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1.
通过对研究区中生代地层典型剖面或代表性剖面系统考察和综合研究,对上侏罗统及其上覆、下伏岩石地层进行进一步系统清理和修订：（1）将济阳坳陷原上侏罗统蒙阴组划归下白垩统,与之相对应的是鲁西南地区为杨家庄组;将山东地区中—上侏罗统三台组界定为中侏罗统;（2）将皖北地区合肥盆地圆筒山组划入中—上侏罗统;原上侏罗统周公山组认为是跨时代地层单元（J3K1）。（3）大别山北麓北淮阳六安、金寨地区的凤凰台组、三尖铺组定为晚侏罗世早期。在此基础上建立了中国东部地区准确可行的地层对比关系,提出了与国际接轨的地层划分与对比表。对比结果表明中国东部晚侏罗世除了在南北缘存在沉积外,整个地区缺失上侏罗统。该现象表明中国东部在晚侏罗世仍为挤压应力环境甚至比早中侏罗世更为强烈,甚至一直维持到早白垩世初。 相似文献
2.
The interpretation of 2-D seismic reflection data provides a modern structural framework including hydrocarbon potential in the present-day stratigraphic and structural traps of both the Davie Fracture Zone and the adjacent Nacala and Angoche basins. Possible stratigraphic traps were identified in submarine fan and channel depositional environments during Cretaceous to Tertiary times. Structural traps are mostly defined within compressional structures formed by a variety of fault-related folds and rift grabens within the Jurassic and Cretaceous successions.The Nacala and Angoche basins form two depressions separated by the Davie compressional zone. This compressional structure is a prominent interior high running approximately north-south. An event of transpression and contraction characterizes the main tectonic setting commonly hosting several detached compressional structures along the western edge of the transform zone.Both basins are associated with the Late Jurassic/Early Cretaceous rifting during the opening of the Mozambique Channel. The Angoche basin is proposed here to have formed by the earliest stage of break-up in mid-Jurassic time. The basin is bounded landward by the Angoche volcanic zone, a dyke swarm branch oriented N64degE forming part of the Karoo and Dronning Maud Land magmatism at c. 180 Ma.Subsequent rifting and break-up led to the drift of East Gondwana southwards along the dextral strike-slip Davie Fracture Zone. At about 150 Ma (Tithonian), East Gondwana appears to have rotated slightly clockwise about a pivot in the proximity of the Angoche basin leading to extension and rifting in the Rovuma basin to the north of the pivot point and compression west of the Davie Fracture Zone to the south. Consequently, the eastern boundary of the Angoche basin was compressed developing a typical growth wedge of massive thrust imbrication structures while extensional tectonics created several depressions and rift-grabens forming the Nacala and Quirimbas basins.Basin stratigraphy is interpreted along seismic reflection lines and correlated to the regional stratigraphic information and wells from the Zambezi Delta and Rovuma basins. 相似文献
3.
Major sequence boundaries associated with eustatic sea level changes are correlated to the general stratigraphy of the north-eastern Gulf of Mexico. The details of a Middle Cretaceous Flooding Surface, marking a major break in sedimentation, are documented. The sequence stratigraphic work provides an example of the ‘stratigraphic signature of the Neogene’. Three major episodes of sediment accumulation are represented by: (1) Late Jurassic (150.5 Ma) to Middle Cretaceous (94 Ma) aggradation and progradation of sediments with significant sediment accumulation in the present shelf and slope areas; (2) an extended period of starved sedimentation during 94-30 Ma corresponding to Middle Cretaceous flooding events (93.5 and 91.5 Ma) and the lack of sediment supply; and (3) since Late Oligocene time, unusually rapid sedimentation rates that characterize the deep water study area. These patterns of sediment accumulation directly affect the formation of allochthonous salt in the study area. 相似文献
4.
