伊通盆地莫里青断陷双阳组湖泊水下扇沉积特征

本文详细研究了伊通盆地莫里青断陷双阳组沉积类型,并将该区湖泊水下扇的岩相组成划分为5种类型：经典浊积岩相、块状砂岩相、砾质砂岩相、颗粒支撑砾岩相、基质支撑砾岩相;将湖泊水下扇划分为内扇、中扇、外扇三个亚相,对各亚相进一步划分了若干微相。湖泊水下扇沉积为该区地层的主要沉积特征,在垂向上具有进积型和退积型两种类型。     

东营凹陷北带古近系沙四段砂砾岩体沉积特征及沉积模式

综合岩心观察、薄片鉴定、砂砾岩厚度及百分含量等资料,对东营凹陷北带沙四段砂砾岩的沉积特征、成因类型及沉积演化模式进行了系统研究。结果表明,东营凹陷北带沙四段砂砾岩储层中块状层理、粒序层理、平行层理、叠覆冲刷构造、交错层理发育,同时变形构造、泥岩撕裂屑、重荷模和火焰构造常见。碎屑颗粒表现为无分选-中等分选、棱角状-次棱角状到次圆状的近物源沉积特征。岩相类型以块状层理砾岩相、递变层理砾岩相、递变层理砂质砾岩相、交错层理砾质砂岩相、平行层理砾质砂岩相、块状层理砾质砂岩相、块状砂岩相、平行层理砂岩相、块状层理砂岩相、变形层理砂岩相、泥质撕裂变形砂岩相、薄层透镜状或压扁层理砂岩相为主。综合古地貌、砂砾岩沉积特征及沉积机制等,认为东营凹陷北带沙四段主要发育近岸水下扇、湖底扇和扇三角洲等成因类型的砂砾岩扇体。在沉积演化上,沙四下亚段沉积时期,胜坨地区和民丰地区发育近岸水下扇沉积,利津地区发育扇三角洲沉积,扇体规模较小,横向连续性较差;沙四上亚段沉积时期,胜坨地区和民丰地区广泛发育近岸水下扇-湖底扇沉积,利津西部地区发育扇三角洲沉积,扇体规模较大,横向连片发育。     

酒西盆地下白垩统下沟组重力流水下扇沉积

重力流水下扇由四种岩相组成:1.砾岩相,属水下碎屑流沉积;2.砾质泥岩相,是多成因的;3.砂岩相,系高密度浊流沉积;4.粉砂岩泥岩相,为低密度浊流和正常湖泊沉积。细分为十五种亚相。岩相的空间配置关系表明水下扇是由突变性洪水事件(和水下滑坡)-水下碎屑流-高密度浊流-低密度浊流的重力流系列形成。本文对重力流沉积从层序结构、沉积体形态、岩相变化和构造控制诸方面进行了探讨。     

秦岭商丹带内黑河地区砾岩沉积及其构造意义

发育于秦岭板块结合部位的黑河砾岩是由水下碎屑流，颗粒流和砾质高密度浊流形成的。它们与周围相关岩相一起构成了二个明显的相组合，代有了二个独立的裙状沉积体。组合Ⅰ中的砾岩是由火山泥流泻入浅水碳酸盐台地之上沉积而成，而组合Ⅱ中的砾岩则与中一细粒浊积岩一起表现为深水远端沉积。砾岩的形成和发展与古生代秦岭板块的俯冲及相邻火山岛弧的演化密切相关，是当时弧前盆地沉积体的一个组成部分。     

大港滩海埕北断阶区沙河街组三段、二段近岸水下扇沉积微相特征

大港滩海埕北断阶区沙河街组沙三段、沙二段砂体是由辫状水道控制的近岸水下扇。主要发育基质支撑砂砾岩相、颗粒支撑砂砾岩相、正递变层理砾岩相、含砾砂岩相、逆递变层理砾岩相、含砾砂岩相、泥质支撑砂岩相和粉砂岩相,粒度粗是其主要特征;水平层理、块状层理、平行层理、交错层理、波状层理、包卷层理和变形层理十分发育;砂球、重荷模、砂岩脉和冲刷面等沉积构造也十分发育：电阻率曲线呈正韵律,曲线由高幅至中幅呈钟形及箱形,与不同岩性和不同沉积相具良好对应关系。通过对区内各井的岩性组合观察,结合各砂层组的沉积特征及其相应的测井相标志将研究区近岸水下扇划分为2个亚相和5个微相：扇中(包括辫状水道、辫状水道间和扇中前缘)和扇端亚相(扇端泥、扇端席状砂)。其中扇中辫状水道为主要储集层。     

