珠江口盆地白云凹陷北坡上新世—第四纪陆架边缘沉积体系特征

运用珠江口盆地新采集的高分辨率多道地震资料,结合前人在本区的钻井、岩心、测井曲线及地震的综合资料,建立了白云凹陷北坡上新世-第四纪的等时地层格架,在此基础上分析了陆架边缘典型沉积体系,并初步探讨了其控制因素。研究表明,上新世-第四纪地层内识别出T0(海底)、T1(1.8 Ma)和T2(5.3 Ma)3个三级层序界面,划分出A、B 2个三级层序。研究区地震相主要有席状平行-亚平行地震相、帚状前积地震相、透镜状前积地震相、谷状充填地震相,不同的地震相及其组合代表特定的沉积体系。地震相特征分析表明,研究区上新世-第四纪发育大规模的陆架边缘三角洲和深切水道群,深切水道是沉积物向下陆坡-深海盆输送的通道。白云凹陷北坡上新世-第四纪沉积体系的发育受陆架边缘的地形、海平面升降、沉积物供给等因素的控制。     

Oligocene sequence stratigraphy and basin development in the Danish North Sea sector based on log interpretations

Five sequences are defined in the Oligocene succession of the Danish North Sea sector. Two of the sequences, 4.1a and 4.3, have been identified onshore Denmark.Two types of prograding lowstand deposits are recognized. Sand-dominated deposits occur proximally, comprising sharp-based forced regressive deposits covered with prograding low-stand deposits. Clay-dominated prograding lowstand deposits occur distally in the sequences. The highstand deposits are proximally represented by thick prograding sandy deposits and distally by thin and condensed intervals.The main sediment input direction was from the north and the northeast. A succession oif lithofacies, from shallow marine facies dominated by sand to outer shelf facies dominated by clay, is mapped in each of the sequences. An overall southward progradation of the shoreline took place during the Oligocene, interrupted only by minor shoreline retreats.     

威海南部近岸泥质区晚更新世以来的沉积环境演化

对威海南部近岸泥质区WHZK01钻孔(孔深25.1 m)岩心开展粒度分析、AMS14C和光释光(OSL)年代学测试,结合地震地层特征以及周边钻孔对比,建立了晚更新世晚期以来的地层框架,揭示出该地区主要经历了3个阶段的演化过程:(1)氧同位素3期晚期(MIS3a)的河流沉积,水动力环境动荡;(2)氧同位素1期(MIS1)早期河漫滩与河口湾沉积,动力环境总体较弱;(3)全新世滨海-浅海沉积,沉积环境弱而稳定。海平面变化是影响研究区晚更新世以来的沉积演化的主要因素,尤其全新世高海平面以来,随着黄海暖流的形成和黄海环流格局的建立,大量黄河物质在山东半岛沿岸流作用下输运到研究区,使得威海近岸泥质区得以快速发育。     

High resolution seismic profile through a Late Cenozoic delta complex in the southern North Sea

A digitally recorded and processed multichannel seismic profile between Cromer (England) and Sylt (Germany) has provided the first continuous section through the Miocene to Middle Pleistocene delta complex of the southern North Sea Basin. The profile depicts the progressive westward expansion of deltaic sedimentation that eventually filled in this gently subsiding epicontinental basin. Significant basinward shifts in seismic facies occur above all but one of 14 seismic sequence boundaries that punctuate the deposition of up to 830 m of deltaic sediments on the profile. These sequence boundaries and the morphology of prodelta, delta front, delta top and fluvio-deltaic seismic facies record the interaction between subsidence, cyclic fluctuation in sediment supply to, and cyclic change of relative sea level within the basin. Two submarine slides were developed within delta front facies in the Pliocene section and the profile has intersected a swarm of Elsterian (Middle Pleistocene) glacial palaeovalleys that have been incised into the upper part of the delta complex.     

