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1.
Diagenetically enhanced bedding in argillaceous platform limestones: stratified cementation and selective compaction 总被引：2，自引：0，他引：2
ROBIN G. C. BATHURST 《Sedimentology》1987,34(5):749-778
A field and petrographic study has been made of 34 massive beds in argillaceous limestones of open marine platform facies in the U.K. Lithologies include grainstones, packstones, wackestones and lime mudstones. The rocks are of Silurian, Carboniferous and Jurassic ages. Additional information was obtained from other limestones in the U.K., the U.S.A., Canada and continental Europe. The beds are parts of sequences composed of couplets of strata, fissile limestones alternating with hard limestones. In the fissile limestones the effects of mechanical compaction and pressure-dissolution have been concentrated, whereas in the hard limestones they are minimal or absent. Bedding planes visible in outcrop are diagenetic in origin and lie in the middle parts of the fissile limestones where compaction has been most severe. The features produced by pressure-dissolution are dissolution seams and fitted fabric: there are no stylolites. The original carbonate sediments were bioturbated and any structures produced by flowing water were destroyed. The vertical distribution of the bedding planes bears no relation to primary depositional bedding planes which are rare or absent. It is inferred that the strata which were to become the hard limestones were selectively cemented before mechanical compaction had been completed. Thenceforth, mechanical compaction and then pressure-dissolution were concentrated in the less cemented strata: these became the fissile limestones. Pressure-dissolution acted late in the diagenetic history and provided only an insignificant part, if any, of the carbonate for cementation. It is concluded that the orientation of beds (couplets) is parallel to successive sea floors and that the sediments that eventually became single beds accumulated synchronously. Similar couplets in platform limestones of the Mississippian and Pennsylvanian of the U.S.A. extend over thousands of square kilometres. The signal that controlled the initial selective cementation must have been widespread and synchronous and also syndepositional in its timing but otherwise cannot be further defined on the basis of the data so far collected. The presumed order of events was (1) accumulation of carbonate sediment, terrigenous clay and organic matter, (2) hydrodynamic reworking and bioturbation. the latter finally overprinting the former, (3) selective cementation of the more carbonate-rich strata yielding couplets, each consisting of a relatively well-cemented stratum and a poorly cemented stratum, (4) mechanical compaction concentrated in the less cemented strata, (5) pressure-dissolution concentrated in the same strata. 相似文献
2.
杜远生 《沉积与特提斯地质》1995,(5):55-70
秦岭微板块位于商丹－武山和勉略－巴山弧断裂之间。泥盆纪时期，微板块主体处于稳定的小型克拉通盆地背景。本文仅从西秦岭中带泥盆系入手，探讨该区泥盆系的沉积体系和盆地格局。小型克拉通盆地北带的西汉水小区以古岛屿滨岸－陆棚沉积体系（艾菲尔期）、碳酸盐台地－生物礁沉积体系（吉维特－弗拉斯期）、深水盆地和泥质浊积岩沉积体系（法门期）为特征。南带武都小区则以陆棚碎屑岩（艾菲尔期）和缓坡型台地－陆棚沉积体系（吉维特－法门期）为主，该小型克拉通，泥盆纪时期是一稳定块体，到二叠纪－三叠纪才受中秦岭裂陷槽分隔成两个块体。 相似文献
3.
J. J. Álvaro E. Vennin A. Muñoz B. Sánchez-Valverde J. L. Ojeda 《International Journal of Earth Sciences》2000,89(2):366-376
The stratigraphy of carbonate/shale couplets, cycles and cycle-stacking patterns in a Cambrian shallow water platform (Iberian
Chains, NE Spain) are related to sea-level changes driven by orbital forcing and by tectonic pulses. The interplay of both
effects can be discriminated in the Iberian fault-controlled platform, in which the tectonic activity can be analysed by accurate
and detailed biostratigraphic correlations based on trilobite zonation. The stratigraphic hierarchy of rhythmically interbedded
limestones and shales, in two coeval but structurally separated geodynamic settings, yields cycle ratios of 1.44 :1. This
ratio is supported by time thickness and spectral analysis, which is based on a graphic method of analysis: the Map of Grey
Lines. The cycle ratio seems to be evidence for orbital forcing by obliquity and precession cycles predicted for early Paleozoic
time. Carbonate/shale couplets, the smallest rhythmic units recognisable in the field, represent short-term, periodic fluctuations
in supply of terrigenous sediments and carbonate productivity of uncertain origin, which could be associated with one of several
harmonics of the former orbital cycles. The pulsating tectonic activity was approximated by using a quantitative analysis
of tectonically induced subsidence (Shaw method). Recurrence frequencies of tectonic pulses were estimated and dated by biostratigraphy.
