共查询到18条相似文献，搜索用时 187 毫秒
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摘要：本文首次对区内杂砾岩（又称红层）的沉积学特征进行研究。据成因之不同,把杂砾岩区分为６类：泥石流、颗粒流、泥流、冲刷砾石层、河道及片流沉积。讨论了各类沉积之特点,尤其是砾石的粒度分布特征。结果表明,不同成因的杂砾岩砾石的粒度分布曲线形态,尤其是量化粒度参数存在明显差异。 相似文献
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冲积扇砂砾岩油藏是准噶尔盆地勘探热点,尤其是玛湖凹陷特大型砂砾岩油藏的发现,更加表明砾质冲积扇储层研究的必要。选取白杨河冲积扇为研究对象,对砾质辫状河型冲积扇内部片流带以及支撑砾岩的沉积特征和分布规律进行研究,结果表明:1）扇内片流带沉积介于扇根补给水道与扇中辫状水道沉积环境之间,与二者呈过渡接触,片流带规模可达千米级别,内部支撑砾岩的发育改善了片流带储层物性;2）识别出三类支撑砾岩,分别是片流支撑砾岩、沿层理面发育的支撑砾岩以及沟槽底部支撑砾岩,前两者均为超临界水流淘洗成因,后者则为径流改造成因;3）片流支撑砾岩发育于片流沉积,具有较好的成层性以及较高的线密度;沿层面发育的支撑砾岩发育于辫状沟槽沉积环境,形态受限于沟槽规模,可与交错层理砾岩匹配形成大规模优质岩相组合;沟槽底部发育的支撑砾岩发育于辫状水道底部,规模小但连通性好。综上,基于野外露头片流带以及支撑砾岩研究可以为井下砂砾岩油藏开发提供理论支撑。 相似文献
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砾质辫状河型冲积扇岩相类型、成因及分布规律 ——以准噶尔盆地西北缘现代白杨河冲积扇为例 总被引：2，自引：2，他引：0
冲积扇砂砾岩储层是准噶尔盆地一类重要的油气储层类型,由于其具岩相类型多、连续性差等特点,对冲积扇内部岩相成因解释一直是冲积扇相带认知的基础和难点。以准噶尔盆地西北缘现代白杨河冲积扇为例,在大量的野外露头资料和粒度分析数据的基础上,结合冲积扇源区母岩类型、水文资料以及冲积扇文献资料,对现代白杨河冲积扇岩相的类型、成因及分布规律进行探讨。按沉积机制,白杨河冲积扇属于辫状河型冲积扇,具有规模大(扇体总面积约327.6 km^2),坡度平缓(约1‰～7‰),沉积粒度粗等特征。在白杨河冲积扇内共可识别出16种岩相类型,并根据岩相形成的流体动力差异划归为5类成因,即重力流成因、高流态牵引流成因、低流态牵引流成因、静水沉积成因以及风成沉积成因。重力流以洪流沉积为主;高流态牵引流主要包括片流沉积和湍流沉积;低流态牵引流以砂(砾)质河道沉积为主;静水沉积以蓄水细粒沉积为主;风成沉积以风携细粒沉积为主。根据各岩相沉积构造、粒度特征及展布规模,可将岩相划分为四类:Ⅰ类岩相沉积构造特征明显并具有较大展布规模;Ⅱ类岩相沉积构造特征明显但展布规模局限;Ⅲ类岩相为不具层理构造但具有较大展布规模的岩相;Ⅳ类岩相不具层理构造并且展布规模局限。其中Ⅰ类和Ⅱ类岩相多为牵引流成因,多发育于洪水期扇体扇中、扇缘区域以及间洪期扇体的扇中区域,并可在地下继承性发育为较好的储集相带。 相似文献
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松辽盆地东南缘六台地区下白垩统营城组二段砾岩沉积特征及成因模型 总被引：1，自引：0，他引：1
松辽盆地东南缘六台地区营城组二段发育一套冲积扇砾岩层。根据砾岩成因不同分为泥石流砾岩、河道砾岩和漫流砾岩等沉积类型,其中泥石流砾岩最为发育。通过研究泥石流砾岩的成分、结构成熟度和粒度分布特征,并运用经验公式最终判断其为再沉积的水上泥石流砾岩。河道砾岩和漫流砾岩沉积类型在本区保存较少,或许曾经在单个旋回中非常发育,但是被下个旋回猛烈的泥石流所改造。河道砾岩和漫流砾岩中层理的收敛方向及硅化木走向均表明本区古水流方向为近北西—东南向。根据古水流向等信息判断出本区砾岩的物源来自北西方向的北山,并在此基础上建立了本区砾岩冲积扇成因模型。 相似文献
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汤原断陷古近系扇三角洲沉积特征 总被引：2，自引：0，他引：2
汤原断陷新安村组-达连河组中广泛发育扇三角洲沉积。根据岩心观察、测井和地震资料分析、岩性鉴定、粒度分析等资料,识别出扇三角洲平原、扇三角洲前缘、前扇三角洲3个亚相,并进一步识别出8个微相。从扇三角洲平原到扇三角洲前缘,不同沉积微相的沉积特征呈现规律性的变化：沉积物结构如支撑关系由杂基支撑到颗粒支撑,颗粒间由点接触变为面接触,颗粒分选由差到好,成熟度由低到高,沉积物的粒度由粗变细等;沉积层理构造由扇三角洲平原砂砾混杂的块状层理到前缘小型低角度的交错层理、波状层理等;概率累计曲线由扇三角洲平原的一段式、低角度两段式到扇三角洲前缘的斜率较大的二段式、三段式;在C-M图上,扇三角洲平原的点群多在C、M值较大的PQ段,前缘多在OR、RS段。在此基础上,结合岩心特征、粒度分析等资料得出扇三角洲的水动力机制主要为牵引流沉积,少量重力流沉积。 相似文献
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剖析了在应用粒度分析解释沉积环境方面存在的问题。认为粒度分布和沉积环境并无直接联系,粒度分布所能反映的只能是沉积时的水动力条件。通过研究粒度曲线和参数在垂向上的变化规律——粒度曲线和参数序列分析,就有可能比较精确的确定沉积环境。 相似文献
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《地质科技情报》2016,(1)
华北克拉通南缘中元古界的沉积学、地层学及大地构造演化等研究一直是前寒武纪地质研究的热点问题。选取豫西济源地区中元古界兵马沟组典型剖面,在野外踏勘和剖面实测基础上,运用镜下薄片观察和粒度参数分析等方法对兵马沟组沉积特征进行了分析,并进行了沉积环境恢复。研究结果表明,济源兵马沟组岩性以紫红色砾岩为主,其次为含砾粗砂岩、粗砂岩等,从下往上砾石粒径逐渐减小,磨圆变好;砂岩的粒度参数特征及概率累计曲线特征表明兵马沟组为重力流沉积,概率累计曲线的变化说明其沉积时水动力条件整体上逐渐减弱。综合各方面特征分析,兵马沟组沉积时期水体动荡,有多期洪流出现,为间歇性的灾变洪流;沉积环境为冲积扇-扇三角洲沉积相,从中可识别出泥石流沉积微相、碎屑流沉积微相、分流河道沉积微相及漫流沉积微相,其中以泥石流和碎屑流沉积为主。该研究对华北克拉通南缘中元古界地层沉积环境演化研究具有重要意义。 相似文献
