共查询到20条相似文献，搜索用时 46 毫秒
1.
Evidence of lacustrine sedimentation in the Upper Permian Bijori Formation, Satpura Gondwana basin: Palaeogeographic and tectonic implications 总被引：1，自引：0，他引：1
The Upper Permian Bijori Formation of the Satpura Gondwana basin comprising fineto coarse-grained sandstone, carbonaceous
shale/mudstone and thin coal bands was previously interpreted as the deposits of meandering rivers. The present study documents
abundance of wave ripples, hummocky and swaley cross-stratification and combined flow bedforms in the Bijori Formation, suggesting
that a significant part of the formation was deposited in a wave-agitated environment. Evidence of near-emergent depositional
conditions provided by repeated occurrence of rootlet beds and hydromorphic paleosols, local flooding surfaces denoting rapid
fluctuation of water level, occurrences of temnospondyl vertebrate fossils, and absence of tidal signatures and marine fossils
suggest a lacustrine rather than marine depositional regime. Five facies associations recognised within the Bijori Formation
are inferred to represent fluvial channels and associated floodplains (FA1), lake shorelines (FA2), subaqueous distributary
channels and associated levees (FA3), waveand storm-affected delta front (FA4), and open lacustrine/lower shoreface (FA5)
deposits. The planoconcave fluvial channel-fill sandbodies with unidirectional cross-beds are clearly distinguishable from
the delta front bars that show a convexo-plan or bi-convex sandbody geometry and dominance of wave and combined flow bedforms.
Some of the distributary channels record interaction of fluvial and wave-dominated basinal processes. Major distributary sandbodies
show a north to northwest flow direction while wave-affected delta front sandbodies show very complex flow patterns reflecting
interaction between fluvial discharge and wave processes. Wave ripple crest trends show that the lake shoreline had an overall
east-northeast to west-southwest orientation. The lack of documented contemporaneous lacustrine or marine sediments in the
Satpura Gondwana basin posed a major problem of basin-scale palaeogeographic reconstruction. The existence of Bijori lake
solves the problem and the lake is inferred to have acted as repository for the contemporaneous alluvial drainage. Development
of the large Bijori lake body implies generation of accommodation space exceeding the rate of sediment supplied and thus represents
locus of high tectonic subsidence. Transition of fluvial sediments with red mudstone and calcareous soil profile in the lower
part of the succession to carbonaceous shale and coal-bearing lacustrine sediments in the upper part, denote a change from
a warm semi-arid climate with seasonal rainfall to a more humid one. 相似文献
2.
准噶尔盆地乌尔禾地区二叠系风城组盐类矿物和成因分析 总被引：1，自引：0，他引：1
二叠系风城组为准噶尔盆地乌尔禾地区重要的勘探层系,也是成因非常特殊的深湖相含盐火山-沉积建造。通过14口钻井岩心观察,296片薄片鉴定,30块扫描电镜和28件X衍射等分析技术手段,较为详细地研究了风城组盐类矿物及伴生矿物的各项特征,识别出硅硼钠石、碳酸钠钙石、白云石等主要盐类矿物和硬石膏、石膏、玉髓、黄铁矿和蒙脱石等伴生矿物,确定风城组深湖相含盐火山-沉积建造与同期相间发生的火山喷发和湖底热液喷流活动有关,其成因可与酒西盆地下沟组湖相喷流岩和东非裂谷坦噶尼喀湖现代深湖底热液喷流沉积作用相类比,提出"深水湖盆热液喷流含盐火山-沉积建造模式"。 相似文献
3.
《Geodinamica Acta》2002,15(4):249-260
A paleomagnetic study has been carried out on three sedimentary formations of the Permian Rodez basin in the southern France. Two of them yield paleomagnetic poles of Saxonian and Thuringian age showing counterclockwise rotation of moderate amplitude, during or after the Thuringian deposition. For the French Massif Central, contrary to its stable southern (Lodève basin) and eastern (Largentière basin) borders, on its southwestern border, in a large area including the Rodez, Saint-Affrique and perhaps Brive basins suffered rotations due to the extensional tectonics during the Late Variscan period. 相似文献
4.