The Triassic through to the Middle Jurassic (Bathonian) stratigraphy of the Kerr McGee 97/12-1 exploration well is described using petrophysical logs, in association with lithological and palaeontological analyses. Over 6210′ of sediment was penetrated, with sixteen Triassic and fourteen Lower–Middle Jurassic sedimentary units recognised, with a total measured depth (T.D) of 7310′ within the Sherwood Sandstone Group, Budleigh Salterton Pebble Beds of Early/Middle Triassic, Olenekian/Anisian age. As expected the sedimentary sequences are comparable to those described from the Wessex Basin, especially the Portland–Wight and Dorset (sub) basins. Of particular note, however, is the very thick halite sequence (1074′) within the Carnian, Dunscombe Mudstone Formation and also an expanded “Paper Shales” (27′) sequence within the earliest Toarcian. A normal fault is noted at 1260′ with the Late Bajocian, Inferior Oolite Group in fault contact with the latest Toarcian, Bridport Sand Formation, Down Cliff Clay Member. The Late Triassic (Rhaetian) to Middle Jurassic (Bathonian) yielded rich microfaunal and palynomorph assemblages, all of which have been previously described throughout northwest Europe. Four microfossils groups (foraminifera, ostracods, dinocysts and miospores) have been used to interpret stratigraphic ages and palaeoenvironments.This study provides new lithological and microfossil data for the Triassic to Middle Jurassic (Bathonian) sequences preserved in the offshore Portland–Wight Basin and provides a key tie-point/reference section for future offshore drilling. 相似文献
5.
Stratigraphic division and depositional processes for the Mesozoic basin in Northern South China Sea
Guo-Qiang Xu Shi-Hu Wu Li Zhang Xiao-Gang Li Hai Yi Lei Lei Xun Xu 《Marine Geophysical Researches》2013,34(3-4):175-194
This paper divided the age of Mesozoic strata in the Northern South China Sea into epochs by the stratigraphic correlation between land and sea areas. A Mesozoic stratigraphic profile from South China to the northern continental slope of the South China Sea was constructed by ground and seismic surveys. The depositional process was illustrated by the chronostratigraphic framework of the Mesozoic basin, and the oil and gas exploration prospect was discussed. Results indicate that the depositional process from the initial transgression in the Late Triassic to the Mesozoic maximum flooding event that occurred in the Early Jurassic period formed a continuous transgression when the depositional environment varied from littoral to semi-closed gulf and shelf. After this maximum flooding event, a continuous marine regressive process developed, including seawater withdrawal from the South China epicontinental region at the end of the Early Jurassic period, seawater withdrawal to the outer shelf of the Northern South China Sea at the end of the Early Cretaceous period, and seawater withdrawal to the slope trough at the end of the Cretaceous period. Research achievement not only connects major Mesozoic geological events but also specifies the time nodes of such events. Thus, an investigation of this event is significant to the Mesozoic tectonic evolution study of the South China Sea and Paleo-Pacific Ocean. 相似文献
6.
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. 相似文献
7.
《Marine and Petroleum Geology》2012,37(1):140-153
The conventional interpretation of the Jurassic–Lower Cretaceous succession in the Porcupine Basin suggests an extensional setting with progressive deepening of the basin. However, well data show a prominent gap of several million years between the Upper Jurassic and Lower Cretaceous. A data base of 15 key wells and approximately 5,000 km of seismic reflection data were examined in the northern Porcupine Basin, in order to understand the nature, controls and mechanisms of this unconformity. Seven seismic markers, constrained by well data, are mapped. It is shown that during the Late Jurassic (possibly the Oxfordian–Kimmeridgian), the basin experienced extension and synrift deposition. During the latest Jurassic–earliest Cretaceous (possibly the Tithonian–early Berriasian), a series of north-trending structural highs and lows developed and extensive areas in the northern Porcupine Basin experienced folding, uplift and erosion. Evidence from the study suggests that compression, uplift and erosion played an important role in the shaping of the depositional and structural architecture of the basin and caused formation of the regional Base Cretaceous Unconformity in the northern basin. It is suggested that the deformation in the northern Porcupine Basin during the latest Jurassic–earliest Cretaceous may be related to the initial closure of the Alpine Tethys during the late Tithonian. This tectonic event may also have resulted in compressional deformation and formation of the Base Cretaceous Unconformity elsewhere in Western Europe. 相似文献
8.
