scholarly journals Tide-storm-dominated shelf sequence of the Neoproterozoic Blaini Formation and its implications on the sedimentation history of Krol-Belt, Kumaun Lesser Himalaya, India

2003 ◽  
Vol 28 ◽  
Author(s):  
Charu C. Pant ◽  
Pradeep K. Goswami

The diamictite bearing Neoproterozoic Blaini Formation constitutes a significant lithostratigraphic unit of the Lesser Himalayan sedimentary pile. These diamictite bearing horizons have implication for the genetic evolution of the Krol-belt. Detailed lithofacies and palaeocurrent analyses of the Blaini Formation suggest that the sediments belong to two distinct facies associations. These are: Strom Dominated Facies Association and Tide Dominated Facies Association. The Strom dominated Facies Association overlies a transgressive lag deposit and comprises offshore, offshore transition and subtidal facies. The ride Dominated Facies Association on the other hand comprises intertidal to supratidal facies. The Blaini succession in the Nainital area overlies the Nagthat siliciclastics deposited in a barrier island set-up having a sharp to erosional contact. The Nagthat Sea gave way to shelf sedimentation of the Blaini times. The high-energy-tide-storm condition of sedimentation in the basin had witnessed mode rate to low energy conditions intermittently, wherein diamictites were emplaced through down slope re-sedimentation of cohesive debris flow. The debris was originated by intermixing of extra-basinal and intra-basinal clasts along with hinterland sediments, which were transported in response to some tectonic adjustments during the terminal stages of Blaini sedimentation. Subsequent tectonic stability and quiescence gave way to thick stromatolitic carbonate succession during the Krol times. The Krol-belt as such is evolved in three distinct cycles of sedimentation, distinguished as the Jaunsar-Simla, the Blaini and the Krol cycles.

2015 ◽  
Vol 45 (suppl 1) ◽  
pp. 13-27 ◽  
Author(s):  
Roberto Cesar de Mendonça Barbosa ◽  
Afonso César Rodrigues Nogueira ◽  
Fábio Henrique Garcia Domingos

ABSTRACTGlaciotectonic features studied in the siliciclastic deposits of Cabeças Formation, Upper Devonian, represent the first evidence of Famennian glaciation in Southeastern Parnaíba Basin, Brazil. Outcrop-based stratigraphic and facies analyses combined with geometric-structural studies of these deposits allowed defining three facies association (FA). They represent the advance-retreat cycle of a glacier. There are: delta front facies association (FA1) composed of massive mudstone, sigmoidal, medium-grained sandstone with cross-bedding and massive conglomerate organized in coarsening- and thickening-upward cycles; subglacial facies association (FA2) with massive, pebbly diamictite (sandstone, mudstone and volcanic pebbles) and deformational features, such as intraformational breccia, clastic dikes and sills of diamictite, folds, thrust and normal faults, sandstone pods and detachment surface; and melt-out delta front facies associations (FA3), which include massive or bedded (sigmoidal cross-bedding or parallel bedding) sandstones. Three depositional phases can be indicated to Cabeças Formation: installation of a delta system (FA1) supplied by uplifted areas in the Southeastern border of the basin; coastal glacier advance causing tangential substrate shearing and erosion (FA1) in the subglacial zone (FA2), thus developing detachment surface, disruption and rotation of sand beds or pods immersed in a diamicton; and retreat of glaciers accompanied by relative sea level-rise, installation of a high-energy melt-out delta (FA3) and unloading due to ice retreat that generates normal faults, mass landslide, folding and injection dykes and sills. The continuous sea-level rise led to the deposition of fine-grained strata of Longá Formation in the offshore/shoreface transition in the Early Carboniferous.