As a result, tectonic disturbances in the Cambrian Iberian platform show an episodic periodicity comparable to that of orbital
eccentricity cycles, which could mask their recognition.
Received: 15 November 1999 / Accepted: 9 February 2000 相似文献
4.
西藏措勤盆地下白垩统多巴组沉积环境分析 总被引：9，自引：3，他引：6
西藏措勤前陆盆地下白垩统多巴组是一套分布面积广大,比较特征的碳酸盐、陆源碎屑混合沉积的地层,本文通过对几条较完整的主干剖面的详细沉积相分析,揭示了多巴组的主要沉积环境包括潮坪、低能潮下带、近岸碳酸盐台地缓坡、台缘介壳滩及碳酸盐台地等几种主要类型,建立了多巴组的沉积相模式,并指出多巴组的沉积演化主要受控于盆地构造运动和全球海平面变化,这将有助于该地区的构造沉积演化研究。 相似文献
5.
碳酸盐岩测井层序识别方法研究——以塔中隆起卡1地区奥陶系为例 总被引：1，自引：0，他引：1
进行碳酸盐岩高分辨率的测井层序识别,建立精细等时地层格架,对碳酸盐岩油气勘探开发具有重要的意义。碳酸盐岩颗粒的大小和圆度不能明显地反映水动力作用的过程和能量;成岩作用往往增强储层非均质性,减弱原生沉积旋回性。这些特征使测井曲线对岩性变化与物性好坏的对应关系变差,测井曲线旋回性减弱,测井响应成为多因素作用的综合结果,划分层序所主要依据的沉积旋回特征隐藏在综合响应之中。测井层序识别的关键是多测井参数综合判定泥岩成因,剔除成岩作用后期改造等因素的响应信息,提取对层序划分有用的原生沉积特征信息。通过自然伽马、自然伽马能谱、FMI、地层倾角、双侧向电阻率等测井参数的综合应用,可以较好地识别碳酸盐岩中泥岩成因类型、不整合面,突出原生沉积旋回特征,在塔中隆起卡1地区奥陶系识别出三种泥质成因、两类层序界面。层序分析结果和缝洞统计规律对比表明:较高的泥质含量不利于溶蚀作用的发生;层序对溶孔的纵向分布有着显著的控制作用,而对裂缝的分布影响较弱。 相似文献
6.
Graded limestones and limestone-quartzite couplets: Possible storm-deposits from the Moroccan Carboniferous 总被引：2，自引：0，他引：2
The Lower Carboniferous (Visean) successions of the Meseta region of central Morocco are dominated by mixed marine carbonate and terrigenous facies bearing the biological and sedimentological hallmarks of deposition in a neritic environment. This study concerns two inter-related types of sedimentary unit, relatively uncommon but displaying features not readily compatible with the depositional mechanisms conventionally envisaged for such an environment. They are described with reference to three sections in which they are well represented.Graded limestones are texturally immature, broadly lenticular or channel-fill units of calcarenite and calcirudite of variable thickness, exhibiting a general upwards diminution in modal or maximum grain size and a somewhat irregular sequence of internal structures, often including large-scale cross-stratification. The compound units, here termed limestone-quartzite couplets, generally comprise a lower calcarenite member, frequently graded, succeeded by more quartzose arenite, often but not invariably finer in grain size. Six main types of couplet are distinguished primarily on the nature of the contact between the carbonate and terrigenous members.From a review of published data on modern and ancient shelf deposits it is concluded that periodic storm-generated mechanisms of transportation and deposition are of considerable geological importance. Two main categories of storm-induced modification of “normal” sedimentation processes are recognised: (1) storm-stirring and erosion; and (2) lateral transfer of storm-mobilised sediment. A process-response model is developed which involves the introduction of coarse sediment by storms on to a substrate of finer indigenous sediment. Comparison of the theoretical sequences produced with the types of couplets and graded limestones commonly encountered in the field strongly indicates that these anomalous associations result from rapid, storm-induced addition of coarse carbonate detritus (from local elevations such as reefs and shell-banks) to slightly deeper environments in which muds and quartzose sands were being deposited by more protracted processes. 相似文献
7.