东海陆架晚第四纪层序地层及其沉积环境

受全球性气候变化影响,晚第四纪以来东海陆架经历了多次海平面升降过程,在沉积地层中留下了明显的地质记录。根据穿越东海陆架的浅地震剖面解释研究,海底以下约120ms时间深度内可识别出6个主层序反射界面,即QT0、QT1、QT2、QT3、QT4和QT5界面,5套反射层序(反射波组),据反射层序的结构及地震相特征和与区内的钻孔地质资料对比分析,可见每套反射层序在沉积环境上均由一个海进海退沉积序列组成。以层序地层学为理论基础,在对中更新世以来的地层层序及其沉积环境条件分析研究基础上,建立了东海陆架晚第四纪地层层序及其发育模式,以期为东海陆架区晚第四纪地层发育层序提供初步认识。     

南海北部陆坡西沙海域沉积发育史及含油气远景初步探讨

在对南中国海西沙海域地震资料综合对比分析的基础上，本文描述了西沙海域的地震反射特征，并依据地震地层学原理，利用地震反射波的振幅、连续性、内部结构和外部形态等地震反射参数特征，将该区域地层自上而上划分为Ａ．Ｂ．Ｃ．Ｄ四个地震层序：层序Ａ代表从海底到Ｔ＾１１反射界面的地层；层序Ｂ代表从Ｔ＾１１反射界面到Ｔ２反界面的地层；层序Ｃ代表从Ｔ２反界面到５３反射界面的地层；层序Ｄ代表从Ｔ３反射层界面到Ｔｇ反射界     

Crustal structure and tectonic provinces of the Riiser-Larsen Sea area (East Antarctica): results of geophysical studies

About 16,000 km of multichannel seismic (MCS), gravity and magnetic data and 28 sonobuoys were acquired in the Riiser-Larsen Sea Basin and across the Gunnerus and Astrid Ridges, to study their crustal structure. The study area has contrasting basement morphologies and crustal thicknesses. The crust ranges in thickness from about 35 km under the Riiser-Larsen Sea shelf, 26–28 km under the Gunnerus Ridge, 12–17 km under the Astrid Ridge, and 9.5–10 km under the deep-water basin. A 50-km-wide block with increased density and magnetization is modeled from potential field data in the upper crust of the inshore zone and is interpreted as associated with emplacement of mafic intrusions into the continental margin of the southern Riiser-Larsen Sea. In addition to previously mapped seafloor spreading magnetic anomalies in the western Riiser-Larsen Sea, a linear succession from M2 to M16 is identified in the eastern Riiser-Larsen Sea. In the southwestern Riiser-Larsen Sea, a symmetric succession from M24B to 24n with the central anomaly M23 is recognized. This succession is obliquely truncated by younger lineation M22–M22n. It is proposed that seafloor spreading stopped at about M23 time and reoriented to the M22 opening direction. The seismic stratigraphy model of the Riiser-Larsen Sea includes five reflecting horizons that bound six seismic units. Ages of seismic units are determined from onlap geometry to magnetically dated oceanic basement and from tracing horizons to other parts of the southern Indian Ocean. The seaward edge of stretched and attenuated continental crust in the southern Riiser-Larsen Sea and the landward edge of unequivocal oceanic crust are mapped based on structural and geophysical characteristics. In the eastern Riiser-Larsen Sea the boundary between oceanic and stretched continental crust is better defined and is interpreted as a strike-slip fault lying along a sheared margin.     

南黄海西部浅部地层地震层序及其沉积特征

南黄海陆架在第四纪具有海侵—海退交替发生、海陆相地层交互沉积的特点,沉积相及其分布主要受海平面变化与古河流及其三角洲的控制。对南黄海西部地区采集的5600km浅层地震剖面进行了层序划分与解释,得到以下认识:(1)早更新世晚期以来的南黄海地层可分为U1—U14共14个地震地层单元,组成6个地震层序,代表了6次大规模海侵-海退过程,其中氧同位素5期海相地层在该地区最发育;(2)根据全新世地层厚度变化,将该区分为6个沉积区:东部弱沉积区、中北部沉积发育区、海州湾外侵蚀区、废黄河口沉积区、射阳河口岸外侵蚀区和苏北浅滩沉积区;(3)氧同位素6期至2期,南黄海西部陆相层内发育了3期埋藏古河道:上层古河道发育于氧同位素2期,古长江水系、古黄河水系分别自南黄海南部、北部流入古黄海;中层古河道发育于氧同位素4期,仅分布于近岸地区;下层古河道发育于氧同位素6期,分布于123°E以西地区,其南部古河道应为古长江水系,规模较大,其北部古河道规模较小,分布范围有限;(4)古长江第四纪早期在古黄海入海,古黄河在氧同位素5期中后期也开始自古黄海入海,其古河道发育具有一定继承性,后期发育规模逐渐增大;(5)气候温暖的高海面时期发育于构造沉降...     