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丹霞盆地是白垩纪形成的内陆山间红色盆地，主要由冲积扇体、曲流河沉积体、滨湖沉积体、浅湖沉积体和火山喷发沉积体组成，其中，冲积扇体和曲流河沉积体的岩石特征是粒度粗、成分复杂，粒度与成分在空间上变化快，较难识别。本文以剖面和钻孔资料为基础，重点研究了砾岩中的砾石特征，包括成分、形态、三轴大小、扁平砾石的产状等，用以确定扇体的物质来源方向和水体的古流向等，更好地识别冲积扇体的空间分布和冲积扇体之间的叠置关系。总体上，丹霞盆地内冲积扇体的发育具有如下规律：在盆地发育初期，冲积扇体较发育，但规模小，且多分布于盆地边缘，常和断裂活动有关。砾石主要来自附近的剥蚀区，砾石的稳定系数普遍较小，且其大小与物源区的地质时代和岩性有关。早期的冲积扇体常常和火山喷发沉积体相伴生，而后期的冲积扇体则和滨-浅湖相沉积伴生。在盆地发育晚期，冲积扇体表现为规模较大，常常和河流相沉积伴生，砾石稳定系数普遍较大。 相似文献
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The fan-delta reservoir play has become an important exploration target within the Junggar Basin, especially in the Mabei area within the Mahu Sag, where a fan-delta oil and gas pool has been recently discovered. The sedimentary characteristics, distribution patterns and formation mechanisms of the fan-delta clastic bodies in Lower Triassic Baikouquan Formation (T1b) were studied using seismic, well log and core data accompanied by a flume tank experiment and a modern analogue depositional study. The T1b in the Mabei area is composed of a fan delta consisting of fan-delta plain (including debris flow deposits, sheetflood deposits, braided channel deposits, and floodplain deposits), fan-delta front (including subaqueous reworked sheetflood deposits and distal sheetflood deposits) and muddy lake deposits. The sheetflood deposits, characterised by moderately sorted conglomerates with brown matrix, form during the peak flooding. They are widespread and sheet-like, occupying the major portion of the fan-delta plain. The braided channel deposits are characterised by well-sorted and clast-supported conglomerates and pebbly sandstones, formed later during the falling flow stage. Owing to the decline in volume and velocity, and the formation of continuously braided fluid flow, the sediments of the flood period are reworked, generating the braided channels. Laterally, the braided channels occur as belts of clastic bodies surrounded by continuous sheetflood deposits. Vertically, the braided channels are interbedded between the sheetflood deposits. The subaqueous reworked sheetflood deposits are characterised by greyish-green, well-sorted and clast-supported conglomerates, whereas the distal sheetflood deposits are characterised by well-sorted sandstones, intercalated with mudstone. The subaqueous reworked sheetflood and distal sheetflood deposits are a distal partly subaqueous extension of the main sheetflood deposits, albeit reworked by basinal currents and waves. The distal sheetflood deposits form on distal fringes of the sheetfloods and are more thoroughly reworked by longshore and wave currents. The braided channel, subaqueous reworked sheetflood and distal sheetflood deposits can form high-porosity reservoirs. These findings challenge the common view and suggest that the channelised facies on the fans are not the main flood events; rather, the more extensive sheetfloods are the major flood events. 相似文献