Woong Mo Koo David Mohrig James Buttles Daniel Sturmer Anna Pontén Thomas Hess 《Sedimentology》2020,67(1):78-95
Clean basal and capping argillaceous sandstone couplets in deep water settings have been previously interpreted as the result of spatially segregated turbidity currents and debris flows or spatio-temporal transitioning of a turbulent flow to a transitional/laminar state. However, this paper presents three-dimensional laboratory experiments demonstrating that a single sediment-gravity flow can develop sand–mud couplets by autogenic remobilization of sediments that are still in the process of being deposited. This remobilization appears common to flows composed of mixtures of sand and mud with viscosities and strengths measurably greater than water, but not so high as to fully suppress the settling of sand through the depositional current. Dewatering in the early sand deposit acts to lubricate the basal portion of the increasingly muddy upper division of the flow, causing it to accelerate downslope, triggering a secondary flow with a sediment composition distinct from the original mixture. Sediment deposition and remobilization processes in a single sediment-gravity flow and their resultant deposit were imaged acoustically and cored at representative locations within the deposit. The acoustic data and cores show sand–mud couplets that are qualitatively similar to interpreted turbidite–debrite-like couplets in natural systems. 相似文献
8.
V. I. Belousov 《Geotectonics》2007,41(5):392-402
The Upper Paleozoic preflysch sedimentary rocks in the Türkstan-Alay ranges are combined in a common section with limestone of autochthon and synsedimentation carbonate nappes, thus forming the upper-most layers of the stratigraphic section of the latter. By their lithology, relatively small thickness, facies variability, and position at the boundary between carbonate and flysch-olistostrome sequences (in the autochthon), these rocks correspond to a certain extent to preflysch of the Urals and the Mediterranean Alpine Belt. This association of clayey, carbonate, and terrigenous rocks is strictly constrained in stratigraphy (the upper portion of the lower Moscovian substage and the lower portion of the upper Moscovian substage) and localization (the southern slopes of carbonate platforms). The formation of this rock association immediately predated the Late Paleozoic overthrusting and deposition of terrigenous flysch. In paleotectonic terms, preflysch is an indicator of the initial stage of tectonic and magmatic activation that led to the replacement of carbonate sedimentation with deposition of terrigenous and clayey sediments, coeval volcanism, and stratiform ore formation. The following sequence of events has been outlined in the Early and Middle Carboniferous: (1) thrusting of volcanic-sedimentary rocks filling troughs over the northern margins of carbonate platforms, (2) lateritic weathering and deposition of marine bauxite in the Bashkirian and early Moscovian, (3) repeated overthrusting and deposition of preflysch on southern slopes of platforms, (4) invasion of the frontal flysch trough from the south, (5) scouring of preflysch and the underlying limestone, and (6) formation of flysch-olistostrome sequences and tectonic and gravity nappes in the late Moscovian time. This interpretation takes into account the southward vergence of thrust sheets and nappes, the structure and localization of allochthonous fragments of marginal zones of carbonate platforms, and the pre-Bashkirian thrusting of volcanic and sedimentary rocks over the condensed pelagic deposits of the Shalan Group. It is suggested that bauxite and preflysch materials had the same source and were deposited in the Middle Carboniferous on the offshore carbonate shoals. 相似文献
9.
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... 相似文献
10.
