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Wyświetlanie 1-11 z 11
Tytuł:
Numerical modelling of rivers on Earth and Titan
Autorzy:
Misiura, K.
Czechowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/2059637.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
titan
Earth
meandering river
erosion
sedimentation
Opis:
The differences in the evolution of rivers on Earth and on Titan are investigated. Dynamical analysis of the rivers was performed using a numerical package CCHE2D developed by the National Center for Computational Hydroscience and Engineering, University of Mississippi. The model is based on the Navier-Stokes equations for depth-integrated two-dimensional turbulent flow and the three-dimensional convection-diffusion equation of sediment transport. The model enables investigation of the evolution of rivers as a function of total discharge and other parameters of the river. Series of short (from one to several hours) and long (up to 67 days) simulations were performed. We have found that three different liquid hydrocarbons considered for Titan’s rivers give similar velocity fields. It was also found that the suspended load is the main means of transport in Titan’s rivers, while in terrestrial ones, for the same discharge, the bedload could be of the same order as suspended load. Moreover, we suppose that for specific boundary conditions, the evolution of rivers on the Earth promotes the development of braided rivers, while for the same conditions evolution on Titan favours regular meandering rivers
Źródło:
Geological Quarterly; 2015, 59, 3; 565--580
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
What was the interglacial river like? Sedimentological investigation of Holsteinian fluvial deposits in eastern Poland
Autorzy:
Zieliński, T.
Terpiłowski, S.
Zieliński, P.
Pidek, I. A.
Godlewska, A.
Czubla, P.
Powiązania:
https://bibliotekanauki.pl/articles/2060162.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
sedimentology
meandering river
palaeoclimate
Pleistocene
MIS 11
Polska
Opis:
Holsteinian fluvial deposits in the Samica River valley in eastern Poland have been studied, in an approximately 12-m-thick succession filling palaeochannels and comprising sandy channel facies succeeded by a package of gyttja, peat and silt deposited in oxbow. Channel belts including palaeochannel fills cut into outwash sands and are overlain by diamictic sands reworked by solifluction under periglacial conditions. Sedimentological and palynological investigations in combination allowed the recognition of glacial and interglacial deposits. The channel belt was formed by a typical sand-bed, meandering river with deposition controlled by abundant point bars. The sedimentary evolution of the Samica valley is interpreted in the context of the glacial-interglacial cycle. Valley-scale erosion and change of river style from braided to meandering occurred coevally with the decay of an ice sheet (deglaciation) and the main phase of meandering river sedimentation is attributed to latest Elsterian and early Holsteinian. The next part of the interglacial, from pioneer stage to established temperate conditions, is recorded in a biogenic oxbow-lake fill. The succession studied has been compared with published data on the European fluvial deposits of Middle Pleistocene interglacials. It is pointed out here that river channel patterns in western and eastern Europe differed. Based on this observation, some general hypotheses regarding the continental-scale climatic distinctness are put forward.
Źródło:
Geological Quarterly; 2016, 60, 1; 149--166
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trace fossils from the Upper Cretaceous Capacete Formation, Sanfranciscana Basin, Central Brazil
Autorzy:
Sedorko, Daniel
Alessandretti, Luciano
Warren, Lucas Veríssimo
Verde, Mariano
Rangel, Caio César
Ramos, Kimberly Silva
Netto, Renata Guimarães
Powiązania:
https://bibliotekanauki.pl/articles/1836263.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
meandering fluvial system
insects
continental trace fossils
Scoyenia ichnofacies
Opis:
The Upper Cretaceous Capacete Formation, from the intracratonic Sanfranciscana Basin, central Brazil, consists of epiclastic sediments with a significant aeolian contribution. This unit has been traditionally interpreted as deposited by alluvial fans distally grading to braided rivers in an arid- to semiarid climate within the central part of southwestern Gondwana. Locally, some expositions with wide lateral extension show architectural elements indicative of deposition in meandering rivers, such as floodplain fines (FF) interbedded with crevasse splay (CR), lateral-accretion macroforms (LA), and channels (CH). Bioturbation within the meandering fluvial deposits is commonly associated with the floodplain element, mainly occurring in fine-grained sandstone and mudstone. The lateral-accretion elements and channel deposits are barren of trace fossils. Sandstone with climbing ripples (Sr) from the element CR show low bioturbation of meniscate trace fossils assigned to Taenidium, Beaconites, and Scoyenia ichnogenera. Simple vertical and horizontal burrows identified as Skolithos and Palaeophycus occur associated with Taenidium and Camborygma in sandstone facies (Sr, St and Sh), as well as rhizoliths, representing the Scoyenia ichnofacies. The predominance of trace fossils related to the FF and CR architectural elements attests to the colonization mostly by insects in episodic and vegetated flood plains of the meandering river system from the Capacete Formation. Thus, despite the primarily arid to semiarid conditions interpreted for the inner parts of the newly formed South American continent during the Upper Cretaceous, our new data support deposition under humid conditions in some intervals of the Capacete Formation from the Sanfranciscana Basin.
