珠江口盆地中部珠海组—珠江组层序结构及沉积特征

南海北部珠江口盆地珠海组分为SQ32、SQ25.5两个三级层序,珠江组划分为SQ23.8、SQ21、SQ17.5和SQ16.5四个三级层序,其中前3个层序分为水进域、高位域,后3个层序分为低位域、水进域和高位域。珠江组初期的白云运动使珠海组的浅水陆架环境变更为珠江组的陆架-陆坡沉积环境,造就了古地貌的更迭、层序界面的形成和沉积相的突变。层序界面在陆架主要为粗粒沉积物形成的侵蚀界面、浅水暴露界面,而陆坡为下切水道、丘状扇体底部侵蚀界面和滑塌层。层序的更迭使古珠江三角洲物源供给强度呈现强-弱-强-弱的特点,即珠海组时期的三角洲为陆架三角洲,沉积规模大;之后珠江组物源变弱,珠江组各层序低位域形成陆架边缘三角洲,水进域、高位域演化为陆架三角洲。低位期的三角洲前缘带越过坡折带沉积,并与陆架外的峡谷水道相连,三角洲进积、加积的碎屑沉积物向上陆坡内的白云凹陷内沉积,形成深水扇。因此,相对海平面变化、构造升降和沉积物供给强度控制着层序结构和沉积体展布。     

Three-dimensional facies architecture analysis using sequence stratigraphy and seismic sedimentology: Example from the Paleogene Dongying Formation in the BZ3-1 block of the Bozhong Sag,Bohai Bay Basin,China

The Bohai Bay Basin is a classic non-marine rift basin in eastern China. The Paleogene Dongying sequences are the main hydrocarbon-bearing stratigraphic unit in the basin. Using three-dimensional (3-D) seismic data and one well control in the BZ3-1 Block in the western slope of the Bozhong Sag, we analyzed 3-D facies architectures of the Dongying sequences. The Dongying Formation, a second-order sequence, can be subdivided into four third-order sequences (from base to top: SQ1, SQ2, SQ3, and SQ4). The facies architecture was analyzed by using the seismic sedimentology approach based on 3-D seismic data. Sediment of the Dongying sequences was derived from the northern Shijiutuo Uplift via four major configurations of incised valleys, namely “V”, “U”, “W”, and composite shaped incised valleys. Seismic stratal slices reveal branching and converging characteristics of the channels from upstream to downstream. On the basis of an integrated analysis of well log, core data, seismic facies based on multi-seismic attributes, three sedimentary facies (e.g., “delta”, “fan-delta”, and “shore” or “shallow lacustrine” facies) have been recognized. The four types of incised valleys and their evolution control the sedimentary systems in the sedimentation area. The numbers and sizes of the fans are controlled by the sedimentary systems at various scales. Incised valley-fill and deltaic sand bodies are excellent hydrocarbon reservoirs and potentially good exploration targets for the study area. The reservoir quality of sequences SQ1, SQ2, and SQ3 become better gradually from base to top. The proposed sediment dispersal patterns may aid in the prediction of potential reservoir distribution. This study also demonstrates that facies architecture analysis using sequence stratigraphy and seismic sedimentology may serve as an effective approach for constructing 3D facies models for petroleum exploration in areas lacking of well or outcrop data.     

Lower Cretaceous lacustrine successions,North Yellow Sea Basin,eastern China: Rift basin sequence stratigraphy and stacking patterns in response to magmatic activity

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.     

Aggrading and prograding infill of a peri-Tyrrhenian Basin (Naples Bay, Italy)

High-resolution seismic reflection data are used in the identification of the stratigraphic succession filling Naples Bay, a tectonically active half-graben located in the extensional margin of the eastern Tyrrhenian Sea. The architecture of the basin infill is characterized by fourth-order depositional sequences correlated to Quaternary eustatic oscillations. These depositional sequences form aggrading and prograding stacking patterns bounded by tectonically enhanced unconformities. The changes that the stacking patterns undergo record variations in accommodation space rates. These variations are a result of the tectonic subsidence produced during the evolution of the half-graben. Received: 7 July 1998 / Revision received: 29 March 1999     

