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以珠江口盆地惠州凹陷南部中新统珠江组陆架泥岩内发育的条带状砂体为研究对象,综合利用岩心、测井、地震以及生产资料,研究砂体的特征、成因以及控制因素。这些砂体粒度较粗、物性好,测井GR曲线整体呈箱形或漏斗形;在地震反射剖面中呈强振幅特征,在均方根振幅属性平面图上呈北北东向的狭长条带状,并平行古岸线孤立展布。这些砂体在层序地层格架内属于强制海退体系域中的强制海退滨岸沉积。砂体的顶面和底面均与陆架泥岩呈突变接触:底面是趋势内强制海退面,具有高穿时特征;顶面是层序界面,对应基准面达到最低的时间点,并在后续的海侵过程中砂体被部分侵蚀改造,顶面也是海侵洪泛面,具有低穿时特征。长周期倾斜度旋回控制研究区内基准面变化,在此旋回的低值区间,全球海平面降低,在珠江口盆地引发强制海退,浅水高能滨岸砂体深入到原陆架区域,进而进入到碳酸盐台地环境。强制海退砂体是重要的油气储层和运移通道,也易于形成岩性圈闭,是油气勘探的重要目标。 相似文献
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河南新郑矿区山西组沉积环境与聚煤特征 总被引：1，自引：0，他引：1
新郑矿区山西组形成于海退环境,自下而上由滨岸海退旋回和二个不完整的三角洲旋回组成、二_1煤是潮汐改造的三角洲河口纵向砂脊上的潮坪泥炭沼泽沉积,由于纵向砂脊呈南东向排列,厚煤带也呈南东向展布。二_1煤形成后,高建设性浅水三角洲继续快速向东南方向推进,在下三角洲平原顶部形成了二_3煤。 相似文献
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晚三叠世鄂尔多斯盆地湖盆沉积中心厚层砂体特征及形成机制分析 总被引：13，自引：2，他引：11
晚三叠世延长组长6、长7油层组沉积期鄂尔多斯盆地湖盆中部深水区稳定发育厚层砂岩,局部地区连续厚度可达上百米。在盆地西南沉积体系,巨型砂带北西—南东向平行于相带界线展布,与三角洲前缘砂体呈现出“断根”的现象;在东北沉积体系,砂带围绕三角洲呈群状、带状分布。厚层砂体成因复杂,总体上可称作深水重力流—牵引流沉积复合体,包括滑塌砂体、砂质碎屑流砂体、浊积砂体、三角洲砂体及底流改造砂体5种成因类型,其中以重力流沉积组合为主,但白豹及其北部主要为三角洲沉积夹重力流沉积。不同成因的砂体纵向叠加,横向复合连片形成了稳定分布、规模宏大的砂带。厚层砂体的形成、展布方向、分布范围主要受控于沉积物的供给速率、湖盆底形及构造活动等因素。 相似文献
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古湖岸线的识别及其对砂体和油气的控制 总被引：1，自引：0，他引：1
古湖岸线是一定历史时期湖平面与古陆地的交线,即陆上与水下沉积的分界线。古湖岸线的识别
过程就是一个沉积环境恢复的过程,识别标志包括地貌特征、特殊岩性、古生物特征、沉积构造、地球化学指
标、地震反射特征以及沉积相变等多个方面。沉积盆地中古湖岸线对于砂体和油气的分布具有明显的控制作用,
主要表现在：（１） 古湖岸线的类型控制了砂体的成因,古湖岸线的位置及迁移控制了砂体的分布和垂向叠加样
式;（２） 古湖岸线控制了优质储集层的形成与发育,一般情况下水下砂体的储集层物性优于水上砂体; （３） 古
湖岸线的频繁迁移为形成良好的储盖组合提供良好的沉积条件; （４） 古湖岸线附近是地层超覆油气藏、不整合
遮挡油气藏及岩性油气藏发育的有利区带,并且油气藏沿古湖岸线呈现裙带状分布。 相似文献
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西湖凹陷平湖组受潮汐影响作用明显,但前人研究鲜有提及潮汐砂脊这种典型的潮汐作用下的沉积体。综合运用地震、测井、岩芯及分析化验资料,在西湖凹陷平湖组发现潮汐砂脊沉积体系。潮汐砂脊在地震振幅属性图上,呈条带状特殊地貌特征;岩芯上为典型的反旋回,旋回上部发育板状交错层理、冲刷面等反映强水动力的沉积构造,旋回下部细粒沉积中则发育潮汐层理、生物扰动等沉积构造;测井曲线上,砂脊底部表现为突变界面,并且砂脊发育区重矿物相对富集。潮汐砂脊砂质纯、物性好,并多发育于泥质背景中,与周围泥岩储盖配置好,可构成良好的岩性油气藏勘探目标。另外,砂脊的发育情况可以反映不同时期西湖凹陷与南部广海的沟通情况,因此对于研究西湖凹陷的古地理具有一定的参考意义。 相似文献
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塔里木盆地顺托果勒低隆起志留系柯坪塔格组下段发育的陆架砂脊为了解古陆架砂脊沉积建造提供了一个理想实例.利用测井和岩心资料, 根据沉积物的岩性和沉积构造特征, 将陆架砂脊划分为6个岩性相: 块状层理中-细砂岩性相(FA1)、丘状交错层理中-细砂岩性相(FA2)、含撕裂状泥砾的中-细砂岩性相(FA3)、双向交错层理含粘土层的细砂岩性相(FA4)、潮汐层理的细砂岩与泥岩互层岩性相(FA5)和水平层理陆架泥岩性相(FA6);依据岩性相的组合特征, 将陆架砂脊划分为4个沉积微相: 砂脊核微相(FA1-FA2-FA3)、砂脊内缘微相(FA4)、砂脊外缘微相(FA5)和陆架泥微相(FA6);陆架砂脊沉积受陆架潮汐、风暴浪的共同影响.利用钻井约束的三维地震切片属性分析, 确定了NE-SW向和NW-SE向两组古陆架砂脊的平面展布特征.古陆架砂脊储层为特低孔、特低渗, 其中砂脊核微相储层物性相对较好, 平均孔隙度6.96%、平均渗透率0.34×10-3 μm2; 工业油流主要集中在砂脊核微相储层.古陆架砂脊的砂体多呈脊状或丘状并被厚层的陆架泥披覆, 常形成同沉积的微幅背斜-岩性圈闭. 相似文献
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重力流沉积体系砂体展布规律极为复杂,通过重力流流体实验,确定了重力流沉积不同岩相的成因及展布规律,并在此基础上,通过岩芯观察及测井、录井资料分析,在滨南油田古近纪沙三下亚段进行重力流砂体展布规律研究,研究结果表明:1)塑性流体在运动过程中被稀释,导致颗粒支撑机制发生复杂的变化,从而出现多种流态的流体,因此塑性流体被稀释到一定程度后会转换为液态流体; 2)重力流沉积层序的垂向演化及横向变化是流体性质演化的结果,即地质记录中的复杂重力流层序为流体性质转换后再沉积的结果; 3)重力流垂向层序与沉积模式的有机结合是进行砂体展布预测的关键。在该模式的指导下,明确了滨南油田沙三下亚段岩相的空间展布和变化规律。 相似文献
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珠江口盆地白云北坡珠江组下部陆架边缘沉积演化 总被引：2，自引：0，他引：2