南天山野云沟石炭系海底扇沉积新发现

南天山野云沟石炭系上部碎屑岩中存在典型的鲍玛序列浊积构造以及滑塌构造、包卷层理等重力流沉积构造。由地层剖面分析和岩相特征及粒度统计分析的CM\%图解可知,南天山野云沟石炭系上部的碎屑岩形成于海底扇环境,可划分出杂乱砾岩相（A1）、无碟状构造块状砂岩相（B2）、近基浊积岩相（C）、远基浊积岩相（D）、滑塌角砾岩相（F）、页岩夹硅质岩相（G）等岩相类型,它们组合构成了Walker海底扇模式中的扇根、扇中、扇端。因而,首次证实南天山野云沟石炭系中存在深水海底扇沉积。古流向资料计算结果表明,其物源来自南侧的古塔里木陆块,古坡向倾向北。碎屑物常量化学成分投点表明,其形成时构造背景属被动大陆边缘。     

碎屑流与浊流的流体性质及沉积特征研究进展

受浊流沉积模式(即鲍马序列和浊积扇模式)的驱动和浊积岩思维定势的影响,自1970s浊流与浊积岩的概念逐渐扩大,特别是通过"高密度浊流"术语的引入,以及将水下浊流与陆上河流的错误类比,使得一部分碎屑流与底流的沉积被认为是浊积岩。随着现代观测设备的应用以及详细的岩芯观察,碎屑流(特别是砂质碎屑流)和浊流被重新认识。浊流是一种具牛顿流变性质和紊乱状态的沉积物重力流,其沉积物支撑机制是湍流。碎屑流是一种具塑性流变性质和层流状态的沉积物重力流,其沉积物支撑机制主要是基质强度和颗粒间的摩擦强度。浊流沉积具特征的正粒序韵律结构,底部为突变接触而顶部为渐变接触;碎屑流沉积一般具上、下两层韵律结构,即下部发育具平行碎屑结构的层流段,上部发育具块状层理的"刚性"筏流段。但当碎屑流被周围流体整体稀释改造且改造不彻底时,强碎屑流可变为中—弱碎屑流,相应自下而上可形成逆—正粒序的沉积韵律结构,其中发育有呈漂浮状的石英颗粒和泥质撕裂屑等碎屑颗粒,明显区别于浊流沉积单一的正粒序韵律结构特征。碎屑流沉积顶、底部均为突变接触。浊流的沉积模式为简单的具平坦盆底的坡底模式,而碎屑流则为复杂的斜坡模式。     

孙吴-嘉荫盆地白垩系淘淇河组水下重力流沉积特征

本文根据露头、岩心、测井、薄片鉴定等资料,对孙吴-嘉荫盆地白垩系淘淇河组水下重力流沉积特征进行了详细的研究,认为淘淇河组水下重力流沉积规模大,为湖底扇沉积,其可进一步划分为内扇、中扇、外扇3种亚相以及主沟道、主沟道外、辫状沟道、辫状沟道间、远源浊积岩5种微相类型。内扇以水下泥石流沉积为主,中扇以液化沉积物流和浊流沉积为主,外扇发育浊积岩。根据地震剖面推断,白垩系淘淇河组时期发生的断层活动是湖底扇沉积发育的主要原因。     

南襄盆地泌阳凹陷深凹区核三段沉积特征及演化

通过测井、录井、粒度分析资料,结合区域地质资料、前人研究成果、岩心描述和地震反射资料,认为核三段发育辫状河三角洲、近岸水下扇、滑塌浊积扇及湖泊沉积,并进一步识别出5个亚相及6个微相。其中,近岸水下扇发育于研究区西南部和东南部的控边断层处,辫状河三角洲发育于东北部,滑塌浊积扇发育于辫状河三角洲前端的半深湖-深湖区域。近岸水下扇岩性主要为灰白色中、细砾岩,砾石成分复杂,分选差,磨圆程度低。辫状河三角洲发育平行层理、交错层理及冲刷充填构造,垂向上构成间断正韵律,其岩性为浅灰色砾岩、砾质砂岩、砂岩,中-厚层或块状,自然电位曲线和电阻率曲线呈钟形或箱型。辫状河三角洲前缘砂体失稳,产生滑塌,在深湖区形成滑塌浊积扇,其岩性为细砂岩、粉砂岩、泥质粉砂岩,多呈正韵律,发育块状层理、液化变形层理、波状层理及泥岩撕裂屑、槽模、沟模构造等,电测曲线表现为钟形、箱形、漏斗形等。湖泊沉积主要发育于三角洲前缘和近岸水下扇前方的深凹区。从H38-H31研究区经历了水体由深到浅再略加深的沉积演化。     