The continental margin of Western Australia is a rifted or “Atlantic”-type margin, with a complex physiography. The margin comprises a shelf, an upper and lower continental slope, marginal plateaus, a continental rise, and rise or lower slope foothills. Notches or terraces on the shelf reflect pre-Holocene deposition of prograded sediment, whose seaward limit was determined by variations in relative sea level, wave energy, and sediment size and volume. The upper continental slope has four physiographic forms: convex, due to sediment outbuilding (progradation) over a subsiding marginal plateau; scarped, due to erosion of convex slopes; stepped, due to deposition at the base of a scarped slope; and smooth, due to progradation of an upper slope in the absence of a marginal plateau. Lying at the same level as the upper/lower slope boundary are two extensive marginal plateaus: Exmouth and Scott. They represent continental crust which subsided after continental rupture by sea-floor spreading. Differential subsidence, probably along faults, gave rise to the various physiographic features of the plateaus. The deep lower continental slope is broken into straight northeasterly-trending segments, that parallel the Upper Jurassic/Lower Cretaceous rift axis, and northwesterly-trending segments that parallel the transform direction. The trends of the slope foothills are subparallel to the rift direction. The four abyssal plains of the region (Perth, Cuvier, Gascoyne and Argo) indicate a long history of subsidence and sedimentation on Upper Jurassic/Lower Cretaceous oceanic crust. 相似文献
9.
Structural analysis of the Indian Merge 3D seismic survey identified three populations of normal faults within the Exmouth Sub-basin of the North West Shelf volcanic margin of Australia. They comprise (1) latest-Triassic to Middle Jurassic N-NNE-trending normal faults (Fault Population I); (2) Late Jurassic to Early Cretaceous NE-trending normal faults (Fault Population II); and (3) latest-Triassic to Early Cretaceous N-NNE faults (Fault Population III). Quantitative evaluation of >100 faults demonstrates that fault displacement occurred during two time periods (210–163 and 145–138 Ma) separated by ∼20 Myr of tectonic quiescence. Latest Jurassic to Early Cretaceous (145–138 Ma) evolution comprises magmatic addition and contemporaneous domal uplift ∼70 km wide characterised by ≥ 900 m of denudation. The areally restricted subcircular uplift centred on the southern edge of the extended continental promontory of the southern Exmouth Sub-basin supports latest Jurassic mantle plume upwelling that initiated progradation of the Barrow Delta. This polyphase and bimodal structural evolution impacts current hydrocarbon exploration rationale by defining the nature of latest Jurassic to Early Cretaceous fault nucleation and reactivation within the southern Exmouth Sub-basin. 相似文献
10.
Top seals and faults represent key risks to trap integrity and therefore preservation of hydrocarbons in the frontier Ceduna Sub-basin, offshore Southern Australia. Due to a paucity of well data in the basin, to provide constraint to the stratigraphic distribution of the prospective Cretaceous deltaic and marine sequences, stratigraphic forward modelling was utilised to create facies, grain size and Vshale volumes. These modelled Vshale volumes were subsequently used to investigate the structural control(s) on potential hydrocarbon leakage and migration within key stratigraphic sequences in the sub-basin.A set of coarse (20 km horizontal resolution), large scale (1100 × 600 km) stratigraphic forward models simulated the deposition of Late Jurassic to Tertiary stratigraphic sequences in the sub-basin with an initial 1 Ma interval. Smaller (80 × 60 km), finer scale (0.5 km horizontal resolution, 200 ka interval), models focussing on the Tiger and Hammerhead Supersequences over the Trim 3D seismic survey were used to investigate fault seal and top seal frameworks, using shale gouge ratio and silt and shale thicknesses from Vshale volume. Four stratigraphic forward models were produced to match a range of estimates of Vshale derived from the Gnarlyknots-1A well, the only well penetrating the central Ceduna Sub-basin. These stratigraphies were in turn integrated into a geological model interpreted from the Trim 3D seismic survey creating a geocellular model to test potential migration and trapping scenarios for potential hydrocarbons generated in the sub-basin.Fault and top seal models from the most likely scenario suggest (i) restricted potential for structural trapping near the base of the Tiger Supersequence, (ii) the possible presence of a regional migration pathway associated with sandy shoreface deposits at the transition between the Tiger and Hammerhead Supersequences, and (iii) the association of intraformational top seals and increasing fault seal potential in the deltaic sediments of the Hammerhead Supersequence feasibly resulting in a series of stacked structural traps. 相似文献
11.
