混积岩的分类和成因

对在混合作用的特征者了系统的阐述和讨论,混积岩是陆源碎屑和碳酸盐颗粒及灰泥混合在一起的沉积岩,属曲型陆源碎屑岩和碳酸盐岩之间的过渡类型,据其成分可分为４类,陆源碎屑和碳酸盐颗粒,灰泥的混合作用从成因上分为５种类型,副件突变沉积混合,相缘渐变沉积混合,原地沉积混合,侵蚀再沉积混合,岩溶穿插再沉积混合。     

寒武系第二统仙女洞组混合沉积特征及古环境意义——以川北旺苍唐家河剖面为例

碳酸盐组分与陆源碎屑物的混合沉积（Mixed siliciclastic-carbonate sedimentation）在古气候、古环境重建方面具有重要作用,近年来受到国内外学者广泛关注。寒武纪沧浪铺早期,上扬子北缘靠近汉南古陆的浅水环境中混合沉积广泛发育,以石英、岩屑等陆源碎屑与碳酸盐的层内混合和间互沉积为主要特征。研究表明,以碎屑颗粒占主导的混积岩（郭家坝组顶部及阎王碥组底部）表现为灰质粉砂岩—泥岩互层,以及灰质粉砂岩—灰质泥岩的间互沉积,形成于陆棚和潟湖等相对低能环境。以碳酸盐占主导的混积岩（仙女洞组）主要发育“碳酸盐岩—混积岩”和“混积岩—混积岩”的沉积序列,表现为:1）泥晶灰岩—灰质泥岩互层,2）灰质岩屑细砂岩—砂质鲕粒灰岩互层,以及3）灰质细砂岩→砂质鲕粒灰岩→亮晶鲕粒灰岩的旋回,形成于台缘斜坡及台地边缘等高能环境。在沧浪铺期海退背景下,川北地区仙女洞组以碳酸盐占主导的混积体系具有“近源”沉积特点。陆源碎屑通过三角洲—河流入海口进入浅海环境,并经过沿岸流和波浪的搬运,对台地边缘相带的微生物丘、古杯丘和鲕粒滩为主的碳酸盐工厂造成影响,形成相缘渐变混合和原地沉积混合的混积类型,其发育与当时气候条件、陆源供给量、水动力条件及生物作用有关。而台缘斜坡—陆棚环境中,风暴、浊流等间断性事件对混积体系起着主要作用,易形成事件突变混合。因此,厘清以唐家河剖面为代表的川北寒武系混积特征及分布发育情况,对于认识上扬子地区北缘寒武纪早期古地理背景、古环境演化,以及混积岩储层发育特征等方面具有促进作用。     

新疆哈密晚石炭世企鹅山组火山碎屑与碳酸盐混合沉积

新疆哈密库木塔格沙垄地区上石炭统企鹅山组发育多套含藻礁的碳酸盐岩沉积,该碳酸盐岩沉积及邻近层位均出现多套火山碎屑和碳酸盐的混合沉积。目前,火山碎屑-碳酸盐混合沉积的研究鲜有报道,该类岩石类型的分类命名也尚无讨论。本文旨在通过分析该类岩石的野外分布状态、矿物组成及岩石地球化学特征等,讨论该类岩石的分类命名,并进一步探讨其成因。研究表明:研究区内企鹅山组的火山碎屑-碳酸盐混合沉积主要为同一岩层内火山碎屑组分和碳酸盐组分混合沉积,在岩性上表现为碳酸盐质-火山碎屑混积岩、含火山碎屑-碳酸盐混积岩、火山碎屑质-碳酸盐混积岩等。就成因而言,该类混合沉积可分为相缘渐变混合沉积、事件突变混合沉积、原地混合沉积。     