2021 ◽  
Vol 151 (2) ◽  
pp. 159
Author(s):  
Emese M. Bordy ◽  
Orsolya Sztanó

Two levels of volcaniclastics, comprising conglomerates, sandstones and mudstones, are interbedded with upper middle Miocene (upper Badenian) andesite pyroclastics near the Hungarian-Slovakian border in the distal region of the Central Slovakian Neogene Volcanic Field. Based on the field sedimentological investigations, the facies of the volcaniclastics (e.g., lateral and vertical grain size changes, sedimentary structures, textures, clast composition), their geometry and field relationships are documented herein with the aim of reconstructing the depositional environment. The silica-cemented volcaniclastics are mostly andesite clasts with only ~ 5% being granitoid, quarzitic, and tuff clasts as well as charred fossil wood fragments. The coarse-grained facies association includes crudely stratified, tabular or lenticular, clast-supported pebble-cobble conglomerates with erosive basal surfaces, b-axis imbrication, alternating with sets of cross-bedding. The fine-grained facies association comprises cross-bedded pebbly to medium-grained sandstone and lenses of tuffaceous clayey siltstone with rare horizontal lamination and water-escape structures. Rip-up mudstone clasts, with diametre up to 1 m, are present in both facies associations, revealing the co-existence of abandoned silty palaeo-channel plugs. Facies associations are arranged in several 0.5-4-m-thick, fining-upwards successions that likely formed in shallow channels as downstream- to laterally accreting longitudinal bars, extensive gravel sheets and bars that migrated in peak flow during floods. Palaeocurrent indicators (i.e., clast imbrication, direction of planar cross-bedding, orientation of petrified wood logs) show bedload transport by traction currents, initially towards ~S, and later towards ~W. Intermittently debris flows also occurred. Cross-bedded sandstones formed as in-channel transverse bars during medium/low discharge. Variation of grain size shows frequent discharge fluctuations during permanently wet conditions in the late Badenian. The 4-5-m-deep, low-sinuosity channels were part of a high-energy, gravel-bed braided-river system on the south-eastern foothills of the Lysec palaeo-volcano. Here, pyroclastics were reworked and redeposited as volcaniclastics during inter-eruption, high-discharge episodes.


2020 ◽  
Vol 90 (4) ◽  
pp. 364-388 ◽  
Author(s):  
María Duperron ◽  
Roberto Adrián Scasso

ABSTRACT The study on a unique set of outstandingly preserved sedimentary surface textures (SSTs) found in the late Tremadocian Áspero Formation of northwestern Argentina, coupled with the sedimentological and ichnological analysis, indicate that they were formed in the intertidal to supratidal setting of a mixed-energy estuary recording storm and tide sedimentation. We recognize seven types of SSTs: probably biotic microbial mat-related SSTs (Kinneyia, elephant skin, exfoliating sandy laminae), abiotic SSTs (elliptical scours and convex parallel ridges type I “wrinkle marks” sensuAllen 1985), and problematic (convex parallel ridges type II and dot matrix texture). Elliptical scours and convex parallel ridges type I show features which indicate reworking of a cohesive sandy substrate in an intertidal or supratidal setting. Abundance of biotic SSTs with specific associated trace fossils reflect matground development and mat-grazing ichnofaunas, indicating the suppression of intense, penetrative bioturbation due to intense physicochemical stress. The “dot matrix” texture, described here for the first time, consists of a regular horizontal network of millimeter-scale pits; it appears associated with exfoliating sandy laminae, probably reflecting a mat-related origin. Three facies associations are defined through paleoenvironmental analysis. Facies association 1 is dominated by high-energy sandy and bioclastic storm deposits with tidal flat facies, and corresponds to the outer bay of a mixed-energy estuary; highly impoverished Cruziana assemblages and distal expressions of the Skolithos Ichnofacies reflect high energy and sedimentation rate. Facies association 2 shows tidal-channel and tidal-flat facies with subordinated storm deposits, representing the middle bay; impoverished Cruziana assemblages dominated by simple facies-crossing structures, with high-density monogeneric opportunistic suites, evidence physicochemical stress associated with subaerial exposure, frequent episodic deposition, high water turbidity, and/or brackish water conditions in these relatively sheltered tidal flats. Facies association 3 is formed by interdistributary-bay deposits with intercalation of channel-fill deposits in the upper part, and represents the river-dominated bay-head delta; low degrees of bioturbation in fine-grained facies indicate brackish- to fresh-water conditions. SSTs are found in tidal flat facies of facies association 2; they indicate an intertidal to supratidal environment subject to localized conditions of intense physicochemical stress. The paleoenvironmental interpretation of SSTs converges with the one performed through sedimentological and ichnological analysis, producing a robust and more detailed paleoenvironmental model for the Áspero Formation. Our study highlights the use of SSTs as a tool for supporting and refining paleoenvironmental analysis.