根据层序地层学理论,运用地震相、地震沉积学等分析手段,结合钻井、测井等资料,对珠江口盆地白云北坡珠江组下部的沉积演化进行了研究,研究发现:珠江组下部发育陆架边缘三角洲-海相沉积体系,地震剖面中陆架边缘三角洲前缘分布在Y2井区及以南区域,平面上呈菱形,其两侧发育改造的滨海砂坝,南部发育斜坡浊积扇,这三者形成了海退体系中的主要岩性圈闭;X1、Y1井区及以北发育海进体系中的滨海砂坝圈闭。海平面升降、物源供给和构造古地貌对沉积演化和圈闭形成过程中起明显的控制作用。21.0~19.0Ma期间,海平面下降和河流回春作用是形成陆架边缘三角洲的主要原因,构造古地貌及其控制的古水深控制了相带展布与边界。 相似文献
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断陷湖盆深水重力流水道的识别标志及沉积模式——以歧口凹陷歧南斜坡沙一段为例 总被引：1，自引：0，他引：1
以歧口凹陷歧南斜坡沙一段的深水厚层砂岩为研究对象,运用地震沉积学基本理论和方法,通过古地貌分析约束物源方向,结合岩心观测描述确定沉积相类型,应用地层切片、反演与三维可视化技术确定空间形态。结果表明:该区广泛发育的深水厚层砂岩为重力流水道沉积,包括滑塌岩、砂质碎屑流砂体与浊积岩3种类型重力流沉积的组合;顺北东向展布的断槽内呈大型条带状展布,可划分为水道中心微相、水道边缘微相和水下漫溢微相;岩心中可识别出7种岩相类型。在沉积特征分析的基础上,建立了发育于斜坡且由顺源断层控制的重力流沉积模式,分析了歧南斜坡重力流水道的成因及其油气成藏特征。研究认为重力流水道是该区一类重要的储集体,具有良好的成藏条件,该成果扩大了歧口凹陷油气勘探领域。 相似文献
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In recent years, a new model for deposition of sand bodies in a shelf environment has appeared. This model, known as the shelf sand-plume model, is hypothesized to result from storm-driven currents that are deflected around a deltaic headland, stripping sand from the headland and redepositing it in a downcurrent ‘plume’ on the inner shelf. The modern analogue for this model is considered to be an arcuate shelf sand body located off the Damietta branch of the Nile Delta. However, the distribution of older deltaic and shoreline sands probably controls the arcuate outline of the sand body. The present current system has certainly reworked these sands into ridges and large-scale bedforms but is not responsible for the overall outline of the sand body. Grain-size range and distribution of sand on the shelf demonstrate that the source of sand in the Nile shelf sand body is not the modern Damietta headland as postulated by the shelf sandplume model. In our view, the shelf sand-plume model is presently unsubstantiated and has orginated as a misapplication of the original Nile example. As a geological model, the shelf sand-plume model lacks a set of observable, consistently applicable criteria. The only common denominator to the model is the ‘plume’ geometry of a sand body located off a deltaic promontory. However, workers postulating the existence of shelf sand-plumes have neither clearly established a ‘plume’ geometry nor shown the juxtaposition of these bodies with respect to coeval deltaic headlands in their outcrop or subsurface examples. The model does not provide criteria to distinguish a ‘shelf sand-plume’ from other classes of shelf sand bodies, notably sand ridges and storm-generated sheet-like sands. Its application to the rock record should be re-evaluated. 相似文献
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研究源-汇系统对于理解岩石风化、河流输砂、泥砂沉积以及陆地和海洋沉积过程具有重要意义。我国江苏省东海岸具有丰富的沉积物供应,在某些沿海地段形成了一系列沙脊,是进行沉积物源-汇过程研究的理想沉积记录之一。但目前对其物源区来自哪里还未达成共识。我们利用已发表的碎屑锆石U-Pb年龄和钾长石Pb同位素数据,结合江苏沙脊及其周缘区域的数据结果,详细厘定江苏沙脊的物源区,并运用蒙特卡罗反演模型定量评估江苏沙脊潜在物源区对其物质贡献率。结果表明江苏沙脊北部的碎屑物质主要受大别山(45%)和鲁中山区(24%)的共同影响;黄河(29%)、古黄河(27%)和长江(25%)的碎屑物质对江苏沙脊中部的物质组成起重要影响。江苏沙脊南部的物源主要来自长江(68%)。江苏沙脊的出现得益于黄河和长江这样的大陆尺度的大河搬运了丰富的碎屑物质到下游,南黄海西海岸的平坦地貌有利于保存这些碎屑物质,末次冰期后东亚陆架海动力过程(潮汐、海浪和沿岸流等)持续对其改造,这体现了河流-海洋在塑造河口-海岸地貌中的交互作用。 相似文献