《Sedimentology》2018,65(4):1097-1131
Wide carbonate platform environments developed on the western passive margin of the Tethys during the Late Triassic, after a major climate change (Carnian Pluvial Episode) that produced a crisis of high‐relief microbial carbonate platforms. The peritidal succession of this epicontinental platform (Dolomia Principale/Hauptdolomit, Dachstein Limestone) is widespread in the Mediterranean region. However, the start‐up stage is not fully understood. The original platform to basin depositional geometries of the system have been studied in the north‐eastern Southern Alps, close to the Italian/Slovenian boundary where they are exceptionally preserved. Sedimentological features have been investigated in detail by measuring several stratigraphic sections cropping out along an ideal depositional profile. The analysis of the facies architecture allowed reconstruction of the palaeoenvironments of the Dolomia Principale platform during its start‐up and early growth stages in the late Carnian. The carbonate platform was characterized by an outer platform area, connected northward to steep slopes facing a relatively deep basin. Southward, the outer platform was connected to inner sheltered environments by a narrow, often emerged shelf crest. Behind this zone, carbonate sedimentation occurred in shallow lagoons and tidal flats, passing inward to a siliciclastic mudflat. The Dolomia Principale platform was initially aggrading and able to keep pace with a concomitant sea‐level rise, and then prograding during the late Carnian. This stratigraphic interval was correlated with the Tuvalian succession of the Dolomites, allowing depiction of the depositional system on a wide scale of hundreds of kilometres. This large‐scale depositional system presents features in common with some Palaeozoic and Mesozoic carbonate build‐ups (for example, the Permian Capitan Reef complex, Anisian Latemar platform), both in terms of architecture and prevailing carbonate producers. A microbial‐dominated carbonate factory is found in the outer platform and upper slope. The recovery of high‐relief microbial carbonate platforms marks the end of the Carnian Pluvial Episode in the Tuvalian of Tethys. 相似文献
11.
综合利用重点剖面实测资料、区域地质调查资料,结合公开发表的成果,讨论了南盘江盆地石炭系沉积体系类型、特征及其分布规律,基于深水沉积相带的分布,预测了南盘江盆地石炭系页岩气有利区。南盘江盆地石炭系发育三角洲—碎屑滨岸、滨海沼泽、陆源碎屑陆架、碎屑陆坡、局限海台地、开阔海台地、台地边缘、深水盆地8种沉积体系。石炭纪,马关隆起、康滇隆起、江南隆起及云开隆起为暴露剥蚀区,但陆源碎屑供应较弱,陆源碎屑沉积主要发育于石炭纪早期,整个石炭纪以内源沉积占优势。早石炭世,云开隆起周边发育陆源碎屑滨岸沉积,在江南隆起南缘发育碎屑滨岸和滨海沼泽沉积,主体为局限台地—开阔台地—孤立台地—台地边缘—深海的沉积格局。晚石炭世,隆起区和深海区均有所缩小,开阔台地范围显著扩大,隆起周缘主要发育局限台地。南丹—河池、罗甸西、柳城—鹿寨—平乐地区、象州—武宣—桂平等地区上古生界出露地表,石炭系埋藏浅,且以深海沉积为主,是寻找石炭系页岩气最为有利的地区。 相似文献
12.
Sedimentation during carbonate ramp-to-slope evolution in a tectonically active area: Bowland Basin (Dinantian), northern England 总被引：3，自引：0，他引：3
ROB L. GAWTHORPE 《Sedimentology》1986,33(2):185-206
The Bowland Basin (northern England) contains a series of carbonates and terrigenous mudstones deposited during the Ivorian to early Brigantian. Two regional depositional environments are indicated by facies and facies associations. Wackestone/packstone and calcarenite facies indicate deposition in a carbonate ramp environment, while lime mudstone/wackestone, calcarenite and limestone breccia/conglomerate facies, often extensively slumped, represent a carbonate slope environment. Stratigraphic relations suggest that the depositional environment evolved from a ramp into a slope through the Dinantian. Two main sediment sources are indicated by the sequence; an extra-basinal terrigenous mud source and a supply of carbonate from the margins of the basin. Deposition from suspension and from sediment gravity flows, in situ production and remobilization of sediment during sedimentary sliding were important processes operating within the basin. Periods of enhanced tectonic activity in the late Chadian to early Arundian and late Asbian to early Brigantian are indicated by basin-wide horizons of sedimentary slide and mass flow deposits. Both intervals were marked by a decline in carbonate production resulting from inundation and uplift/emergence. The first of these intervals separates deposition on a seafloor with gentle topography (carbonate ramp) from a situation where major lateral thickness and facies variations were present and deposition took place in a carbonate slope environment. The second interval marks the end of major carbonate deposition within the Bowland Basin and the onset of regional terrigenous sedimentation. 相似文献
13.
