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晋中盆地是位于汾渭地堑系中部的新生代陆内断陷沉积盆地,研究晋中盆地第四纪的沉积序列对于进一步认识该盆地区域构造和区域气候环境变化具有重要意义。为查明晋中盆地第四纪沉积序列结构、研究揭示晋中盆地第四纪沉积环境及演化,通过构造岩相学方法,对晋中盆地地表和钻孔内第四纪沉积物和沉积环境进行了研究。结果表明:晋中盆地清徐地区地表第四纪沉积序列结构为盆地内部沱阳组河床相和河漫滩相-盆地边缘汾河组河流相—盆山过渡带峙峪组河流相、汾河组冲积扇相及马兰组风积相-基岩山地（盆地外围）二叠系浅海相。钻孔岩芯内第四纪沉积序列结构为下更新统浅湖相和滨湖相—中更新统浅湖相和河流相—上更新统河流相和冲积扇相—全新统冲积扇相。研究认为晋中新生代陆内断陷盆地内沉积序列和演化结构为早更新世陆相湖盆沉积环境—中更新世萎缩湖泊环境—晚更新世强烈萎缩的湖泊和河流环境—全新世再度沉降的陆相湖盆;陆相湖盆从中心向山地沉积环境分带为湖泊沉积环境—河流和湖泊沉积环境—冲积扇沉积环境（盆地边缘出山口区）。盆山过渡带地区上更新世沉积物错位现象与同沉积活动断裂有关,断裂活动性揭示了晋中盆地阶梯式断陷成盆的动力学机制。这些研究成果为区域气候环境变化和晋中盆地区域构造研究提供了新证据,也为太原市城市群建设中工程场址的选择提了供参考。 相似文献
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The Lower Freshwater Molasse (Untere Susswasser Molasse) crops out over a wide area of the Swiss Molasse Basin. Coarse grained alluvial fan conglomerates dominate in proximal basin areas along the Alpine front. These conglomerates pass northwards into sandstones and mudstones of an extensive northeastward draining meandering river system which ran parallel to the basin axis. Sedimentological study of outcrops, quarry exposures and boreholes in the basal Miocene (‘Aquitanian‘) has permitted detailed facies analysis of this distal alluvial sequence. The distal Aquitanian is made up of distinct ‘architectural elements’characterized by their geometries and sedimentary structures. Each may be assigned to a particular depositional setting: meander belt, levees, crevasse channels and splays, overbank fines and palaeosols, and lacustrine. Meander belt sandstones were deposited in mixed load channels with a dominant bedload component. Sandstones commonly comprise amalgamated and locally stacked ribbon bodies 2–15 m thick and 150–1500 m wide. Interbedded rippled, laminated and mottled fine grained levee sandstones and siltstones form lenticular packages up to 3 m thick and 30–100 m across. Small scale crevasse channel sandstones 2–4 m thick and 5–10 m across pass laterally into metre scale, medium to fine grained crevasse sandstone sheets. Rare laminated lacustrine siltstones occur only in the north-east part of the basin. Floodplain mudstones and marls make up the remainder of the succession. These display a variety of pedogenic features recording cyclical palaeosol development. Palaeosols show strong variations in morphology and maturity both laterally across the floodplain and downstream along the basin axis, reflecting local variation in aggradation rate associated with proximity to alluvial channel courses as well as regional variation in subsidence and floodplain drainage. Analysis of the organization and distribution of the various sediment bodies permits reconstruction of the fluvial system and allows development of a model for the sedimentary architecture of the Lower Freshwater Molasse in the study area. Integration of palaeosol studies into a well defined architectural framework assists recognition of areal facies belts and may aid location of sand-prone sequences in the subsurface. 相似文献
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High energy, lake‐shoreline carbonate sequences are rarely documented in the geological record. However, one example occurs in the Upper Triassic Mercia Mudstone Group (MMG) of southern Britain. The MMG is one of a number of thick, non‐fossiliferous mudstone deposits associated with North Atlantic Mesozoic rift basins. The origin of the MMG mudstones is the subject of current debate, with marine, playa‐lacustrine and alluvial–aeolian models having been proposed. Shoreline features have been