Źródło:
Annales Societatis Geologorum Poloniae; 2020, 90, 3; 247-260
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evidence for a very low-energy fluvial system: a case study from the dinosaur-bearing Upper Triassic rocks of Southern Poland
Autorzy:
Gruszka, B.
Zieliński, T.
Powiązania:
https://bibliotekanauki.pl/articles/2060617.pdf
Data publikacji:
2008
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Polska
Late Triassic
sedimentology
vertisol
meandering river
anastomosing river
Opis:
The Upper Triassic succession in S Poland in which dinosaur bones have been found consists predominantly of siltstones and claystones. Three units are distinguished. The lower most and the upper most units reflect an alluvial environment, whereas the middle one represents lacustrine facies. The lower alluvial unit is interpreted as a record of ephemeral, sinuous, suspended-load channels with rapid vertical accretion. Channel barforms are lack ing. The environmentis interpreted as a low-en ergy anastomosing fluvial system. The clayey middle unit is interpreted as having formed in a wide long-lived lake. The top of the lacustrine deposits shows signs of vertisol-type pedogenesis, most probably under subtropical conditions, with seasonally-inuced wet and dry intervals. The upper unit reflects a low-energy meander ingriver system. Silty point bars were abundant and the channels migrated freely. The energy level of this fluvial system was slightly higher than that of the earlier one, which is interpreted as an effect of base-level lowering in combination with an increasingly humid climate. The al most exclusively silty/clayey alluvial deposits represent an exceptionally rare facies. The drainage basin must have been an extremely flat lowland. The presence of vertebrate bones within the anastomosing and meandering river deposits indicates that low-en - ergy alluvial plains were apparently favourable habitats for both reptiles and amphibians during the Late Triassic: under the subtropical, seasonally dry conditions, the animals must have preferred moist lowareas, i.e. the flood basins and abandoned channels on the flat valley floors.
Źródło:
Geological Quarterly; 2008, 52, 3; 239-239
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
How to resolve Pleistocene stratigraphic problems by different methods? A case study from eastern Poland
Autorzy:
Terpiłowski, S.
Zieliński, T.
Kusiak, J.
Pidek, I.A.
Czubla, P.
Hrynowiecka, A.
Godlewska, A.
Zieliński, P.
Małek, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059725.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
chronostratigraphy
geochronology
interglacial meandering river
Pleistocene
Mazovian/Holsteinian
Eastern Poland
Opis:
Different methods have been used to determine the stratigraphic position of Pleistocene alluvial deposits, particularly fluvial interglacial deposits. Near-surface deposits of a meandering river, developed in point-bar and oxbow lake facies, in the Samica River valley (near Łuków, eastern Poland) have been investigated. The fossil valley is incised into the till plain and the outwash. The fluvial succession is locally overlain by solifluction deposits. All the deposits underwent sedimentological analysis. The petrographic composition of basal till occurring in the vicinity of a fossil valley was determined with the method of indicator erratics. Fluvial deposits were examined by pollen analysis and plant macrofossil analysis of oxbow lake facies. Absolute dating methods were applied to the deposits (thermoluminescence methods: TL and additionally IRSL). Lithological differences between fluvial and the surrounding glaciofluvial deposits were identified and their lithostratigraphic position assigned. Petrographic analysis of till and palaeobotanical analyses of oxbow lake facies gave compatible results. Fluvial deposits were formed after the Sanian 2/Elsterian Glaciation, during the Mazovian/Holsteinian Interglacial. Luminescence dating of the fluvial deposits by the TLMAX method yielded the most relevant results (412-445 ka), which indicate that these deposits were formed during the end of the MIS 12 and beginning of the MIS 11 stage.
Źródło:
Geological Quarterly; 2014, 58, 2; 235--250
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fluvial architecture element analysis of the Brushy Basin Member, Morrison Formation, western Colorado, USA
Autorzy:
Galli, K.
