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1.
西沙周缘新生代构造演化与盆地充填响应特征   总被引:1,自引:1,他引:0  
利用南海西沙周缘地震资料,进行了地震相研究,并结合邻区地质资料,进行了南海西沙周缘新生代沉积相分析,讨论了盆地的充填演化历史。研究认为,南海西沙周缘盆地充填断陷期以陆相和海陆过渡相沉积为主;坳陷期以海陆过渡相和海相沉积为主,自下而上充填了一套冲积相-湖相(始新统)-海陆交替相(渐新统)-滨浅海台地相(中-下中新统)-浅海、半深海相(上新统-第四系)沉积序列,盆地的充填历史反映了南海西沙周缘沉积环境由陆相向海相逐渐过渡的过程。通过对油气地质条件分析,认为始新世-渐新世早期是重要的烃源岩发育期;渐新世晚期-中新世中期是储层发育期;中新世晚期后是区域该层发育时期。  相似文献   

2.
Two depocentres, >4200 m and >3200 m thick, have been recognized in the Mesohellenic piggy-back basin of middle Eocene to middle Miocene age, where submarine fans have accumulated unconformably over an ophiolite complex. The hydrocarbon potential is indicated by the presence of kerogen types II/III with minor amounts of type I; the evidence is mostly for wet gas and gas, with minor oil. Source rocks are the middle Eocene to lower Oligocene Krania and Eptachori formations, of up to 2000 m total thickness, reaching maturation during the early Miocene. The source rocks consist of outer fan and basin plain deposits. They are conformably overlain by the lower member (late Oligocene) of the up to 2600 m thick Pentalophos Formation, which consists mostly of thick submarine sandstone lobes. Possible stratigraphically trapped reservoirs include the lower member of the Pentalophos Formation, which overlies source rocks, as well as limestones tectonically intercalated within the ophiolite complex, underlying the source rocks. Traps may have formed also on the western side of an internal thrust (Theotokos Thrust), which influenced the evolution of the depocentres.  相似文献   

3.
Using recently gathered onland structural and 2D/3D offshore seismic data in south and central Palawan (Philippines), this paper presents a new perspective in unraveling the Cenozoic tectonic history of the southeastern margin of the South China Sea. South and central Palawan are dominated by Mesozoic ophiolites (Palawan Ophiolite), distinct from the primarily continental composition of the north. These ophiolites are emplaced over syn-rift Eocene turbidites (Panas Formation) along thrust structures best preserved in the ophiolite–turbidite contact as well as within the ophiolites. Thrusting is sealed by Early Miocene (∼20 Ma) sediments of the Pagasa Formation (Isugod Formation onland), constraining the younger limit of ophiolite emplacement at end Late Oligocene (∼23 Ma). The onset of ophiolite emplacement at end Eocene is constrained by thrust-related metamorphism of the Eocene turbidites, and post-emplacement underthrusting of Late Oligocene – Early Miocene Nido Limestone. This carbonate underthrusting at end Early Miocene (∼16 Ma) is marked by the deformation of a seismic unit corresponding to the earliest members of the Early – Middle Miocene Pagasa Formation. Within this formation, a tectonic wedge was built within Middle Miocene (from ∼16 Ma to ∼12 Ma), forming a thrust-fold belt called the Pagasa Wedge. Wedge deformation is truncated by the regionally-observed Middle Miocene Unconformity (MMU ∼12 Ma). A localized, post-kinematic extension affects thrust-fold structures, the MMU, and Late Miocene to Early Pliocene carbonates (e.g. Tabon Limestone). This structural set-up suggests a continuous convergent regime affecting the southeastern margin of the South China Sea between end Eocene to end Middle Miocene. The ensuing structures including juxtaposed carbonates, turbidites and shallow marine clastics within thrust-fold belts have become ideal environments for hydrocarbon generation and accumulation. Best developed in the Northwest Borneo Trough area, the intensity of thrust-fold deformation decreases towards the northeast into offshore southwest Palawan.  相似文献   

4.
Four specimens of the thyasirid Conchocele bisecta (Conrad) and one small specimen of the vesicomyid Hubertschenckia ezoensis (Yokoyama), each with a drill hole made by a naticid gastropod, were found at a cold‐seep site in the upper Eocene Poronai Formation of Hokkaido. This is apparently the oldest record not only of drill holes, but also of predation scars, in a cold‐seep fauna. In addition, drilled vesicomyids are known from several Miocene cold‐seep sites in Japan. We suggest that the Eocene and Miocene chemoautotrophic bivalves were drilled only in the shallow‐water settings preferred by most naticids. The lack of drill holes in Oligocene chemoautotrophic bivalves in the northwestern USA suggests that this innovation, which allowed naticids to prey upon highly toxic bivalves, first appeared in the western Pacific during the Eocene.  相似文献   