documented from the northern margin of the basin, but the rarity of such features elsewhere in the MMG has led many workers to doubt a lacustrine origin for the mudstones. Wave‐dominated, lake‐shoreline deposits have been recognized in several sections from the southern basin margin in the Clevedon area of the Bristol Channel in south‐west England. These deposits provide evidence for the development of a sizeable perennial to semi‐perennial hypersaline lake in which the MMG mudstones accumulated. Shoreline sediments overlie alluvial stream and sheet‐flood deposits, and pass from transgressive gravel–conglomerate beach units with bioclasts, influenced by shore‐normal waves (deposited under semi‐humid conditions), to lower gradient, highstand oolitic sands affected by more varied wave approach (deposited under progressively more arid conditions), which culminated in lowstand, oolitic strand‐plain deposits overlain by a playa‐mudflat unit. Shoreline deposits record a simple shallowing‐upward transgressive–highstand–lowstand sequence. However, a change from a reflective (transgressive) to dissipative (highstand) shoreline is believed to represent a climatically induced change in prevailing wind direction. Shoreline features recognized in the MMG are similar to those of recent playa‐lacustrine basins of the western United States. Ooids display a variety of size, fracture and dissolution features in addition to beachrock fabrics, suggesting that they were originally composed of radial aragonite, similar to modern ooids from the Great Salt Lake, Utah. 相似文献
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根据札达盆地剖面中地层的接触关系、沉积旋回、沉积体系和岩相岩性特征,可将上新统河湖相地层划分为2个组、5个沉积相、8个岩段。古格组(N22g)一岩段为砾岩,属河流相沉积;二、三、五岩段以细碎屑岩为主,属浅湖相沉积;四岩段以含粘土质细碎屑岩为主,属深湖相沉积。托林组(N21t)一、二、三岩段为一套砾岩、含砾中粗粒钙质长石岩屑砂岩和中细粒砂岩的碎屑岩,为典型冲(洪)积扇沉积物。ESR法和古地磁法测年结果表明,古格组形成时代为上新世晚期(4.40～2.47Ma);托林组形成时代为上新世早期(5.44～4.40Ma)。札达盆地为一同生断陷盆地,在上新世时期的构造运动过程中,盆地演化经历了水进体系域—湖泊扩张体系域—湖泊收缩体系域3个发展阶段。 相似文献
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川西前陆盆地上三叠统沉积特征 总被引：7，自引：1，他引：7
应用层序地层学方法将川西前陆盆地上三叠统划分为4个三级层序和12个体系域。在层序格架内，研究了不同时期的古地理背景、物源、沉积类型和沉积相展布，明确了上三叠统存在龙门山古陆、米仓山-大巴山古陆、康滇古陆、江南古陆4个物源，识别出上三叠统海湾、冲积扇、曲流河、辫状河、扇三角洲、辫状河三角洲、曲流河三角洲和湖泊8种沉积相类型。层序Ⅰ沉积时期，盆地处于海陆交互相向陆相转变的时期，整体具有填平补齐的沉积特征，发育海湾等沉积；层序Ⅱ沉积时期，川西前陆盆地成为统一的内陆湖盆，其湖侵期为须家河期最大的湖侵期，主要发育三角洲沉积和湖相沉积；层序Ⅲ沉积时期，米仓山-大巴山古陆提供充足的物源，在米仓山-大巴山两逆冲推覆带前缘广泛发育大型冲积扇、辫状河、辫状河三角洲沉积体系；层序Ⅳ沉积时期，主要受江南古陆的影响，发育三角洲沉积和湖泊沉积。整体上，川西前陆盆地沉积相带的展布格局受构造控制，具有平行构造带展布的特点。盆地西北部陡坡带发育粗粒的冲积扇、扇三角洲-湖底扇，西南部陡坡带发育辫状河三角洲、北部-东北部陡坡带发育辫状河三角洲，而在东南部缓坡带则发育远源的曲流河、曲流河三角洲。 相似文献
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陆相伸展盆地的层序类型、结构和序列与充填模式--以冀中坳陷下第三系为例 总被引：6，自引：2，他引：6
陆相层序受自然地理景观、影响地层发育的地质营力及地层类型等因素影响,因此层序类型多种多样。在冀中坳陷同伸展期发育洪积层序、湖泊层序和冲积层序等三种层序类型。洪积层序是盆地伸展初期地貌反差较大物源供给充分气候干旱条件下发育的一种陆相层序类型,以冲积扇沉积为主,山高盆窄,汇水湖泊面积较小;湖泊层序发育在盆地强烈伸展基底快速沉降气候湿润湖泊水域宽深时期,湖泊水域宽,连通好,湖水深,是烃源岩发育的黄金时期。湖泊层序以湖泊沉积为主,其次为河流和少许冲积扇沉积。冲积层序是在盆地伸展末期地貌反差强度减弱物源距离逐渐加大时的沉积产物,主要为干旱气候条件下的河流、三角洲沉积,湖泊沉积局限。研究表明,影响陆相层序形成的构造、物源、气候等因素与湖泊水体或水平面变化构成一种多元“函数”关系,湖平面变化是上述因素的综合体现。陆相断陷盆地的层序结构大多与湖泊水体之间存在密切联系,因此层序的结构以三分为主。受地壳构造运动控制,断陷盆地发育的层序具有序列性,即下部洪积层序、中部湖泊层序和上部冲积层序。这种序列性是盆地充填对地壳幕式伸展的沉积响应。在盆地充填过程中,不同类型的陆相层序其体系域发育程度具有较大差异。一般地,洪积层序的低位域沉积? 相似文献
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Elodie Lebas Sebastian Krastel Bernd Wagner Raphael Gromig Grigory Fedorov Marlene Baumer Natalia Kostromina Haflidi Haflidason 《Boreas: An International Journal of Quaternary Research》2019,48(2):470-487