Arturo Diego-Orozco Yan Chen Bernard Henry Jean-François Becq-Giraudon 《Geodinamica Acta》2013,26(4):249-260
Abstract A paleomagnetic study has been carried out on three sedimentary formations of the Permian Rodez basin in the southern France. Two of them yield paleomagnetic poles of Saxonian and Thuringian age showing counterclockwise rotation of moderate amplitude, during or after the Thuringian deposition. For the French Massif Central, contrary to its stable southern (Lodève basin) and eastern (Largentière basin) borders, on its southwestern border, in a large area including the Rodez, Saint-Affrique and perhaps Brive basins suffered rotations due to the extensional tectonics during the Late Variscan period. © 2002 Editions scientifiques et médicales Elsevier SAS. All rights reserved. 相似文献
5.
河南登封地区上二叠统石千峰组以湖泊相碎屑岩为主,其中发育有典型的风暴岩沉积,在风暴岩中发育有冲刷面、丘状交错层理、包卷层理、波痕和泄水构造等风暴沉积构造,并存在典型的序列,自下而上可划为Sa,Sb,Sc,Sd和Se五段.同时深入探讨了风暴岩的类型,主要包括原地风暴岩和异地风暴岩,并论述了其研究意义.风暴岩是湖泊发育的典型标志, 所以风暴岩的提出对确定研究区的沉积相类型增加了新的认识,并且对上二叠统石千峰组的古地理恢复也具有重要意义. 相似文献
6.
晚石炭世末期-三叠纪东澳大利亚的鲍恩-冈尼达-悉尼（Bowen- Gunnedah-Sydney）盆地系是位于拉克伦（Lachlan）褶皱带和新英格兰（New England）褶皱带之间的一个长条形的构造盆地。从北部的冈尼达（Gunnedah）到南部的巴特曼斯（Batemans）湾，悉尼盆地是鲍恩-冈尼达-悉尼盆地系南端的一个次级盆地。悉尼盆地的二叠系包括河流、三角洲、滨浅海沉积岩和火山岩地层。南悉尼盆地的西南部二叠系不整合覆盖于变形变质的拉克伦（Lachlan）褶皱带之上。二叠系由下部的塔拉特郎（Tallaterang）群、中部的肖尔黑文群（Shoalhaven Group）和上部的伊勒瓦拉煤系（Illawarra Coal Measures）组成。从晚石炭世末到中三叠世悉尼盆地经历了弧后扩张到典型的前陆盆地的不同阶段：弧后扩张阶段、被动热沉降阶段和挤压挠曲负载阶段。 相似文献
7.
K. V. Syromyatnikov 《Lithology and Mineral Resources》2000,35(5):466-474
A facies classification of sedimentary rocks is presented for the Upper Permian Inta Formation of the southern Pechora Coal
Basin. A correlation has been revealed between clay mineral assemblages and certain facies types of lacustrine sediments. 相似文献
8.
9.
《Sedimentology》2018,65(2):335-359
Predominantly fine‐grained strata were deposited in the Smith Bank Formation (Early Triassic) in the Central North Sea area of the Northern Permian Basin. Previously regarded as monotonous red claystone, examination of continuous core reveals abundant stratification, significant variation in colour, siltstone as the prevalent average grain size, and claystone is rare. Loessite occurs beyond the north‐western lacustrine margin, and aerosol dust has inundated clay pellets derived from aeolian reworking of the desiccated lake floor. The loessite has limited evidence of pluvial reworking but rare fossil roots testify to sufficient moisture to sustain plants. Loessite has not previously been differentiated successfully from other fine‐grained strata in the subsurface, but this study defines the presence of random grain‐fabric orientation as an intrinsic unequivocal characteristic of loessite that formed during air‐fall deposition of aerosol dust. Comparison with outcrop data verifies the utility of grain fabric to differentiate loessite. Tosudite, an aluminous di‐octahedral regularly ordered mixed‐layer chlorite/smectite, which is rare in sedimentary rock, forms a significant proportion (10 to 21%) of the clay mineral fraction of loessite along with a similar quantity of kaolinite. In all other samples, only illite and chlorite are identified, which is typical of fine‐grained Triassic strata. In a location, close to the southern lake margin, lacustrine strata are characterized by fining‐upward couplets of very fine‐grained sandstone into siltstone and mudstone, with occasional desiccated surfaces. Small sand injections and associated sand extrusions are common and indicate periodic fluidization of sand. Precise stratigraphic location of the Smith Bank Formation is problematic because of extremely sparse fossil preservation; however, there is no sedimentological evidence for a period of hyperaridity known from the early Olenekian in continental Europe, which may mean that the North Permian Basin was never hyperarid or that the Smith Bank Formation is restricted to the Induan. 相似文献
10.