塔里木盆地巴楚—麦盖提地区石炭系混合沉积研究*

通过岩心、薄片观察,从岩石学特征入手,结合测井资料,对塔里木盆地巴楚—麦盖提地区石炭系的陆源碎屑—碳酸盐混积岩和混积层系进行了研究。根据混积强度将混积岩划分为混积型碎屑岩、混积型碳酸盐岩和高度混积岩。巴楚组下泥岩段和中泥岩段发育混积型碎屑岩,巴楚组生屑灰岩段、中泥岩段和小海子组发育混积型碳酸盐岩,卡拉沙依组上泥岩段、巴楚组下泥岩段及巴什托局部地区的中泥岩段发育高度混积岩。高度混积岩出现在海退期沉积的碎屑岩段,代表了陆源碎屑—碳酸盐强烈混合的过渡性沉积环境。研究区石炭系可识别出4个三级层序,混积层系主要发育在海侵体系域早期和高位体系域晚期,以间断混合和相缘混合为主。研究认为混积强度是评价混合沉积环境性质的主要参数,并将其划分为4级。下泥岩段存在混积强度达3级以上的混积界面,能用于地层对比。最后,结合混合沉积特征讨论了构造运动和海平面变化对研究区石炭系层序组以上的混合沉积的控制作用。     

渤海湾盆地饶阳凹陷大王庄地区古近系沙三上亚段混积模式研究

利用岩芯、薄片、测录井以及测试分析等资料,结合区域地质,研究了渤海湾盆地饶阳凹陷大王庄地区古近系沙三上亚段（Es₃上）I油组发育的混积岩特征,分析了其沉积环境,探讨了其沉积模式。研究结果表明:大王庄地区古近系沙三上亚段I油组混积岩分为（含）陆源碎屑质—碳酸盐岩和（含）碳酸盐质—陆源碎屑岩两大类,以灰（云）质砂岩、砂质泥晶云岩为主,（含）陆源碎屑质—碳酸盐岩主要分布于工区中部和北部,（含）碳酸盐质—陆源碎屑岩分布于西部和南部;混积成因类型以原地混合和相源混合为主,相源混合出现于Es₃上I油组早中期,原地混合出现于Es₃上I油组早期;少量母源混合出现于Es₃上I油组晚期。饶阳凹陷大王庄地区古近系沙三上亚段I油组沉积环境主要位于滨浅湖,可划分为砂质混积滩坝沉积、碳酸盐岩混积滩坝沉积以及滨浅湖泥混积3种沉积微相类型。综合分析湖平面变化、构造演化、古地貌等对混合沉积的控制作用,建立了湖平面先稳定上升后下降的混积岩沉积模式:随着湖平面的缓慢上升,混合沉积呈增多趋势,以相源混合和原地混合为主;当湖平面到达一定高度时,纯碳酸盐岩增多,混合沉积减少,以相源混合为主;后期,湖平面下降,可能形成母源混合沉积。     

西藏羌塘盆地东部中侏罗统混合沉积层序地层学研究

西藏羌塘盆地东部中侏罗统广泛发育陆源碎屑与碳酸盐的混合沉积。综合前人研究成果,结合区域地质资料和室内样品分析,本文对陆源碎屑岩、碳酸盐岩、混积岩及混积层系,混合层序地层进行了详细研究。研究结果表明,混合沉积在微观上表现为陆源碎屑与碳酸盐沉积物组分的混积岩,宏观上则表现为陆源碎屑岩、碳酸盐岩、混积岩相互叠加的混积层系,发育滨岸、碳酸盐岩缓坡、潮坪-溻湖、三角洲等沉积体系。运用层序地层学原理将中侏罗统划分为SQ1-SQ4四个三级层序,提高了研究区层序地层划分精度;探讨了混合沉积与层序地层的对应关系。总体上看,以陆源碎屑沉积为主的沉积背景下,混合沉积主要发育在海侵体系域的早期和高位体系域的晚期。以碳酸盐沉积为主的沉积背景下,混合沉积主要发育在海侵体系域的早期和高位体系域的晚期。     