A multi‐channel, high‐resolution seismic reflection survey using a Micro‐GI airgun was carried out in the framework of the Russian‐German project PLOT (Paleolimnological Transect) on Lake Levinson‐Lessing, Taymyr Peninsula, in 2016. In total, ~70 km of seismic reflection profiles revealed in unprecedented detail the glacial and postglacial sedimentary infill of the lake basin. Five main seismic units have been recognized and interpreted as glacial (Unit V), subglacial and proglacial (Unit IV), marine (Unit III), fluvial‐lacustrine (Unit II) and lacustrine (Unit I) sediments. Of particular significance are imbricated, south‐orientated structures present in the southernmost part of the lake basin within Unit V and a large topographic ridge recognized in front of those structures. We interpret these structures as push moraines and an end moraine, respectively, left by the glacier after its retreat. The depositional pattern of the units above the moraines documents past lake‐level fluctuations. We interpret Unit IV, Unit III and Unit I as highstand deposits, and Unit II as lowstand deposits. Gas‐charged sediments dominate the northern part of the lake basin, whilst they occur only sporadically and in limited spatial extent in the central and southern parts of the lake. In the latter areas, the seismic and echo‐sounder data suggest recent tectonic activity. Our study contributes to the reconstruction of environmental conditions in the Taymyr Peninsula directly following the Early Weichselian deglaciation and shows that deep tectonic lake basins affected by several glaciations can preserve important palaeoenvironmental records, which contributes significantly to our understanding of palaeoenvironmental changes in the Taymyr Peninsula and the central Russian Arctic. 相似文献
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吐鲁番-哈密盆地从晚二叠世到晚第三纪经历了复杂的,多旋回的沉积构造演化历史,造成主要地层间均以不整合为界。盆地内沉积相类型丰富,沉积环境随时间的推移而发生改变。在晚石炭世,盆地北部为浅海环境;到晚二叠世,沉积环境由海相转变为陆相,并在上二叠统下部形成大量冲积相或河流相粗碎屑沉积;在三叠纪,沉积物主要形成于冲积相或河流-湖泊环境中,古气候则由干旱转为温暖湿润。早、中侏罗世,沉积环境以湖泊-沼泽相为主;到晚侏罗世,则以辫状河流相为主及干旱气候为特征。在白垩纪,盆地的沉积范围大为缩小,以湖泊环境为主;第三纪,沉积范围则扩大到整个盆地,沉积相以辫状河流及冲积相为特征,沉积气候干旱,局部地区接受了盐类沉积。古流向分析显示,吐-哈盆地具有复杂的沉积搬运体系。在盆地南侧,沉积物搬运方向总是由南向北,表明觉罗塔格山是盆地的主要物源区;而在盆地北侧,博格达山自晚侏罗世开始隆起,构成盆地的另一新的物源区,沉积物搬运方向由北向南。在白垩及第三纪,博格达山成为盆地的主要物源区。 相似文献
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西藏阿里札达盆地上新世—早更新世河湖相地层层序地层分析 总被引：1，自引：0，他引：1
根据札达盆地河湖相剖面地层岩性、粒度、沉积构造、古生物等反映的沉积岩相,以及不整合面等沉积特征,可将札达盆地上新世—早更新世河湖相地层,初步划分为两个三级层序(Ⅰ、Ⅱ)。层序Ⅰ代表上新统地层层序,并进一步区分出退积准层序组和进积准层序组。对应上新世湖相沉积由低位体系域—湖泊扩张体系域—湖泊收缩体系域的演化,反映湖泊由源区水系冲积亚相—滨湖三角洲亚相—滨浅湖亚相—半深湖亚相—滨浅湖亚相的湖泊,由扩张到萎缩的一个完整的发展演化旋回。层序II代表下更新统地层层序,反映一个盆地受构造和气候(冰期—间冰期)双重控制的夭折型冰湖形成演化的由冰水冲积相到冰湖沉积相的不完整沉积旋回,为青藏高原新近系上新统与第四系的研究与划分提供了重要依据。 相似文献
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The response of lake margin sedimentary systems to climatically driven lake level fluctuations: Middle Devonian,Orcadian Basin,Scotland 
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下载免费PDF全文 Lake margin sedimentary systems can provide highly sensitive records of sedimentary response to climate change. The Middle Old Red Sandstone of Northern Scotland comprises a thick succession of cyclic lacustrine sediments. Within this succession the deepest lake phase, the Achanarras fish bed, allows bed‐scale correlation over 160 km across the basin. This provides a unique opportunity to examine the character of synchronous lake margin deposits, and their response to climatically driven lake level fluctuations, across a large continental basin. Detailed characterization of two separate lake margin systems was carried out utilizing multiple sections in western Orkney, in the north, and Easter