5.
This paper discusses origin and charging directions of oil fields on the Shaleitian Uplift, Bohai Bay basin. The Shaleitian Uplift is a footwall uplift surrounded by three sags containing mature source rocks. The origins of the four oil fields on the Shaleitian Uplift, both in terms of source rock intervals and in terms of generative kitchens, were studied using biomarker distributions for 61 source rock samples and 27 oil samples. Hierarchical cluster analysis using 12 parameters known to be effective indicators of organic matter input and/or depositional conditions allowed the identification of six oil types or classes. These six oil classes could then be linked to three distinct source rock intervals ranging in age from 43.0 Ma to 30.3 Ma. The third member (43.0–38.0 Ma in age) and first member (35.8–32.8 Ma) of the Eocene Shahejie Formation, and the third member of the Oligocene Dongying Formation (32.8–30.3 Ma) each sourced one class of oil. The other three classes represent mixtures of oil generated from multiple source rock intervals. Traps on the Shaleitian Uplift were charged in the east by oil generated from the Eocene Shahejie Formation in the Bozhong Sag, in the southeast by oil generated from the Eocene Shahejie and then Oligocene Dongying formations in the southwestern part of the Bozhong Sag and/or in the eastern part of the Shanan Sag, and in the southwest by oil generated from the Eocene Shahejie Formation in the western part of the Shanan Sag. The estimated migration distances range from less than 5 km to about 20 km. The compositional heterogeneity within fields and multiple-parameter comparisons between oils from nearby wells in different fields have proven to be a powerful tool to determine the in-filling histories of oil fields in cases where multiple source rock intervals and multiple generative kitchens exist.  相似文献   

6.
The Middle Eocene deposits in the Fayoum Ranges are composed of complex alternative clastic (claystone and sandstone) and carbonate (limestone and dolostone) facies and dominated carbonate (limestone) facies. Facies are arranged mainly in regression and shallowing upward (emergence) cycles and sequences. Field stratigraphic and microfacies analysis of the study area permits recognition of four major sequences, reflecting 3rd-order cycles. Depositional sequences and cycles are bounded by subaerial erosive surfaces or caliche deposits, ferruginous crust, and by their correlative conformities. Sequence-1 consists of two shallowing-upward cycles (dominate carbonate facies), each of which starts with nummulitic wackestone, capped with nummulitic packstone including Globigerinatheka subconglobata subconglobata biozone. These cycles were deposited under tropical to subtropical conditions as evidenced by the carbonate nature of the rocks and the abundance of nummulites, which need warm conditions for their flourishing. Sequence-2 consists of four emergence cycles based with claystone and capped with wackestone including Morozovella lehneri biozone. The duration (Ma) of sequence-2 (Morozovella lehneri zone) is 3.05 Ma (44.25 Ma for the upper of TA3 3.3 to 41.2 Ma for the lower of TA3 3.5). Sequence-3 includes three rock units (includes Trucorotaloides rohri biozone). The lower unit involves lowstand systems tract, the middle unit contains transgressive systems tract and the upper rock unit includes highstand systems tract. The lowstand systems tract consists of emergence cycles of mixed clastic- carbonate facies, clays at the base and capped with wackestone and packstone facies. The transgressive systems tract consists of dominant carbonate facies, wackestone at the base and capped with packstone facies. Sequence 4 involves transgressive systems tract. The duration of both sequence-3 and sequence 4 has been estimated as 1.8 Ma.  相似文献   

7.
苏北盐城凹陷复合含油气系统   总被引:1,自引:0,他引:1  
苏北盐城凹陷含油气系统可划分为上、下2个复合含油气系统。上复合含油气系统,即Pz、K2p、K2t(生)-K2t、E1f1(储)一E1f1 E1f2(盖),古生界、中生界浦口组和泰州组为烃源岩层,泰州组和阜宁组一段为储集层,阜宁组一段顶部至二段暗色泥岩为区域盖层,油气沿深大断裂运移,油气成藏关键时刻在古近纪晚期至新近纪早期,有利勘探区在深大断裂附近的中、新生界发育地区;下复合含油气系统,即Pz、K2p(生)-Pz、K2p(储)-K2p3 K2p4(盖),油气通过断层或不整合运移,油气大量生成的关键时刻为古近纪早期,该系统中气藏分布在古生界被中生界覆盖地区。  相似文献   

