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1.
Ritesh Purohit Harsh Bhu Prakshal Mehta P. C. Avadich 《Journal of the Geological Society of India》2012,79(2):135-150
Present study reviews the tectono-stratigraphic status of Babarmal pink marble from the Aravalli Supergroup through mapping
and petrographic study of marble as well as associated lithologies. The pink marble is predominantly calcitic and characteristically
different from dolomitic carbonate rocks of the Jhamarkotra Formation, the Lower Aravalli Group. The marble is devoid of organic
matter and phosphate content unlike the Jhamarkotra dolomite. The pink marble is underlain by quartz-pebble rich conglomerate.
This assemblage represents a rare lithological association which has not been reported so far from the Aravalli Supergroup. 相似文献
2.
R. C. Dey 《Journal of the Geological Society of India》2009,74(1):131-137
The subsurface Nagaur Basin in northwest Haryana and southwest Punjab hosts evaporite sequence, conformably overlain by Nagaur
red beds and grey beds. A polymictic conglomerate intervenes the Nagaur sequence and the overlying Tertiary sequence. The
focus is on the new finds of (i) distinctive ‘grey beds’ overlying ubiquitous red beds, (ii) ‘Malout conglomerate and grit’
horizon (Palaeocene-Miocene) marking an unconformity over the Nagaur Group (early Cambrian) and (iii) ‘entrapped gas and dried-up
leaves/carbonaceous flakes’ in the conglomerate unit and succeeding Tertiary rocks. Palaeoenvironmental significance has been
discussed. The Nagaur ‘red beds’ has been likened to ‘continental red beds’ of Schreiber (1978) and ‘reworked red beds’ of
Krynine (1949). The ‘grey beds’ are channel fillings, fresh material having been derived from fresh cuttings by streams/rivers
following structural grains in the Aravalli landscape where the interfluves provided weathered (oxidised) materials for the
red beds. Association of continental red beds and grey beds is known in the Newark Series (Triassic) of the Eastern United
States and the Keweenawan ‘late Precambrian’ of the Lake Superior region. 相似文献
3.
The Banded Gneissic Complex (BGC) of Rajasthan, considered to form the basement underlying the Precambrian (Proterozoic) Aravalli metasediments, shows an erosion surface marked by a conglomerate and an angular unconformity, with gneissic foliation crossing the metasedimentary bands at only a few places. The BGC is a composite gneiss, evolved by extensive migmatization of metasedimentary rocks of diverse composition, and possibly metaigneous rocks. The contact between the BGC and the Aravalli rocks is a gently curved surface, whereas the gneissic foliation, as well as the large-scale metasedimentary enclaves within the gneissic complex, show all the intricate patterns of super-imposed folding traceable in the Aravalli rocks. This implies that the “basement” gneisses have been involved in ductile deformation with the Aravalli rocks, the migmatization being synkinematic with the first deformation in the latter. All these apparently conflicting lines of evidence can be resolved if the gneisses, as we see them now, represent not the original, but the mobilized basement, with the BGC-Aravalli boundary representing, for a large part, a migmatite front, rather than the original basement-cover interface. Only at a few places was there a chance of the original basement escaping mobilization and thus, little chance of identifying this original interface. 相似文献
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松辽盆地东南隆起区营城组一段熔浆胶结复成分砾岩特征及其成因分析 总被引:4,自引:3,他引:1
对野外剖面实际测量及室内薄片鉴定等资料研究表明,松辽盆地营城组一段复成分砾岩共有4种胶结成岩类型:熔浆胶结、灰泥球胶结、凝灰质胶结和砂泥质胶结。其中以熔浆胶结发育最为广泛。砾岩中砾石成分复杂,以基底花岗岩及二叠系变质岩为主,原地火山岩次之。砾石整体分选性差,磨圆度中等-好,以次圆状-次棱角状最为发育。自基底向火山活动中心,砾岩中外来砾石逐渐减少,原地火山岩砾石逐渐增多。基质成分由底部的砂泥质向上过渡为凝灰质并最终完全过渡到熔浆质胶结。砾岩是冲积扇或辫状河等沉积环境下已经堆积但未固结或半固结的砂砾质沉积物,在火山活动期被火山碎屑流或熔浆流再搬运,这种碎屑流、熔浆流和水介质构成的多相混合物通过岩浆冷凝和压实复合成岩作用而形成的岩石,实质是爆发相热碎屑流亚相的另一种表现形式。由于该类砾岩主要见于断陷盆地边缘火山岩序列下部靠近基底一侧,说明其形成与构造-岩浆活动密切相关,是火山旋回早期所特有的产物。 相似文献
6.