Ross, in the south. Seven facies have been recognized, which include upper and lower shoreface, deep lake, shallow lake, playa, turbidite and fluvial facies. Differences in vertical and lateral facies stacking patterns reflect the response of these systems to climatically driven fluctuations in lake level. Comparison of the northern and southern systems examined highlights the variable response of lake margin systems to the same climatic change and related lake level fluctuations. In the south, a greater fluvial influence is recognized on the development of the lake margin successions, whereas in the northern example, which lay on the downwind margin of the lake, shore zone facies are more commonly developed. The variability recognized can be accounted for by regional variations in sediment supply, coastal physiography, lake size, bathymetry and potential fetch. Lake level stability is also recognized as a major control on the development of lake margin sedimentary systems, as is the linked or unlinked relationship of the catchment and the lake basin climate for which a conceptual model is proposed. 相似文献
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Fine‐grained meandering systems of the Lower Permian Clear Fork Formation of north‐central Texas,USA: Lateral and oblique accretion on an arid plain 下载免费PDF全文
下载免费PDF全文 Facies models that adequately represent the diverse range of fine‐grained fluvial systems are currently lacking from the literature. In this paper, the spectrum of these systems on the arid plains of western equatorial Pangea is explored, as well as the source and nature of the fine‐grained sediments. Eight fluvial elements in the Early Permian Clear Fork Formation of north‐central Texas represent channel systems up to 7 m deep with coarse basal deposits, three types of lateral‐accretion deposits and sandstone sheets, with laminated, disrupted and massive mudstones laid down in abandoned channels and on floodplains. The three fine‐grained fluvial styles represent a continuum between two end‐members: sustained lateral accretion of bedload composed of quartzose sediments and mud aggregates on point bars, and oblique accretion of suspended sediment on steep accretionary benches and banks with limited lateral migration. This spectrum is controlled, in part, by grain size and the proportion of suspended to bedload sediments. The presence of rarely documented swept ripples on exhumed accretion surfaces is attributed to rapid decline in water levels and downstream re‐entry of overbank floodwaters into the channel. Rill casts, roots and disrupted mudstones low down in channel bodies indicate periods of near‐dryness. Laterally extensive sheet sandstones were formed by episodic flows in broad, sandbed channels. The fluvial sediments were primarily intrabasinally sourced with extrabasinal sediments brought in during major floods from upland source areas or reworked from local storage in the basin, representing a supply limited system. The upward change in cement composition from mainly calcite and ankerite to dolomite and gypsum with minor celestine implies increasingly saline groundwater and progressive aridification, supporting Late Palaeozoic palaeoclimatic models. By integrating petrographic data with sedimentology, a plethora of information about ancient landscapes and climate is provided, allowing a fuller comparison between the Clear Fork Formation and modern dryland alluvial plains. 相似文献