2016 ◽  
Vol 66 (3) ◽  
pp. 304-320
Author(s):  
Piotr Łuczyński ◽  
Stanisław Skompski ◽  
Wojciech Kozłowski

Abstract The paper summarises the effects of recent studies carried out by a team from the Department of Historical and Regional Geology of the Faculty of Geology, University of Warsaw on the upper Silurian of Podolia (western part of Ukraine). The sedimentary history of the Silurian succession of Podolia is characterised by its cyclic pattern, with shallowing-upward cyclothems. In the traditional interpretation, the occurrence of stromatoporoid beds within each cyclothem marks the deepest (or most open-marine) sedimentary environment within the cycle. According to the results of recent studies, their occurrence is connected rather with a relatively shallow-water environment and with high energy phenomena. A substantial reinterpretation of the main sedimentary processes governing the deposition and facies distribution on the shelf is presented. Particularly, there are recognised and described high-energy sedimentary events repeatedly punctuating the generally calm sedimentation that prevailed in the lagoonal settings, some of which are interpreted as tsunami induced. Further perspectives for studies on the Silurian successions of Podolia are also discussed. The main problem is the precise correlation of particular sections that are scattered over vast distances and developed in similar facies associations.


Author(s):  
Finn Dalhoff ◽  
Lars Stemmerik

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Dalhoff, F., & Stemmerik, L. (2000). Depositional history of the fluvial Lower Carboniferous Sortebakker Formation, Wandel Sea Basin, eastern North Greenland. Geology of Greenland Survey Bulletin, 187, 65-77. https://doi.org/10.34194/ggub.v187.5195 _______________ The Lower Carboniferous non-marine Sortebakker Formation is restricted to the south coast of Holm Land. It is estimated to exceed 1000 m in thickness and is subdivided by a low-angle disconformity into a lower mudstone-dominated unit (c. 335 m) and an upper sand-dominated unit (c. 665 m). The lower mudstone-dominated succession consists of stacked 0.5–6 m thick fining-upward cycles of fine- to medium-grained sandstone and mudstone. Cycles in the upper part of the formation are up to 20 m thick. They are dominated by thick tabular sandstones up to 13 m thick overlain by shaly units that resemble those in the lower mudstone dominated cycles. Six facies associations are identified and together describe a fluviatile–lacustrine depositional system. Five of the facies associations characterise different parts of a meandering riverdominated flood plain whereas the sixth facies association represents more permanent lakes.


2021 ◽  
Vol 38 (1) ◽  
pp. 55-64
Author(s):  
Ananda Badekar ◽  
Uttaran Goswami ◽  
Sweta Samant

The Gish and Lish rivers are flowing through Higher Himalaya, Lesser Himalaya, Sub Himalaya and Quaternary Alluvium of the Sikkim- Darjeeling region. These thrust bounded tectonostratigraphic zones are comprised of different lithologies. Comparative sedimentological studies of the sediments of these rivers were undertaken to understand landforms developed by these rivers and source to sink relationships of these sediments. The Gish River fans are broad and wider as compared to the narrow and linear shaped fans of the Lish River. Textural analysis of these fan sediments revealed high energy conditions of deposition within these rivers.  The petrographic analysis of the Gish River sediments shows dominance of Quartz (Qt63%F4% L33%) in the framework components, while the Lithic metamorphic fragments (Lm62% LV0% Ls 38%) show dominance over Lithic sedimentary fragments. This is also supplemented by the dominance of Quartz Polycrystalline grains (Qp62% Lv0% Ls38%) over Lithic sedimentary fractions. The Lish river sediments show dominance of Lithic fragments (Qt39% F2% L59%) in the framework components, while the Lithic sedimentary fragments (Lm44% Lv0% Ls56%) show dominance over lithic metamorphic fragments. This is also supplemented by Lithic sedimentary fractions (Qp41% Lv0% Ls59%) dominance over the Quartz Polycrystalline grains. These results of Quartz dominance in the Gish River sediments indicate higher contribution is from gneissic and metamorphic sources. While, Lithic dominance in the Lish River sediments infers higher contribution from sedimentary and metamorphic sources.