Powiązania:
https://bibliotekanauki.pl/articles/2077338.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
meandering
anastomosing
Morrison Formation
Kimmeridgian
Colorado
meandryzacja
anastomizacja
Formacja Morrisona
Opis:
The 85-m Brushy Basin Member of the Morrison Formation in western Colorado, USA, comprises dinosaur-bearing sandstones (architectural element CHR and CH), crevasse-splay deposits and minor levee deposits (architectural element CS), mudstones, marlstones, altered ash beds and minor limestones as well as caliche paleosols and noncalcareous paleosols (architectural element FF). Channel sandstones occur at five stratigraphic levels at Trail Through Time (TT), eleven levels at Fruita Paleontological Research Area (FP), and at five levels at Echo Canyon (EC). River-channel sandstones hosted by floodplain mudstones tend to have cut down to resistant caliche paleosols. Depositional facies and architectural element analysis show that the rivers were low gradient, mainly anastomosing, with perennial flow, but seasonal with “flashy” peaks in discharge. Dinosaur bone accumulations are found in some floodplain ponds. Isolated bones are present in anastomosing channel sandstones at TT and in channel sandstone 2 at EC. At FP, major accumulations of bones were rapidly buried in the deep pools at three bends in the meandering river resulting in the formation of channel sandstone 2. There is no evidence for a large lacustrine or playa system at the three localities.
Źródło:
Volumina Jurassica; 2014, 12, 2; 69--106
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zmiany układu koryta Chodelki koło Chodlika w późnym vistulianie i holocenie
Autorzy:
Dzierżak, Malwina
Bałaga, Krystyna
Powiązania:
https://bibliotekanauki.pl/articles/763309.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
meandering river
anastomosing river
lithofacies
palynological analysis
rzeka meandrująca
rzeka anastomozująca
litofacje
analiza palinologiczna
Opis:
In this paper the evolution of paleogeographic models of the middle part of the Chodelka valley near Chodlik is presented. In the relief of the bottom valley clear traces of palaeochannels are present. Lithological and palynological analysis helped distinguish two phases in the development of this river. The first phase started in Late Vistulian, and continued in the early Holocene. At that time Chodelka was an anastomosing river. But later it changed its channel pattern to the meandering one. Nowadays the Chodelka river cannot develop naturally, because its trough is largely limited by flood bank.
Artykuł nie zawiera abstraktu w języku polskim
Źródło:
Annales Universitatis Mariae Curie-Sklodowska, sectio B – Geographia, Geologia, Mineralogia et Petrographia; 2013, 68, 1
0137-1983
Pojawia się w:
Annales Universitatis Mariae Curie-Sklodowska, sectio B – Geographia, Geologia, Mineralogia et Petrographia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural and anthropogenic indicators of fluvial system changes, the Bobrza Valley (Holy Cross Mts) as an example
Autorzy:
Rutkiewicz, P.
Gawior, D.
Powiązania:
https://bibliotekanauki.pl/articles/100816.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Śląski. Wydział Nauk o Ziemi
Tematy:
meandering river
fluvial relief
sediments
human impact
Juncus subnodulosus
rzeka meandrująca
osad rzeczny
wpływ człowieka
Bobrza
Opis:
Transformations of a fluvial system are caused both by natural factors and human pressure. These factors model the system independently at different times and with different intensities or they affect it simultaneously. The aim of this study is to identify the transformation of the Bobrza river valley system occurring under natural conditions and that occurring under the influence of human activity. The identification was based on specific indicators The study was conducted in the valley mouth of the Bobrza River (Holy Cross Mountains), where three research sites were located. The investigation concerned the relief of the valley and the mineral and organic deposits. A wide range of research methods were used during the study e.g. analysis of LiDAR data, macronutrient analysis, and radioactive dating. The analyses enabled the natural and anthropogenic transformations of the Bobrza river system to be distinguished using the following indicators: morphometric and sedimentological characteristics of the palaeomeander (natural transformation), the sequence of mineral and organic deposits in exposures on the contemporary floodplain (natural and anthropogenic transformation) and transformation associated with the operation of a water mill (anthropogenic transformation). In addition, it is worth mentioning that the Bobrza channel is the location which has provided the only fossils of Juncus subnodulosus in south-east Poland.
Źródło:
Contemporary Trends in Geoscience; 2016, 5, 1; 46-60
2299-8179
Pojawia się w:
Contemporary Trends in Geoscience
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The sedimentary environment of Devonian siliciclastics in the Babí lom locality (Brunovistulian Platform cover, Southern Moravia, Czech Republic)
Autorzy:
Wojewoda, J.
Nehyba, S.
Gilíkova, H.