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Climate variability in the Salawusu River valley of the Ordos Plateau (Inner Mongolia,China) during Marine Isotope Stage 3 总被引：1，自引：0，他引：1
Fluctuations in climatic proxies of the Milanggouwan section in the Salawusu River valley of the Ordos Plateau (Inner Mongolia, China) during Marine Isotope stage 3 (MIS 3) coincide well with sedimentary cycles for palaeo‐mobile dune sands alternating with fluvial–lacustrine facies and palaeosols. We compared the palaeo‐mobile dune sands with modern mobile dune sands (products of a cold and dry climate dominated by the East Asian winter monsoon), whereas the fluvial–lacustrine facies and palaeosols were controlled by a wet–warm climate similar to that of the East Asian summer monsoon. The MIS 3 climate of the Salawusu River valley appears to have experienced at least nine wet–warm and ten cold–dry fluctuations, divided into five stages: MIS 3e (58 900–49500 yr BP), MIS 3d (49 500–40 700 yr BP), MIS 3c (40 700–36 900 yr BP), MIS 3b (36 900–27 000 yr BP) and MIS 3a (27 000–22 300 yr BP). The 19 cold–warm climatic fluctuations corresponded roughly to the GRIP and Guliyan records, and with fluctuations in the North Atlantic climate. Notable peaks in the spectral analysis occurred at 19 500 yr, 1020 yr, 640 yr and 500 yr. Our results show that the millennial–centennial climate was closely related to the relative strengths of East Asian monsoons, which are controlled by the North Atlantic thermohaline circulation, and which is also closely linked to the Sun's precession period. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Flow dynamics,sedimentation and erosion of glacial lake outburst floods along the Middle Pleistocene Scandinavian Ice Sheet (northern central Europe) 下载免费PDF全文
下载免费PDF全文 Jutta Winsemann Petteri Alho Leena Laamanen Nils Goseberg Jörg Lang Josef Klostermann 《Boreas: An International Journal of Quaternary Research》2016,45(2):260-283
During the Middle Pleistocene late Saalian glaciation of northern central Europe numerous pro‐glacial lakes formed along the southwestern margin of the Scandinavian Ice Sheet. Little is known about the drainage history of these lakes, the pathways of glacial lake outburst floods and their impacts on erosion, sedimentation and landscape evolution. This study investigated the impact of the late Saalian Weser and Münsterland Lake (Germany) outburst floods. In particular, we reconstructed the routing and flow dynamics of the lake outburst flood and analysed the flood related sediments. We employed one‐dimensional hydraulic modelling to calculate glacial lake outburst flood hydrographs. We modelled the flow pathway and local flow conditions along the pathway based on the boundary conditions of two different hydrographs and two different ice‐margin positions. The modelling results were compared with geomorphological and sedimentological field data in order to estimate the magnitude and impact of the flood on erosion and sedimentation. Two major lake drainage events are reconstructed for the study area, during which approximately 90–50 km3 of water was released. Modelling results indicate that the lake outburst floods created a high‐energy flood wave with a height of 35–50 m in confined valley areas that rapidly spread out into the Lower Rhine Embayment eventually flowing into the North Sea basin. The sedimentary record of the outburst floods comprises poorly sorted coarse‐grained gravel bars, long‐wavelength bedforms and sandy bedforms deposited by supercritical and subcritical flows. Some parts of the sandy flood deposits are rich in reworked mammoth bones or mammoth and horse teeth, pointing to reworking of older fluvial sediments, hydraulic concentration and subsequent re‐sedimentation of vertebrate remains. These deposits are preserved in sheltered areas or at high elevations, well above the influence of postglacial fluvial erosion. The flood‐related erosional features include up to 80‐m‐deep scour pools, alluvial channels and streamlined hills. 相似文献