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江苏沿海辐射沙脊群在国内潮成沙体中较为罕见,有关辐射沙脊形成的动力机制已有定论,但对其形成时间和物质来源说法不一。运用长时间尺度动力地貌过程数学模型复演了辐射沙脊群形成演变过程,结果表明:江苏岸外辐聚辐散的流场不依赖于局部海底地形而独立存在;不同初始地形下只要泥沙供给充足,经过150年左右潮流动力对地形不断塑造,辐射状"水道-沙脊"相间的地貌格局都能基本形成;辐射沙脊群是废黄河北归约150年后,随着废黄河水下三角洲不断被侵蚀,辐聚辐散的潮流对不同来源物质重新塑造的结果,是动力-泥沙-地形相互作用的产物。 相似文献
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Bedform distribution and inferred sand transport on Georges Bank, United States Atlantic Continental Shelf 总被引：1，自引：0，他引：1
DAVID C. TWICHELL 《Sedimentology》1983,30(5):695-710
Four bedform provinces have been identified on Georges Bank using sidescan-sonar and echo-sounding techniques: large sand waves superimposed on sand ridges, small sand waves, megaripples, and featureless seafloor. The large sand waves and sand ridges are found on the bank crest where the surface tidal currents are strongest. Areas of small sand waves and megaripples, formed where tidal currents are moderate in strength, border the area of large sand waves to the north and south. Featureless seafloor is found farthest from the bank crest where surface tidal currents are weakest. Sand-wave asymmetry and surface-sediment texture have been used to infer bedload transport paths on Georges Bank. In the large sand-wave area, bedforms indicate a clockwise transport around each of the linear north-west-striking sand ridges with slight convergence of the sand waves on the ridge crests. This transport pattern implies erosion from the troughs and accumulation on the sand ridges. The asymmetry of the small sand waves along the south side of Georges Bank indicates that sand is also transported southward away from the linear sand ridges on top of the bank. Although the asymmetry of megaripples could not be determined, the occurrence of megaripples between the small sand-wave province and areas of featureless seafloor suggests a decreasing effectiveness of sand transport away from the bank crest. This sand dispersal pattern is further supported by the surface sediments which become progessively finer to the north and SW away from the crest of Georges Bank. 相似文献
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The most extensive Jurassic marine transgression in North America reached its maximum limits during the Oxfordian Age. At this time, siliciclastic sediments were being brought into the North American seaway from an uplifted zone to the west. Within this setting, complexes of sand ridges and coquinoid sands layers were deposited. Coquinoid sandstones appear to fill erosional scours and were interpreted as channel fills. Re-evaluation of these features in the light of recently discovered attributes of modern shelf sediments and processes has produced a revised model of coquinoid sand deposition in this setting. Coquinoid sandstones which fill ‘channel-like’ scours in the Oxfordian (Upper Jurassic) rocks of central