8.
The Late Miocene Zeit Formation is exposed in the Red Sea Basin of Sudan and represents an important oil-source rock. In this study, five (5) exploratory wells along Red Sea Basin of Sudan are used to model the petroleum generation and expulsion history of the Zeit Formation. Burial/thermal models illustrate that the Red Sea is an extensional rift basin and initially developed during the Late Eocene to Oligocene. Heat flow models show that the present-day heat flow values in the area are between 60 and 109 mW/m2. The variation in values of the heat flow can be linked to the raise in the geothermal gradient from margins of the basin towards offshore basin. The offshore basin is an axial area with thick burial depth, which is the principal heat flow source.The paleo-heat flow values of the basin are approximately from 95 to 260 mW/m2, increased from Oligocene to Early Pliocene and then decreased exponentially prior to Late Pliocene. This high paleo-heat flow had a considerable effect on the source rock maturation and cooking of the organic matter. The maturity history models indicate that the Zeit Formation source rock passed the late oil-window and converted the oil generated to gas during the Late Miocene.The basin models also indicate that the petroleum was expelled from the Zeit source rock during the Late Miocene (>7 Ma) and it continues to present-day, with transformation ratio of more than 50%. Therefore, the Zeit Formation acts as an effective source rock where significant amounts of petroleum are expected to be generated in the Red Sea Basin.  相似文献   

9.
位于主动大陆边缘的缅甸安达曼海域中部天然气资源丰富,成因多样。天然气成因类型直接影响勘探领域与方向的确定。通过气体组分、CH4和CO2碳同位素资料,对缅甸安达曼海域中部天然气成因类型及气源岩进行了判识。结果表明:上新统部分天然气具有较轻CH4碳同位素,为生物成因气,部分碳同位素较重的天然气属于热成因气;中新统及渐新统天然气CH4碳同位素均较重,属于热成因气;CO2碳同位素显示其存在无机、有机2种成因;此外,还存在少量生物气与热成因气或无机气的混源气。认为该区无机成因CO2与CH4共存体系通过基底断裂来源于地壳深部或上地幔;上新统生物气来自上新统未熟源岩;产于上新统、中新统热成因气,来源于上新统下部、中新统或渐新统上部等深层高-过成熟烃源岩。  相似文献   

10.
泰国湾区域经历了前裂谷期、裂谷期、裂后期的构造演化阶段,形成了多个裂谷盆地。泰国湾区域东北部在渐新世经历了一次明显构造反转,较泰国湾区域大部分地区强烈。通过对比区内钻井,结合地震解释,对该区的沉积特征和构造演化进行了分析,认为这次反转构造导致了反转构造带上构造、沉积特征与邻区有较大的不同。由于这次反转构造,泰国湾东北部在新层系发育新类型的油气系统,即深部的始新统油气系统:烃源岩为中始新统湖相泥岩,储层为上始新统-渐新统三角洲相砂岩,盖层为下中新统三角洲前缘相泥岩和上中新统以上的海相泥岩。该油气成藏系统已被钻井钻遇油气显示,是本区有效油气成藏系统。  相似文献   