天山东段地区二叠系芦草沟组的沉积时代、沉积环境和构造背景存在争议。根据芦草沟组中发现的标准化石桃树园吐鲁番鳕、托姆介介形虫和孢粉化石组合,结合沉积地层中大量碎屑锆石最年轻峰值年龄261 Ma,认为芦草沟组的沉积时代为瓜德鲁普世(中二叠世)而非乌拉尔世(早二叠世)。近年来,在芦草沟组中发现典型海相指示矿物海绿石、海相或海陆交互相托姆介介形虫,加之超高盐度咸化湖盆的证实,认为芦草沟组主体为湖相沉积,但部分沉积时段受到海侵(泛)事件影响。天山东段地区准噶尔盆地、三塘湖盆地、吐哈盆地二叠系芦草沟组具有相似的岩石组合、动物群面貌和构造特征,但不同盆地古盐度、古气候、古氧化还原条件、古水深、初级生产力及热液输入强度等具有差异,分析认为芦草沟组形成于相似的伸展裂谷构造背景,但不同盆地之间沉积特征具有差异、不具备统一的沉积中心,为一系列弥散性裂谷盆地群。 相似文献
11.
松辽盆地嫩江组大型陆相坳陷湖盆湖底水道的发现及其石油地质意义 总被引：14，自引：2，他引：14
松辽盆地属于大型陆相中生界含油气盆地,通过高分辨率三维地震资料分析,首次在中央坳陷区大庆长垣嫩江组一段湖相泥岩中发现了发育完整的大型湖底水道系统,该系统由3个主干水道和4个末梢分支水道构成,沿大庆长垣自北向南延伸,水道系统延伸最大直线距离71km,水道最大宽度600m。研究认为该水道系统可能为河流直接入湖而形成,电测解释和岩心观察表明水道砂体具有很好的含油气性。因此,这一水道系统的发现为在松辽盆地中央坳陷区广泛发育的湖相泥岩中寻找油气储层提供了一个新勘探领域,具有极其重要的石油地质意义。 相似文献
12.
榆林气田陕151井区山西组二段储集层是实现增储上产的主力产层。影响该区天然气富集高产的主要因素:石炭—二叠系煤系烃源岩提供了丰富的生气母质,在低孔、低渗背景上发育了多期水下分流河道石英砂岩和岩屑石英砂岩有效储层,在平缓构造背景上发育的低幅度鼻隆构造带严格控制着气、水分布;山西组顶部发育的浅湖相泥岩提供了良好的盖层条件。 相似文献
13.
为了认识陕西省洛南地区二叠系石盒子组砂岩特征及其物源,给探索渭河盆地前新生代基底组成提供依据,本文综合分析了洛南二叠系石盒子组砂岩组分和重矿物特征。结果表明,砂岩物源区主要为再旋回造山带和克拉通地块,物源区与北秦岭造山带的演化关系密切,南秦岭构造带北部下古生界也为石盒子组提供部分物源,中二叠世晚期华北、秦岭板块面接触碰撞,北秦岭构造带快速隆升,南秦岭物源区提供物源减少,砂岩物源主要为中酸性岩浆岩+低级变质岩+沉积岩。二叠纪鄂尔多斯盆地南缘向南延至洛南—栾川断裂附近,洛南地区二叠系石盒子组河流沼泽相含煤岩系沉积应该属于鄂尔多斯盆地南缘沉积,结合渭北—渭河—洛南地区晚古生代地层对比成果,认为渭河地区二叠纪至少曾沉积过二叠系石盒子组地层,渭河新生代盆地基底具有残存二叠系的可能。 相似文献
14.
