Sedimentology of Wartanian outwash near Bełchatów, central Poland

The braided outwash of Wartanian age near Bełchatów, central Poland, was formed synchronously by two river systems: glacier streams flowing from the northwest and west and periglacial rivers flowing from the south and southwest. An extensive alluvial fan was formed which later developed into a highly aggrading fan due to a rising water level in the proglacial lake to the north. Braided streams were represented by relatively low-energy systems with shallow-channel and/or transverse bar deposition. Sporadically, rapid inflows of meltwater caused more energetic conditions and formation of large scours. The latter were found only in the glacier streams and this was confirmed by palaeocurrent measurements and analyses of quartz roundness.     

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Abstract

The southeast of the Betic Cordilleras has long been recognized as an area with numerous geothermal anomalies of regional character. Many thermal springs appear related to currently tectonically active fault systems. Carbon dioxide and other gases in these waters have been mobilized through those fault systems. The great depth of these “slip-strike zones” affects the entire thickness of the lithosphere and leads to contrasting crustal domains of different natures and structures. In this area, the detrital aquifer of the Alto Guadalentín has thermal waters with high salinity and unusually high contents of CO₂ gas. The utilization of Principal Components Analysis (PCA) in the hydrogeochemical study of this aquifer has revealed that the origin of the salinity of its waters is due essentially to processes of dissolution of the Miocene evaporite rocks, principally sulphate, and to the contribution of deep hydrothermal waters that show signs of endogenous CO₂ contamination. To a lesser extent, infiltration waters also form an input, with elevated sulphate, chloride and nitrate content. Likewise, PCA has enabled the differentiation of distinct groups of water to which these processes have had a variable contribution.     

Saalian sediments of the Belchatów outcrop, central Poland

The deposits of six glacial episodes, including five till beds and fluvial deposits of one temperate substage, stratigraphically lying between the Holsteinian and Eemian Interglacials have been recognized in the geological record of the Kleszczów Graben, central Poland. Two other temperate substages have been recognized on the basis of well-developed weathering horizons on the tills. The depositional environments and general petrological features of these sediments are described and their stratigraphical position is discussed. The Saalian Complex of the Kleszczów Graben has been subdivided into the Older Saalian (three glacial episodes), the Pilica Interstadial and the Younger Saalian (three glacial episodes and two presumed interstadials). This sequence cannot be simply correlated with other Saalian stratigraphic sequences in Europe, although the pre-Odranian and Odranian (=main Drenthe) tills most probably belong to the Older Saalian, and the Wartanian (Warthe) tills to the Younger Saalian. The geological record presented here suggests that reforestation phases occurred during the Saalian. This contradicts recently developed continental stratigraphics.     

Middle and Late Weichselian stratigraphy and palaeoenvironments in central Poland

The moraine plateau near BetchatÓw (central Poland) was incised at the beginning of the Middle Weichselian. Valleys 20–35 m deep were formed and then infilled with silts, sands, gravels, organic sediments and slope diamictons of the Piaski Formation, which is characterized by highly varying sedimentary environments. Initially - 40,000–30,000 BP - lacustrine sediments with an obvious colian supply (re-worked loess) and locally fluvial suites were deposited in depressions. Slope sediments were simultaneously deposited at the valley margins. The Middle Weichselian was relatively mild and dry, but the milder interstadial periods have not been precisely established. Semi-anastomosing, stable-channel, highly aggrading and ephemeral streams of a semi-arid climate (subpolar desert) formed c. 30,000–22,000 BP. Continuous permafrost is implied from cyclic sedimentary processes reflecting summer melting and from periglacial structures. This was succeeded by a highly aggrading, high-energy and ephemeral braided fluvial system in an arid climate (polar desert), reflecting a complete lack of vegetation and increased eolian activity. These braided rivers formed during a period which may be directly correlated with the time of the maximum extent of the last ice sheet (22,000–14,350 BP), characterized by the most severe climatic conditions with strong periglacial activity. Finally - (14,350-12,700 BP)- eolian sediments were deposited, reflecting milder climatic conditions at the time of the abrupt ice sheet decay.     