辽西北票地区义县组地层层序与化石层位 总被引:14,自引:2,他引:12
辽西北票地区义县组是一套中生代火山-沉积地层.义县组火山活动具有明显的旋回性特征,主要由下部基性-中基性火山喷发-沉积旋回和上部酸性、偏碱性火山活动旋回组成.具体可划分6个岩性段,自下而上分别为底砾岩段,基性、中基性火山岩段,湖相沉积岩段,酸性、偏碱性火山岩段,上部基性火山岩段和顶部砾岩段.义县组底砾岩段和基性、中基性火山岩段的沉凝灰岩中产有丰富的以鹦鹉嘴龙为主的古脊椎动物化石.湖相沉积岩段含有大量热河生物群化石,包括著名的中华龙鸟、孔子鸟和辽宁古果等珍稀化石,该层位记录了侏罗-白垩纪界限附近重大的生物演化事件. 相似文献
7.
楚雄盆地北部上三叠统储集体构型及空间分布 总被引:2,自引:0,他引:2
通过实测野外露头,沉积层序与高分辨层序地层学相结合,采用扩展Simpon方法,扩展Simpon3/8方法及Trapezoidal方法,研究储集体构型及空间展布。上三叠统储集体为砂砾岩,总体上表现为自下而上逐渐减薄。普家村期(T3p),北部太平场和南部洒芷两个扇储集体互不连通,自成体系。南部扇连通较好,是有希望目的层。干海子期(T3g)时的河控三角洲砂体与浪控三角洲砂体的连通性和非均质程度差别颇大。舍资期(T3s)时砂体呈环状分布。湖成砂体连通性差,河道砂体则均质性高,连通较好。 相似文献
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The Guevgueli Ophiolite Complex near Demir Kapija (Eastern Vardar Ophiolitic Unit) was studied for the age and facies of the overlying sediments. Cherts in direct contact with basalts are dated to late Bathonian–early Callovian with radiolarians. The post-obduction sequence, here informally named the Demir Kapija group, is composed of polymictic conglomerate, probably Kimmeridgian in age, and a more than 350-m thick carbonate succession. The carbonate succession consists of hemipelagic, slope and platform margin facies and contains algae and benthic foraminifers indicative of the Tithonian age. These new data support the previously proposed palaeogeographical connection between the Guevgueli and South Apuseni ophiolite complexes. 相似文献
10.
The Mesta Basin in southwest Bulgaria is a graben that contains a Paleogene‐age siliciclastic and volcaniclastic succession deposited in alluvial and fluvial settings. A sedimentological analysis has shed light on conglomerate provenance, and the links between deposition and tectonic setting. Petrographical and chemical analysis of conglomerate clasts and matrix from the Dobrinishka, Gradinishka, Osikovo (or Osenovo) and Zlataritsa formations reveal both local, and more distal source provenance ages. The basal conglomerates are subdivided into three types, a lower and upper polymictic and a middle granitic conglomerate type. Petrographical and chemical analysis reveals granite, gneiss and amphibolite clasts that were sourced from the Sidironero–Mesta Unit of the Middle Allochthon of the Rhodope Metamorphic Complex, and the Rila–Rhodope Batholith to the east of the basin. Cathodoluminescence analysis of quartz sand grains reveals an increased input of red‐ and violet‐luminescent volcanic grains. Volcanic quartz in the oldest conglomerates indicates a hitherto unknown early (pre‐Oligocene) phase of volcanic activity in the vicinity of the Mesta Basin. The conglomerates were deposited in association with movement on the Ribnovo low‐angle normal fault during the Late Eocene, creating subsidence and the development of considerable accommodation space. The establishment of a fluvial environment followed subsequent Oligocene‐age volcanic activity. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
11.
滇中地区“因民角砾岩”的成因及归属问题目前暂无定论。笔者通过对东川-易门地区前人所划的因民组“因民角砾岩”进行1:5万野外地质调查工作,对其进行了初步的分类。根据其成因及时代划分为复成分砾岩、冰碛砾岩、滑塌角砾岩、引爆角砾岩和构造角砾岩。对“因民角砾岩”成因及时代的研究,特别是“冰碛砾岩、复成分砾岩”的提出,对于解决滇中早前寒武纪地层层序、时代归属、构造格架、大地构造位置及大区域地层对比,探讨滇中元古宙地史演化、古环境研究以及指导找矿都具有重要的指示意义。 相似文献
12.
