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G. W. FARQUHARSON 《Sedimentology》1982,29(5):717-725
Sedimentary rocks of late Mesozoic age exposed at Camp Hill, northern Antarctic Peninsula, are associated with calc-alkaline volcanic rocks. They represent deposition on a fault-controlled floodplain, with marginal alluvial fans, on a volcanic arc. Finely laminated mudstone and occasional graded laminae were deposited from suspension and by density underflow currents, respectively, in small shallow lakes. Thickening- and coarsening-upward sandstone bodies overlying the lake deposits are interpreted as lacustrine deltas of which two types are preserved: (1) Gilbert-type with steep foresets and (2) mouth-bar type which lack steep foresets. Sections through the latter type reveal the presence of sub-environments characteristic of fluvial-dominated marine deltas, i.e. prodelta, distributary mouth-bar and distributary channel. Abandoned mouth-bars resulting from avulsion are recognized. It is suggested that the processes which operated during formation of the mouth-bar deltas resulted from hyperpycnal flow. By contrast, the Gilbert-type delta is thought to be the consequence of a reduced inflow of suspended sediment causing homopycnal flow, and thorough mixing of the river and lake waters. 相似文献
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LUIS A. BUATOIS NUBIA SANTIAGO MEYLIN HERRERA PIRET PLINK‐BJÖRKLUND RON STEEL MARÍA ESPIN KAOLU PARRA 《Sedimentology》2012,59(5):1568-1612
Analysis of Neogene cores from the Eastern Venezuela Basin along 65 km of a west–east trending shoreline allows characterization of the sedimentological and ichnological signatures of wave, river and tidal processes. The area displays deltas prograding northward from the Guyana Shield. Twenty‐three facies are defined and grouped into four categories (wave‐influenced, river‐influenced, tide‐influenced and basinal). Wave‐dominated deltaic deposits occur mostly in the Tácata Field. The delta plain was characterized by tide‐influenced distributary channels separated by interdistributary bays. Fluvial discharge in the delta front and prodelta was repeatedly interrupted by storm‐wave reworking and suspended sediment fallout. Delta‐front and prodelta deposits contain some ichnotaxa that typically do not occur in brackish water (for example, Chondrites and Phycosiphon). Amalgamated storm deposits are unburrowed or contain vertical Ophiomorpha. Lateral (especially on the updrift side) to the river mouths, waves caused nearly continuous accretion of the associated strandplains. These deposits are the most intensely bioturbated, and are dominated by the estenohaline echinoid‐generated ichnogenus Scolicia. River‐dominated deltaic deposits are present in the Santa Bárbara, Mulata, Carito and El Furrial Fields. Low‐sinuosity rivers characterized the alluvial plain, whereas the subaerial delta plain was occupied by higher‐sinuosity rivers. The subaqueous delta plain includes distributary channels and tide‐influenced interdistributary bays. Further seaward, successions are characterized by