Wyoming and south-central Montana, appear to have formed through the migration of sand waves across the crests of inner shelf sand ridges during periods of storm and tidal flow. Erosion in the zone of flow reattachment in the troughs between sand waves resulted in the development of shell lags. Migration of these scour zones as the sand waves advanced resulted in the deposition of sheet-like coquinoid sandstone bodies. Sand waves crossing the ridge crest tended to migrate more slowly and to be overstepped by later sand waves. Sand wave troughs thus buried have channel-like geometries with apparent epsilon bedding. 相似文献
16.
Architecture and recognition criteria of ancient shelf ridges; an example from Campanian Almond Formation in Hanna Basin,USA 
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下载免费PDF全文 Julio Leva López Valentina Marzia Rossi Cornel Olariu Ronald J. Steel 《Sedimentology》2016,63(6):1651-1676
Shelf ridges are sedimentary bodies formed on the continental shelf due to transgressive reworking (tidal or storm) of lowstand deposits. Common on modern shelves, they are under‐represented in the geological record due to a lack of recognition criteria and facies model. This article proposes a new facies and architectural model for shelf ridges, linked to their inception–evolution–abandonment cycle and the process regime of the basin. The model is mainly based on new outcrop data and interpretations from three sandstone bodies of the Almond Formation, an overall transgressive interval during the infill of the Campanian Western Interior Seaway. Building from the case study, and ancient and modern examples, six characteristics are proposed for the recognition of ancient shelf ridges. Shelf ridges: (i) are encased between thick marine mudstone intervals; (ii) have a basal unconformity that erodes into marine muds or into the remnants of a previous shoreline; (iii) have a non‐erosional upper boundary that transitions into marine muds; (iv) are characterized by clean and well‐sorted sandstones, often cross‐bedded; (v) contain fully marine ichnofauna; and (vi) present compound architectures with large accretion surfaces and lower order structures. Although shelf ridges have been described in previous studies as generated exclusively by either tidal or storm currents, it is clear, from modern examples and the case study, that these two processes can be recorded and preserved in a single shelf ridge. The stratigraphy of these sandstone bodies is therefore much more complex than previously recognized, bearing the signature of changing tidal and storm intensity through time. Because they are developed during transgressions, shelf ridges are commonly subject to strong changes in process regime as sea‐level changes can easily affect the oceanographic conditions and the morphology of the basin. For this reason, shelf ridges can provide the best record of shelf process variability during transgressions. 相似文献
17.