Evolution of the Grenada and Tobago basins and implications for arc migration

The tectonic mechanisms controlling how volcanic arcs migrate through space and geologic time within dynamic subduction environments is a fundamental tectonic process that remains poorly understood. This paper presents an integrated stratigraphic and tectonic evolution of Late Cretaceous to Recent volcanic arcs and associated basins in the southeastern Caribbean Sea using seismic reflection data, wide-angle seismic refraction data, well data, and onland geologic data. We propose a new tectonic model for the opening of the Grenada and Tobago basins and the 50-250-km eastward jump of arc volcanism from the Late Cretaceous Aves Ridge to the Miocene to Recent Lesser Antilles arc in the southeast Caribbean based on the mapping of three seismic megasequences. The striking similarity of the half-graben structure of the Grenada and Tobago basins that flank the Lesser Antilles arc, their similar smooth basement character, their similar deep-marine seismic facies, and their similar Paleogene sediment thickness mapped on a regional grid of seismic data suggest that the two basins formed as a single, saucer-shaped, oceanic crust Paleogene forearc basin adjacent to the now dormant Aves Ridge. This single forearc basin continued to extend and widen through flexural subsidence during the early to middle Eocene probably because of slow rollback of the subducting Atlantic oceanic slab. Rollback may have been accelerated by oblique collision of the southern Aves Ridge and southern Lesser Antilles arc with the South American continent. Uplift and growth of the southern Lesser Antilles arc divided the Grenada and Tobago basins by early to middle Miocene time. Inversion of normal faults and uplift effects along both edges of the Lesser Antilles arc are most pronounced in its southern zone of arc collision with the South American continent. The late Miocene to Recent depositional histories of the Grenada and Tobago basins are distinct because of isolation of the Grenada basin by growth and uplift of the Neogene Lesser Antilles volcanic ridge.     

Seismic stratigraphy and evolution of the Raggatt Basin,southern Kerguelen Plateau

Six major seismic stratigraphic sequences in the Raggatt Basin on the southern Kerguelen Plateau overlie a basement complex of Cretaceous or greater age. The complex includes dipping reflectors which were apparently folded and eroded before the Raggatt Basin developed. The seismic stratigraphic sequences include a basal unit F, which fills depressions in basement; a thick unit, E, which has a mounded upper surface (volcanic or carbonate mounds); a depression-filling unit, D; a thick unit C which is partly Middle to Late Eocene; and two post-Eocene units, A and B, which are relatively thin and more limited in areal extent than the underlying sequences. A mid or Late Cretaceous erosional episode was followed by subsidence and basin development, interrupted by major erosion in the mid Tertiary. Late Cenozoic sedimentation was affected by vigorous ocean currents.     