Burianek, D
Powiązania:
https://bibliotekanauki.pl/articles/2059824.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
southern Moravia
Brno Massif
Devonian siliciclastics
facies analysis
heavy minerals
alluvial fan
braided river
meandering river
palaeotransport
Opis:
Sandstones and conglomerates, which northwards of Brno agglomeration build a hill (ridge) named Babí lom are strongly diagenezed (anchi-metamorphozed) and tectonically deformed. Their regional distribution and stratigraphic position between the Cambrian(?) clastics and Upper Devonian limestones, as well as their appearance meant that they age is considering as Middle Devonian. They are distinguished as the so-called „Basal Devonian Clastics“. Almost all primary sedimentary features are well preserved and distinct. In the metasediments of the Babí lom hill were distinguished both the facies and structures typical of alluvial fans and rivers. Among others they are channel lags with imbricated grains, cross beddings and debrites. Within sedimentary association was established the way-up direction what clearly evidences a coarsening upwards sequence. Assuming the lack of rotation of series of sediments in the X-Y plane, the palaeotrasport was toward the north while major supply with material was from the east.
Źródło:
Geological Quarterly; 2015, 59, 1; 229--238
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial model of the unsprung wheeled machine’s dynamic system
Autorzy:
Chwastek, S.
Powiązania:
https://bibliotekanauki.pl/articles/241952.pdf
Data publikacji:
2014
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
spatial model
dynamic system
mobile heavy machines
unsprung vehicles
"galloping" effect
"snake meandering” effect
adhesion factor
slipping action
vibration
differential gear
Opis:
Mobile heavy machines as unsprung vehicles exhibit low dissipation ability, hence the ride even at low speeds may give rise to intensive vertical and angular vibration. Vibrations thus produced are mostly in the low-frequency range and hence energy dissipation in tires will reduce the vibration intensity in a minor degree only. Particularly dangerous situations occur when the road wheels break away from the road surface due to the ’galloping’ effect. Kinematic excitation acting on the wheels is mostly uncorrelated stochastic (random) processes, giving rise to the "snake meandering" effect. That implies a major restriction on the ride velocity, which negatively affects the machine performance. The motion of tired wheels will always involve certain slipping. While investigating the feasibility of increasing the efficiency of the vibration reduction systems, one ought to take into account the variable adhesion of road wheels due to different dynamic loading acting on the vehicle axles during the ride. This study investigates the motion of unsprung mobile machines, taking into account the dynamic processes in the driving system under the conditions of the variable adhesion of road wheels. The model of interaction between a tired wheel and the terrain takes into account the relationship between the road wheel adhesion factor and the slipping action, as well as the impacts of the differential gear on distribution of drive torque. The 3D (spatial) model of a backhoe loader is considered. It is a two-axle self-propelled machine on a wheeled chassis. The mathematical model constitutes nonlinear and non-stationary differential equations of motion. Their stability is therefore associated with vibration intensity. Simulations in the time domain were supported by Matlab-Simulink. The purpose of this study is to improve the safety features during the ride of mobile heavy machines, basing on the parametric optimization of the model.
Źródło:
Journal of KONES; 2014, 21, 2; 45-52
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
River response to climate and sea level changes during the Late Saalian/Early Eemian in northern Poland – a case study of meandering river deposits in the Chłapowo cliff section
Autorzy:
Moskalewicz, D.
Sokołowski, R. J.
Fedorowicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/94416.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
point-bar succession
meandering fluvial system
Quaternary geology
fluvial sedimentology
Eemian Sea
następstwo odsypu meandrowego
meandrujący system rzeczny
geologia czwartorzędu
sedymentologia rzeczna
morze eemskie
Opis:
Fluvial sediments in the Chłapowo cliff section were studied in order to reconstruct their palaeoflow conditions and stratigraphical position. Lithofacies, textural and palaeohydraulic analyses as well as luminescence dating were performed so as to achieve the aim of study. Sedimentary successions were identified as a record of point bar cycles. The fluvial environment probably functioned during the latest Saalian, shortly after the retreat of the Scandinavian Ice Sheet. Discharge outflow was directed to the northwest. The river used the older fluvioglacial valley and probably was directly connected to the Eem Sea. Good preservation and strong aggradation of point-bar cycles were related to a rapid relative base level rise. The meandering river sediments recognised showed responses to climate and sea level changes as illustrated by stratigraphical, morphological and sedimentological features of the strata described. The present study also revealed several insights into proper interpretation of meandering fluvial successions, in which the most important were: specific lithofacies assemblage of GSt (St, Sp) → Sl → SFrc → Fm (SFr) and related architectural elements: channel/sandy bedforms CH/SB → lateral accretion deposits LA → floodplain fines with crevasse splays FF (CS); upward-fining grain size and decreasing content of denser heavy minerals; estimated low-energy flow regime with a mean depth of 1.6–3.3 m, a Froude number of 0.2–0.4 and a sinuosity of 1.5.
Źródło:
Geologos; 2016, 22, 1; 1-14
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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