11.
This study provides the results of the first integrated study of Oligocene–Pliocene basins around Norway.Within the study area, three main depocentres have been identified where sandy sediments accumulated throughout the Oligocene to Early Pliocene period. The depocentre in the Norwegian–Danish Basin received sediments from the southern Scandes Mountains, with a general progradation from north to south during the studied period. The depocentre in the basinal areas of the UK and Norwegian sectors of the North Sea north of 58°N received sediments from the Scotland–Shetland area. Because of the sedimentary infilling there was a gradual shallowing of the northern North Sea basin in the Oligocene and Miocene. A smaller depocentre is identified offshore northern Nordland between Ranafjorden (approximately 66°N) and Vesterålen (approximately 68°N) where the northern Scandes Mountains were the source of the Oligocene to Early Pliocene sediments. In other local depocentres along the west coast of Norway, sandy sedimentation occurred in only parts of the period. Shifts in local depocentres are indicative of changes in the paleogeography in the source areas.In the Barents Sea and south to approximately 68°N, the Oligocene to Early Pliocene section is eroded except for distal fine-grained and biogenic deposits along the western margin and on the oceanic crust. This margin was undergoing deformation in a strike-slip regime until the Eocene–Oligocene transition. The Early Oligocene sediments dated in the Vestbakken Volcanic Province and the Forlandssundet Basin represent the termination of this strike-slip regime.The change in the plate tectonic regime at the Eocene–Oligocene transition affected mainly the northern part of the study area, and was followed by a quiet tectonic period until the Middle Miocene, when large compressional dome and basin structures were formed in the Norwegian Sea. The Middle Miocene event is correlated with a relative fall in sea level in the main depocentres in the North Sea, formation of a large delta in the Viking Graben (Frigg area) and uplift of the North and South Scandes domes. In the Norwegian–Danish Basin, the Sorgenfrei-Tornquist Zone was reactivated in the Early Miocene, possibly causing a shift in the deltaic progradation towards the east. A Late Pliocene relative rise in sea level resulted in low sedimentation rates in the main depositional areas until the onset of glaciations at about 2.7 Ma when the Scandes Mountains were strongly eroded and became a major source of sediments for the Norwegian shelf, whilst the Frigg delta prograded farther to the northeast.  相似文献   

12.
Rock fragments dredged from four R/VNatsushima stations contain Tertiary foraminifera. The oldest sample is an upper bathyal biomicrite of Early Eocene age (52 to 53.5 Ma) from the the Trobriand Platform. Upper Oligocene-Lower Miocene neritic limestones were located off the Trobriand Platform and on the inner wall of the New Britain Trench. Miocene bathyal sediments come from the Trobriand Platform; similar Pliocene rocks were recovered here as well as from the inner wall of the New Britain Trench and the central part of the Solomon Sea Basin. No reworked pre-Tertiary foraminifera are present in any sample.  相似文献   

13.
We present new biostratigraphic analyses of approximately 200 outcrop samples and review biostratigraphic data from 136 public domain exploration wells across western New Guinea. Biostratigraphic ages and palaeodepositional environments were interpreted from occurrences of planktonic and larger benthic foraminifera, together with other fossils and environmental indicators where possible. These data were compared with existing geological maps and exploration well data to reconstruct the palaeogeography of western New Guinea from the Carboniferous to present day. In addition, we used the known bathyal preferences of fossils to generate a regional sea-level curve and compared this with global records of sea-level change over the same period. Our analyses of the biostratigraphic data identified two major transgressive-regressive cycles in regional relative sea-level, with the highest sea levels recorded during the Late Cretaceous and Late Miocene and terrestrial deposition prevalent across much of western New Guinea during the Late Paleozoic and Early Mesozoic. An increase in the abundance of carinate planktonic foraminifera indicates a subsequent phase of relative sea-level rise during a regional transgressive event between the Late Jurassic and Late Cretaceous. However, sea-levels dropped once more during a regressive event between the Late Cretaceous and the Paleogene. This resulted in widespread shallow water carbonate platform development in the Middle to Late Eocene. A minor transgressive event occurred during the Oligocene, but this ceased in the Early Miocene, likely due to the collision of the Australian continent with intra-Pacific island arcs. This Miocene collision event resulted in widespread uplift that is marked by a regional unconformity. Carbonate deposition continued in platforms that developed in shallow marine settings until these were drowned during another transgressive event in the Middle Miocene. This transgression reached its peak in the Late Miocene and was followed by a further regression culminating in the present day topographic expression of western New Guinea.  相似文献   

14.
The Oligocene Ruslar Formation is a hydrocarbon source rock in the Kamchia Depression, located in the Western Black Sea area. Depositional environment and source potential of the predominantly pelitic rocks were investigated using core and cuttings samples from four offshore wells. In these wells the Ruslar Formation is up to 500 m thick. Based on lithology and well logs, the Ruslar Formation is subdivided from base to top into units I–VI. Dysoxic to anoxic conditions and mesohaline to euhaline salinities prevailed during deposition of the Ruslar Formation. Relatively high oxygen contents occurred during early Solenovian times (lower part of unit II), when brackish surface water favoured nannoplankton blooms and the deposition of bright marls (“Solenovian event”). Anoxic conditions with photic zone anoxia were established during late Oligocene times (units III and IV) and, probably, reflect a basin-wide anoxic event in the Eastern Paratethys during Kalmykian times. Organic carbon content in the Ruslar Formation is up to 3%. Autochthonous aquatic and allochthonous terrigenous biomass contribute to the organic matter. Relatively high amounts of aquatic organic matter occur in the lower part of the Ruslar Formation (units I and II) and in its upper part (unit VI). Diatoms are especially abundant in the lower part of unit VI. The kerogen is of type III and II with HI values ranging from 50 to 400 mgHC/gTOC. Units I and II (Pshekian, lower Solenovian) are characterized by a fair (to good) potential to produce gas and oil, but potential sources for gas and oil also occur in the Upper Oligocene units IV–VI.  相似文献   