南海南部南安盆地新生代以来构造-沉积演化特征及区域成藏模式

南安盆地是南海南部重要的大型含油气盆地之一,深入分析其构造-沉积演化特征对盆地油气勘探具有重要的指导作用。结合已有研究成果,开展盆地二维地震资料解释,识别出南安盆地新生代以来5个主要的二级层序界面和4套地震层序。在层序地层格架下,根据地震反射特征识别出南安盆地楔形、S型（丘状）等5类地震相类型;砂包泥岩、砂泥岩互层等7类地震岩相类型以及扇三角洲、河流三角洲等8类主要沉积相。综合盆地构造演化特征,南安盆地新生代以来主要分为4个阶段：初始裂陷阶段、主裂陷阶段、断拗转换阶段和拗陷热沉降阶段。其中,中中新世以前为盆地裂陷阶段,发育陆源碎屑沉积,早期为湖相沉积,晚期为滨浅海相沉积;中中新世以后为拗陷阶段,发育陆源碎屑沉积和碳酸盐岩沉积。通过油气成藏模式研究,南安盆地烃源岩发育且品质较好,有利储集相带纵向厚度大且横向范围广,区域盖层覆盖整个盆地,并形成了早期的自生自储和晚期的下生上储两类油气成藏系统。     

Seismic stratigraphy and hydrocarbon prospectivity of the Lower Cretaceous Knurr Sandstone lobes along the southern margin of Loppa High,Hammerfest Basin,Barents Sea

The Lower Cretaceous Knurr Sandstone deposited along the southern slope of Loppa High and overlain by the Kolje and Kolmule seals forms an attractive play in the Hammerfest Basin of the Barents Sea. Late Jurassic organic-rich Hekkingen shale directly underlies the Knurr Sandstone and acts as a source to provide effective charge. Three wells, 7120/2-2, 7122/2-1 and 7120/1-2, have proven the Knurr-Kolje play in structural traps, with an oil discovery in 7120/1-2. Prospectivity related to stratigraphic traps is, however, highly under-explored.In order to document and map the reservoir distribution and stratigraphic-trap fairway, the Lower Cretaceous sedimentary package containing the Knurr Sandstone is divided into a number of depositional sequences and systems tracts using key regional seismic profiles calibrated with logs. Mapping of the key surfaces bounding the Knurr sandstone has been carried out using all the seismic vintages available from Norwegian Petroleum Directorate (NPD).The thick massive nature of the sandstone (123 m in well 7122/2-1), sedimentary features characteristic of gravity flow deposits, high-resolution internal seismic reflections and stratal geometries (truncations and lapout patterns), and sequence stratigraphic position of the Knurr Sandstone on seismic profiles confirm that the lobes identified on the seismic section are gravity driven base of the slope lobes. These Knurr lobes and slope aprons were formed as a result of uplift of the Loppa paleo-high in the Late Jurassic to Early Cretaceous times which caused subaerial exposure and incision. The characteristic mounded, lobate geometry evident on the seismic can be mapped along the toe-of-slope and records multiple stacked lobes fed by multiple feeder canyons. Lateral partitioning and separation of the lobes along the toe-of-slope could potentially create stratigraphic traps. The existing 2D seismic coverage is, however, not sufficient to capture lateral stratigraphic heterogeneity to identify stratigraphic traps. 3D seismic coverage with optimum acquisition parameters (high spatial and vertical resolution, appropriate seismic frequency and fold, long offsets and original amplitudes preserved) can allow for the reconstruction of 3D geomorphologic elements to de-risk potential stratigraphic traps prior to exploratory drilling.     

Postglacial depositional environments and sedimentation rates in the Norwegian Channel off southern Norway

Based on seismic profiles, multibeam bathymetry and sediment cores, an improved understanding of the deglaciation/postglacial history of the southern part of the Norwegian Channel has been obtained. The Norwegian Channel Ice Stream started to recede from the shelf edge ca. 15.5 ka BP (¹⁴C ages are used throughout). Approximately 500–1000 years later the ice margin was located east of the deep Skagerrak trough. At that time, the Norwegian Channel off southern Norway had become a large fjord-like embayment, surrounded by the grounded ice sheet along the northern slope and possibly stagnant ice remnants at the southern flank. The Norwegian Channel off southern Norway has been the main sediment trap of the North Sea, and south of Egersund more than 200 m of sediments have been deposited since the start of the deglaciation. Five seismic units are mapped. The oldest unit E occurs in some of the deepest troughs, and was deposited immediately after the ice became buoyant. Unit D is acoustically massive and comprises mass-movement deposits in eastern Skagerrak and south of Egersund. Unit C (in the channel southwest of Lista/Egersund) is interpreted to comprise mainly bottom current deposits derived from palaeo-rivers, e.g. Elben. During deposition of unit C (ca. 14.5–13 ka BP), there was limited inflow of Atlantic water. A change in depositional environment at ca. 13 ka BP is related to an increased inflow of saline water and more open hydrographic circulation. Widely distributed, acoustically stratified clays of unit B were deposited ca. 13–10 ka BP. The Holocene Unit A shows a depositional pattern broadly similar to that of unit B.     