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The turbidite dominated, Oligo-Miocene Pindos foreland basin of western mainland Greece contains two thick (60–72 m), matrix supported conglomerates. The conglomerates are ungraded and contain three clast types: (1) polymict, rounded, extrabasinal clasts (long axes 3–50 cm); (2) tightly folded, intrabasinal clasts (long axes 1–10 m); and (3) tabular, largely undeformed, intrabasinal blocks (long axes 18–300 m). Clasts are isolated within a slit dominated matrix. These chaotic, matrix supported conglomerates are interpreted as mega-debris flow deposits. During transport, extrabasinal clasts were supported by a combination of matrix cohesion and clast dispersive pressure, folded intrabasinal clasts were supported by a combination of buoyancy (Archimedes principle) and clast dispersive pressure. The large tabular clasts were transported by gravity sliding/gliding within the flow on films at high pore fluid pressure. These different clast support mechanisms were active simultaneously within the Pindos mega-debris flow deposits. As a result, the deposits have no systemic vertical stratigraphy, in contrast to many described large scale mass flow deposits. The mega-debris flow deposits are significantly thicker than most described ancient siliciclastic debris flow deposits and provide an ancient analogue for the thick Recent siliciclastic debris flow deposits on continental margins. 相似文献
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Detailed analysis is presented of a conformable succession of Early Miocene conglomerates and sandstones lying between massive marine mudstones. The coarse sediments reflect deposition by a spectrum of subaqueous debris-flow mechanisms during an early pulse of tectonism that ultimately resulted in Plio-Pleistocene eversion of the Kaikoura Mountains.Sparse pebbly mudstones and rare sandy conglomerates show disoriented clasts and reflect high-viscosity flows and slurry-creep flow mechanisms. Other deposits have little mud matrix, hence appear to reflect low-viscosity flow processes. The largest clasts in these have a preferred planar orientation, probably reflecting dispersive grain pressure, and a preferred long-axis orientation parallel to flow direction. Common sorted sandstones and some conglomeratic sandstones show diffuse parallel lamination; with rare exceptions neither grading nor traction structures are present. Other conglomeratic sandstones show trough cross-bedding which we attribute to entrained bedload movement during intersurge episodes of debris flow.Microfossil data from the mudstones indicate sedimentation in an environment of outer neritic to upper bathyal aspect. Most detritus is abraded, suggesting derivation from terrestrial or inner neritic sources, but angular calcilutitic clasts and irregular sandstone and mudstone clasts and rafts were probably derived from submarine erosion between the