Tectono-stratigraphy of Lower Cretaceous Tanan sub-basin,Tamtsag Basin,Mongolia: Sequence architecture,depositional systems and controls on sediment infill

Tanan sub-basin is an active-fault bounded basin. The spatial distribution and temporal evolution of depositional systems were significantly influenced by tectonics. Fault movement and stages of basin development controlled the subsidence rates and the potential for erosion and the rate of sediment supply. Distinct stages of rift evolution during the early Cretaceous can be recognized, namely the early syn-rift, rift climax and late syn-rift stages. Three types of lacustrine sequence, consisting of distinctive depositional systems, are distinguished: (1) the early syn-rift sequences (SQ1 + SQ2), which are composed mainly of fan delta and shallow lacustrine depositional systems; (2) the rift climax sequences (SQ3) which developed in response to rapid and differential tectonic subsidence rates, and consist of fan delta, deep lacustrine and sublacustrine fan depositional systems; and (3) the late syn-rift sequences (SQ4) which are comprised of braided-delta and shallow lacustrine depositional systems. Each of the three lacustrine sequence architectures stands for a particular stage of basin fill and reflects variable rates of basin subsidence. Within each sequence, depositional systems and their stacking patterns are interpreted to have been a function of the interaction between tectonics and sediment supply. Differential subsidence across the basin, related to rotation of fault blocks, resulted in the formation of distinct paleomorphologies in different structural settings. These settings were fault-scarp zones controlling the development of fan-deltas, fault-terrace zones controlling the development of fan-delta and sublacustrine fans, half-graben dip-slope zones controlling the development of braided river and braided deltas, and intra-basinal fault-break zones controlling the development of sublacustrine fans. During the late syn-rift stage, active tectonism, displacement on the boundary faults had ceased. At this stage the depositional systems and their stacking patterns were dominantly related to the sediment supply rates, and not to tectonic activity.     

Sedimentology and depositional architecture of tidal compound dunes on a carbonate ramp: The lower Miocene deposits of the central Apennine (Latium,Italy)

The sedimentology and sequence stratigraphy of the central Apennine lower Miocene carbonate deposits (Guadagnolo Formation) are the goal of this paper. The Guadagnolo carbonate ramp deposits consist of a thick succession of three main lithofacies: marls, marly limestones and cross-bedded limestones. The lateral and vertical facies distribution, as well as the biota assemblages, suggests a deposition of these sediments along the middle-outer ramp sector of the Latium-Abruzzi carbonate platform. All the data suggest sedimentation under the influence of tidal currents that were responsible of bedforms generation as simple and compound dunes. These bodies are developed on metric and decametric scale, and are stacked one to other to form complex sedimentary bodies extending both in strike and dip section for several tens to hundred meters. The dune system developed in a semiclosed basin (the Paleoadriatic sea), open in the southern and closed in the northern sector respectively. Within this basin a probably amphidromic system developed. The flow sediment transport was dominantly westward, and was conditioned by the ramp paleotopography. From a sequence stratigraphic point of view several high and low rank depositional sequences that were differentiated basing on their relative physical scale (thickness of each unit) and on the lateral extension of the unconformities and the correlative conformities bounding them were recognized. The hierarchy of recognized sequence-stratigraphic units include, from the smallest to the largest: simple depositional sequences, low-rank composite depositional sequences and high-rank composite depositional sequences. In the Guadagnolo succession four high-rank composite depositional sequences having a duration variable from 0.9 to 1.6 Ma, and named Guadagnolo 1, 2, 3, and 4, were recognized. These high-rank composite sequences are internally constituted by a stacking of simple and low-rank composite depositional sequences, having a duration ranging from 40 ka to 200 ka. All these units constitute part of a higher-rank composite sequence developing between 21 and 14.80 Ma that we name “The Guadagnolo Depositional Sequence”. The wedge-shaped geometry, the thickness variation and the stacking pattern of the Guadagnolo succession are the response to eustasy and tectonic subsidence. The glacial eustasy mostly controlled the formation of the high-frequency depositional sequences, tectonic subsidence, related to the roll-back of the hinge west-directed subduction in turn connected to the advancement of the Apennine thrust modulated the accommodation space.     