Understanding the geometry and distribution of fluvial channel sandstones and coal in the Walloon Coal Measures,Surat Basin,Australia

Understanding the controls on coal seam distribution and geometry is fundamental for planning coal seam gas production. In the Jurassic Surat Basin of South East Queensland, Australia, the spatial continuity of coal seams in the Walloon Coal Measures is highly variable and often difficult to map and predict, even with closely spaced (<1000 m) drillings. This paper investigates the frequency and location of thick sandstone in relation to thick coal seams or plies across three broad stratigraphic divisions, Upper Juandah (UJ), Combined Lower Juandah-Taroom (CLJT) and Condamine Coal Measures (CCM), within the Walloon Coal Measures. Basic depositional facies, e.g. channel, floodplain, marginal mire, and coal mire, were interpreted from geophysical logs. An in-house code was used to count the number of coal plies thicker than 2 m, and channel sandstones thicker than 5 m for the UJ and CLJT and 3 m for the CCM at each borehole. Isopleth maps of the numbers of both coal plies and channel sandstones were generated across the basin for the three subdivisions. Results show that there is an upward stratigraphic trend from thick to thin, and then to thick stacked coal plies. This corresponds to a similar vertical thickness change in channel sandstones. The incidence of thick coal and thick sandstone is associated with rising base level within an early transgressive systems tract which was followed by a high stand prior to a regional erosive event above the UJ. Thick and stacked coal plies have a marked tendency to occur in belts adjacent to the thick channel thoroughfares in the basin.     

南黄海B10岩心的地球化学特征及其对古环境和古气候的反映

通过对南黄海中部B10岩心的碳酸钙、常量元素和微量元素分析发现,岩心的地球化学特征基本反映了该海区晚第四纪气候变化、海面波动以及沉积物供应的变化.在玉木亚间冰期(末次冰期亚间冰期)高海面时期,黄河可能直接注入南黄海,在南黄海中部发育水下三角洲沉积.晚玉木冰期(末次冰期盛冰期),南黄海出露成陆,局部发育陆相泥炭层.冰后期(全新世)海侵到达现今80 m等深线附近的时间大约在距今13 ka。在距今11.0～10.3 ka出现新仙女木事件.全新世中晚期海面进一步上升,沉积物粒度较细,化学风化作用加强.岩心50～0 cm段沉积物中的碳酸钙、氧化钙、锶、氧化镁含量及Sr/Ba比值低,而铜等微量元素含量增加,这可能与公元1855年黄河北迁后进入南黄海中部的黄河物质减少有关.     

Stratigraphic evolution of Eocene clinoforms from northern Santos Basin,offshore Brazil: Evaluating controlling factors on shelf-margin growth and deep-water sedimentation

In order to assess the controlling factors on the evolution of a shelf margin and the timing of sediment transfer to deep waters, a seismic stratigraphic investigation was carried out in the Eocene interval of northern Santos Basin, offshore Brazil. The studied succession configures a complex of prograding slope clinoforms formed in a passive margin and encompasses five seismic facies and their respective depositional settings: shelf-margin deltas/shorefaces, oblique slope clinoforms, sigmoidal slope clinoforms, continental to shelfal deposits and mass-transport deposits. These are stratigraphically arranged as seven depositional sequences recording a total shelf-edge progradation of about 35 km and a progradation rate of 1,75 km/My. Two main types of sequences can be recognized, the first one (type A) being dominated by oblique slope clinoforms and shelf-margin deltas/shorefaces in which shelf-edge trajectories were essentially flat to descending and extensive sandy turbidites were deposited on the foreset to bottomset zones. Sequences of this type are dominated by forced-regressive units deposited during extensive periods of relative sea-level fall. Type B comprises an upper part represented by aggradational shelfal deposits and a lower part composed of mass-transport deposits and high-relief sigmoidal clinoforms with descending shelf-edge trajectory. Steep slump scars deeply cut the shelfal strata and constitutes the boundary between the two intervals observed in type B sequences. Sandy turbidites occur at the same frequency in both forced- and normal-regressive units but are more voluminous within forced-regressive clinoforms associated with shelf-margin deltas/shorefaces. Major slope failures and mass-transport deposits, by the other hand, occurred exclusively in type B sequences during the onset of sea-level fall and their volume are directly related to the thickness of the shelfal sediments formed during the pre-failure normal regressions.     