陆表海碎屑岩—碳酸盐岩混积层系沉积相研究——以鄂尔多斯东北部大牛地气田为例

陆源碎屑岩和碳酸盐岩的混合沉积是陆表海重要的沉积现象,反映了其沉积特征。鄂尔多斯东北部大牛地气田本溪组和太原组是典型的陆表海碎屑岩—碳酸盐岩混积层系。结合区域地质研究,建立了陆表海碎屑岩—碳酸盐岩混积层系的沉积相模式。根据华北晚古生代聚煤盆地的地质背景和沉积演化过程,认为大牛地气田本溪组、太原组是陆表海碎屑滨岸—碳酸盐岩台地混积体系和海岸平原沉积体系：本溪组下段为碎屑滨岸相局限浅海亚相,上段为碳酸盐岩台地相和碎屑滨岸相;太原组下段为三角洲相和碎屑滨岸相→碎屑滨岸相;中段为盆控型泥炭沼泽相→碳酸盐岩台地相和碎屑滨岸相;上段为三角洲相和碎屑滨岸相→碳酸盐岩台地相和碎屑滨岸相→三角洲相和碎屑滨岸相→碳酸盐岩台地相和碎屑滨岸相。     

澳大利亚北卡那封盆地晚三叠世混合沉积特征

在澳大利亚北卡那封盆地的东南部,上三叠统Brigadier组为三角洲砂泥岩,在西北部则发育纯碳酸盐岩。盆地东南部有明显的河流及碎屑物源供应的证据,靠近物源区为三角洲碎屑岩沉积,远离物源区为生物礁滩沉积及滑塌沉积,总体上具有明显的混积特征。Brigadier组混合沉积形成的主要原因是碎屑物源输入的停止和水动力的减弱,碳酸盐岩沉积在早期河道砂泥岩之上,这属于典型的相混合成因类型。     

渤海古近系混合沉积发育特征与沉积模式

陆源碎屑与湖相碳酸盐混合沉积在渤海海域古近系普遍发育,已经成为重要的油气勘探目标.基于90余口已钻井,结合地震、测井以及相关分析化验资料,以渤海海域古近系钻遇的混合沉积为研究对象,开展了沉积特征与成因背景分析,建立了混合沉积发育模式.研究表明:渤海古近系混合沉积发育近岸混积扇、近岸混积滩坝、远岸混积滩坝3种沉积相、7种沉积亚相和14种沉积微相.近岸混积扇以发育混积沟道为典型特征,岩性为含生屑的砂砾岩或中粗砂岩,为陡坡扇三角洲环境短源水道废弃后与生物碎屑间歇性间互沉积;近岸混积滩坝,为近源搬运沉积的陆源碎屑与盆内碎屑之间的混合沉积,典型沉积特征为发育高陆源碎屑含量的各种粒屑滩或坝;远岸混积滩坝为典型的以富含生物碎屑为主的混合沉积,陆源碎屑含量低,一般为盆内低隆或孤立潜山之上原地生长生物与少量供给的陆源碎屑发生的混合沉积.混合沉积发育模式和规模受古气候与古水体环境、古构造与水动力、陆源碎屑物质供给、古地貌条件等共同控制,其中古地貌特征起主导作用.混合沉积发育模式的建立,对混积型储层预测和油气勘探具有重要意义.      

