor. In addition, this mid-Cretaceous sequence contains two broad submarine channels that trend southward into the graben from the southern tip of the slide block (?) and the adjacent structural high. The channels appear to be erosional features formed by turbidity currents and mass-wasting processes. The Brent slide block (?) may represent an additional hydrocarbon prospect within the lease Block 34/8.     

On the structural evolution of the Central Trough in the Norwegian and Danish sectors of the North Sea

The Central Trough of the North Sea is not a simple rift graben. It is an elongated area of regional subsidence which was initiated in mid Cretaceous times and continued to subside through to the late Tertiary. Its form is not representative of pre-mid Cretaceous tectonics.In Late Permian times the North Sea was divided into a northern and southern Zechstein basin by the E-W trending Mid North Sea-Ringkøbing-Fyn High. The latter was dissected by a narrow graben trending NNW through the Tail End Graben and the Søgne Basin. The Feda Graben was a minor basin on the northern flank of the Mid North Sea High at this time. This structural configuration persisted until end Middle Jurassic times when a new WNW trend separated the Tail End Graben from the Søgne Basin. Right lateral wrench movement on this new trend caused excessive subsudence in the Tail End and Feda Grabens while the Søgne Basin became inactive.Upper Jurassic subsidence trends continued during the Early Cretaceous causing the deposition of large thicknesses of sediments in local areas along the trend. From mid Cretaceous times the regional subsidence of the Central Trough was dominant but significant structural inversions occurred in those areas of maximum Early Cretaceous and Late Jurassic subsidence.     

冲绳海槽断裂、岩浆构造活动和洋壳化进程

讨论了冲绳海槽断裂、岩浆构造活动特征和它们之间的关系,认为雁行排列的地堑斜交于陆架外缘隆起带,海槽北段断块隆脊、龙王构造带和海槽南段"棉花构造带"可能保留了海槽各幕断陷前的火山岩浆活动特征,而现在活动的吐噶喇火山岛弧可沿海槽南段岛坡追踪到台湾。吕宋岛向台湾的碰撞挤压引起的旋张活动加强了海槽南段的地壳拉张,诱发了地堑内火山岩浆活动,在洋壳化进程中起关键作用,其中最典型的八重山地堑已经形成洋壳。断裂和岩浆活动主要是单向地向岛弧侧迁移,由洋中脊扩张产生的对称条带状磁异常模式难以解释冲绳海槽的洋壳化进程。     

Oblique rifting in the Havre Trough and its propagation into the continental margin of New Zealand: Comparison with analogue experiments

The Havre Trough is opening by oblique back-arc rifting which is propagating into the continental margin of New Zealand at the Taupo Volcanic Zone. Variations of deformational style along the rift axis have been investigated by comparison with analogue experiments which incorporate brittle and ductile rheologies and are scaled for gravity. Based on the results of the analogue experiments, we present a tectonic model for oblique rifting in the Havre Trough, which involves the rheological contrast between oceanic and continental lithosphere and the oblique geometry of the continental margin of New Zealand with respect to the regional rift trend. The model shows that the continental margin, which is weaker than both oceanic and continental lithosphere, cannot support large shear stresses. The two lithospheres can be decoupled during extensional events along the marginal shear and, depending on the continental margin orientation, this shear can modify the regional stress field. A heterogeneous stress field will rotate normal stresses to be perpendicular or parallel to the margin. As the two lithospheres decouple during extension, the rift grabens and internal faults of the oblique rift system propagate normal to the marginal shear. This model explains the oblique trend of the Havre Trough's tectonic fabric and its relationships to the Vening Meinesz Fracture Zone which represents the oceanic/continental lithospheric boundary.As the Havre Trough rift propagates into the continental margin, rheological differences between oceanic and continental lithosphere result in variations in distribution of strain along the rift axis. Extension of oceanic sub-arc lithosphere is localized into a single rift graben. At the transition into continental rifting, the zone of extension widens into a number of rift grabens forming complex indentations into the margin. This change in deformation style is consistent with analogue experiments as well as other natural examples and results from the contrast in lithospheric rheology and its influence on the process of strain localization.     