During specific intervals within Mesozoic and Cenozoic times, several areas of the southwestern Barents Sea were subjected to uplift and erosion. Areas with missing shallow stratigraphic interval sections and major erosion can be seen at several places along interpreted regional profiles in the southwestern Barents Sea. A new Normal Compaction Trend (NCT) for two selected shale– and sandstone–dominated lithologies has been constructed based on sonic logs in the southwestern Barents Sea. The shale– dominated NCT is calibrated to the Cretaceous shales in the northern North Sea and Norwegian Sea and applied to the Cretaceous shales of the Barents Sea. The sandstone–dominated NCT is calibrated to the Lower Jurassic Åre Formation of the Norwegian Sea and applied to the Lower Jurassic–Upper Triassic coastal plain section in the Barents Sea. By utilising the NCT model, the study estimates net apparent erosion in 28 selected Barents Sea wells based on comparison of sonic log velocities. A net apparent erosion map of the study area was constructed by gridding of the well values. The accuracy of the map is limited in areas with little well control, such as in the northwest, where the east–west transition into the southwestern Barents Sea region is poorly constrained. With that in mind, the map clearly shows two regional trends which dominate the erosion pattern in the study area; an increasing amount of erosion towards the north and a sharp decrease of erosion westwards of the hinge zone into the southwestern Barents Sea. The highest erosion estimates are observed towards Svalbard, with values up to 2500 m. The results of this study can be further utilized in petroleum system studies in the eroded areas. 相似文献
12.
Michael B.W. Fyhn Lars H. Nielsen Lars O. Boldreel Le D. Thang Jørgen Bojesen-Koefoed Henrik I. Petersen Nguyen T. Huyen Nguyen A. Duc Nguyen T. Dau Anders Mathiesen Ian Reid Dang T. Huong Hoang A. Tuan Le V. Hien Hans P. Nytoft Ioannis Abatzis 《Marine and Petroleum Geology》2009
Seismic stratigraphic and structural analyses of the northwest Phu Khanh Basin, offshore Central Vietnam, based on 2-D seismic data, indicate that the initial rifting began during the latest Cretaceous? or Palaeogene controlled by left-lateral transtension along the East Vietnam Boundary Fault Zone (EVBFZ) and northwest–southeast directed extension east of the EVBFZ. Rifting stopped due to transpression during middle Oligocene times but resumed by left-lateral transtension during the Late Oligocene. Thick sequences of lacustrine and alluvial sediments were deposited during the Palaeogene rift periods. The Late Oligocene rifting ended due to inversion, triggered by right-lateral wrenching near the Palaeogene–Neogene boundary. Following the onset of this inversion regional uplift and volcanism took place in the southern half of the study area and contemporaneous subsidence and transgression took place farther north, leading to widespread carbonate deposition. As the right-lateral wrenching decreased during the early Neogene, thermal subsidence and siliciclastic sedimentation became dominant, resulting in the buildup and southward propagation of the shelf slope. Sediment accumulation and subsidence rates increased after the Middle Miocene times due to eastward tilting of Central Vietnam and the adjacent offshore area. 相似文献
13.