terminal distributary‐channel and distributary mouth‐bar deposits, as well as by delta‐front and prodelta deposits showing evidence of sediment gravity‐flow and fluid‐mud emplacement. Delta‐front and prodelta deposits are unbioturbated to sparsely bioturbated, suggesting extreme stress, mostly as a result of high fluvial discharge and generation of sediment gravity flows. Tidal influence is restricted to interdistributary bays, lagoons and some distributary channels. From an ichnological perspective, and in order of decreasing stress levels, four main depositional settings are identified: river‐dominated deltas, tide‐influenced delta plains, wave‐dominated deltas and wave‐dominated strandplain–offshore complexes. 相似文献
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CORNEL OLARIU JANOK P. BHATTACHARYA MATTHEW I. LEYBOURNE STEPHEN K. BOSS ROBERT J. STERN 《Sedimentology》2012,59(2):704-728
Basin‐floor topography influences the flow path of hyperpycnal plumes and delta morphology during progradation of the Red River delta in Lake Texoma, USA. The Red River discharge is typically a hyperpycnal plume due to elevated total dissolved solids. Because the river plume is a bottom‐hugging hyperpycnal flow, lake bathymetry and topography strongly influence deposition and subsequent delta morphology. In addition to elevated total dissolved solid concentrations compared with Lake Texoma water, the density contrast of the Red River outflow is increased by high suspended‐sediment concentrations during high‐discharge events. Steep lateral slopes in the Lake Texoma basin deflect hyperpycnal river plumes and, subsequently, change the delta progradation direction before the delta reaches the opposite bank of the lake. Analysis of multi‐temporal aerial and satellite images indicates that the hyperpycnal delta follows the steepest lake‐bottom gradients, corresponding to the pre‐impoundment river thalweg (i.e. bypassing shallow parts of the lake). An analytical model for the hyperpycnal‐plume trajectory indicates plume deflection during low‐discharge or high‐discharge events, towards the deepest part of the basin. The magnitude of plume deflection is a function of river discharge and basin‐margin gradients. Plume deflection can vary between 10° and 80° from the channel axis towards the old river thalweg. The high deflection appears in the case of maximum basin side gradients of 12·8° and in conditions of low river discharge. During low‐discharge periods, the Red River delta builds a lobate shape with multiple terminal distributary channels whereas, during high‐discharge periods the Red River delta builds an elongate shape with a single large distributary channel. The elongate morphology of the delta is formed through the development of a single distributary channel and abandonment of the other distributaries. Therefore, the lobate shaped delta is expected to be preserved in the rock record. 相似文献
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重新认识处于开发中后期油藏的沉积环境、沉积微相及其特征,建立准确的储集层模型,对于查明剩余油分布和挖掘剩余油潜力、提高采收率具有重要的现实意义。综合利用岩心、测井、录井及相关测试资料,对文留油田文72断块沙三中亚段五砂组沉积微相进行了系统研究。结果表明:该区沙三中亚段为一套曲流河三角洲沉积,主要发育水下分流河道、河口坝、远砂坝、支流间湾及前三角洲泥5个微相,水下分流河道和河口坝砂体为储集层骨架砂体。对研究区各小层沉积微相的时空展布特征进行了分析,讨论了沉积微相与含油性的关系,认为油气的聚集受沉积微相的控制：水下分流河道的储集性能最好,河口坝次之,远砂坝较差,为油田开发方案的调整和动态分析提供了可靠的地质依据。 相似文献