2020 ◽  
Vol 5 (8) ◽  
pp. 870-876
Author(s):  
Shettima Bukar ◽  
Mohammed Bukar ◽  
Asabe Kuku ◽  
Bintu Shettima ◽  
Ishaku H. Kamale

This research was carried out in the Gongola Sub-basin of the Northern Benue Trough aimed at deciphering of the paleo-depositional environment of the Yolde Formation based on facies on facies analysis. Six lithofacies were identified to include trough crossbedded sandstone facies (St), massive bedded sandstone facies (Sm), planar crossbedded sandstone facies (Sp), ripple laminated sandstone facies (Sr), parallel sandstone facies (Sl) and mudstone facies (Fm). These build into two facies association of fluvial channel and tidally influenced fluvial channel facies associations. The fluvial successions typical characterizes the lower stratigraphic horizons and their contained dominances of trough crossbedded sandstone facies with high channel to overbank facies and contained mud-clast reflecting deep, high energy braided river system. The submergences of these channels by surging sea level rise generated the tidally influenced fluvial facies association and this package characteristically defines the upper interval stratigraphic architecture of this formation, displaying occasional bi-directional current system and abundant marine ichnogenera. This architectural symmetry is reflective of an incised valley fills, developing as a consequence of Cenomanian transgressive phase induced by the mid-Cretaceous global marine transgression.       


1984 ◽  
Vol 75 ◽  
pp. 599-602
Author(s):  
T.V. Johnson ◽  
G.E. Morfill ◽  
E. Grun

A number of lines of evidence suggest that the particles making up the E-ring are small, on the order of a few microns or less in size (Terrile and Tokunaga, 1980, BAAS; Pang et al., 1982 Saturn meeting; Tucson, AZ). This suggests that a variety of electromagnetic and plasma affects may be important in considering the history of such particles. We have shown (Morfill et al., 1982, J. Geophys. Res., in press) that plasma drags forces from the corotating plasma will rapidly evolve E-ring particle orbits to increasing distance from Saturn until a point is reached where radiation drag forces acting to decrease orbital radius balance this outward acceleration. This occurs at approximately Rhea's orbit, although the exact value is subject to many uncertainties. The time scale for plasma drag to move particles from Enceladus' orbit to the outer E-ring is ~104yr. A variety of effects also act to remove particles, primarily sputtering by both high energy charged particles (Cheng et al., 1982, J. Geophys. Res., in press) and corotating plasma (Morfill et al., 1982). The time scale for sputtering away one micron particles is also short, 102 - 10 yrs. Thus the detailed particle density profile in the E-ring is set by a competition between orbit evolution and particle removal. The high density region near Enceladus' orbit may result from the sputtering yeild of corotating ions being less than unity at this radius (e.g. Eviatar et al., 1982, Saturn meeting). In any case, an active source of E-ring material is required if the feature is not very ephemeral - Enceladus itself, with its geologically recent surface, appears still to be the best candidate for the ultimate source of E-ring material.


2014 ◽  
Vol 4 (3) ◽  
pp. 95-98
Author(s):  
Iana Proskurkina

Abstract The growing number of foreign applicants looking forward to getting education in Ukrainian medical universities makes us find the ways how to improve and make effective the pre-professional training system of foreign medical applicants for further education. The article deals with the issues of the history of formation and development of the preprofessional training system of foreign medical applicants in Ukraine. On the ground of the electronic databases of the official websites of higher educational establishments, the data on years of opening first offices of the dean, departments and preparatory faculties for foreign medical applicants in Ukrainian medical universities are analyzed and systematized. Also the data on the setting up preparatory faculties at other universities who carry out licensed training of foreign students of the medical profile are presented. The data on the operating and management of such institutions in the system of the University administration are generalized. It’s revealed that during the years of its functioning the pre-professional training has changed, in particular the system was commercialized and the institutions involved in training foreign applicants have been reorganized. The modern trends in teaching foreign medical students at the preparatory faculties of the Ukrainian medical universities are displayed. Based on the analysis of the data it is concluded that the system of the pre-professional training of foreign medical applicants was set up in the 50s-60s years of the twentieth century. During this time, some positive experience in the preparation of future international medical specialists has been gained. The system of the pre-professional training of foreign medical applicants has been comprehensively improved and an effective system of managing foreign medical applicants has been created.


