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Petrographic analyses and indicator erratics of gravels of the Odra lobe

Górska-Zabielska M., Zabielski R.

Studia Quaternaria

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2010

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Vol. 27

17-25

EN

Fennoscandinavian erratics found in the glacial deposits till and in the glaciofluvial sediments within the main limit of the Odra glacier lobe (NW Poland and NE Germany), have been examined in two fractions: of 4-10 mm and 2060 mm. The most numerous in the fraction of 4-10 mm are: crystalline rocks (Cr; 35-40%) originating in the Protero zoic Baltic Shield as well as Lower Palaeozoic limestones (LPL; 35-40%) - from the sedimentary sheet covering the Proterozoic Baltic Shield in the area of central Baltic Sea. Percentage of sandstones (S) amounts to 10-15%. The re maining rock types (several percent each) are: Palaeozoic shales (PS), the outcrops of which are localized in Scania (Skane) and on Bornholm, Cretaceous limestones (CL) and flintstones (F) originating from the western part of the southern Baltic Sea as well as quartz (Q), milk quartz (MQ) and isolated grains of Devonian dolomites (DD). From the analysis of indicator erratics, which was carried out in the 20-60 mm fraction, it appears that mainly the outcrops localized in Smaland (e.g. red and grey Viixjo granites, Paskallavik porphyries or Tessini and Kalmarsund sandstones) as well as in Scania (Hoor and Hardeberga sandstones) and Region Blekinge-Bornholm (e.g. Karlshamn and Halen granites as well as Nexo and Bavnodde sandstones) had been subjected to the glacial plucking. Theoretical boulder centres (TBC, German: TGZ das Theoretische Geschiebezentrum, Uittig 1958), which were calculated for 23 samples, are localized mostly in a small area in Smiiland, between 15°E-16°E and 56.5°N-58.5°N. Apart from indicator erratics the statistical ones are numerous, that are first of all grey and red Lower Palaeozoic limestones with their outcrops localized at the bottom of the central Baltic Sea. Taking into account the TBC values of indicator erratics as well as high percentage of statistical erratics it can be pronounced that the section of central and western Baltic Sea as well as the one of south-eastern Sweden had been subjected to the heaviest glacial plucking by that part of the Pleistocene ice-sheet which reached the studied area during the Pomeranian Phase.

2

Palaeoglaciology of the Weichselian Odra ice lobe, NE Germany and NW Poland

Hermanowski P.

Landform Analysis

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2010

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Vol. 14

12-24

EN

Southern part of the Scandinavian Ice Sheet terminated in large lobes projecting tens of kilometres beyond the main ice sheet margin. One of the main ice lobe was the Odra lobe localized in NE Germany and NW Poland. In this study concise description of current morphology of the Odra lobe area is given with special reference to subglacial hydraulic conditions during the ice sheet advance. Subglacial conditions were simulated by using time-dependant three-dimensional numerical model, and obtained results were compared to geological observations. The results show entire groundwater system alternation that affected the ice/bed coupling and influenced formation of specific subglacial landforms. Coupling the simulation results with empirical estimates of basal melting rate suggests that only a small fraction of basal meltwater could have drained to the ice forefield as groundwater. Adverse slope of the low-permeable ice bed hampered water drainage, and led to water accumulation at the ice/bed interface that in turn facilitated basal sliding and bed deformation.

3

Drenaż subglacjalny i jego wpływ na dynamikę lobu Odry zlodowacenia wisły

Hermanowski P., Piotrowski J. A.

Przegląd Geologiczny

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2009

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Vol. 57, nr 6

504-504

EN

In this paper we have analyzed the influence of the Weichselian ice sheet advance on the groundwater system in the Odra lobe area using hydrogeological numerical modelling performed with the finite difference method. The results indicate entire re-organization of the groundwater system in relation to non-glacial times mainly affecting the flow directions, velocities and fluxes. The re-organization of groundwater flow was caused by the pressure gradient imposed by the sloping ice sheet surface especially obvious under the ice margin and some distance in front of it. Simulated groundwater flow velocities are significantly higher than the present velocities in that area while the major groundwater flow direction is to the south, i.e. opposite to the present direction. Coupling the simulation results with assumed basal melting rate suggests that only a small fraction of basal meltwater [~24%) could have drained through the bed. The surplus water likely accumulated at the ice/bed interface facilitating faster ice flow of the Odra lobe due to enhanced basal sliding and bed deformation.

4

Litostratygrafia glin lodowcowych i osadów proglacjalnych okolic Szczecina, Polska północno-zachodnia

Krzyszkowski D., Czerwonka J. A., Dobracki R.