海洋碎屑沉积物的粒度特征是海底沉积动力环境的直接体现,是用来研究海洋动力环境变化的重要手段,尤其是陆架海底表层沉积物的粒度分布,对于研究沿岸和水柱底边界层现今海洋动力环境可起到重要作用。该项研究通过调查遍布泰国湾至湄公河口海底表层沉积物陆源碎屑的粒度分布特征,以期获得影响现今特定海域沉积作用的海洋动力环境过程。粒度分析的结果显示,泰国湾表层沉积物的陆源碎屑以细砂-细粉砂为主,分选总体较差,频率分布以正偏为主。其中,细砂-极细砂组分主要分布在曼谷湾和柬埔寨沿岸。湄公河岸外沉积物为细砂,且分选比泰国湾区域的沉积物要好。这些表层沉积物的粒度特征具有良好的环境变化指示作用。湄公河岸外分选较好、近于正态分布的中砂沉积物指示了波浪作用下的沉积环境。曼谷湾和柬埔寨沿岸分选较差的中砂-细砂粗粒沉积物反映了潮汐和波浪的共同作用;泰国湾东西沿岸区域分选中等、呈正偏态的极细砂-中粉砂沉积物体现了潮汐的控制作用;而泰国湾中部分选较差的沉积物则指示了表层洋流作用。研究表明,泰国湾和湄公河岸外表层沉积物陆源碎屑的粒度分布特征可用于区分不同海洋动力因素的控制作用,揭示出泰国湾的沉积动力环境主要受潮汐、波浪和洋流的共同影响,湄公河岸外的沉积动力环境主要受波浪的影响。 相似文献
18.
The only reported occurrence of quartz-rich sands in Jamaica is on the plains of Black River, St Elizabeth, where they outcrop in isolated pockets. The sands overlie limestones of the White Limestone Supergroup and the Coastal Group, and partly underlie Holocene peat deposits. Monocrystalline quartz, containing fluid and mineral inclusions, is the dominant mineral of the sands, with the heavy minerals. magnetite, haematite, epidote, rutile, anatase, zircon and tourmaline, occurring in minor amounts. Grain surface texture studies of the quartz grains have identified a series of mechanical and chemical features. Microtextures depicting marine, aeolian and pedological environments have been retained on the grains and represent the last three stages in the history of the grains. The petrography of the sands indicates an igneous provenance, with the major source of the detrital minerals being the Cretaceous granitoids that outcrop in the eastern half of the island. These rocks were unroofed during the uplift of Jamaica in the Late Tertiary and were subjected to extensive chemical weathering, which accounted for the breakdown of the majority of their primary silicate minerals. Fluvial transportation and deposition of detritus onto the shelf of the south coast commenced during this period and continued into the Pleistocene, providing terrigenous sand that was modified along the coast to quartz arenite by moderate to high energy marine conditions. Tidal currents, east-west longshore currents and weathering contributed to the maturity of the sand by the time it had been transported along the shelf to the vicinity of Black River. During low sea level stands in the Pleistocene, some of this sediment that became trapped on the shelf was blown inland by south-east winds. 相似文献
19.
东海陆架平湖海域改造砂沉积特征 总被引：3，自引：0，他引：3
东海陆架平湖海域分布的改造砂。其物质来源为晚更新世末生成的沙脊物质,是在晚更新世末至全新世初期间,原始物质被掀起再沉积的产物。 相似文献
20.
EDWARD COTTER 《Sedimentology》1985,32(2):195-213
Within the Kinsale Formation (Lower Carboniferous) of southern Ireland are pebbly sandstones and conglomerates contained in what is known locally as the Garryvoe conglomerate facies. In this facies there are three main groups of lithologies: (a) heterolithic mudrocks and sandstones characterized by a wide variety of wave-produced structures; (b) sandstones dominated by swaley cross-stratification (SCS), parallel lamination, and rare hummocky cross-stratification (HCS); and (c) pebbly sandstones and conglomerates occurring as discrete beds or as gravel clasts dispersed through SCS sets. Successions of the facies comprise units of heterolithic mudrock and rippled sandstone alternating repeatedly with coarsening-upward units of SCS pebbly sandstone capped by top-surface granule and pebble lags. The Garryvoe conglomerate facies accumulated in a system of offshore bars on a muddy shallow-marine shelf that was dominated by waves and currents generated by storms. Sands and gravels were bypassed from a contemporaneous northerly coastal zone to the shelf, where they were moulded by the storm-generated flow into low, broad, sand ridges (offshore bars). The elongate bars were spaced kilometres apart, oriented obliquely to the coast, and separated by muddy interbar troughs. Their surfaces were largely covered by hummocky and swaley forms. Long-term, gradual seaward migration of the offshore bars concentrated gravels on landward flanks from the dispersed pebbly sands that were on the crests and seaward flanks. Exceptionally intense storms could form laterally extensive winnowed gravel lags above thinned bar sequences. Such storms could also flush gravel-bearing turbidity currents into muddy interbar trough areas. 相似文献