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What was the interglacial river like? Sedimentological investigation of Holsteinian fluvial deposits in eastern Poland

Zieliński T., Terpiłowski S., Zieliński P., Pidek I. A., Godlewska A., Czubla P.

Geological Quarterly

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2016

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Vol. 60, No. 1

149--166

EN

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.

2

Natural and anthropogenic indicators of fluvial system changes, the Bobrza Valley (Holy Cross Mts) as an example

Rutkiewicz P., Gawior D.

Contemporary Trends in Geoscience

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2016

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Vol. 5, iss. 1

46--60

EN

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.

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The sedimentary environment of Devonian siliciclastics in the Babí lom locality (Brunovistulian Platform cover, Southern Moravia, Czech Republic)

Wojewoda J., Nehyba S., Gilíkova H., Burianek D

Geological Quarterly

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2015

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Vol. 59, No. 1

229--238

EN

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.

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Numerical modelling of rivers on Earth and Titan

Misiura K., Czechowski L.

Geological Quarterly

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2015

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Vol. 59, No. 3

565--580

EN

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

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Evidence for a very low-energy fluvial system: a case study from the dinosaur-bearing Upper Triassic rocks of Southern Poland

Gruszka B., Zieliński T.

Geological Quarterly

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2008

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Vol. 52, No 3

239-239

EN

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.