四川龙门山地区中泥盆统金宝石组混合沉积特征

四川龙门山地区是中国泥盆系出露较好、研究程度较高的地区。中泥盆统金宝石组发育由碎屑岩、碳酸盐岩、混积岩组成的混积沉积。本研究以平武县平驿铺剖面和北川县甘溪剖面为切入点,基于实测资料和薄片观察对金宝石组沉积相开展详细研究,认为龙门山地区中泥盆统金宝石组发育河流、碎屑滨岸、陆棚和碳酸盐岩缓坡4种沉积相,沉积演化经历了2个沉积旋回。金宝石组以相混合和原地混合2种方式形成混合沉积。相对海平面的变化、陆源碎屑的供应、碳酸盐生产速率和古气候是引起相混合的主要控制因素,波浪和风暴浪则是引起陆源碎屑和碳酸盐组分混合沉积的主要作用方式。对金宝石组沉积序列、沉积特征及沉积演化过程的研究,有利于增进对龙门山地区泥盆系沉积古环境的认识。     

Depositional environments of the Triassic system in central Saudi Arabia

Facies analysis of Triassic rocks in central Saudi Arabia indicates a wide expanse of interfingering siliciclastic and carbonate rocks with some evaporites. Eight distinctive sedimentary facies have been recognized. The distribution of these facies show a systematic gradual change in their presumed depositional environments, laterally as well as vertically. The Lower Triassic Sudair facies represents a widespread regressive condition where the Upper Permian marine conditions gave way to the Lower Triassic with predominantly fine clastic deposits representing a restricted shallow marine shelf. This fine-grained clastic facies consists mainly of unfossiliferous, laminated or massive, varicoloured shale with some silty shale, siltstone and very fine-to fine-grained sandstone. The facies is highly calcareous and gypsiferous in the northern area. A belt of Middle Triassic rocks of mostly non-marine sandstone with some shale is present in the southern area passing into mixed siliciclastic-carbonate facies of continental aspect with some intermittent emergence and nearshore conditions in the central area. This facies grades in the northern area into carbonate-evaporite facies of restricted to more open marine shelf conditions. Thick siliciclastic deposits characterize the Upper Triassic Minjur facies, where a uniform repeated fining-upward sequence of mainly sandstone and some shale developed in a non-marine environment with some intermittent emergence in the northern area.     

Siliciclastic and volcaniclastic influences on equatorial carbonates: insights from the Neogene of Indonesia

ABSTRACT In active tectonic areas of humid equatorial regions, nearshore shallow‐water environments are commonly sites of near‐continuous siliciclastic influx and/or punctuated volcaniclastic input. Despite significant clastic influence, Neogene carbonates developed in SE Asia adjacent to major deltas or volcanic arcs, and are comparable with modern mixed carbonate–clastic deposits in the region. Research into delta‐front patch reefs from Borneo and fore‐arc carbonate platform development from Java is described and used to evaluate the effects of siliciclastic and volcaniclastic influx on regional carbonate sedimentation, local changes in carbonate‐producing biota and sequence development. Regional carbonate development in areas of high siliciclastic or volcaniclastic input was influenced by the presence of antecedent highs, changes in the amounts or rates of clastic input, delta lobe switching or variations in volcanic activity, energy regimes and relative sea‐level change. A variety of carbonate‐producing organisms, including larger benthic foraminifera, some corals, coralline algae, echinoderms and molluscs could tolerate near‐continuous siliciclastic or volcaniclastic influx approximately equal to their own production rates. These organisms adopted various ‘strategies’ for coping with clastic input, including a degree of mobility, morphologies adapted to unstable substrate inhabitation or shedding sediment, and shapes adapted to low light levels. Local carbonate production was also affected by energy regime, clastic grain sizes and associated nutrient input. Clastic input influenced the inhabitable depth range for photoautotrophs, the zonation of light‐dependent assemblages and the morphology and sequence development of mixed carbonate–clastic successions. This study provides data on the dynamic interactions between carbonate and non‐carbonate clastic sediments and, when combined with information from comparable modern environments, allows a better understanding of the effects of siliciclastic and volcaniclastic influx on carbonate production.     