Sedimentary facies associations and sequence stratigraphy of source and reservoir rocks of the lacustrine Eocene Niubao Formation (Lunpola Basin,central Tibet)

The Eocene Niubao Formation of the Lunpola Basin, a large Cenozoic intermontane basin in central Tibet, is an important potential hydrocarbon source and reservoir unit. It represents ∼20 Myr of lacustrine sedimentation in a half-graben with a sharply fault-bounded northern margin and a low-angle flexural southern margin, resulting in a highly asymmetric distribution of depositional facies and sediment thicknesses along the N-S axis of the basin. An integrated investigation of well-logs, seismic data, cores and outcrops revealed three third-order sequences (SQ1 to SQ3), each representing a cycle of rising and falling lake levels yielding lowstand, transgressive, and highstand systems tracts. Lowstand systems tracts (LST) include delta and fan delta facies spread widely along the gentle southern margin and concentrated narrowly along the steep northern margin of the basin, with sublacustrine fan sand bodies extending into the basin center. Highstand systems tracts (HST) include expanded areas of basin-center shale deposition, with sublacustrine fans, deltas and fan deltas locally developed along the basin margins. Sequence development may reflect episodes of tectonic uplift and base-level changes. The southern margin of the basin exhibits two different structural styles that locally influenced sequence development, i.e., a multi-step fault belt in the south-central sector and a flexure belt in the southeastern sector. The sedimentary model and sequence stratigraphic framework developed in this study demonstrate that N2 (the middle member of Niubao Formation) exhibits superior hydrocarbon potential, characterized by thicker source rocks and a wider distribution of sand-body reservoirs, although N3 (the upper member of Niubao Formation) also has good potential. Fault-controlled lithologic traps are plentiful along the basin margins, representing attractive targets for future exploratory drilling for hydrocarbons.     

珠江口盆地白云凹陷早中新世深水层序模式

近年来深水勘探已成为寻找油气的重要领域,白云凹陷在早中新世经历了复杂的构造沉积环境,解剖深水层序模式有利于揭示深水沉积演化规律。通过井震结合及属性分析对白云凹陷早中新世层序地层进行研究,识别出3个层序界面:ZJSB1(23.8 Ma),ZJSB2(22Ma),ZJSB3(21Ma)。其中ZJSB1、ZJSB3为重大不整合面,ZJSB2为水道下切侵蚀面。与之对应的界面发育3套层序:ZJSQ1,ZJSQ2,ZJSQ3。由于白云凹陷构造运动及古地貌的差异性,总结了2套深水层序模式:水道—深海披覆泥层序模式与块状搬运复合体—砂质碎屑流深海扇—水道—深海泥层序模式,在不同的演化阶段,前者主要受海平面的变化控制,而后者是受构造和海平面双重影响的。而同一地质时期古地貌又控制了沉积发育,高地势区发育下切水道,而低洼区发育深海披覆泥岩。因此,深水层序模式下研究深海沉积单元,对指导深水沉积和油气勘探具有极其重要的意义。     

Tectono-sequence stratigraphic analysis of the Lower Cretaceous Abu Gabra Formation in the Fula Sub-basin,Muglad Basin,southern Sudan

The Fula Sub-basin of the Muglad Basin of southern Sudan is an active-fault bounded basin with an area of approximately 3300 km². The Lower Cretaceous Abu Gabra Formation formed during the first of three rifting cycles. It can be subdivided into five 3rd-order sequences named SQA∼SQE from bottom to top, indicating five stages of tectonostratigraphy and tectonosedimentary evolution. The spatial distribution and temporal evolution of clastic depositional systems are described in this paper based on integrated analysis of seismic, core and well logging data. In the Abu Gabra Formation of the Fula Sub-basin, a variety of depositional systems are recognized, namely, fan delta, braided delta, delta, sublacustrine fan and lacustrine system. The Fula Sub-basin has undergone a complex and phased rifting evolution, and a high abundance of transfer zones developed, causing the resulting distribution and architecture of both the sequence and depositional system to be controlled by various types of transfer zones. The following three types of sequence architectures from northern to southern part of the Fula Sub-basin have been identified: simple dustpan-shaped sequence architecture in the north, transfer-zone sequence stratigraphic architecture in the middle and graben-shaped sequence architecture in the south. The sequence architecture is under the control of the large-scale central transfer zone, and nine models are built to study the effect of at least three categories of small-scale transfer zones on the depositional systems in the Fula Sub-basin. The small-scale transfer zones play significant roles in basin fill, primarily in controlling of the positions of deposit-input points. This study provides valuable insights into tectonic control of depositional systems and sequence architectures in a continental rift basin such as the Fula Sub-basin.     