东海陆架盆地南部及邻近陆域中生代地层格架对比

在大量收集东海陆架盆地南部海域和邻近浙闽陆域中生界露头、钻井和地震资料的基础上,按由陆及海的思路,从构造、地层和沉积等方面入手,对海域和陆域中生界进行了划分及对比,探讨了这一区域的中生代地层格架和盆地类型,初步建立了东海陆架盆地南部及邻区中生代地层格架对比关系。东海陆架盆地南部中生代地层格架的厘定具有重要的理论和油气勘探实际意义。     

Structure of the basins of the White Sea rift systems

For the first time, the structure of the sedimentary basins of the Late Proterozoic rift system in the White Sea is characterized based on a set of new marine geological geophysical data such as the results of the common depth point seismic method, gravity and magnetic data, and seismoacoustics. The main tectonic structures in the topography of the heterogeneous basement within the basin of the White Sea are distinguished and described. A structural tectonic scheme of the basement surface is presented. The thicknesses of the sediments are estimated and the stratigraphic confinement of the seismic units recognized is done.     

南黄海盆地下三叠统层序地层格架

南黄海盆地是下扬子地块向海洋的延伸,中、古生界海相地层研究程度较低,仍未开展过系统的地层格架研究,制约了研究区的油气勘探进程。结合陆域下扬子的研究成果,利用研究区以及陆上苏北盆地的地质、钻井、测井、岩心等资料建立起下三叠统的三级层序地层格架。研究结果表明:三级层序边界为岩性转换界面或者不整合面;下三叠统可以划分为3个三级层序,其中每个三级层序又可以划分为海侵和高位体系域,低位体系域均不发育。以上研究为后期沉积相划分、储层预测等提供了可靠的地质依据。     

Seismic stratigraphic framework and depositional sequences in the Santos Basin,Brazil

The Santos Basin, situated offshore southern Brazil, is one of nine marginal rift basins in the equatorial South Atlantic. It formed by the collapse of a thermal dome in the late Jurassic and by subsequent rifting and opening of the South Atlantic in the early Cretaceous. Rifting was accompanied by immense volcanic outpouring seen at the surface today throughout the onshore Paraná Basin and thought to underlie the entire Santos Basin, and the adjacent São Paulo Plateau. Vulcanism was followed by subsidence of up to 10 km from Aptian to Recent time, and a coastal hingeline coincides with the Serra do Mar uplift. The basin depocentre, which is 700 km long, is bounded to the north and south by basement and volcanic highs, respectively. A restricted water circulation in the ocean basin, which prevailed up to the Santonian stage, has important repercussions for the hydrocarbon potential of the area. The nine genetically related basins have collective reserves of ≈ 5 billion barrels of oil and associated gas. A stratigraphic framework, based largely on seismic data, has been erected for the Santos Basin. Seven regional unconformities, or ‘R’ reflections, can be traced throughout the basin and form the boundaries for seismic sequences. Isopaching the seismic sequences defines the principal depositional units in the basin and also shows how the basin depocentre shifted with time. Limited well control has enabled the seismic sequences to be correlated with litho-environmental sequences which more fully reflect the geological evolution and provide a working exploration model. Finally, an attempt has been made to recognize and map seismic facies within the seismic sequences and to predict the lithofacies in areas away from well control