浙江江山藕塘底组陆源碎屑与碳酸盐混合沉积特征及其构造意义

浙江江山藕塘底组是晚石炭世威宁期陆源碎屑与碳酸盐的混合沉积,包括两种组分在同一岩层内相互混杂形成混积岩和陆源碎屑岩与碳酸盐岩互层形成混积层系。藕塘底组是海陆交互环境的沉积产物,剖面结构具有下细上粗的岸进序列。混积岩形成于滨岸浅滩环境,由沿岸流和回流将河口或滨岸海滩的石英砂带到滨岸浅滩和潮坪相碳酸盐沉积区混杂而成。具两种混积层系类型,即浅海滨岸环境中砂岩与碳酸盐岩互层、河流相碎屑岩与海相碳酸盐岩互层。研究表明,混合沉积成因属“相混合”,主要受区域构造隆升、全球海平面上升和盆地水介质条件特性控制。区域海平面周期性变化和岸进序列可能是华夏古陆强烈隆起的结果。作者还讨论了混合沉积的分类和命名,将陆源碎屑与碳酸盐层相互交替构成的互层和夹层组合称为“混积层系”,并建议将“混积岩”一词用来表征两种组分相互混杂这种特殊沉积事件,而不用作具体岩石名称.     

Actualistic approaches to the systematics and facies relations of clastic karst deposits

Clastic karst deposits occur at different positions within karst areas, whereas surface karst deposits, sediments of the crack filling facies, the cave entrance facies and the inner cave facies have to be distinguished. The karstification itself is of minor importance for the formation of clastic deposits. Except for incasional debris and impure limestones or marls the contribution of carbonate rocks to clastic karst deposits is low. The majority of clastic material is allogenic and siliciclastic.

Regarding the depositional processes cave sediments can be divided into fluvial cave deposits, gravitative or percolative deposits, decomposition deposits and rock breakdown. An actualistic approach could be a useful tool for the identification of fluvial cave deposits. By means of the depositional features of recent cave sediments and classical sedimentological features cave deposits of unknown origin can be classified.     

Mixing Deposition of Upper Carboniferous in Jiangshan, Zhejiang Province and its Tectonic Significance

<正>The Outangdi Formation in Jiangshan,Zhejiang,is the mixing deposit of terrigenous clastics and carbonates in Weiningian of the late Carboniferous.The mixing deposits include interbeddings, which constitute a series of alternated clastic and carbonate beds and mixing within the same bed which forms"hunji rock".The Outangdi Formation has the features of intercalated marine and terrestrial deposits with the progradational sequences,which are lower fine and upper coarse sedimentary granularity in the section.Hunji rock is formed in a seashore environment.It is a mixed carbonate sediment found in beaches or tideland facies with quartz sand taken from a bayou or beach by coastwise flow and circumfluence.There are two kinds of hunji sequences:(1) interbeds of sandstone and carbonate rock in seashore environments;and(2) interbeds of clastics in river facies and carbonate rock in ocean facies.It is indicated that mixing depositions belong to"facies mixing",affected mainly by regional tectonic uplift,rise of the global sea level,and the dynamics of water medium in the basin. Regional sea level periodic changes and progradational sequences probably resulted from the intense uplift of the old land called Cathaysia.The classification and name of mixed sediments are also discussed in the present study.Interbeds and alternated beds of clastic and carbonate beds are named"hunji sequence",a new genetic term.It is suggested that hunji rock means a special sediment event of mixing terrigenous clastics and carbonates instead of a name of a specific rock.     

Depositional framework and controls on mixed carbonate-siliciclastic gravity flows: Pennsylvanian-Permian shelf to basin transect, south-western Great Basin, USA