为了探讨南海碳酸盐台地的发育过程及控制因素, 采用有机分子化合物指标方法对其进行了研究.有机分子化合物指标BIT(branched isoprenoid tetraether)是沉积物中源自陆源的细菌膜脂支链甘油双烷基链甘油四醚(branched glycerol dialkyl glycerol tetraethers,简称bGDGTs)与主要来自海洋泉古菌中的类异戊二烯GDGTs(isoprenoid GDGTs,简称iGDGTs)的含量之比,在古环境研究中,用来区分沉积物有机质的来源、判断沉积环境.通过对西科1井的数据研究发现,西科1井BIT指数随深度呈现三段式规律性变化,从下到上呈现高-低-高的变化,反映了中中新世以来南海海平面变化及碳酸盐台地生长发育的过程:在中中新世晚期,受全球及区域海平面变化下降影响,西沙地区碳酸盐台地形成礁-滩交互的沉积地层,由于大气淡水的影响,造成BIT指数呈现高值;到晚中新世至上新世,全球及区域海平面出现持续上升,有利于西沙碳酸盐台地的生长发育,使该井沉积环境以礁内泻湖相为主,造成BIT指数呈现低值;在第四纪冰期,全球及区域海平面出现总体下降趋势,西沙碳酸盐台地又频繁暴露于地表,造成BIT指数又呈现高值.研究表明,西沙地区碳酸盐台地受区域相对海平面变化影响更大,说明南海海平面变化既受全球海平面变化的影响,也受南海区域构造沉降的控制. 相似文献
14.
笔者于1986至1988年期间,对贵州及邻区早奥陶世岩相古地理进行了大量的野外及室内研究。在前人工作的基础上,综合自己的观察研究,对贵州及邻区红花园期岩相古地理特征获得较系统的认识。一、地层概况贵州及邻区早奥陶世红花园期的地层主要为: 在三都一带的同高组下部,湖南吉首为桃花石组或马刀堉组,向西至四川南部及贵州大部称红花园组。靠近古陆边缘的滇东及川西南为红石崖组下部。 相似文献
15.
Relatively pure lacustrine carbonates referred to as marl are being deposited in Littlefield Lake, central Michigan, a hard-water lake with little terrigenous clastic influx. Thick accumulations of marl form both progradational marl benches along lake margins, and islands or lakemounts in the lake centre. Marl benches develop flat platforms up to 20 m wide in very shallow water and steeply inclined slopes, up to 30°, extending into deep water. The flat landward platform is frequently covered by algal pisoliths while the upper portion of the lakeward-sloping bottom is overgrown by Chara which in the summertime becomes thickly encrusted with low-magnesian calcite. Marl islands are flat-topped features that formed over relict highs on Pleistocene drift which underlies the lake basin. These are fringed by marl benches identical to those found along lake margins. Marl benches are composed of four units: two thin facies deposited on the shallow-water bench platform and two thicker faces deposited on the bench slope developed in moderate water depths. These in turn overlie a fifth facies deposited in deep water. A coarsening-upward sequence is developed in these sediments as a result of both mechanical sorting, and primary production of carbonate sand and gravel in shallow water. In addition to facies sequences and size grading, trends upsection of increasing carbonate content and decreasing insoluble content may serve to identify temperate-region lacustrine carbonate deposits in the rock record. 相似文献
16.
LUISA A. REBATA-H. MURRAY K. GINGRAS† MATTI E. RÄSÄNEN MAIRA BARBERI‡ 《Sedimentology》2006,53(5):971-1013
Miocene siliciclastic sediments of the Marañón Foreland Sub‐basin in Peru record the sedimentary response to regional marine incursions into Amazonia. Contrary to previous interpretations, the Late Miocene Nauta Formation provides evidence of the last known marine incursion before the current Amazonia river basin became established. Sedimentological, ichnological and palynological data from well‐exposed outcrops along a ca 100 km road transect suggest that the Nauta Formation represents a shallow, marginal‐marine channel complex dominated by tidal channels developed in the inactive, brackish‐water portions of a delta plain. The main facies associations are: FA1 – slightly bioturbated mud‐draped trough cross‐stratified sand; FA2 – locally, pervasively bioturbated inclined heterolithic stratification (IHS); and FA3 – moderately bioturbated horizontally bedded sand–mud couplets. These identify subtidal compound dunes, tidal point bars and shallow subtidal to intertidal flats, respectively. Bi‐seasonal depositional cycles are ascribed to the abundant metre‐ to decimetre‐scale sand–mud couplets that are found mainly in the IHS association: semi‐monthly to daily tidal rhythmicity is inferred from centimetre‐ and millimetre‐scale couplets in the mud‐dominated parts of the decimetre‐scale couplets. The ichnology of the deposits is consistent with brackish depositional conditions; the presence of Laminites, a variant of Scolicia, attests to episodic normal marine conditions. Trace fossil suites are assigned to the Skolithos, Cruziana and mixed Skolithos–Cruziana ichnofacies. Pollen assemblages related to mangrove environments (e.g. Retitricolporites sp., Zonocostites sp., Psilatricolporites maculosus, Retitricolpites simplex) support a brackish‐water setting. Uplift of the Mérida Andes to the North and the consequent closure of the Proto‐Caribbean connection, and the onset of the transcontinental Amazon drainage, constrain the deposition of the Nauta sediments with around 10 to 8 Ma, probably contemporaneous to similar marine incursions identified in the Cuenca (Ecuador), Acre (Brazil) and Madre de Dios (Southern Peru) (sub)basins, and along the Chaco‐Paranan corridor across Bolivia, Paraguay and Argentina. 相似文献
17.