15.
The Baram Delta Province is located in the northern part of Sarawak (West Baram Delta) and extends north-eastward into Brunei and further into the south-western part of Sabah (East Baram Delta). The delta is a Neogene basin which developed over an accretionary wedge implying Cretaceous to Eocene sediments during the Late Eocene to Late Miocene times (Tongkul, 1991; Hutchison et al., 2000; Morley et al., 2003; Sapin et al., 2011).Facies and well log analyses were carried out on core and well data for the Late Miocene successions of Baram field, a medium-sized oilfield located in the north-eastern flank of the Baram Delta Oil Province, offshore Sarawak. A numerical model of sea-level fluctuations and progradational basin-fill was generated using the Clastic Modeling Program (Hardy and Waltham, 1992a and 1992b; Waltham, 1992) software to evaluate the possible controls of sea-level changes in the development of the siliciclastic successions and their bounding surfaces. This model was based on four lines of evidence, namely core data, fieldwide wireline logs correlation, seismic sections and average thickness variations across the field.Cored intervals of the Upper Cycle V (Late Miocene) display reservoir successions dominated by thick swaley cross-stratified (SCS) sandstones, thin hummocky cross-stratified sandstones and other shallow marine, wave and storm-dominated facies, interbedded with laminated shelfal mudstones. The vertical facies organisation suggests deposition during shoreface progradation associated with a fall of relative sea level.Analysis and correlation of well logs reveal stacking patterns comprising three scales of depositional cyclicity: the parasequences (∼10–∼30 m thick), the parasequence sets (∼45–∼130 m thick) and the major cycles (∼600–800 m thick).Field-wide, dip-oriented seismic sections show very well-developed horizontal to slightly upward convex layers traceable over great distances, which suggests a ramp-type margin, in which the basin floor dipped gradually seaward and lacked a distinct shelf-slope margin.The evidences gathered demonstrate that the deposition and build-up stratigraphy of the Late Miocene sedimentary successions could have been strongly controlled by superimposed short-term, medium-term and long-term sea-level changes.The simulated sea level and sedimentary basin-fill model, generated by the Clastic Modelling Program, match to the well log correlation. This model illustrates that high frequency sea-level fluctuations enable sands to be distributed over large areas within a shallow, low gradient shelf. Our study shows that integrated studies incorporating cores, well logs, seismic sections and simulated models can be employed as important tools for correlation and reservoir modelling.  相似文献   

16.
法尔维海盆位于西南太平洋海域豪勋爵海丘东侧、新喀里多尼亚岛西侧,是全球油气勘探的前沿地区。但目前对于该海盆的构造演化研究较为薄弱,限制了该海盆油气资源的进一步勘探开发。本文通过从新西兰塔斯曼海数据库搜集到大量地球物理资料,使用2D Move软件,通过平衡剖面技术进行构造演化模拟,结合区域动力学机制将海盆北部和南部的构造演化分为7个阶段:(1)早白垩世至晚白垩世陆内裂谷阶段;(2)晚白垩世断坳过渡阶段;(3)始新世早期坳陷阶段;(4)始新世晚期一次构造反转阶段;(5)始新世至渐新世热沉降阶段;(6)渐新世至中新世二次构造反转阶段;(7)中新世至今海洋沉降阶段。由于海盆中部未发现有明显的二次构造反转阶段,所以将海盆中部的构造演化划分为5个阶段:(1)早白垩世至晚白垩世陆内裂谷阶段;(2)晚白垩世断坳过渡阶段;(3)始新世早期坳陷阶段;(4)始新世晚期构造反转阶段;(5)中新世至今海洋沉降阶段。此阶段海盆整体下坳,逐渐形成现今样貌。法尔维海盆北部受到区域构造活动影响较大,白垩系地层发育较多的断裂构造;海盆中部晚白垩统地层发生较多的底辟构造;海盆南部从形成至今,受到构造活动影响较小,发育地层完整,前新生代地层较厚。整个法尔维海盆北部构造活动较强,中部较弱,南部较小。沉积地层从北到南由厚变薄。  相似文献   