Several diagenetic models have been proposed for Middle and Upper Jurassic carbonates of the eastern Paris Basin. The paragenetic sequences are compared in both aquifers to propose a diagenetic model for the Middle and Late Jurassic deposits as a whole. Petrographic (optical and cathodoluminescence microscopy), structural (fracture orientations) and geochemical (δ18O, δ13C, REE) studies were conducted to characterize diagenetic cements, with a focus on blocky calcite cements, and their connection with fracturation events. Four generations of blocky calcite (Cal1–Cal4) are identified. Cal1 and Cal2 are widespread in the dominantly grain-supported facies of the Middle Jurassic limestones (about 90% of the cementation), whereas they are limited in the Oxfordian because grain-supported facies are restricted to certain stratigraphic levels. Cal1 and Cal2 blocky spars precipitated during burial in a reducing environment from mixed marine-meteoric waters and/or buffered meteoric waters. The meteoric waters probably entered aquifers during the Late Cimmerian (Jurassic/Cretaceous boundary) and Late Aptian (Early Cretaceous) unconformities. The amount of Cal2 cement is thought to be linked to the intensity of burial pressure dissolution, which in turn was partly controlled by the clay content of the host rocks. Cal3 and Cal4 are associated with telogenetic fracturing phases. The succession of Cal3 and Cal4 calcite relates to the transition towards oxidizing conditions during an opening of the system to meteoric waters at higher water/rock ratios. These meteoric fluids circulated along Pyrenean, Oligocene and Alpine fractures and generated both dissolution and subsequent cementation in Oxfordian vugs in mud-supported facies and in poorly stylolitized grainstones. However, these cements filled only the residual porosity in Middle Jurassic limestones. In addition to fluorine inputs, fracturation also permitted inputs of sulphur possibly due to weathering of Triassic or Purbeckian evaporites or H2S input during Paleogene times. 相似文献
14.
A series of Mesozoic rift basins formed in eastern China were associated with magmatic activity and subduction along the Eurasia, Izanagi and Pacific plate margins. The impact of magmatic activity on lacustrine sequence development was documented with well-log and 3-D seismic data from the Jupiter Depression in the North Yellow Sea Basin. We identified key surfaces, retrogradational and progradational parasequence sets, and defined the characteristics of systems tracts and the internal sequence components for the Lower Cretaceous (K1SQ1). A 2-D SEDPAK numerical stratigraphic forward modeling was used to further constrain sequence development in the Jupiter Depression by considering different modeling parameters and the spatial-temporal characteristics of magmatic activity. Modeling results were compared and matched with the sequence architecture observed from seismic and well interpretations. Magmatic activity impacts on the development of the K1SQ1 sequence in the North Yellow Sea Basin include topographic variation, lake level fluctuation, and sediment supply ratios. Results suggest that magmatic upwelling uplifted the northwestern area of the Jupiter Depression and formed its slope break during the late Jurassic or early Cretaceous. Along with uplifting, relative lake level dropped sharply and lake accommodation was reduced, but with increased sediment supply. Therefore, sediment accumulated along the slope break as a lowstand systems tract. Later on, as lake level continuously rose, transgressive and highstand systems tracts were developed. The proposed stacking pattern provides an analog, and a useful model, for lacustrine sequence development in response to magmatic activities in eastern China and other rift basins of similar tectonic setting. 相似文献
15.