Mixed carbonate-siliciclastic sediment gravity flow deposits of Late Pennsylvanian to Early Permian age are exposed in the Death Valley - Owens Valley region of east-central California. The Mexican Spring unit constitutes the upper part of the Keeler Canyon Formation and is characterized by turbidites, debris flow deposits and megabreccias, all of mixed carbonate-siliciclastic composition. The mixed composition of the Keeler Canyon Formation provides an opportunity to link facies architecture to controls on depositional system development. Depositional relationships indicate that the deposits represent a non-channellized base of slope carbonate apron system with inner, outer and basinal facies associations. These gravity flow deposits are characterized by repeated stacked, small scale (<15 m) coarsening and thickening upward cycles with superimposed medium scale (>100 m) coarsening and thickening upward cycles. Contemporaneous outer shelf and upper slope deposits of the Tippipah Limestone are exposed at Syncline Ridge on the Nevada Test Site. The deposits consist of carbonate buildups directly overlain by cross bedded, quartz-rich sandstone and conglomerate which filled channels that traversed across the previously existing carbonate shelf. Detritus was transported to the west, down the upper slope by gully systems that fed the temporally persistent base of slope apron of the upper part of the Keeler Canyon Formation. This style of deposition differs from point-sourced siliciclastic submarine fan depositional systems. However, the Keeler Canyon system has lithofacies similar to some sandy siliciclastic turbidite systems, such as the delta-fed submarine ramp facies model, which is a line-sourced, shelf-fed system that is not supply limited. The mixed clastic apron systems of the Keeler Canyon Formation differ from classical carbonate aprons in that the former is characterized by an abundance of sedimentary cycles. Controls on the development of these cycles and of the facies distribution may have resulted from changes in type and rate of sediment supply, relative sea level changes and/or tectonic events. Interpretation of the data is focused on relative changes in sea level as the most significant control on development of the depositional system. Relative sea level changes serve two important functions: (1) they provide a mechanism for bringing coarse siliciclastic and bioclastic grains together on the outer shelf, and (2) shelf margin collapse may be initiated during relative lowstands allowing for transport of the sediment to the deep basin and development of deep basinal cycles. Therefore, an abundance of mixed clastic gravity flow deposits such as these in the rock record may be an indicator of periods of high frequency changes in relative sea level, which is a characteristic of Late Palaeozoic sea level history.     

碎屑岩-碳酸盐岩混合地层沉积特征与演化－以神木气田太原组为例

鄂尔多斯盆地东缘的神木气田太原组为特征性的碎屑岩与碳酸盐岩互层含煤岩系.近期天然气勘探证实其具有良好的开发潜力.为指导神木气田太原组开发和盆地太原组储层勘探,根据测井、录井、常规薄片、铸体薄片、物性和粒度资料,结合岩芯描述,研究了神木气田太原组地层组合、沉积特征、沉积环境演化、砂体宽度以及沉积相对储层控制作用.太原组地...     

混合沉积和混积岩的讨论

混合沉积物是指陆源碎屑与碳酸盐(包括异化粒等)在沉积上的混合。混合沉积可分为狭义的和广义的,狭义的是指陆源碎屑与碳酸盐组份的混合(在同一岩层内),而广义的混合则包括了狭义的和陆源碎屑与碳酸盐层构成交替互层或夹层的混合。混合沉积很早就引起了人们的注意,尽管碎屑岩和碳酸盐岩的研究与应用已很成熟,但对混积岩的研究多被忽视了。对狭义的混合沉积物有必要起一成因名称——混积岩。当人们接触到混合沉积时,除了分析研究它们的组分和结构特征外,还必须去思考,它们为什么能经常频繁地交互出观,或是直接混合在一起?倒底是：①陆源碎屑跑到碳酸盐的沉积背景里?②碳酸盐跑到陆源碎屑的沉积背景里?③二分别从各自的源地跑到第三种沉积背景里?还是④二本来就在同一沉积背景里?接下来就要思考是什么动力条件使它(们)能从这个沉积背景(环境)“跑”到另一个沉积背景(环境)里去?是水?是风?是自身?还是别的什么力量?那么,又是怎样的水动力或风动力条件呢?是正常条件,还是突发事件?很明显,要分析研究混合沉积和混积岩。这些问题就不得不细细加以考虑,深入进行研究。