emergent source area and the site of accumulation. Deposits generally appear to infill broad shallow channels. Paleocurrent and fabric analysis indicate a markedly uniform flow direction throughout succession, and suggest that the locus of channeling remained relatively fixed in space throughout accumulation of hundreds of metres of superimposed, commonly amalgamated debris-flow deposits. Although lateral control away from the measured sequence is limited, we infer that the locus of deposition lay shoreward of any submarine canyon or fan. 相似文献
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贺兰奥拉槽早古生代深水重力流体系的沉积特征和充填样式 总被引：6，自引：1，他引：6
位于鄂尔多斯西缘的贺兰构造带为一中元古代一古生代的奥拉槽。在区内的中寒武和中奥陶统中识别了一套巨厚的深水重力流沉积,其中包括下斜坡滑塌泥石流复合体、浊积扇以及碳酸盐岩斜坡扇裙等沉积类型。主要的相单元包括充填沟道或进入扇面形成的泥石流钙质角砾岩和砾岩、充填辫状水道的多层叠置的砂岩和砂砾岩、上叠扇的砂、泥岩互层以及浊积砂屑或含砾砂屑灰岩等。在中奥陶世该奥拉槽发展成一深水一半深水海槽,沿盆地西侧发育有浊积扇,而东侧仅有碳酸盐岩滑塌扇裙。它们可能是沿深水盆地两侧深大断裂产生的陡坡或水下断崖分布的,代表了早古生代贺兰奥拉槽在强烈沉陷期特定的深水盆地充填。 相似文献
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通过露头实测、岩心观察及测录井资料分析等结果表明,克拉玛依油田一中区克拉玛依组S7、S5和S4砂层组沉积时期以发育辫状河为特征,可进一步划分为近源砾质辫状河、远源砾质辫状河和砂质辫状河沉积3种类型。上述3种类型的辫状河沉积在沉积特征、河道空间叠置样式及组合关系等方面存在明显的差异。近源砾质辫状河河道岩性以砾岩为主,为中孔低渗储层。单河道沉积厚度2~4.5m,宽度500~800m,表现为河道-河道直接接触的连片组合方式;远源砾质辫状河河道岩性仍以砾岩为主,含少量砂岩,物性较近源砾质辫状河略好,为中孔低渗储层。单河道沉积厚度为1.5~4m,河道砂体宽度400~750m,表现为河道-溢岸-河道的连片组合方式;砂质辫状河河道岩性以砂岩为主,为中孔低渗储层,物性优于砾质辫状河。单层厚度为0.5~2.5m,宽度为300~700m,但河道沉积分布范围有限,河道之间多为带状或交织带状组合方式。根据上述对比分析认为砾质辫状河河道砂体虽然物性相对较差、非均质性较强,但砂体厚度大、分布广泛、连通性好,目前为全区主要油气开发的目的层;砂质辫状河河道砂体尽管物性较好,但由于厚度较薄,分布局限,仅在东部地区其累计厚度较大,当与其它成藏条件匹配时,可形成具有开发潜力的目的层。 相似文献
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The tectono‐sedimentary evolution of the Rotliegend deposits of the northernmost margin of NE German Basin (NEGB) has been analysed on the basis of detailed sedimentary logs of 300 m of core material together with the re‐evaluation of 600 km of seismic lines. Three distinct phases were recognized. During the initial Phase I, basin geometry was largely controlled by normal faulting related to deep‐seated ductile shearing leading to a strong asymmetric shape, with a steep fault‐controlled eastern margin and a gently, dipping western margin. The results of forward modelling along a cross‐section fit the basin geometry in width and depth and reveal a footwall uplift of c. 1000 m. Adjacent to the steep faults, local sedimentation of Lithofacies Type I was confined to non‐cohesive debris flow‐dominated alluvial fans, whereas the gently dipping western margin was dominated by alluvial‐cone sedimentation. During the post‐extensional period (Phase II), cooling of the lithosphere generated additional accommodation space. The sediments of Lithofacies Type II, comprising mainly clast‐supported conglomerates, are interpreted as braided ephemeral stream flow‐surge deposits. Tectonic quiescence and an increase in flood events resulting from wetter climate led to progradation of this facies over the entire region. At the end of this period, the