柴达木盆地西部阿尔金山前中生界浊积岩特征及意义

野外勘查发现柴达木盆地西部阿尔金山前中生界黑色泥岩层中广泛发育浊积岩层，具有冲刷面、槽模等层面构造和粒序层理、水平层理、流水波纹层理、同生叠瓦状等层内构造。鲍玛序列存在6种组合。浊积岩相分为块状砂岩相（B1）和近基浊积岩相（C），为近源水下缓坡沉积体系。浊积岩的存在及其沉积构造特征所提供的大量古水流信息表明：柴西中生代古水流格局总体上是自东北向西南，阿尔金山斜坡带在侏罗纪中后期处于持续沉降时期，为一沉积坳陷，而柴达木盆地的腹地则为隆起和物源区。     

东营凹陷永55区块沙四上亚段深水浊积扇沉积与油气

深水浊积扇是东营凹陷北部陡坡带永55区块沙四上亚段最发育的沉积相,也是最有利的砂砾岩储层。在岩心观察基础上,通过薄片鉴定、粒度分析等测试手段,综合地质、物探和测井资料,对永55区块砂砾岩体储层的沉积特征进行了研究。结果表明,本区深水浊积扇沉积具有如下特征：(1)岩石成分成熟度和结构成熟度均较低;(2)碎屑物质以递变悬浮搬运为主;(3)沉积构造具有典型的重力流成因特征;(4)岩心中见典型鲍马沉积序列。建立了深水浊积扇退积型沉积模式,并进一步细分为内扇、中扇和外扇3个亚相及4个微相。位于中扇的辫状沟道砂体物性好,可以构成优质储层,较深湖暗色泥岩为主要的烃源岩和盖层,本区生、储、盖发育齐全,有着良好的勘探开发前景。     

Facies architecture of a submarine fan channel–levee complex: the Juniper Ridge Conglomerate, Coalinga, California

The Upper Cretaceous Juniper Ridge Conglomerate (JRC) near Coalinga, California, provides a rare, high-quality exposure of a submarine channel to overbank transition. The facies architecture of the JRC comprises a thick, predominantly mudstone sequence overlain by a channellized conglomerate package. Conglomeratic bounding surfaces truncate successions of interbedded turbiditic sandstones and mudstones both vertically and laterally. Thick-bedded, massive sandstones are interbedded with conglomerates. Facies architecture, palaeocurrent indicators, slump features, sandstone percentages and sandstone bed thickness trends lead to the interpretation that these elements comprise channel and overbank facies. A vertical sequence with conglomerate at the base, followed by thick-bedded sandstone, and capped by interbedded turbiditic sandstone and mudstone form a fining-upward lithofacies association that is interpreted as a single channel-fill/overbank system. Three similar lithofacies associations can be related to autocyclic processes of thalweg migration and submarine fan aggradation or to allocyclically driven changes in sediment calibre.     

乌里雅斯太凹陷斜坡带湖底扇相砾岩体沉积特征与隐蔽油藏勘探

乌里雅斯太凹陷南洼槽斜坡带发育一套厚度大、粒级粗和相变快的砾岩体,根据岩心观察、岩电组合特征和地震相分析等手段,结合岩矿等分析化验资料,认为该套砾岩体属具补给水道的湖底扇相沉积。砾岩体夹于较深湖亚相的深灰色泥岩中,发育沉积物重力流成因的沉积构造,内扇、中扇和外扇等相带发育齐全,并具有多期发育的特点。物源区具有的线物源或多物源特征,以及极粗的粒级造成补给水道的稳定性较差、规模较小、迁移性较强,沿斜坡带形成了纵向上由南向北依次叠置、横向上叠加连片的多个湖底扇相砾岩体。坡度很陡的斜坡,特别是构造坡折带的存在控制了湖底扇的形成和发育,使湖底扇相砾岩体主要沿构造坡折带下部分布,具有很好的隐蔽油藏成藏条件,以中扇辫状沟道微相区最为有利,已有多口井发现厚油层并获工业油流,实现了隐蔽油藏勘探的重大突破。     