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Shoal‐water deltas in high‐accommodation settings: Insights from the lacustrine Valimi Formation (Gulf of Corinth,Greece) 
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下载免费PDF全文 The stratigraphic architecture of shoal‐water deltaic systems developed in low‐accommodation settings is relatively well‐known. In contrast, the features of shoal‐water deltas developed in high‐accommodation settings remain relatively poorly documented, especially when compared with the available data sets for Gilbert‐type deltaic systems developed in the same settings. The lacustrine Valimi Formation (Gulf of Corinth, Greece) provides an opportunity to investigate the facies assemblage and architectural style of shoal‐water deltaic systems developed in high‐accommodation settings. The studied interval accumulated during the Pliocene and Pleistocene and represents part of the early syn‐rift Gulf of Corinth succession. Six facies associations, each described in terms of depositional processes and geometries, have been identified and interpreted to represent a range of proximal to distal deltaic sub‐environments: delta plain, distributary channel, mouth‐bar, delta front, prodelta and open lake. The facies associations and their architectural elements reveal characteristics which are not common in traditionally described shoal‐water deltas. Of note, different facies arrangements are observed in the distributary channels in different sectors of the delta, passing from thick single‐storey channel fills embedded within delta‐plain fines in landward positions, to thin, amalgamated and multi‐storey channels closer to the river mouth. This study proposes a new depositional model for shoal‐water deltas in high‐accommodation settings documenting, for the first time, that shoal‐water delta deposits can form a substantial part of stratigraphic successions that accumulate in these settings. The proposed depositional model provides new criteria for the recognition and interpretation of these deposits; the results of this study have applied significance for reservoir characterization. 相似文献
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以岩心、录井、测井、分析化验和地震资料为基础,结合区域地质背景,对高邮凹陷北斜坡戴二段沉积相类型、展布及其演化规律进行研究。在总结、比较各类型三角洲特征的前提下,认定北斜坡戴二段主要发育辫状河三角洲相,局部发育曲流河三角洲和湖泊相。在此基础上,重点对戴二段辫状河三角洲各亚相、微相进行分析,划分出辫状河三角洲平原、辫状河三角洲前缘和前辫状河三角洲亚相,并针对各亚相对其包含的微相进行进一步划分。在综合考虑目标区域沉积背景和沉积特征的基础上,对沉积相展布和演化进行分析,并对辫状河三角洲形成机理进行了探讨。 相似文献
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鄂尔多斯盆地神木地区太原组是在北隆南倾的古地形背景下形成的以浅水三角洲为主的充填沉积。携带沉积物的河流进入海水后,由于河水与海水之间存在着较大的密度差异、侧向扩散较少,其三角洲前缘沿着海底继续向前快速推进,使水下分流河道延伸较远。研究区地形坡度平缓、水体浅,三角洲平原向前推进并进一步降低了地形坡度,从而减弱了携带沉积物的流体的动能,使得大部分沉积物在三角洲平原的分流河道中沉积下来。同时因水体浅,河口坝、席状砂等前缘沉积物常遭受进积的水下分流河道的冲刷和侵蚀而难以保存。研究区三角洲平原分流河道沉积极为发育,前三角洲相对不发育,三角洲前缘也以水下分流河道沉积为主。分流河道、水下分流河道常对下伏沉积物强烈冲刷,切割先期的沉积物乃至包括海相沉积物在内的深水沉积物。在三角洲废弃期,三角洲前缘沉积物常被潮汐作用改造。三角洲平原分流河道及三角洲前缘水下分流河道砂体呈带状分布,是天然气勘探的有利目标。 相似文献