Structural architecture and tectonic evolution of the Yelleg inverted half graben,northern Sinai,Egypt

The Gebel Yelleg area includes a number of folds belonging to the northern Sinai Syrian Arc structures. Detailed surface structural mapping and subsurface (seismic and borehole) data show that the Gebel Yelleg structures are related to Late Cretaceous-Early Tertiary inversion of a Jurassic asymmetric (or half) graben formed during the opening of Neotethys. The inversion structures include a large (45-km long) asymmetric fold (Yelleg Anticline) with a steep flank overlying the southeastern (main) bounding fault of the inverted half graben as well as some right-stepped en echelon folds overlying the northwestern bounding fault of the half graben. The large inversion anticline is dissected by a large number of long, nearly orthogonal normal faults whereas the en echelon folds are dissected by transverse normal faults and two sets of oblique-slip faults. Inversion of the northern Sinai extensional basins is related to Africa-Eurasia convergence and was probably transpressional with a small component of dextral slip. This study shows that the magnitude of inversion in the northern Sinai fold belt decreases toward the southern boundary of the Jurassic extensional province.     

Petroleum retention in the Mandal Formation,Central Graben,Norway

Upper Jurassic organic matter-rich, marine shales of the Mandal Formation have charged major petroleum accumulations in the North Sea Central Graben including the giant Ekofisk field which straddles the graben axis. Recent exploration of marginal basin positions such as the Mandal High area or the Søgne Basin has been less successful, raising the question as to whether charging is an issue, possibly related to high thermal stability of the source organic matter or delayed expulsion from source to carrier.The Mandal Formation is in part a very prolific source rock containing mainly Type II organic matter with <12 wt.-% TOC and HI < 645 mg HC/g TOC but Type III-influenced organofacies are also present. The formation is therefore to varying degrees heterogeneous. Here we show, using geochemical mass balance modelling, that the petroleum expulsion efficiency of the Mandal Formation is relatively low as compared to the Upper Jurassic Draupne Formation, the major source rock in the Viking Graben system. Using maturity series of different initial source quality from structurally distinct regions and encompassing depositional environments from proximal to distal facies, we have examined the relationship between free hydrocarbon retention and organic matter structure. The aromaticity of the original and matured petroleum precursors in the Mandal source rock plays a major role in its gas retention capacity as cross-linked monoaromatic rings act on the outer surface of kerogen as sorptive sites. However, oil retention is a function of both kerogen and involatile bitumen compositions. Slight variations in total petroleum retention capacities within the same kerogen yields suggest that texture of organic matter (e.g. organic porosity) could play a role as well.     

Faulting, magmatism and crustal oceanization of the Okinawa Trough

The paper focuses on the characteristics of faulting and magmatism of the Okinawa Trough and the relation between them.En-echelon grabens are ranked oblique to the continental shelf edge uplift,and the Longwang uplift,the rifting block ridge in the northern segment and the“Mianhua uplift”in the southern segment have possibly preserved characteristics of volcanism and magmatism occurring with those rifting phases.The clockwise rotation of the southern Ryukyu Islands,driven by collision between Luzonand Taiwan,has played a key role in the crustal oceanization,enhancing the crustal extension of the southern segment and inducing volcanic magmatism in those grabens,among which the Yaeyama graben is a typical example of the presence of oceanic crust.Faulting and magmatism were mainly migrating towards the island are asymmetrically.The crustal oceanization of the Okinawa Trough is difficultly interpreted by the linear magnetic anomaly model,which is fit for the symmetric spreading of the mid-oceanic ridges.     

4D analogue modelling of transtensional pull-apart basins

Scaled sandbox models were used to investigate the 4D evolution of pull-apart basins formed above underlapping releasing stepovers in both pure strike-slip and transtensional basement fault systems. Serial sectioning and 3D volume reconstruction permitted analysis of the full 3D fault geometries. Results show that very different pull-apart basins are developed in transtension compared to pure strike-slip. Both types of models produced elongate, sigmoidal to rhomboidal pull-apart systems, but the transtensional pull-apart basins were significantly wider and uniquely developed a basin margin of en-echelon oblique-extensional faults. Dual, opposing depocentres formed in the transtensional model whereas a single, central depocentre formed in pure strike-slip. In transtension, a distinct narrow graben system formed above the principal displacement zones (PDZs). Cross-basin fault systems that linked the offset PDZs formed earlier in the transtensional models.Sequential model runs to higher PDZ displacements allowed the progressive evolution of the fault systems to be evaluated. In cross-section, transtensional pull-aparts initiated as asymmetric grabens bounded by planar oblique-extensional faults. With increasing displacement on the PDZs, basin subsidence caused these faults to become concave-upwards and lower in dip angle due to fault block collapse towards the interior of the basin. In addition, strain partitioning caused fault slip to become either predominantly extensional or strike-slip. The models compare closely with the geometries of natural pull-apart basins including the southern Dead Sea fault system and the Vienna Basin, Austria.     