2019 ◽  
pp. 134-197
Author(s):  
V.E. . Sergei

The article is dedicated to the history of the Military Historical Museum of Artillery, Engineering and Signal Corps. The author examines the main stages of the museums formation, starting with the foundation of the Arsenal, established in St. Petersburg at the orders of Peter the Great on August 29th 1703 for the safekeeping and preservation of memory, for eternal glory of unique arms and military trophies. In 1756, on the base of the Arsenals collection, the General Inspector of Artillery Count P.I. created the Memorial Hall, set up at the Arsenal, on St. Petersburgs Liteyny Avenue. By the end of the 18th century the collection included over 6,000 exhibits. In 1868 the Memorial Hall was transferred to the New Arsenal, at the Crownwork of the Petropavlovsky Fortress, and renamed the Artillery Museum (since 1903 the Artillery Historical Museum). A large part of the credit for the development and popularization of the collection must be given to the historian N.E. Brandenburg, the man rightly considered the founder of Russias military museums, who was the chief curator from 1872 to 1903. During the Civil and Great Patriotic Wars a significant part of the museums holdings were evacuated to Yaroslavl and Novosibirsk. Thanks to the undying devotion of the museums staff, it not only survived, but increased its collection. In the 1960s over 100,000 exhibits were transferred from the holdings of the Central Historical Museum of Military Engineering and the Military Signal Corps Museum. In 1991 the collection also received the entire Museum of General Field Marshal M.I. Kutuzov, transferred from the Polish town of Bolesawjec. The Military Historical Museum of Artillery, Engineering and Signal Coprs is now one of the largest museums of military history in the world. It holds an invaluable collection of artillery and ammunition, of firearms and cold steel arms, military engineering and signal technology, military banners, uniforms, a rich collection of paintings and graphic works, orders and medals, as well as extensive archives, all dedicated to the history of Russian artillery and the feats of our nations defenders.Статья посвящена истории создания ВоенноИсторического музея артиллерии, инженерных войск и войск связи. Автор рассматривает основные этапы становления музея, начиная с основания Арсенала, созданного в СанктПетербурге по приказу Петра I 29 августа 1703 года для хранения и сохранения памяти, во имя вечной славы уникального оружия и военных трофеев. В 1756 году на базе коллекции Арсенала генеральный инспектор артиллерии граф П. И. создал мемориальный зал, установленный при Арсенале, на Литейном проспекте СанктПетербурга. К концу 18 века коллекция насчитывала более 6000 экспонатов. В 1868 году Мемориальный зал был перенесен в Новый Арсенал, на венец Петропавловской крепости, и переименован в Артиллерийский музей (с 1903 года Артиллерийский Исторический музей). Большая заслуга в развитии и популяризации коллекции принадлежит историку Н.Е. Бранденбургу, человеку, по праву считавшемуся основателем российских военных музеев, который был главным хранителем с 1872 по 1903 год. В годы Гражданской и Великой Отечественной войн значительная часть фондов музея была эвакуирована в Ярославль и Новосибирск. Благодаря неусыпной преданности сотрудников музея, он не только сохранился, но и пополнил свою коллекцию. В 1960х годах более 100 000 экспонатов были переданы из фондов Центрального исторического военноинженерного музея и Музея войск связи. В 1991 году коллекцию также получил весь музей генералфельдмаршала М. И. Кутузова, переданный из польского города Болеславец. Военноисторический музей артиллерии, инженерных войск и войск связи в настоящее время является одним из крупнейших музеев военной истории в мире. Здесь хранится бесценная коллекция артиллерии и боеприпасов, огнестрельного и холодного оружия, военной техники и сигнальной техники, военных знамен, обмундирования, богатая коллекция живописных и графических работ, орденов и медалей, а также обширные архивы, посвященные истории русской артиллерии и подвигам защитников нашего народа.


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