C. Hübscher M.B. Hansen S.P. Triñanes H. Lykke-Andersen D. Gajewski 《Marine and Petroleum Geology》2010,27(4):923-938
The post-Permian sequence stratigraphical and structural evolution of the Northeastern German Basin and its transition onto the Baltic Shield has been studied in the Bay of Mecklenburg (SW Baltic Sea) by means of seismic interpretation. Five major sequences have been identified: Middle Triassic, Upper Triassic, Jurassic, Cretaceous and Cenozoic. Time–isochore maps allowed the identification of several phases of salt pillow growth. The contemporaneity of active salt tectonics and the well studied tectonic evolution of the Northeastern German Basin suggest a causative correlation. The E–W directed extension during the Triassic-Early Jurassic marking the beginning break-up of Pangaea is seen as the trigger process for the first period of salt movement. A fault system outside the limit of the Zechstein evaporates is understood as the consequence of thin-skinned faulting and brittle thick-skinned deformation that accompanied this extension. The observed pronounced erosion of Upper Triassic and Lower Jurassic strata is considered to result from the uplift due to the Mid North Sea Doming event in Middle Jurassic times. The seismic data show an undisturbed Late Cretaceous succession which reflects a period of rising sea level, tectonic quiescence and no salt movement. In contrast to the salt pillows which emerged above Triassic fault systems in the westernmost Baltic and western North German Basin, the Cenozoic salt movement activity is the most pronounced. This period of reactivated salt pillow growth started coevally with the onset of the Alpine orogeny at the Cretaceous/Cenozoic transition when the Africa-Arabian plate collided with Eurasia. Generally, no significant faults were identified in the overburden of the salt floored southern Bay of Mecklenburg where ductile Zechstein salt decouples deep rooted faulting from supra-salt deformation. 相似文献
16.
Evolution of the western Barents Sea 总被引：2，自引：0，他引：2
Jan Inge Faleide Steinar T. Gudlaugsson Gerard Jacquart 《Marine and Petroleum Geology》1984,1(2):123-150
Information from multichannel seismic reflection data complemented by seismic refraction, gravity and magnetics forms the basis for a regional structural and evolutionary model of the western Barents Sea during post-Caledonian times. The western Barents Sea contains a thick succession, locally > 10 km, of Upper Paleozoic to Cenozoic sedimentary rocks covering a basement of probably Caledonian origin. The area is divided into three regional geological provinces: (1) an east-west trending basinal province between 74°N and the coast of Norway; (2) an elevated platform area to the north towards Svalbard; and (3) the western continental margin. Several structural elements of different origin and age have been mapped within each of these provinces. The main stratigraphic sequence boundaries have been tentatively dated from available well information, correlation with the geology of adjacent areas, and correlation with the interregional unconformities caused by relative changes of sea level. The main structural elements were developed during three major post-Caledonian tectonic phases: the Svalbardian phase in Late Devonian to Early Carboniferous times, the Mid and Late Kimmerian phase in Mid Jurassic to Early Cretaceous times and Cenozoic tectonism related to the progressive northward opening of the Norwegian-Greenland Sea. The sediments are predicted to be of mainly clastic origin except for a thick sequence of Middle Carboniferous — Lower Permian carbonates and evaporites. Salt diapirs have developed in several sub-basins, especially in the Nordkapp Basin where they form continuous salt walls that have pierced through > 7 km of sediments. 相似文献
17.
The Fingerdjupet Subbasin in the southwestern Barents Sea sits in a key tectonic location between deep rifts in the west and more stable platform areas in the east. Its evolution is characterized by extensional reactivation of N-S and NNE-SSW faults with an older history of Late Permian and likely Carboniferous activity superimposed on Caledonian fabrics. Reactivations in the listric NNE-SSW Terningen Fault Complex accommodated a semi-regional rollover structure where the Fingerdjupet Subbasin developed in the hangingwall. In parallel, the Randi Fault Set developed from outer-arc extension and collapse of the rollover anticline.N-S to NNE-SSW faults and the presence of other fault trends indicate changes in the stress regime relating to tectonic activity in the North Atlantic and Arctic regions. A latest Triassic to Middle Jurassic extensional faulting event with E-W striking faults is linked to activity in the Hammerfest Basin. Cessation of extensional tectonics before the Late Jurassic in the Fingerdjupet Subbasin, however, suggests rifting became localized to the Hammerfest Basin. The Late Jurassic was a period of tectonic quiescence in the Fingerdjupet Subbasin before latest Jurassic to Hauterivian extensional faulting, which reactivated N-S and NNE-SSW faults. Barremian SE-prograding clinoforms filled the relief generated during this event before reaching the Bjarmeland Platform. High-angle NW-prograding clinoforms on the western Bjarmeland Platform are linked to Early Barremian uplift of the Loppa High. The Terningen Fault Complex and Randi Fault Set were again reactivated in the Aptian along with other major fault complexes in the SW Barents Sea, leading to subaerial exposure of local highs. This activity ceased by early Albian. Post-upper Albian strata were removed by late Cenozoic uplift and erosion, but later tectonic activity has both reactivated E-W and N-S/NNE-SSW faults and also established a NW-SE trend. 相似文献
18.