Pleistocene glaciolacustrine sedimentation in a tectonically active zone, Kleszczów Graben, central Poland

The Kleszczów Graben in central Poland was formed by late Oligocene to Middle Pleistocene extensional tectonics. During the Pleistocene it was infilled with a 200 m thick sequence of predominantly glacial sediments. Four distinct formations of Elsterian and Saalian age are identified, each containing 15–40 m of glaciolacustrine strata. The boundaries between formations are marked by erosional surfaces and, in part, by angular discordances caused by tectonism. Glaciolacustrine sedimentation was tectonically controlled: the thickness of the sequences in the graben are three to five times greater than outside the area of fault-controlled subsidence. Deposition in the proglacial lakes was controlled by differential subsidence rates within the basin: deep-lake facies (varved clays) were deposited in sub-basins with high subsidence rates and deltaic to shallow-water facies accumulated in areas of moderate subsidence or occasional uplift. These variations led to the development of a very complex, ‘mosaic’ of lateral facies relationships, suggesting that several sub-basins with differing subsidence rates were present. The Vertical successions show proximal-distal sequences typical of glacier-fed lakes that have limited contact with the ice sheet. However, gravity flow facies are very common, and occur both in the shallow- and deep-water deposits. These deposits are interpreted to have been formed adjacent to active fault scarps which bordered the lake basin. Although several distinct phases of glaciolacustrine sedimentation occurred during the history of trough infilling, the location of the areas of high subsidence varied through time.     

The thermal structure of Hansbreen, a tidewater glacier in southern Spitsbergen, Svalbard

Ice temperature measurements were taken from three shallow and five deep (to bedrock) boreholes on Hansbreen, Svalbard, in selected years between 1988 and 1994. In general, results show a subpolar, polythermal structure. The glacier accumulation zone is of warm ice within the entire vertical profile except the uppermost layer of seasonal temperature fluctuations where there is an upper cold ice layer in the ablation zone which varies in thickness and may even be absent in the western lateral part. The upper layer of cold ice thins along the glacier centre-line from the equilibrium line altitude down to the glacier front. The depth of the pressure melting, indicating the base of the cold ice layer, was defined at the borehole measurement sites but was not manifested as an internal reflection horizon using multi-frequency radar methods. The isotherm lies about 20 m above a radar internal reflecting horizon near the equilibrium line altitude and about 40 m above it in the frontal part of the glacier. The internal reflection horizon almost certainly reflects the high water content within temperate ice and not the cold/temperate ice interface. At 10 m depth, the temperatures are 2–3°C higher than the calculated mean annual air temperatures, demonstrating the importance of meltwater refreezing on the release of latent heat.     

THE EFFECTIVE STRESS PRINCIPLE: INCREMENTAL OR FINITE FORM?

Different expressions of the effective stress principle can be found in the literature, in particular some are written in finite form and others in incremental form. For the purpose of the paper we take for granted that stress–strain relationships exist or can be obtained for the effective stress coming from both formulations. We investigate the consequences of the choice of particular finite or differential forms when they are introduced in a weak form of the linear momentum balance equation of two- of three-phase porous media for its numerical solution. For partially saturated geomaterials the importance of the capillary pressure–saturation relationship is pointed out.     

GEOMORPHOLOGICAL CHANGES WITHIN A HILLSLOPE CAUSED BY A WINDTHROW EVENT IN THE TATRA MOUNTAINS,SOUTHERN POLAND

Tree uprooting plays an important role in hillslope evolution. The geomorphological impact of tree uprooting after a foehn wind occurrence, in December 2013 in the Tatra Mountains, was investigated. Geomorphological mapping was conducted in three watersheds. Additionally, in one of the watersheds, 459 windthrow pits were measured, in an area of 6.4 ha. The mean volume of a pit was 2.41 m³, and the mean surface area was 5.47 m². 3.9% of the area was affected by windthrow pits, however locally the magnitude of changes was significantly higher, reaching up to 14.5% of the surface area. Slope inclination weakly influenced the effects of uprooting, and a decrease in the average depth of pits on steep slopes was observed. Individual windthrow pits (five cases) initiated the activity of geomorphological processes, and two cases of periodic springs were noted. Changes in the relief of small landforms caused by tree uprooting were documented. Windthrow creation facilitated the delivery of the soil material from the slopes into the channels.