白云南洼恩平组海相烃源岩空间展布规律及发育模式

通过借助层序地层学理论、构造古地貌分析、古生物资料、沉积速率与可容纳空间关系对比,以及典型地震相识别、地震相与沉积相剖面及平面分析等,结合区域地质资料及前人的研究成果,对白云南洼恩平组烃源岩的叠置关系、影响因素、空间展布规律及发育模式进行了研究,得到如下认识:白云南洼恩平组对应一个完整的二级层序,可细分为3个三级层序,自下至上为SQ1、SQ2、SQ3,海平面总体为上升特征,SQ3的最大海泛面对应了整个恩平组二级层序的最大海泛面;白云南洼恩平组为局限浅海环境,具备发育较好海相烃源岩的条件,稳定半封闭的古构造背景,有利于烃源岩有机质的富集保存;沉积速率小,且小于可容空间增长速率,沉积物向陆退积,沉积水体深度变大,利于海相烃源岩的发育;恩平组烃源岩为大陆边缘半闭塞—欠补偿—湿润海湾模式,优质烃源岩主要发育在受隆起及断层遮挡形成的海湾区。     

Sequence stratigraphy and importance of syndepositional structural slope-break for architecture of Paleogene syn-rift lacustrine strata,Bohai Bay Basin,E. China

Sequence stratigraphy and syndepositional structural slope-break zones define the architecture of the Paleogene syn-rift, lacustrine succession in eastern China's Bohai Bay Basin. Jiyang, Huanghua and Liaohe subbasins are of particular interest and were our primary research objectives. Interpretation of 3D seismic data, well logs and cores reveals: One first-order sequence, 4 second-order sequences, and ten to thirteen third-order sequences were identified on the basis of the tectonic evolution, lithologic assemblage and unconformities in the subbasins of Bohai Bay Basin. Three types of syndepositional paleo-structure styles are recognized in this basin. They are identified as fault controlled, slope-break zone; flexure controlled, slope-break zone; and gentle slope.The three active structural styles affect the sequence stratigraphy. Distinct third-order sequences, within second-order sequences, have variable systems tract architecture due to structuring effects during tectonic episodes. Second-order sequences 1 and 2 were formed during rifting episodes 1 and 2. The development of the third-order sequences within these 2 second-order sequences was controlled by the active NW and NE oriented fault controlled, slope-break zones. Second-order sequence 3 formed during rifting episode 3, the most intense extensional faulting of the basin. Two types of distinctive lacustrine depositional sequence were formed during rifting episode 3: one was developed in an active fault controlled, slope-break zone, the other in an active flexure controlled, slope-break zone. Second-order sequence 4 was formed during the fourth episode of rifting. Syndepositional, fault- and flexure-controlled slope-break zones developed in the subsidence center (shore to offshore areas) of the basin and controlled the architecture of third-order sequences in a way similar to that in second-order sequence 3. Sequences in the gentle slope and syndepositional, flexure controlled slope-break zones were developed in subaerial region.Distribution of lowstand sandbodies was controlled primarily by active structuring on the slope-break zones, and these sandbodies were deposited downdip of the slope-break zones. Sand bodies within lowstand systems tracts have good reservoir quality, and are usually sealed by the shale sediments of the subsequent transgressive systems tract. They are favorable plays for stratigraphic trap exploration.     