Deep structure of the Moscow Aulacogene in the western part of Moscow

Geological and geomorphological studies of the Moscow Aulacogene in the western part of Moscow suburbs have been conducted. This deep structure has been studied by microseismic sounding. The resulting section presents the faults which frame the Teplostanskii Graben in the south (Ramenskii or Butovskii, expressed on the surface as a ledge in the relief) and in the north (Pavlovo-Posadskii, being traced on the surface as a series of lineaments and the valley of Setun’ River). The position of the surface Archean-Lower Proterozoic crystalline basement within the limits of the graben and within the limits of buried elevated blocks (Krasnogorskii and Tumsk-Shaturskii) frame it in the north and south, respectively. Additionally, another fault has been identified in the central part of the graben: the Solntsevskii fault, which has a north-western course and which separates the deflection of the basement in two blocks that are sunken in a slightly different degree. The low-velocity horizons of the Riphean-Vendian complex which make up the graben at depths of 2 to 4.5 km have been found. Down to depths of 15 km, as a component of the upper crust, the graben is underlain by a high-velocity material which also forms the upper part of the section of the crystalline basement in the neighboring elevated block. A low-velocity block of the lithosphere is located in the larger (northern) part of the graben deeper (down to 40 km) beneath the zones of Pavlovo-Posadskii and Solntsevskii faults; in the southern part there is a high-velocity block. In the fault zones framing the graben in the north and south, the surface layer and soil displays a flow of juvenile hydrogen and helium which exceeds several tenfold the background values. According to the collected data, the Teplostanskii Graben has roots traceable through the entire crust and penetrating into the upper mantle.     

Structural styles and depositional architecture in the Triassic of the Ninian and Alwyn North fields: Implications for basin development and prospectivity in the Northern North Sea

Interpretation of well-calibrated three-dimensional seismic volumes, sedimentological analysis and electrical well-log correlations from the Ninian and Alwyn North fields challenge the long-held view that Mid-Late Jurassic extensional faults in the East Shetland Basin represent a simple reactivation of older (Triassic) fault systems. Restoration for the effects of the younger, predominantly eastward-dipping, Mid-Late Jurassic structures clearly demonstrates that Triassic precursors had a steep, westerly dip. In contrast to the eastern flank of the Viking Graben (e.g. Troll and Oseberg areas), where the west-dipping Triassic structures are reutilised in the Mid-Late Jurassic, those of the East Shetland Basin have largely been dissected and rotated during the later event. Those west-dipping faults that did see later movement appear to have simply acted as minor antithetic structures to the throughgoing east-dipping ones.The Triassic normal fault patterns actively controlled sediment thicknesses and facies distribution within the Lunde and Teist Formations in the basin. Use of seismic stratigraphic surfaces, calibrated by biostratigraphy and chemostratigraphic markers, provides strong evidence that the Triassic depocentres are spatially offset from their Mid-Late Jurassic counterparts. The combination of structural, stratigraphic and sedimentary effects reveal the existence of an emergent deeper Triassic play opportunity in footwall locations to the Mid-Late Jurassic normal faults, which has the potential to extend the life of what is otherwise mature acreage.     

A study of faulting patterns in the Pearl River Mouth Basin through analogue modeling

The Pearl River Mouth Basin is one of the most favorable areas for gas exploration on the northern slope of the South China Sea. Differences of fault patterns between shelf and slope are obvious. In order to investigate the tectonic evolution, five series of analogue modeling experiments were compared. The aim of this study is to investigate how crustal thickness influences fault structures, and compare this to the observed present-day fault structures in the Pearl River Mouth Basin. The initial lithospheric rheological structure can be derived from the best fit between the modeled and observed faults. The results indicate. (1) Different initial crustal rheological structures can produce different rift structures in the Pearl River Mouth Basin. (2) We also model that the Baiyun Sag in the southern Pearl River Mouth Basin may have had a thinned crust before rifting compared to the rest of the basin. (3) The thickness ratio of brittle to ductile crust in southern Pearl River Mouth Basin is less than normal crust, suggesting an initially hot and weak lithosphere. (4) Slightly south of the divergent boundary magma may have taken part in the rifting process during the active rift stage.     