准噶尔盆地玛湖凹陷下二叠统古老碱湖成因探究：来自全球碱湖沉积的启示 总被引：1，自引：0，他引：1
碱湖沉积在全球范围内均有分布,在特定的构造背景、火山活动、热液作用及气候条件下形成。我国准噶尔盆地玛湖凹陷风城组发育的碱湖沉积形成年代老且埋藏较深,在完整的沉积-成岩演化研究中具有独特优势。此外,风城组碱湖沉积的分布与页岩油藏的分布具有密切关系,其形成演化对碱湖页岩油藏研究提供重要支持。通过全球尺度下碱湖及碱湖沉积主要特征分析,总结碱湖沉积特征和成因,为准噶尔盆地玛湖凹陷风城组碱湖沉积成因分析提供借鉴。综合分析表明,同期火山活动和特定气候条件均可主控碱湖沉积的形成。此外,碱湖沉积形成需湖盆水文封闭、充足的溶质供给、低硫酸盐占比及强蒸发环境条件。汇总分析全球碱湖沉积矿物种类与埋深关系,发现成岩作用下矿物转变规律:单斜钠钙石随成岩作用增强依次转变为钙水碱、碳钠钙石,苏打石和天然碱转变为碳酸氢钠石。通过与全球碱湖沉积实例对比分析可知,玛湖凹陷风城组碱湖沉积中碳酸氢钠石和碳钠钙石经成岩作用形成,钠硅酸盐矿物和特征矿物与火山活动及热液作用有关。碳酸氢钠石生长形态及磁黄铁矿指示玛湖凹陷风城组碱湖沉积中心为高盐度分层且底部缺氧的常年生湖泊。下二叠统风城组碱湖沉积形成与周缘火山岩及同沉积火山活动密切相关,受气候、构造背景、火山活动和后期成岩作用的共同控制。 相似文献
15.
以四川古蔺芭蕉村二叠系剖面为研究对象,在野外沉积特征详细观测的基础上,利用岩石薄片鉴定、全岩X衍射分析、元素地球化学与碳、氧、锶同位素分析,对其地层、沉积环境与演化特征进行研究,为四川盆地二叠系沉积特征研究与天然气勘探提供基础资料。研究表明,四川古蔺芭蕉村地区从中二叠世的梁山—栖霞组沉积时期开始海侵,栖霞组由下向上水体先变深又变浅,呈缺氧—贫氧环境;茅口组底部又一次海侵,以继承栖霞组沉积环境为特征,在茅口组一段水体最深,向上逐渐变浅,呈缺氧—贫氧特征;龙潭组沉积水体最浅,氧化环境为主,局部呈还原环境;长兴组底部沉积水体最深,整体呈缺氧—贫氧特征,其碳酸盐岩沉积的海平面相对中二叠统应较浅。宏观上,四川盆地中二叠统栖霞组、茅口组由东向西为碳酸盐岩缓坡逐渐向台地演化。茅口组三段发育大型的溶蚀孔洞和后期溶蚀缝洞,推测该区茅口组有可能形成岩溶缝洞型储层。长兴组的底部发育水体较深的台盆次相沉积,环台洼或台盆可能是礁滩发育的有利区。见大量的沥青质充填,考虑到川南地区二叠系发育富有机质的碳酸盐岩与黑色页岩及煤层,认为该区二叠系具备形成古油藏的可能。 相似文献
16.
巴北凹陷是银根-额济纳旗盆地(简称银额盆地)苏红图坳陷北部的一个次级构造单元,通过埋汗哈达组的孢粉组合特征研究及碎屑锆石U-Pb同位素测试,探讨了地层年代及物源方向。从孢粉组合特征可以看出,除晚古生代和中生代都存在的类型外,仅在白垩纪出现的类型没有见到,且见到的绝大多数类型都出现在晚古生代和三叠纪;银额盆地苏红图坳陷北部埋汗哈达组碎屑岩锆石阴极发光图像和Th/U值(0.4),表明大部分属于岩浆成因锆石。锆石年龄分布在246～1010Ma之间,集中分布在246～390Ma、400～560Ma,最年轻的峰值为260Ma。综合分析后将埋汗哈达组归入二叠系,与切刀古隆起和巴彦诺尔公—狼山—阴山一带岩浆岩的年龄分布相似,由此认为,切刀古隆起和巴彦诺尔公—狼山—阴山一带的岩浆岩可能为埋汗哈达组的沉积物质来源。 相似文献
17.