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川西前陆盆地中侏罗统沙溪庙组具有巨大的勘探开发潜力,但对研究区沉积相研究成果却相对较少。本文根据岩性组合,岩石颜色,沉积构造等多种因素将研究区沙溪庙组划分出冲积扇、河流、扇三角洲、三角洲和湖泊五个沉积相,并对各沉积亚相构成特征进行了详细的研究。沉积相平面展布特征为物源主要来自于盆地西北部的龙门山,自西北向东南依次为冲积扇相-河流相-三角洲相-扇三角洲相-湖泊相。相的垂向序列反映湖泊具收缩-扩张-再收缩-再扩张的演变过程。 相似文献
16.
志靖安塞地区位于鄂尔多斯盆地陕北斜坡中部。以钻井取心观察为基础,结合砂岩厚度、砂地比、自生绿泥石分布、古生物化石分布等因素,对长9油层组2个层段沉积相空间展布特征及沉积演化规律进行研究。结果表明,长9油层组发育一套三角洲-湖泊沉积,北部主要发育三角洲前缘沉积,在南部发育浅湖沉积。长92沉积期,湖盆范围较小,长91沉积期湖盆初始扩张,湖岸线向北推进,湖域面积增大。从长92沉积期到长91沉积期,研究区经历了沉积水体由浅变深的过程,并在长91顶部发育一套具有生烃潜力的高阻泥岩。三角洲前缘水下分流河道砂体是较有利的储集砂体。 相似文献
17.
Variable style of transition between Palaeogene fluvial fan and lacustrine systems, southern Pyrenean foreland, NE Spain 总被引：1，自引：0，他引：1
Two Palaeogene fluvial fan systems linked to the south‐Pyrenean margin are recognized in the eastern Ebro Basin: the Cardona–Súria and Solsona–Sanaüja fans. These had radii of 40 and 35 km and were 800 and 600 km2 in area respectively. During the Priabonian to the Middle Rupelian, the fluvial fans built into a hydrologically closed foreland basin, and shallow lacustrine systems persisted in the basin centre. In the studied area, both fans are part of the same upward‐coarsening megasequence (up to 800 m thick), driven by hinterland drainage expansion and foreland propagation of Pyrenean thrusts. Fourteen sedimentary facies have been grouped into seven facies associations corresponding to medial fluvial fan, channelized terminal lobe, non‐channelized terminal lobe, mudflat, deltaic, evaporitic playa‐lake and carbonate‐rich, shallow lacustrine environments. Lateral correlations define two styles of alluvial‐lacustrine transition. During low lake‐level stages, terminal lobes developed, whereas during lake highstands, fluvial‐dominated deltas and interdistributary bays were formed. Terminal lobe deposits are characterized by extensive (100–600 m wide) sheet‐like fine sandstone beds formed by sub‐aqueous, quasi‐steady, hyperpycnal turbidity currents. Sedimentary structures and trace fossils indicate rapid desiccation and sub‐aerial exposure of the lobe deposits. These deposits are arranged in coarsening–fining sequences (metres to tens of metres in thickness) controlled by a combination of tectonics, climatic oscillations and autocyclic sedimentary processes. The presence of anomalously deeply incised distributary channels associated with distal terminal lobe or mudflat deposits indicates rapid lake‐level falls. Deltaic deposits form progradational coarsening‐upward sequences (several metres thick) characterized by channel and friction‐dominated mouth‐bar facies overlying white‐grey offshore lacustrine facies. Deltaic bar deposits are less extensive (50–300 m wide) than the terminal lobes and were also deposited by hyperpycnal currents, although they lack evidence of emergence. Sandy deltaic deposits accumulated locally at the mouths of main feeder distal fan streams and were separated by muddy interdistributary bays; whereas the terminal lobe sheets expand from a series of mid‐fan intersection points and coalesced to form a more continuous sandy fan fringe. 相似文献
18.