南海北部陆架北部湾盆地古湖泊与烃源条件

利用地震资料对整个盆地的追踪和对比,结合钻井资料,对北部湾古湖进行分析发现：古湖发育始于古新世,到始新世流沙港期进入鼎盛时期,湖泊规模最大达5000km^2,沉积了巨厚沉积物,最大沉积厚度达4700m。井资料分析显示,在始新统流沙港三段、二段各古湖沉积物中浮游藻类和沉积有机质含量高,说明该两段具有较高的生物生产力;流一段和涠洲组沉积物中仅在涠西南古湖和乌石古湖内浮游藻类和沉积有机质具有较高的含量,因此涠西南与乌石具有更好的烃源条件。     

Geologic structure and neotectonics of the North African Continental Margin south of Sicily

Marine geological and geophysical data together with drilling information indicate that the North African passive continental margin has been subjected to extension and wrenching after it collided with the northern part of Sicily. The area of the Tripolitania Basin, Jarrafa Trough, Melita and Medina Bank and the Ragusa-Malta Plateau has formed part of a sinking passive margin since the dispersal of Gondwanaland at about 180 My ago as observed from geohistory diagrams. A record of rifting in a NW-SE direction accompanied by dextral shear along the southern troughs is observed in seismic reflection data. The rifting started during the Neocomian and lasted until the Eocene when activity became minor. A pre-Middle Miocene period of northward subduction of oceanic crust is inferred from the geology in NE Sicily. Uplift of the northern part of the African margin after collision in the Middle Miocene is seen in wells in southern Sicily. After the Messinian a rift and dextral shear zone established itself across the African Margin from the Strait of Sicily to the Medina Ridge in the lonian Basin. The zone is marked by up to 1.7 km deep grabens, narrow active wrench faulted channels, volcanic fissures and local uplifted ‘Keilhorsts’ such as Malta. This zone, which varies in width from 100 to 35 km, forms the southern boundary of a microplate which includes Sicily. We speculate that the present motion of this microplate is partly due to the eastward movement of the Calabrian Arc with the Sicilian block over the last remaining oceanic lithosphere in the Eastern Mediterranean.     

持续沉降是墨西哥湾油气区优质烃源岩形成的重要条件

墨西哥湾盆地是一个典型的中生代—新生代裂谷盆地,形成于北美克拉通南部边缘,大部分时间处于持续而稳定的沉降作用过程中。自晚侏罗世以来持续稳定的沉降形成了中生代富有机质的缺氧海相碳酸盐岩、黑色钙质页岩和泥质石灰岩等优质烃源岩,以及新生界以陆源碎屑为主的巨厚沉积物,存在大量的潜在烃源岩,加之良好的生储盖组合,从而形成了墨西哥湾盆地丰富的油气聚集。     

Tectonics, global changes in sea level and their relationship to stratigraphical sequences at the US Atlantic continental margin

The principal factors that control the extent of seas through geological time are vertical movements of the lithosphere and global changes in sea level. The relative height of the sea surface determines the facies and the thickness of sediments that can accumulate in a sedimentary basin. Backstripping studies show that the primary factors affecting the subsidence of rifted sedimentary basins are thermal contraction, following heating and thinning of the lithosphere at the time of rifting, and sedimentary loading. Factors such as compaction, palaeobathymetry, erosion and global sea level changes also contribute, but their combined affects are small compared to those of thermal contraction and sedimentary loading. Simple models have been constructed which combine the effects of sedimentary loading and thermal contraction with those of compaction, sub-aerial erosion and global changes in sea level. In the models it was assumed that the lithosphere was heated and thinned by stretching at the time of rifting, sedimentary loading occurs by flexure of a lithosphere that progressively increases its flexural rigidity with age following rifting and, that sediment compaction and bathymetry change across a basin but do not vary significantly with gwological time. Furthermore, different assumptions were made on the magnitude of curves of global sea level changes and the relationship between denudation rate and regional elevation. The models show that tectonics, in the form of thermal contraction of the lithosphere and flexure and slowly varying global changes in sea level, can explain a number of the stratigraphic features of the US Atlantic continental margin. In this Paper some of the implications of these results are examined for studies of (a) sea level changes through geological time; and (b) the maturation history of continental margin basins.     