西藏朗杰学群复理石粒度特征及沉积环境分析

西藏朗杰学群作为雅鲁藏布江结合带洋板块地层序列的重要组成部分,其形成的环境对研究特提斯构造运动具有重要的意义。论文系统总结了朗杰学群的岩石组合特征、构造变形特征; 通过鲍马序列的识别,建立了4种基本层序; 根据物质组成、结构构造及层序分析,认为其发育海底扇相模式,整体属浊积扇内扇-外扇亚相环境,发育少部分主水道亚相的砂砾岩沉积,具有鲍马层序由A、C段向B、C、D和C、D、E段组合转变的特点,反映了由高流态向低流态转变的特征。运用粒度分析对朗杰学群物质成分的成熟度、分选性、搬运及沉积的形式进行了探讨,认为其与哈德逊浊积扇和现代深海阿里斯托亚扇的粒度曲线相似,应属重力流沉积中的浊流沉积类型,指示其形成于大陆斜坡环境。     

The lower Devonian Kowmung volcaniclastics: A deep‐water succession of mass‐flow origin,northeastern Lachlan Fold Belt,N.S.W.

The Lower to ?Middle Devonian Kowmung Volcaniclastics form the upper part of a succession of Upper Siluran to mid‐Devonian flyschoid rocks in the Yerranderie area of N.S.W., and contain two major facies associations. (1) A mudstone facies association represents the ambient, background sedimentation, comprising predominantly buff mudstone that is host to an assemblage of coarser‐grained sediments, including graded‐bedded to massive siltstone, sandstone, conglomerate, allodapic limestone, and large allochthonous limestone blocks and associated limestone breccia. Bouma sequences are common, sole structures occur and maximum bed thickness is about 3 m. (2) A volcaniclastic facies association intrudes and interrupts the accumulation of the ambient mudstone facies association, and contains massive to partly graded, quartzofeldspathic siltstone, sandstone, breccia and conglomerate. Sedimentation units in the volcaniclastic facies association are up to 120 m thick. The two facies associations interfinger. Stratigraphically, the base of the Kowmung Volcaniclastics is taken as the first sedimentation unit of the volcaniclastic facies association. The mudstone facies association below this level is part of the Siluro‐Devonian Taralga Group.

Both facies associations were deposited in relatively deep‐water. The dominant transport process in both associations was mass‐flow, involving granular mass‐flows (turbidity currents, grain flows), debris flows and avalanches. Massive mudstone is hemipelagic in origin. The volcaniclastic facies association probably represents a submarine volcanic apron around the emergent, volcanic Bindook Complex. Grossly, the succession coarsens upwards, and there is evidence of several sources of sediment, rather than a single point at the head of a submarine fan.

Provenance is diverse. In the mudstone facies association, framework grains in sandstone are microlitic volcanic‐rock fragments with a mafic to intermediate volcanic source. Clasts in conglomerate and breccia are consistent with derivation from the regionally extensive, quartzose Ordovician flyschoid successions. Clasts of ?penecontemporaneous limestone also occur. The volcaniclastic facies association was probably derived largely from the nearby, coeval Bindook Complex, which consists of silicic ash‐flow and ash‐fall tuff, lava, associated sediment and granitoids. Detritus was either derived directly from volcanic eruptions or was worked in fringing littoral and fluvial environments prior to redeposition by mass‐flow. Quartzite boulders mixed with volcanic clasts in the conglomerate suggest that Ordovician quartzarenite was also exposed around the volcanic complex. Tentative provenance correlations have been made between the different rock units in the Kowmung Volcaniclastics and their possible sources in the northern part of the Bindook Complex.     

江西修水地区中元古界双桥山群浊流沉积

对江西修水地区双桥山群安乐林组和修水组的岩石组合、沉积构造、浊积岩岩相、垂向演化序列进行了详细论述,识别出两个比较完整的浊积扇,其内部可进一步划分为内扇主水道、次级水道、高阶地;中扇分支水道、分支水道漫滩、外缘垛体;外扇沉积,反映了一个从进积到退积的沉积旋回,揭示了从安乐林组发生海退到修水组发生海侵的总体变化趋势.对修水组底部砂岩和砾岩结构、层序特征、横向变化等的系统研究,显示其具有明显的深水重力流特征,系海平面快速下降过程中形成的浊积扇内扇主水道砾岩.研究表明安乐林组与修水组为连续沉积,"修水运动"不存在.     