17.
The Late Devonian to Early Mississippian Bakken Formation in the Williston basin of North Dakota, USA, shows a tri-partite subdivision: a middle mixed carbonate-siliciclastic member is sandwiched in-between two black siliciclastic mudstones, the lower and upper Bakken member shales. However, the transition from the lower shale member to the middle member does not represent a gradual coarsening but contains in places several millimeter - to centimeter-thick siliciclastic mudstones and carbonates that consist of three facies: (1) a glauconitic carbonate-rich siliciclastic mudstone, (2) a carbonate mud-to wackestone, and (3) an echinoderm wacke-to packstone with shell fragments. These three facies are present in many (all?) of the cores close and directly in the basin center in Mountrail County, North Dakota. At least one of these three facies is present in all 23 cores included in this study.This thin carbonate unit at the transition between the lower and the middle Bakken members is interpreted as representing the remnants of the transgressive systems tract. It is assumed that relative sea-level fell before deposition of the middle Bakken member establishing a proximal coarse-grained to distal fine-grained depositional transect that successively migrated into the basin. During the subsequent transgression, the siliciclastic input was low to absent, and the entire sedimentary system switched to depositing carbonates. The proximal to distal transect during this time showed coarse-grained packstones (and grainstones?) close to the shoreline, and a fining outwards towards the distal parts of the basin. This transgression also eroded what remained of the regressive and most of the subsequent transgressive sediments, leaving only the thin carbonate layer behind. Evidence for the regression, even though no sediment is directly preserved along the lower to middle Bakken member contact, comes from the fill of clastic dykes that cut through the lower Bakken member shale. The fill of the clastic dykes is partly siliciclastic and partly carbonate and not similar to any of the surrounding sediment. This indicates that these dykes must have originated before the middle Bakken member was deposited, yet the overlying sediment must have been carbonate at some point and siliciclastic another time. As it is not present anymore, this sediment must have been entirely removed by erosion.The here presented model suggests that the Bakken Formation reflects two entire sea-level oscillations. The first encompasses the lower Bakken member shale and the siliciclastic regressive portion of the lowstand only preserved as infill of the clastic dykes. The subsequent transgression deposited the carbonates now blanketing the lower to middle Bakken member transition, and the highstand and subsequent regression plus lowstand are represented by the middle Bakken member. The transgressive surface and therewith the onset of the topmost Bakken transgression is marked by the transition from the middle to the upper Bakken shale member.  相似文献   

18.
中、新生代华南陆缘离散地块的基本特征及演化过程   总被引:3,自引:0,他引:3  
华南陆缘晚中生代以来大规模的地块离散运动形成了华南陆缘离散地块-地堑系,其演化过程可分为K_2—E_1~3,E_2~1—E_3~1,E_3~2—N_1~1和N_1~2—Q等四个阶段。南海即是该陆缘离散地块-地堑系演化的产物。  相似文献   

19.
张镇海 《台湾海峡》1991,10(1):85-92
本文根据近年对福建邻近海域油气普查成果,研究了福建东部海域的油气构造,认为福建东部海域新生代沉积的基底面,由大陆向海倾斜延伸,其间形成较厚的新生代沉积,有厦门、乌丘屿、东引岛盆地和九龙江、晋江、韩江等构造凹陷。提出了可能存在的油气储层为古新统、渐新统、中新统,可能存在“新生古储”和“古生新储”等组合,对佛昙群还应注意“自生自储”的可能性。各时代地层中的泥岩、页岩及孔渗条件较差的玄武岩则作为盖层。  相似文献   

20.
The increase of total organic carbon content of the late Oligocene-early Miocene terrigenously-dominated marine shales in the shallower depth intervals was reported in the Ying-Qiong Basin, South China Sea. The organic enriched lower Sanya Formation shales(early Miocene) have biomarker characteristics of tropical/subtropical plants, with abundant high molecular weight n-alkanes, angiosperm-derived oleanane,rearranged oleananes Ⅰ, Ⅱ, Ⅱ, tricyclic/tetracyclic terpanes including des-A-oleanane, X, ...  相似文献   

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