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利用鄂尔多斯盆地镇泾油田沉积微相展布与演化规律分析油田开发调整方向 总被引：1，自引：1，他引：0
油田沉积微相的展布与演化规律控制着主要有利储层的分布,因而油田开发调整方向可根据这些规律来综合考虑。镇泾油田位于鄂尔多斯盆地西南部,该油田长6油层组属于浅湖背景下的辫状河三角洲前缘沉积,其主要沉积微相包括水下分流河道、河口坝、远砂坝、席状砂、水下分流间及前三角洲泥。该区三角洲分布主要受控于两个大致平行分布的南西-北东向主河道,受基准面升降与沉积物供应的共同作用,三角洲演化呈阶段性变化,大致经历了初始发育期、繁盛发育期、间歇发育期、活化发育期等4个演化阶段,其中繁盛发育期与活化发育期的三角洲水下分流河道与河口坝砂体是主力含油储层。研究区辫状三角洲展布与演化的特点决定了今后油田开发的重点在西南部河道带两侧及东北部三角洲前缘的前端;而垂向上应以优先考虑三角洲繁盛发育期与活化发育期的叠加砂体厚度较大为原则。 相似文献
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中国东部箕状断陷湖盆扇三角洲与辫状河三角洲对比研究 总被引：1，自引：0，他引：1
中国东部箕状断陷湖盆短轴方向,常常发育扇三角洲和辫状河三角洲,二者均可形成良好的油气储集体,但在岩芯以及地球物理资料的识别上常常容易混淆。通过对它们沉积特征、地球物理资料特征、含油气性和控制因素的对比研究和分析认为:扇三角洲是陡坡带冲积扇直接入湖形成,地震反射特征为楔形前积,沉积物成分成熟度和结构成熟度均低于辫状河三角洲,沉积特征反映重力流和牵引流双重作用;辫状河三角洲是缓坡带辫状河入湖形成的三角洲,向湖盆方向推进较远,地震反射特征为叠瓦前积,沉积特征反映牵引流作用。扇三角洲易形成构造-岩性油气藏和岩性油气藏,有利相带为扇三角洲前缘水下分流河道、席状砂以及前扇三角洲容易发育的滑塌浊积扇;辫状河三角洲易形成地层-岩性油气藏和岩性油气藏,有利相带为辫状河三角洲平原辫状分流河道,辫状河三角洲前缘水下分流河道、河口坝、席状砂以及半深湖中的浊积岩体。古气候变化、构造-古地貌以及湖平面变化速率三者共同作用于扇三角洲和辫状河三角洲的沉积特征,其中构造-古地貌是主控因素。结合二者沉积特征差异,建立了中国东部箕状断陷湖盆扇三角洲和辫状河三角洲沉积模式图,以期能对相似构造背景下扇三角洲和辫状河三角洲的分析与研究提供一定的指导作用。 相似文献
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Lake Hazar lies within a small pull-apart basin along the East Anatolian Transform Fault in south-eastern Turkey. Deltas are formed where streams debouch into the low-energy lacustrine environment. The facies constituting the deltas include delta plain debris flow, braided stream, and marginal lacustrine deposits; delta front foreset and mouth bar deposits; prodelta and lacustrine deposits. The facies are spatially restricted with sharp transitions. Facies sequences and relationships indicate two distinct styles of deltaic sedimentation. Fan deltas with a tripartite structure characteristic of Gilbert-type deltas comprise the marginal drainage system and form along the basin margins. Mouth bar deltas develop where the axial drainage system of the basin debouches into the lake. The distribution of the two deltaic types is thought to be a function of gradient and controlled by position relative to faults within the basin. 相似文献
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琼东南盆地崖13-1气田陵三段沉积微相对储层非均质性及流动单元划分的影响 总被引：6，自引：2，他引：4
崖13-1气田陵三段是河控与潮控的辫状三角洲,主要储层沉积微相为分流河道、水下分流河道、河口坝、远砂坝及席状砂,其中河口坝的储层物性比分流河道和水下分流河道微相好,席状砂与远砂坝的物性相对较差,而各类正韵律河道与反韵律的砂坝决定了各垂向流动单元储层韵律特征。气田内的隔夹层与不同规模的海泛面相关,隔层以前三角洲泥为主,分布稳定,而夹层以分流间湾与水下分流间湾泥为主,分布较局限。结合沉积微相分布、储层非均质性及断层的分布,可以把气田区分为两个大区及6个流动单元,而南II、南III区仍可有较好的储层,但由于构造上处于低部位,含气前景还需进一步论证。 相似文献
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运用岩心观察、粒度分析、地震及测井曲线形态分析等资料,结合单井相、剖面相分析,对永安镇油田沙三段上亚段一沙二段下亚段沉积特征进行系统研究,确定其发育河流一三角洲相沉积和湖泊相沉积。三角洲相沉积在该地区发育三角洲平原亚相和三角洲前缘亚相。湖泊相发育滑塌沉积。系统研究了储集砂体的时空演化、展布规律及砂体发育的控制因素,分流河道微相和河口坝微相是该区最有利的储集砂体,对下一步石油地质勘探研究具有重要的地质意义。 相似文献
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自浅水三角洲的概念提出以来,已经历了60多年的研究历史。虽然在诸多方面取得了较大的研究进展,但在浅水三角洲的概念内涵、砂体成因类型及沉积构型样式等方面仍存在一定的分歧。本文探讨了浅水三角洲概念的内涵,并总结和分析了其沉积构型特征和样式。根据浪基面和河-盆水深比(初始河道深度与河口盆地水体深度比值),可将三角洲分为极浅水三角洲、较浅水三角洲和较深水三角洲。典型的浅水三角洲为极浅水三角洲,发育于河-盆水深比值大于或等于1的浅水水体,分流河道可下切至下伏的前三角洲沉积。根据三角洲前缘分流河道与河口坝的组合样式,将河控浅水三角洲的端元类型分为分流砂坝型和指状砂坝型。分流砂坝型三角洲为河道入海(湖)后形成的多级分叉的河口坝与分流河道系统,平面上呈扇状,河—坝组合呈现“河在坝间”的样式,而指状砂坝型三角洲为指状砂坝与分流间湾相间分布的系统,平面上呈枝状,河—坝组合呈现“河在坝内”的样式。 相似文献