低勘探程度盆地模拟研究——以南黄海盆地北部坳陷为例

盆地模拟已成为当前沉积盆地研究的重要工具。南黄海盆地北部坳陷自裂陷期演化以来沉积了巨厚的中-新生代碎屑沉积,近年来的地质调查获取的数据为其盆地模拟研究提供了条件,本次研究在收集相关基础数据的基础上,首先对盆地构造热演化史进行了模拟,重建了盆地热史,模拟结果显示其古热流在中-晚侏罗世平均值约为61mW/m²,在约145-74Ma间不断上升至约80 mW/m²,随后缓慢下降至65 mW/m²,并持续到渐新世末期,据此将盆地演化阶段划分为裂前期、裂陷期及裂后期。盆地模拟结果显示北部坳陷在白垩纪逐步进入强裂陷演化阶段并经历快速沉积过程,至晚白垩纪裂陷发育程度中等,在此基础上,对研究区进行了三维盆地模拟,结果显示北部坳陷生烃门限深度大致位于古近系阜宁组顶部,下伏的侏罗系及白垩系烃源岩基本完成生排烃过程,其中侏罗系烃源岩生排烃主要发生在盆地发育的裂陷期及裂后期,而白垩系及古近系烃源岩生排烃主要发生在裂后期。尽管研究区尚处在低勘探程度阶段,但盆地模拟结果已能为研究区下一步的勘探提供重要的信息,此外,本次研究对模拟过程中的主要不确定性也进行了分析。     

Hydrocarbon systems of Northeastern Venezuela: plate through molecular scale-analysis of the genesis and evolution of the Eastern Venezuela Basin

The prolific, oil-bearing basins of eastern Venezuela developed through an unusual confluence of Atlantic, Caribbean and Pacific plate tectonic events. Mesozoic rifting and passive margin development created ideal conditions for the deposition of world-class hydrocarbon source rocks. In the Cenozoic, transpressive, west-to-east movement of the Caribbean plate along the northern margin of Venezuela led to the maturation of those source rocks in several extended pulses, directly attributable to regional tectonic events. The combination of these elements with well-developed structural and stratigraphic fairways resulted in remarkably efficient migration of large volumes of oil and gas, which accumulated along the flanks of thick sedimentary depocenters.At least four proven and potential hydrocarbon source rocks contribute to oil and gas accumulations. Cretaceous oil-prone, marine source rocks, and Miocene oil- and gas-prone, paralic source rocks are well documented. We used reservoired oils, seeps, organic-rich rocks, and fluid inclusions to identify probable Jurassic hypersaline-lacustrine, and Albian carbonate source rocks. Hydrocarbon maturation began during the Early Miocene in the present-day Serrania del Interior, as the Caribbean plate moved eastward relative to South America. Large volumes of hydrocarbons expelled during this period were lost due to lack of effective traps and seals. By the Middle Miocene, however, when source rocks from the more recent foredeeps began to mature, reservoir, migration pathways, and topseal were in place. Rapid, tectonically driven burial created the opportunity for unusually efficient migration and trapping of these later-expelled hydrocarbons. The generally eastward migration of broad depocenters across Venezuela was supplemented by local, tectonically induced subsidence. These subsidence patterns and later migration resulted in the mixing of hydrocarbons from different source rocks, and in a complex map pattern of variable oil quality that was further modified by biodegradation, late gas migration, water washing, and subsequent burial.The integration of plate tectonic reconstructions with the history of source rock deposition and maturation provides significant insights into the genesis, evolution, alteration, and demise of Eastern Venezuela hydrocarbon systems. We used this analysis to identify additional play potential associated with probable Jurassic and Albian hydrocarbon source rocks, often overlooked in discussions of Venezuela. The results suggest that oils associated with likely Jurassic source rocks originated in restricted, rift-controlled depressions lying at high angles to the eventual margins of the South Atlantic, and that Albian oils are likely related to carbonate deposition along these margins, post-continental break up. In terms of tectonic history, the inferred Mesozoic rift system is the eastern continuation of the Espino Graben, whose remnant structures underlie both the Serrania del Interior and the Gulf of Paria, where thick evaporite sections have been penetrated. The pattern of basin structure and associated Mesozoic deposition as depicted in the model has important implications for the Mesozoic paleogeography of northern South America and Africa, Cuba and the Yucatan and associated new play potential.