Lars Stemmerik 《Sedimentology》2001,48(1):79-97
The carbonate platform of the Upper Permian Wegener Halvø Formation in the Karstryggen area of central East Greenland is an example of a carbonate system with low production rates (2–3 cm kyr–1 ) and differs from most other carbonate platforms by the lack of well-developed highstand progradation. The platform consists of three depositional sequences that formed in response to Kazanian sea-level cycles. Pinning point curves for the subaerial exposure surfaces separating the depositional sequences quantify the amplitude of the relative sea-level fluctuations in the range of 70–140 m. The platform developed on the karstified surface of an older Permian carbonate platform with a topographic relief locally exceeding 70 m. The predepositional relief influenced deposition in all three sequences. Transgressive systems tracts are thin and commonly dominated by condensed siliciclastic deposits in off-platform areas and palaeo-lows. Over palaeotopographic highs they consist of aggrading cementstones. Highstand deposits are limited to palaeotopographic elevated areas and consist of cementstone build-ups along the basin margin, and shallow subtidal to intertidal carbonates and evaporites in the platform area. Elsewhere, carbonate deposition took place during falling sea-level, and thin laterally extensive units of shallow-marine grainstones rest directly on top of deeper marine shales in the two first sequences, whereas thick prograding units of oolitic grainstones form the forced regressive systems tract of the uppermost sequence. 相似文献
18.
混合沉积是指碳酸盐岩与陆源硅质碎屑在沉积上的混合,它是一种沉积机理特殊而又具有重要意义的沉积现象。混合沉积分为4种沉积模式:间断混合,相混合,原地混合和源地混合。通过对南海北部陆坡的研究,识别了其中中新世碳酸盐岩台地、碳酸盐岩斜坡和混合沉积,并对其平面分布进行了研究。结合前人研究,参考区域构造背景,通过地震资料的解释认为研究区的混合沉积属于源地混合沉积,并建立了适合研究区的混合沉积模式。研究区陆源硅质碎屑分别来自北部华南隆起以及西南部中南半岛,而碳酸盐岩碎屑则来自神狐隆起、西沙隆起以及南部的广乐隆起。研究区对混合沉积的影响因素包括构造作用、物源、再改造和沉积作用、海平面升降变化以及气候,对研究区混合沉积起主要作用的是构造作用及海平面升降变化。 相似文献
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金湖凹陷是苏北盆地的主要含油气凹陷,阜宁组二段沉积时期广泛发育陆源碎屑与湖相碳酸盐的混合沉积,结合研究区内岩芯、录井、测井等资料对金湖凹陷阜二段的混合沉积进行了系统研究。其中,金湖凹陷阜二段沉积时期,混合沉积微观上表现为陆源碎屑组分与碳酸盐组分混合沉积形成混积岩,宏观上表现为陆源碎屑岩—碳酸盐岩层系、陆源碎屑岩—混积岩层系、碳酸盐岩—混积岩层系和混积岩层系;混积类型主要发育渐变式和复合式混合沉积,少量发育突变式混合沉积。通过对比分析区域地质背景、岩石学特征、沉积环境等,建立了阜二段混合沉积相模式。对研究区的混合沉积控制因素进行了讨论,认为其主控因素为阜二段沉积时期的海侵作用,同时构造作用、气候条件、湖平面变化、物源等也对研究区混合沉积有重要的影响。 相似文献