辽东湾晚第四纪层序地层

通过对辽东湾高分辨率浅地层剖面声学地层与典型钻孔沉积地层的对比分析,揭示了研究区晚第四纪MIS5以来的地层层序。辽东湾高分辨率浅地层剖面自下而上划定的6个声学地层单元(SU₅、SU₄、SU₃、SU₂、SU₁²、SU₁¹)与钻孔岩芯划分的6个沉积地层单元(DU₅、DU₄、DU₃、DU₂、DU₁²、DU₁¹)具有良好的对应关系。分别与MIS4期、MIS2期低海面时期的沉积间断密切相关的两个层序界面R5、R3,将辽东湾识别出的地层单元自下而上划分为3个层序(SQ3、SQ2、SQ1)。其中SQ3仅识别出上部的海侵体系域与高水位体系域,对应MIS5期海平面相对较高时期的滨浅海相沉积(DU₅);SQ2自下而上由低水位体系域(MIS...     

Tracing of deeply-buried source rock: A case study of the WC9-2 petroleum pool in the Pearl River Mouth Basin, South China Sea

The identification of a deeply-buried petroleum-source rock, owing to the difficulty in sample collection, has become a difficult task for establishing its relationship with discovered petroleum pools and evaluating its exploration potential in a petroleum-bearing basin. This paper proposes an approach to trace a deeply-buried source rock. The essential points include: determination of the petroleum-charging time of a reservoir, reconstruction of the petroleum generation history of its possible source rocks, establishment of the spatial connection between the source rocks and the reservoir over its geological history, identification of its effective source rock and the petroleum system from source to trap, and evaluation of petroleum potential from the deeply-buried source rock. A case study of the W9-2 petroleum pool in the Wenchang A sag of the Pearl River Mouth Basin, South China Sea was conducted using this approach. The W9-2 reservoir produces condensate oil and gas, sourced from deeply-buried source rocks. The reservoir consists of a few sets of sandstone in the Zhuhai Formation, and the possible source rocks include an early Oligocene Enping Formation mudstone and a late Eocene Wenchang Formation mudstone, with a current burial depth from 5000 to 9000 m. The fluid inclusion data from the reservoir rock indicate the oil and the gas charged the reservoir about 18–3.5 Ma and after 4.5 Ma, respectively. The kinetic modeling results show that the main stages of oil generation of the Wenchang mudstone and the Enping mudstone occurred during 28–20 Ma and 20–12 Ma, respectively, and that the δ¹³C₁ value of the gas generated from the Enping mudstone has a better match with that of the reservoir gas than the gas from the Wenchang mudstone. Results from a 2D basin modeling further indicate that the petroleum from the Enping mudstone migrated upward along the well-developed syn-sedimentary faults in the central area of the sag into the reservoir, but that the petroleum from the Wenchang mudstone migrated laterally first toward the marginal faults of the sag and then migrated upward along the faults into shallow strata. The present results suggest that the trap structure in the central area of the sag is a favorable place for the accumulation of the Enping mudstone-derived petroleum, and that the Wenchang mudstone-derived petroleum would have a contribution to the structures along the deep faults as well as in the uplifted area around the sag.     

Unique vs. non-unique stratal geometries: Relevance to sequence stratigraphy

The sequence stratigraphic architecture includes a complex array of stratal geometries with different degrees of stratigraphic significance. The ‘non-unique’ variability of the sequence stratigraphic framework (i.e., stratal geometries which are not diagnostic for the definition of systems tracts and bounding surfaces) is irrelevant to the workflow of sequence stratigraphy. What is relevant is the observation of the ‘unique’ stratal geometries that are diagnostic for the definition of units and surfaces of sequence stratigraphy. In downstream-controlled settings, these unique stratal stacking patterns relate to the forced regressive, normal regressive, and transgressive shoreline trajectories. Multiple controls interact during the formation of each type of stacking pattern, including accommodation, sediment supply, and the energy of the sediment-transport agents. This interplay explains the non-unique variability, but does not change the unique criteria that afford a consistent application of sequence stratigraphy. The distinction between unique and non-unique stratal geometries is critical to the sequence stratigraphic methodology. Failure to rationalize the non-unique variability within the context of unique stratal geometries is counterproductive, and obscures the simple workflow of sequence stratigraphy. This is the case with uncalibrated numerical modeling, which may overemphasize non-unique or even unrealistic stratigraphic scenarios. While useful to test the possible controls on stratigraphic architecture, modeling requires validation with real data, and plays no role in the sequence stratigraphic methodology.     