华北地台区古近系—新近系在渤海湾盆地非常发育,在南华北地区也有较大厚度,而在鄂尔多斯盆地则不甚发育,仅在西北部有少量沉积。渤海湾盆地古近纪以断陷型沉积为主,主要为滨浅湖相沉积,物源来自多个方向,如北部的燕山褶皱带、西部的太行山隆起、南部的鲁西隆起、东部的辽东隆起区以及盆地内部的沧县隆起和埕宁隆起等。南华北地区古近纪发育大小不一多个沉积中心,以河流相沉积为主;鄂尔多斯盆地古近纪仅在西北部出现沉积,发育河流相,缺失古新统—始新统沉积。新近系沉积区主要位于渤海湾盆地、南华北地区以及鄂尔多斯盆地外围的地堑中,主要为河流相和滨浅湖相沉积。新近纪早期渤海湾盆地大面积隆升,导致湖盆收缩,部分地区遭受剥蚀夷平,中晚期盆地整体形成统一坳陷,主要为河流相沉积,局部发育滨浅湖相;南华北地区进入裂谷期后坳陷发育阶段,大面积接受沉积,主要发育河流相沉积。华北地台区西部沿鄂尔多斯盆地周缘形成了一套以河流相与滨浅湖相为主的山前盆地沉积。华北地台区古近纪—新近纪油气的有利勘探区域为渤海湾盆地。 相似文献
19.
大别山北缘早白垩世黑石渡组沉积体系研究 总被引：3，自引：0，他引：3
分布于大别山北缘晓天-磨子潭断裂以北和金寨-响洪甸-西汤池断裂以南呈东西向延伸的早白垩世黑石渡组,厚达千米,岩相主要有角砾岩、砾岩、砂岩、粉砂岩、泥岩等,包括冲积扇、河流、扇三角洲和湖泊沉积体系,其中河流沉积主要由洪泛平原和决口扇组成。黑石渡组属于向上变细层序,早期为冲积扇沉积,中期为洪泛平原、决口扇和扇三角洲沉积,晚期为深湖浊流沉积。冲积扇和湖相浊流沉积主要发育于盆地东段舒城晓天地区,洪泛平原和决口扇沉积主要发育于盆地西段霍山地区,扇三角洲在两地都比较发育。这是一个不对称的断陷盆地,晓天-磨子潭断裂可能对盆地的发育具有控制作用。 相似文献
20.
The bulk of sedimentary material is supplied to Lake Ladoga in the form of suspension in river water. Rivers annually deliver 1.2 Mt of sedimentary material. A significant portion of clastic material in the sedimentation basin is also related to shore and bottom abrasion. Average sedimentation rate in the lake is 0.4 mm/yr for the last 10 ka. The wide grain size spectrum of lacustrine sediments is caused by textural inhomogeneity of Quaternary rocks, which are the main source of sedimentary material. Variably-grained relict sands at the depth of 12–20 m originated during a relatively low lake level. Silt, sand, and clay at 30–75 m are formed as a result of integration of the relict and newly supplied material. The sediment composition is principally defined by Cambrian–Ordovician rocks in the southern part of the lake, morainal and postglacial deposits in the eastern part, and crystalline basement rocks and their derivatives in the northern and western parts. Textural, mineral, and petrographic transformations of the surficial sediments take place under the influence of waves, induced currents, and gyres. Waves and induced currents mainly produce mature sediments, whereas gyres lead to the integration of materials supplied from different sources and the formation of petrographicaly mixed deposits. Based on the comprehensive analysis of sedimentological information, conditions of sedimentation and main features of lithodynamics are characterized. The results obtained may serve as a basis for the creation of a conceptual model of sedimentogenesis in Lake Ladoga. 相似文献