accommodation space was almost completely filled resulting in a level topography. Phase III was controlled by the thermal‐induced subsidence of the southerly located NEGB in post‐Illawarra times. The formerly isolated region tilted towards the SW, thus forming the northern margin of the NEGB during uppermost Havel and Elbe Subgroup times. The sediments of Lithofacies Type III were divided into a marginal sandstone‐dominated environment and a finer‐grained facies towards the SW. The former consists of poorly‐sorted coarse‐grained sandstones of a proximal and medial ephemeral stream floodplain facies. The latter comprise mud flat fines and fine‐grained distal ephemeral stream deposits. The end of the tectono‐sedimentary evolution is marked by the basinwide Zechstein transgression. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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R. J. WASSON 《Sedimentology》1977,24(6):781-799
Alluvial fans of the last glacial age in the lower Derwent Valley in southeastern Tasmania were built by debris flows and stream flows. The deposits were derived from periglacial and nivational slope mantles at the highest altitudes in the fan catchments, and from regolith of uncertain affinities at the lowest elevations. The apical and middle parts of the fans commonly consist of coarse-grained debris flow and water-laid deposits, while the distal deposits are predominantly water-laid sheetflood silts and clays. Channels are important in the proximal parts of the fans and are mostly filled with water-laid sediments, less commonly by debris flow deposits. A first approximation to the mean velocity of the last stage of debris flow in a channel is between 4 m/sec and 6 m/sec. A group of ‘water-laid’ sediments shows very poor separation of particle sizes, and two explanations have been offered for these sediments. Firstly, the large quantities of unsorted debris available from the catchments produced moderately well-sorted slurries, or, secondly, openwork stream gravels were infiltrated by later water flows charged with fines. The streams crossing the fans also produced water flows with relatively low suspended sediment concentrations resulting in reasonably good sorting. The debris flows and ‘water-laid’ muddy sediments cannot be distinguished using CM plots. The debris flows display considerable variation in thickness and grain-size characteristics, which is attributable to properties inherent in debris flow behaviour. 相似文献
18.
以东营凹陷沙三中亚段三角洲前缘滑塌型重力流砂体为研究对象,利用三维地震、钻井岩心、测录井和分析测试等资料,开展三角洲前缘滑塌型重力流砂体岩相和岩相组合类型划分及分布特征研究。根据泥质含量和沉积构造,划分出13种岩相类型,其中块状层理砂岩相在研究区最为发育。以泥岩、冲刷面或岩相转化面为界,划分出20种岩相组合类型,分为5大类,分别是保留原始沉积构造的岩相组合、变形构造发育的岩相组合、块状层理和碎屑发育的岩相组合、下部碎屑流和上部浊流沉积的岩相组合,以及不完整鲍马序列的岩相组合,反映重力驱动事件中的滑动、滑塌、碎屑流、碎屑流-浊流、浊流沉积作用。根据不同类型重力流的垂向组合和典型剖面岩相分布特征,认为从盆地斜坡到盆地平原,重力流呈现滑动-滑塌-碎屑流-浊流演化特征,滑塌近端主要发育滑动作用岩相组合和滑塌作用岩相组合,滑塌中部主要发育碎屑流岩相组合和碎屑流与浊流过渡转化岩相组合,滑塌远端主要发育浊流作用岩相组合。 相似文献