Variations in architecture and cyclicity in fault-bounded carbonate platforms: Early Miocene Red Sea Rift,NW Saudi Arabia

The Early Miocene was a period of active rifting and carbonate platform development in the Midyan Peninsula, NW Saudi Arabia. However, there is no published literature available dealing with the detailed characterization of the different carbonate platforms in this study area. Therefore, this study aims to present new stratigraphic architectural models that illustrate the formation of different carbonate platforms in the region and the forcing mechanisms that likely drove their formation. This study identified the following features formed during active rifting: a) a Late Aquitanian (N4) fault-block hangingwall dipslope carbonate ramp, b) a Late Burdigalian (N7-N8) isolated normal fault-controlled carbonate platform with associated slope deposits, and c) a Late Burdigalian (N7-N8) attached fault-bounded platform with reef buildups, rimmed shelf developed on a footwall fault-tip within a basin margin structural relay zone that formed coinciding with the second stage of rifting. Variations in cyclicity have been observed within the internal stratigraphic architecture of each platform and also between platforms. High-resolution sequence stratigraphic analysis shows to be parasequences the smallest depositional packages (metre-scale cycles) within the platforms. The hangingwall dipslope carbonate ramp and the attached platform demonstrate aggradational-progradational parasequence stacking patterns. These locations appear to have been more sensitive to eustatic cyclicities, despite the active tectonic setting. The isolated, fault-controlled carbonate platform reveals disorganized stratal geometries in both platform-top and slope facies, suggesting a more complex interplay of rates of tectonic uplift and subsidence, variation in carbonate productivity, and resedimentation of carbonates, such that any sea-level cyclicity is obscure. This study explores the interplay between different forcing mechanisms in the evolution of carbonate platforms in active extensional tectonic regions. Characterization of detailed parasequence-scale internal architecture allows the spatial variation in syn-depositional relative base-level changes to be inferred and is critical for understanding the development of rift basin carbonate platforms. Such concepts may be useful for the prediction of subsurface facies relationships beyond interwell areas in hydrocarbon exploration and reservoir modeling activities.     

珠江口盆地文昌A凹陷油气差异分布特征

在烃源岩分布特征、有机质丰度、类型和成熟度分析的基础上,运用含油气盆地数值模拟技术,定量恢复了烃源岩热成熟演化史,探讨了油气差异分布特征。研究表明,文昌A凹陷各层系烃源岩分布广,厚度大,有机质丰度高;有机质类型文昌组偏Ⅱ1型,恩平组偏Ⅲ型,二者现今多处于高成熟—过成熟阶段。凹陷内烃源岩成熟时间早(文昌组约45.5Ma),现今成熟度高,以干气生成为主;凹陷边缘烃源岩成熟时间较晚(文昌组约30.0Ma),现今成熟度相对较低,以石油生成为主。凹陷现今油气差异分布的格局受制于有机质类型差异和热演化史不同,且下一步油气勘探方向,凹陷内以天然气为主,凹陷边缘以石油为主。     

歧口凹陷滩海区下第三系地震反射特征及层序划分

本文主要利用地震反射同相轴的终止形式和不连续类型 ,对歧口凹陷滩海区下第三系地层进行层序的划分 ,并对不同体系域内部及层序界面的地震反射特征进行较为详尽的描述。研究结果表明 ,歧口凹陷下第三系发育有六个层序 ,每个层序的顶、底界面分别对应于区内七个地震反射界面。不同成因及不同沉积环境的层序内部具有不同的地震反射相。并讨论体系域与油气赋存的关系     

Palynological,palaeoenvironmental and sequence stratigraphical analyses of a Turonian-Coniacian sequence,Beni Suef Basin,Eastern Desert,Egypt: Implication of Pediastrum rhythmic signature