Biuletyn Państwowego Instytutu Geologicznego

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2007

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nr 425

47-74

PL

W regionie szczecińskim występuje 9 poziomów różnowiekowych glin lodowcowych, które zdefiniowano na podstawie ich składu petrograficznego oraz pozycji w sukcesji litostratygraficznej. Poziomy te reprezentują najstarsze zlodowacenie (jedna glina), zlodowacenia południowopolskie (2 gliny), zlodowacenia środkowopolskie (3 gliny) oraz zlodowacenia północnopolskie (2 gliny o regionalnym zasięgu i jedna glina występująca lokalnie, w strefie moren czołowych fazy poznańskiej). Dla wszystkich poziomów glin dokonano formalizacji litostratygraficznej. Niektóre poziomy glin regionu szczecińskiego posiadają cechy, które pozwalają korelować je z glinami o podobnych cechach z zachodniej i centralnej Polski. Wiek innych poziomów glin określono na podstawie ich pozycji w stosunku do horyzontów przewodnich. Kierunki transportu glacjalnego dla wczesnych stadiałów zlodowaceń są zazwyczaj z NW na SE, podczas gdy w młodszych stadiałach zmieniają się na NE-SW, a w najmłodszych na ENE-WSW. W regionie szczecińskim nie udokumentowano istnienia żadnych osadów interglacjalnych lub interstadialnych, natomiast występują powszechnie osady proglacjalne, w tym bardzo miąższe serie zastoiskowe. Te ostatnie udokumentowano prawie dla wszystkich awansów lądolodów i reprezentują one głównie zbiorniki z faz transgresywnych zlodowaceń. W badanym regionie wydzielono dwie główne kopalne powierzchnie erozyjno-denudacyjne, jedną z okresu międzylodowcowego pomiędzy zlodowaceniami południowopolskimi a środkowopolskimi, a drugą z okresu interglacjału eemskiego i wczesnego Vistulianu. Różniły się one intensywnością erozji i charakterem dominujących procesów: w pierwszym okresie przeważała denudacja i powierzchniowe obniżanie terenu, a w drugim prawdopodobnie bardziej intensywna była głęboka erozja rzeczna. Starsze i młodsze serie glacjalne zawierają domieszki materiału wczesnokenozoicznego, podczas gdy osady ze zlodowaceń środkowopolskich takich domieszek nie mają. Świadczy to o występowaniu licznych wychodni podłoża neogeńskiego, a pośrednio też o intensywnej erozji przed i w czasie zlodowaceń najstarszych, południowopolskich i północnopolskich. Natomiast w czasie zlodowaceń środkowopolskich lądolody nasuwały się na obszar z ciągłą pokrywą starszych osadów glacjalnych.

EN

In the vicinity of Szczecin, NW Poland, 9 till horizons occur which have been defined by their petrographic composition and position in lithostratigraphic succession. The tills include to the "oldest glaciation", two tills to Elsterian, three tills to Saalian and three tills to Weichselian (two of them with regional extent, and one local, connected with the marginal zone of the Pomerania Phase). This stratigraphic subdivision was formalized. Some tills of the Szczecin region indicate features which are correlative with till horizons in western and central Poland. The age of other tills has been established in relation to these index horizons. Glacial palaeotransport was usually from NW to SE during the first stadials of each glaciation, then changed from NE to SW in the middle, and finally to ENE-WSW in the final stadials. There are no interglacial or interstadial deposits near Szczecin, but proglacial sediments have a widespread occurrence, particularly glaciolacustrine series. The latter are quite thick and occur in almost all glacial horizons. Glaciolacustrine deposits were formed mainly during the ice sheet advances. Two regional, buried palaeosurfaces have been documented in the studied area. They were formed during the Mazovian (Holstein) Interglacial (Elsterian/Saalian ice free period) and during the Eemian and early Vistulian. Each of them was formed by different processes, the first one by regional denudation and slow lowering of the surface, and the second one probably also by more intensive and deep fluvial erosion. The sediments from the oldest glaciations (San 1 and San 2) and Vistulian contain admixtures of early Cenozoic material, whereas Middle Polish (Saalian) deposits do not. From this it follows that during the first there were many outcrops of older sediments, exposed due to intensive erosion, whereas the Middle Polish (Saalisan) ice sheets advanced to the area covered by continuous cover of older glacial deposits.

5

Petrographic characteristics of fluvioglacial deposits of the Odra lobe, Poland: a statistical analysis

Górska M., Zabielski R.

Geological Quarterly

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2006

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Vol. 50, No. 2

239-246

EN

The fluvioglacial deposits of the Odra lobe, laid down during the Pomeranian phase of the last glaciation in northeastern Germany and northwestern Poland, have been analysed petrographically and interpreted in a regional perspective. The deposits have been classified in terms of the percentage of 10 selected petrographical groups and 5 petrographical coefficients. Statistical analysis of their values has shown significant petrographic differences that relate to the morphological characteristics of the study area. The greatest petrographic diversity was observed between Mecklenburg–Western Pomerania and the Odra lobe as well as between the Odra lobe and middle Pomerania. The differentiating features are: crystalline rocks, grey Palaeozoic limestones and flints and all of the petrographical coefficients. The differences within the Odra lobe itself are small by comparison with those in the neighbouring regions. They are the most evident between Uckermark and theMyśliborskie Lakeland. The differentiating features are: flints and quartz as well as a maximumof four out of five petrographical coefficients.