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鄂尔多斯盆地东北缘神木地区浅湖三角洲沉积作用及煤聚集 总被引：2，自引：0，他引：2
鄂尔多斯盆地东北缘延安组含有大量的优质煤,属稳定大地构造条件下的浅湖三角州沉积物。三角洲体系有以下单元组成:(1)前三角洲;(2)三角洲前缘(水下分流河道相和河口坝相);(3)三角洲平原(分流河道相,天然堤、决口扇、沼泽和具决口三角洲的分流间湾);(4)废弃三角洲平原.通过详细的露头观察和岩心研究及沉积岩的地质填图工作,浅湖三角洲特征可归纳如下:(1)推进速度非常快、舌形体长而窄,间湾在其间发育,决口事件频繁发生;(2)前三角洲非常薄(0.2～0.5m),三角洲剖面几乎绝大部分由三角洲前缘和三角洲平原构成;(3)河口坝相由砂岩和泥岩互层组成;(4)水下分流河道砂岩厚度在0.5～3.5m范围内,被河口坝沉积物围绕;(5)在废弃三角洲平原中,由于极少沉积物带入沼泽,因此沉积了厚的低灰煤层。 相似文献
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RAYMOND S. EILERTSEN GEOFFREY D. CORNER ODD AASHEIM LOUISE HANSEN 《Sedimentology》2011,58(7):1784-1809
Lithofacies characteristics and depositional geometry of a sandy, prograding delta deposited as part of the Holocene valley‐fill stratigraphy in the Målselv valley, northern Norway, were examined using morpho‐sedimentary mapping, facies analysis of sediments in exposed sections, auger drilling and ground penetrating radar survey. Various lithofacies types record a broad range of depositional processes within an overall coarsening‐upward succession comprising a lowermost prodelta/bottomset unit, an intermediate delta slope/foreset unit containing steeply dipping clinoforms and an uppermost delta plain/topset unit. Bottomset lithofacies typically comprise sand‐silt couplets (tidal rhythmites), bioturbated sands and silts, and flaser and lenticular bedding. These sediments were deposited from suspension fall‐out, partly controlled by tidal currents and fluvial effluent processes. Delta foreset lithofacies comprise massive, inverse graded and normal graded beds deposited by gravity‐driven processes (mainly cohesionless debris flows and turbidity currents) and suspension fall‐out. In places, delta foreset beds show tidal rhythmicity and individual beds can be followed downslope into bottomset beds. Delta plain facies show an upward‐fining succession with trough cross‐beds at the base, followed by planar, laminated and massive beds indicative of a bedload dominated river/distributary system. This study presents a model of deltaic development that can be described with reference to three styles within a continuum related primarily to water depth within a basin of variable geometry: (i) bypass; (ii) shoal‐water; and (iii) deep‐water deltas. Bypass and deep‐water deltas can be considered as end members, whereas shoal‐water deltas are an intermediate type. The bypass delta is characterized by rapid progradation and an absence of delta slope sediments and low basin floor aggradation due to low accommodation space. The shoal‐water delta is characterized by rapid progradation, a short delta slope dominated by gravity‐flow processes and a prodelta area characterized by rapid sea‐floor aggradation due to intense suspension fallout of sandy material. Using tidal rhythmites as time‐markers, a progradation rate of up to 11 m year?1 has been recorded. The deep‐water delta is characterized by a relatively long delta slope dominated by gravity flows, moderate suspension fall‐out and slow sea‐floor aggradation in the prodelta area. 相似文献