《Journal of African Earth Sciences》2000,30(3):535-553
Sediments of the Upper Carboniferous to Lower Jurassic Karoo Supergroup (∼ 4.5 km thick) were deposited in the mid-Zambezi Valley Basin, southern Zambia. The Upper Palæozoic Lower Karoo Group in this area ends with a Late Permian sedimentary unit called the Madumabisa Mudstone Formation. The formation is 700 m thick and comprises four lithofacies grouped into two facies assemblages, collectively interpreted as lacustrine deposits. Sediments of a massive mudrock facies assemblage were deposited from suspension, probably from sediment-laden rivers entering a lake. Concretionary calcilutite beds probably mark the positions of palæosediment-water interfaces where calcite was precipitated. A laminated mudrock facies assemblage is attributed to lacustrine deposition from inflowing rivers at the lake margins and shallow parts of the lake. Repeated thickening-upward cycles are evidence of upward shallowing, interrupted by events of more abrupt deepening. Sandstone interbeds are interpreted as fluvial deposits laid down during low lake stands, with cross-lamination and asymmetrical ripples indicating current rather than wave deposition. A fossil assemblage of ostracods, bivalves, gastropods, fish scales, the alga Botryococcus sp. and fossil burrows is consistent with a lacustrine origin for the formation. 相似文献
18.
以准噶尔盆地南缘韭菜园子沟剖面中二叠统芦草沟组野外露头为研究对象,结合该地区芦草沟组沉积时期坳陷湖盆的沉积特征和大套灰黑色油页岩的发育背景,对芦草沟组上部砂体进行了观察描述和沉积分析。在露头剖面上,芦草沟组以灰黑色油页岩为主,但笔者首次在该组上部发现了厚约60m的砂岩,其与上覆红雁池组灰黑色油页岩呈整合接触,具有明显的深水沉积背景。通过对该套砂体的岩石类型划分与沉积现象解析,共识别出2大类10种砂泥岩类型,明确了牵引流和浊流共同发育的特征。该套砂体中可识别出深水扇的3种沉积亚相和相应沉积微相,由3期富砂型湖泊深水扇叠置形成。结合此次露头观察与特征描述,分析了研究区由厚层砂岩到泥砂岩互层的演化过程,并建立了芦草沟组富砂型湖泊深水扇沉积模式。这个典型露头的沉积解剖,是对准噶尔盆地南缘芦草沟组深水沉积体系研究的有益补充。 相似文献
19.
准噶尔盆地东部(准东)油气勘探成效差,是否发育规模有效烃源岩是必须回答的关键科学问题。通过地球化学法、ΔlgR法、井震结合对准东地区二叠系平地泉组烃源岩进行识别和评价,探讨烃源岩的空间分布。研究表明,平地泉组烃源岩以暗色泥岩为主,丰度为中等-好,以半深湖-深湖相泥页岩为优,优质烃源岩在平二段富集。平面上烃源岩富集在准东北部的克拉美丽山前带和南部的博格达山前带,中间被奇台凸起所分割。南、北带内部烃源岩的丰度受次级凹陷分割,表现出西高(TOC>1.5%)东低(0.5%相似文献
20.
G. F. Ufimtsev 《GeoJournal》1991,25(4):359-366
The order in structure of planetary relief is characterized by the following symmetrical attitudes of forms: antisymmetry of the north and south hemisphere (polar antisymmetry), underlined by availability of antianalogical forms; symmetry of cone in the Laurasian continental massif in the north hemisphere; symmetry of axis of the 4th order in the south hemisphere. In the West Pacific region the summation of private dissymetries of planetary relief structure occurs. The Earth's equatorial belt has a system of sinistral oroclines. Symmetrical peculiarities of planetary relief structure may allow us to suppose that the main process of the Earth's development during the Post-Gondwanian epoc (middle-Jurassic-Cenozoic period) was anisotropic expansion, mainly in the south hemisphere. Other tectonic processes, including lithospheric plate displacements, occur simultaneously with the normal process of the Earth's expansion. 相似文献