鄂尔多斯盆地西南部延长组6段重力流沉积特征及其油气地质意义

鄂尔多斯盆地南部延长组长6油层组中发现大量块状无层理砂岩,属陡坡带处堆积的三角洲前缘沉积物沿斜坡滑塌形成的重力流沉积。综合岩芯、露头、测井及分析化验资料,认为延长组发育滑塌岩、液化沉积物流、砂质碎屑流和经典浊流等多种类型的重力流,不同类型重力流沉积特征差异明显;其中地形坡度、物源供给和一定的触发机制是形成长6重力流沉积的基本条件;在流动过程中由于水的混入和沉积物卸载,重力流沉积物发生浓度变化和流态转换,形成滑塌岩-砂质碎屑流、砂质碎屑流-浊流、浊流等不同组合类型;重力流砂岩延伸至半深湖-深湖相泥岩中,与长7烃源岩侧向连通,形成有利的成藏组合,是研究区延长组重要的勘探目标区。     

Deep-water fan-channel conglomerates of Late Cretaceous age, southern Chile

The exceptionally well exposed Lago Sofia conglomerate and sandstone lenses in the Upper Cretaceous Cerro Toro Formation of southern Chile are interpreted as the channel and channel margin facies of a deep-sea fan. The north-to-south oriented channels formed on an elongate fan in a narrow retroarc basin between a rising cordillera to the west and the South American craton to the east. The great length of some of the channels (> 120 km) seems to reflect the long duration (> 30 m.y.) and stable nature of the basin. Enclosing the lenses is the fine-grained Cerro Toro Formation which represents overbank turbidite flows and hemipelagic sedimentation on levee and levee flank areas. Foraminiferal assemblages suggest deposition in 1000-2000 m of water. Most of the conglomerate has features developed by tractive currents (parallel- and cross-stratified conglomerate). Most is moderately well sorted, imbricated, and has parallel to inclined stratification; large-scale dunes up to 4 m high are exposed. Typical sediment, gravity flow structures and bedding styles (e.g. pebbly mudstones, graded conglomerate, giant flutes) are not as common in the channel deposits as are tractive features. Tractive features in the gravels apparently were developed by rolling, sliding, and saltation as the bed-load component of highly turbulent, moderate- to low-density turbidity currents flowing in a confined channel. Graded-to-massive conglomerates appear to have been deposited rapidly from fully turbulent flows; diamictites were deposited from debris flows in which fluid viscosity, yield strength, and buoyancy of the fluid were dominant. The three major conglomerate classes recognized do not occur in a systematic manner; vertical and lateral heterogeneity is the rule.     

海底扇沉积相模式、沉积过程及其沉积记录的指示意义

海底扇是由沉积物重力流形成的海底沉积体。其分类学和相模式研究表明,海底扇主要由海底水道、溢岸及朵叶体等沉积单元构成。然而古代和现代海底扇沉积均无法由单一的通用相模式进行解释。以粒度差异所建立的相模式类型涵盖了多方面信息,相对简单实用。海底扇的触发机制主要包括海底沉积物失稳、洪水型异重流、海洋动力过程及复合成因机制等类型。海底扇的主导流体类型（碎屑流与浊流）、海底地貌形态（限制性与非限制性）及海洋动力条件（底流作用）深刻影响了海底扇的沉积作用、平面形态及空间组合特征,整体上分为三类。其中,浊流沉积主导的海底扇在非限制性海底环境中主要表现为扇状或指状形态,在限制性海底环境中则直接受控于盆地的地貌形态;碎屑流沉积主导的海底扇以块体搬运为特征,平面上表现为舌状和叶状展布形态;底流与重力流共同作用形成的混合型海底扇朵叶体沿底流流向侧向偏转,部分受底流改造沉积形成孤立漂积丘状形态。海底扇沉积物记录了环境信号从“源”到“汇”传输效率和保存程度,对构造变形和古气候变化具有重要的指示作用。人类世以来的现代海底扇沉积物同时也是深海微塑料、陆源有机碳的重要储库,定量评估其丰度特征对于环境评价、污染治理与管控及全球碳循环均具有深远的现实意义。