岩性地层油气藏是我国陆上油气勘探的重点领域之一,本文针对我国西部前陆盆地勘探程度相对较低的中深层陆相砾岩油藏,选取准噶尔盆地西北缘八区中-下二叠统作为研究对象,综合岩心观察、测井和三维地震资料的精细解释,在开展层序地层学和沉积相研究的基础上重点解剖典型的扇三角洲砾岩油藏,分析层序地层格架内砾岩油藏的分布特征,揭示出研究区具有一扇多藏的油藏分布规律。勘探开发实践表明,研究区砾岩油藏主要发育于水进体系域扇三角洲前缘水下分流河道储集体中,其次为高水位体系域中,以物性遮挡岩性油藏、物性封闭岩性油藏以及断裂-岩性复合油藏为特征。 相似文献
13.
The Neoproterozoic Malani magmatism of the northwestern Indian shield: implications for crust-building processes 总被引:1,自引:0,他引:1
Kamal K. Sharma 《Journal of Earth System Science》2004,113(4):795-807
Malani is the largest event of anorogenic felsic magmatism (covering ∼50, 000 km2) in India. This magmatic activity took place at ∼750 Ma post-dating the Erinpura granite (850 Ma) and ended prior to Marwar
Supergroup (680 Ma) sedimentation. Malani eruptions occurred mostly on land, but locally sub-aqueous conditions are shown
by the presence of conglomerate, grits and pillow lava. The Malani rocks do not show any type of regional deformation effects.
The Malanis are characterised by bimodal volcanism with a dominant felsic component, followed by granitic plutonism and a
terminal dyke phase. An angular unconformity between Malani lavas and basement is observed, with the presence of conglomerate
at Sindreth, Diri, and Kankani. This indicates that the crust was quite stable and peneplained prior to the Malani activity.
Similarly, the absence of any thrust zone, tectonic mélange and tectonised contact of the Malanis with the basement goes against
a plate subduction setting for their genesis. After the closure of orogenic cycles in the Aravalli craton of the northwestern
shield, this anorogenic intraplate magmatic activity took place in a cratonic rift setting under an extensional tectonic regime. 相似文献
14.
该文通过对哀牢山构造带西侧云南省南涧地区下白垩统南新组砾岩层的砾性、砾度、砾态和砾向等的详细研究与分
析,结合盆地基岩地层特点和周边构造带的岩性组合特征,发现南新组砾岩总体上具有砾石成分复杂、分选性较差、磨圆程
度中等-较好(次圆状-圆状)、风化程度较低等特征;探讨了砾岩层本身的性质、物质来源,以及砾石沉积时盆地的水动力条
件、气候环境、古地貌特征和构造条件。认为南新组砾岩层为半干旱-干旱古气候条件下的一套冲积扇-辫状河相粗碎屑沉
积,具有快速堆积的特点;砾岩层沉积前砾石遭受了较强的物理化学作用。根据盆地基岩及周边地层岩性特点和砾石扁平面
倾向统计,砾石的主要来源是盆地内部的基底地层及其东缘的哀牢山构造带。 相似文献
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B. Peng Z. Jin J. Wang H. Jia X. Zhu T. Chang K. Yuan 《Russian Geology and Geophysics》2018,59(6):606-619
The sedimentology and sequence stratigraphy of a retrogradational fan-delta system within Lower Triassic in the Mabei area of Junggar Basin in northwestern China were investigated using seismic, well log, and core data, complemented by the modern deposition and a flume tank experiment. The Lower Triassic in the Mabei area is dominated by fan deltas, which are composed of fan-delta plain (including subaerial debris flow, braided channel, conglomerate overbank, and floodplain), fan-delta front (including conglomerate shoal and sandy shoal), and prodelta. The braided channels form during the low flood period. The conglomerate overbanks form during the flood period and occupy most part of the fan-delta plain. The conglomerate shoals and sandy shoals form by a sheet flow prograding into lakes and occur as a sheet. The braided channels, conglomerate shoals, and sandy shoals are easy to form high-porosity reservoirs. One long-term base level cycles (LSC1), three middle-term base level cycles (MSC1, MSC2, and MSC3), and fifteen short-term base level cycles are identified. MSC1 is dominated by the fan-delta plain; MSC2 is dominated by the fan-delta front; and MSC3 is dominated by the fan-delta front and prodelta. The stratigraphy shows a proximal-middle-distal trend demonstrating an overall retrogradation stacking pattern. The sequence architecture is controlled by an interplay between lake level changes and sediment supply. The quick rise in the lake level and the creation of accommodation outpacing the rate of sediment supply result in a retrogradational fan-delta syste. 相似文献
17.