The Orange Basin records the development of the Late Jurassic to present day volcanic-rifted passive margin of Namibia. Regional extension is recorded by a Late Jurassic to Lower Cretaceous Syn-rift Megasequence, which is separated from a Cretaceous to present day post-rift Megasequence by the Late Hauterivian (ca. 130 Ma) break-up unconformity. The Late Cretaceous Post-rift evolution of the basin is characterized by episodic gravitational collapse of the margin. Gravitational collapse is recorded as a series of shale-detached gravity slide systems, consisting of an up-dip extensional domain that is linked to a down-dip zone of contraction domain along a thin basal detachment of Turonian age. The extensional domain is characterized by basinward-dipping listric faults that sole into the basal detachment. The contractional domain consists of landward-dipping listric faults and strongly asymmetric basinward-verging thrust-related folds. Growth stratal patterns suggest that the gravitational collapse of the margin was short-lived, spanning from the Coniacian (ca. 90 Ma) to the Santonian (ca. 83 Ma). Structural restorations of the main gravity-driven system show a lack of balance between up-dip extension (24 km) and down-dip shortening (16 km). Gravity sliding in the Namibian margin is interpreted to have occurred as a series of episodic short-lived gravity sliding between the Cenomanian (ca. 100 Ma) and the Campanian (ca. 80 Ma). Gravity sliding and spreading are interpreted to be the result of episodic cratonic uplift combined with differential thermal subsidence. Sliding may have also been favoured by the presence of an efficient detachment layer in Turonian source rocks. 相似文献
19.
渤海海域凹陷由于资料的限制,其沉积相研究多为宏观的区域性研究,制约了储层的精细解释。基于最新采集的高精度地震三维资料,结合地震地层学、层序地层学、地震沉积学等理论方法,开展渤中凹陷西斜坡BZ3-8区块东营组重点目的层,东二下层序高分辨率井震层序分析及其地震沉积学研究。结果表明,研究区南北两侧具有不同的物源体系和沉积相模式。低水位体系域(LST)和高水位体系域(HST)时期,研究区北部物源均形成扇形、朵形的地震多属性及振幅切片异常,对应于扇三角洲沉积;南部物源均形成NE向展布的条带状地震多属性及振幅切片异常,对应于辫状河三角洲沉积。海进体系域(TST)时期,湖平面快速上升导致扇体不发育,仅在研究区北部局部发育小规模的扇三角洲沉积。东二下层序LST(富砂)-TST(富泥)-HST(富砂)的岩相演化规律,充分反映了经典层序地层学理论层序格架中的地层岩相组合分布规律,对储层和烃源岩的预测具有指示意义。 相似文献
20.
This paper presents a detailed seismic analysis of a hitherto undescribed Permian succession interpreted to consist of interbedded anhydrite and carbonate from the northern flank of the Loppa High, western Barents Sea. The Fafner succession forms a locally restricted transgressive unit down-dip on the rotated Loppa High. It is subdivided into four seismic sequences each interpreted to be composed of a basal transgressive anhydrite overlain by highstand carbonates. Fafner seismic sequences 2 and 3 include well-developed buildup complexes which in map view form polygonal patterns.Analysis of attribute maps indicates that the Fafner succession is overprinted by two dissolution systems related to two prominent events of subaerial exposure, creating numerous paleo-sinkholes, breccia-pipes, and collapsed composite cavern systems.The stratigraphical position of the Fafner succession, below the Mid Sakmarian – Artinskian Bjarmeland Group and above the Top Ørn unconformity, resembles that of the Lower Permian Gipshuken Formation on Spitsbergen, and the Fafner succession is thus regarded as its offshore equivalent. 相似文献