Sixteen samples from the “E” to “B” members of the Abu Roash Formation encountered in the Beni Suef Basin, Eastern Desert of Egypt were palynologically analyzed for palaeoenvironmental and sequence stratigraphic investigations. The integrated palynofacies and lithofacies analysis of the studied section indicates deposition of five alternating regressive and transgressive sequences in well-oxygenated, proximal shelf settings. The Abu Roash “E” and the upper “D” to the lower “C” members were deposited during pronounced regressive phases in oxic, shallow marginal marine settings. The upper “B” Member was deposited during a recurring regressive phase but of a lower magnitude in oxic, shallow inner neritic conditions. The lower “D” Member was deposited during a minor transgression phase in dysoxic, shallow inner neritic settings. While the upper “C” to the lower “B” section was deposited during a stronger transgressive episode in a relatively deep, inner neritic environment of prominent dysoxic conditions. This interchange in the depositional setting was documented by the pronounced and concurrent, cyclic nature of the freshwater algae, peridinioid dinoflagellate cysts, pteridophyte spores, and reworked sporomorphs with variable intensities. Their increasing and conversely their diminishing trends clearly reflect alternating regressive-transgressive periods of reduced and relatively normal salinity conditions, respectively. Overall, sedimentation of the studied Abu Roash section indicates a recurring rise in sea level, which accentuated during the earliest Santonian time.The analogous peaking in the Pediastrum signals with those of the pteridophyte spores and reworked taxa indicate a good connection between these Pediastrum signals and the pronounced fluviatile influxes of terrigenous sediments during regressive phases. Accordingly, this can be used to identify regressive sequence boundaries and hence the clastic reservoirs. Even with the small counts recorded herein, we believe high ratios of peridinioid/gonyalulacoid dinocysts are significantly paralleled by peaking signals of freshwater algae and regressive sedimentation phases. This must be preliminary documented here. Probably future palynological studies will be able to fully interpret and address this important Pediastrum rhythmic event in different sequence stratigraphic settings.The palynological parameters, age controlled sporomorph marker taxa, lithology, and gamma ray data were used to differentiate the Abu Roash members into three distinctive 3rd order depositional sequences (AR SQ1, AR SQ2, and AR SQ3). These sequences match well with the global stratigraphic sequences Tu 3, Tu 4, and Co 1 and connect the local rise in sea level to the global eustatic sea level rise.     

西湖凹陷平湖斜坡带始新统平湖组层序地层

运用高分辨率层序地层学的理论和技术,以钻井、测井、地震资料为基础,对西湖凹陷平湖斜坡带始新统平湖组进行了层序地层研究。研究区向上“变深”的非对称型短期旋回层序最为发育,反映了研究区在平湖组沉积时期处于距物源区较近或物源供给较充分的环境下;中期旋回以发育上升半旋回沉积厚度大于下降半旋回的不对称型旋回为主,层序分界面两侧为有利砂体发育的部位;在不同级次基准面旋回层序划分的基础上,建立了以中期旋回为时间-地层对比单元的钻（测）井高分辨率层序地层格架。     

Neogene sequence stratigraphic architecture of the Nile Delta,Egypt: A micropaleontological perspective

The sequence stratigraphic architecture of the Neogene section from the subsurface Nile Delta is resolved based on exceptionally well-preserved microfossils from the offshore NDOB-1 borehole. The architecture is configured on bathymetry variations and statistical parameters as deduced from the relative abundance of foraminiferal associations. The statistical parameters include ratios of planktic versus benthic foraminifera, and cluster and correspondence analysis of the twelve most commonly used benthic foraminiferal genera as proxies of water depths. The combination of cluster and correspondence analysis was employed to decipher the evolution and dynamics of the basin and the mechanisms that controlled the deposition of Neogene sequences in the Nile Delta region. Four basic environmental settings were recognized: 1.) a middle to outer neritic eutrophic setting, 2.) a middle to outer neritic mesotrophic setting, 3.) an outer neritic to upper bathyal mesotrophic setting and 4.) an upper bathyal mesotrophic setting.Eight stratigraphic sequences were identified in the Neogene Nile Delta section. Three sequence in the Miocene (MSeq1, MSeq2 and MSeq3), three in the Pliocene (PSeq1, PSeq2 and PSeq3) and two in the Pleistocene (PtSeq1 and PtSeq2). These sequences are systematically measured and described in terms of time, space and water bathymetry. The sequence boundaries and flooding surfaces were dated using high-resolution microfossil biochronology and stratigraphic index markers. Individual sequences and boundaries were correlated with international and local sequence stratigraphic models. The new sequence stratigraphic model established here provides age calibrated surfaces for inter-basinal correlations and opens new avenues for hydrocarbon reservoir exploration.