滇中地区因民角砾岩类型、特征及找矿意义 总被引:1,自引:0,他引:1
滇中地区“因民角砾岩”的成因及归属问题目前暂无定论。笔者通过对东川-易门地区前人所划的因民组“因民角砾岩”进行1:5万野外地质调查工作,对其进行了初步的分类。根据其成因及时代划分为复成分砾岩、冰碛砾岩、滑塌角砾岩、引爆角砾岩和构造角砾岩。对“因民角砾岩”成因及时代的研究,特别是“冰碛砾岩、复成分砾岩”的提出,对于解决滇中早前寒武纪地层层序、时代归属、构造格架、大地构造位置及大区域地层对比,探讨滇中元古宙地史演化、古环境研究以及指导找矿都具有重要的指示意义。 相似文献
18.
Structural studies on Proterozoic rocks belonging to the Lunavada Group, Southern Aravalli Mountain Belt (SAMB), India, have shown that they underwent three episodes of deformation which have led to the formation of various regional scale interference patterns. Whilst the northern parts of the SAMB underwent brittle-ductile deformation, the southern portion underwent more ductile deformation. On the basis of structural as well as metamorphic studies it has been established earlier that the region was subjected to uplift orogenesis during its evolutionary history. In the present paper an attempt is made to visualize the possible causes that led to deformation of the SAMB, the structural geology of which has been established by the authors, and to constraint the timing of these events on the basis of already available geochronological data. A “working-hypothesis” is proposed according to which it is suggested that deformation of the SAMB is a result of the accretion of the three protocontinents viz. Aravalli, Dharwar and Singhbhum during the Mesoproterozoic. It is envisaged that the accretion of Aravalli and Singhbhum Protocontinents occurred between 1600 and 1400 Ma along the NE-SW trending Son Suture and this event led to development of NE-SW trending structures in the SAMB. Suturing of Aravalli and Dharwar Protocontinents between 1400 and 935 Ma along the E-W Narmada Suture was responsible for the E-W to NW-SE trending D3 structures of the SAMB. It is postulated that the Satpura orogeny which resulted in deformation of rocks in Satpura mountain range lying to the south of Narmada Suture was coeval with the accretion of Aravalli and Dharwar Protocontinents. 相似文献
19.
The Ordovician mafic volcanic rocks in the Parkes region of New South Wales occur as three distinct packages of volcaniclastic and coherent volcanic rocks and minor limestone that formed part of an oceanic island arc succession. The oldest package is the Early Ordovician Nelungaloo Volcanics and overlying Yarrimbah Formation. These formations consist of volcanic siltstone, sandstone, polymictic breccia, conglomerate facies interpreted as moderately deep-water turbidites and coarser grained debris-flow deposits emplaced in the medial to distal part of a subaqueous volcaniclastic apron flanking an active volcanic centre(s). Broadly conformable massive to brecciated andesites in the apron deposits are interpreted as synsedimentary sills and/or lava flows. A hiatus in volcanism occurred between the Bendigonian and early Darriwilian (ca 476 – 466 Ma). Deposition of the second package, which produced the Middle to Late Ordovician Goonumbla Volcanics, Billabong Creek Limestone and Gunningbland Formation, commenced with shallow-water limestones and minor volcaniclastic rocks. During an approximately 15 million years period, a thick sequence of bedded volcanic sandstone, limestone and minor siltstone and volcanic breccia were deposited in very shallow to moderate water depths. The top of this package is marked by thick volcanic conglomerate and sandstone mass-flow deposits and approximately coeval basaltic andesite lavas and sills sourced from a nearby volcano. The upper age limit of this package is constrained as approximately 450 Ma by Ea3/4 fossils and monzodiorite that intrudes the Goonumbla Volcanics. The lower limit of the third package, which constitutes the Wombin Volcanics, is poorly constrained and the duration of the hiatus that separates the Goonumbla and Wombin Volcanics is unknown but may be as long as 10 million years. The Wombin Volcanics record development of a thick, proximal volcaniclastic apron flanking a compositionally more evolved volcanic edifice in the immediate Parkes area. Thick crystal-rich turbiditic sandstones of mafic provenance are intercalated with polymictic volcanic breccias and megablock breccias that are interpreted as proximal subaqueous debris-flow and debris-avalanche deposits, respectively. The sequence also includes numerous trachyandesite bodies, many of which were emplaced within the volcaniclastic apron as synsedimentary sills. No evidence was found at Parkes to support the existence of a previously proposed 22 km diameter collapse caldera and the source volcanoes for the Ordovician are envisaged as complex stratovolcanoes. 相似文献
20.
Martin G. Lockley 《Geological Journal》1983,18(1):93-99
Brachiopod-dominated assemblages from the Allt y Clych conglomerate near Llanafan Fawr provide good evidence for a Silurian (Lower Llandovery) age. The conglomerates are interpreted as mass flow deposits and are related to the revised stratigraphy of Davies (1980) by emendation of some of the author's previous interpretations. 相似文献