Beata Gruszka

ABSTRACT Glaciolacustrine kames in the Bielsk Podlaski area (eastern Poland) exhibit a unique regular pattern. Three representative morphological kame types were chosen for detailed sedimentological analyses, specifically: isolated, isometric mounds; isolated, elongated hills; and branching ridges. All types comprised fine-grained sandy and sandy/silty deposits. Lithofacies analysis resulted in the distinction of several lithofacies associations. Associations dominated by medium- or large-scale, massive or horizontally laminated sands are interpreted as proximal subaqueous fans; associations dominated by medium- or small-scale lithofacies of ripple-drift cross-laminated sand are interpreted as distal subaqueous fans; and those dominated by sandy/silty, silty or silty/clayey lithofacies with horizontal lamination are interpreted as lake bottomsets. Rates of sediment accumulation appear to have been fast, resulting in syndepositional and metadepositional deformation structures of two types: water-escape structures, and slumps on subaqueous slopes. After the ice-walled lake basins filled with sediment, glaciofluvial erosion and deposition alternated, resulting in erosional channels of up to 1 m deep, later filled with gravel or gravely sand. The results indicate that kames developed in a supraglacial environment within a topography of ice-cored moraines containing ice-walled lakes that persisted due to the presence of permafrost. Pauses during retreat of the ice walls resulted in ice-contact deformations at the edges of the kames. Kame formation is therefore consistent with a continental climate and this may explain the increased abundance of this type of kame system in Eastern Europe.

Abstract A well-exposed section in an esker near Ryssjon (S Sweden), strongly affected by several phases of glacitectonism, showed two phenomena that are uncommon and that seem to have a causal relationship. The first phenomenon is the occurrence of a load cast consisting predominantly of gravel in deposits formed just inside or outside a tunnel mouth. The load cast is over 3 m high and 8 m wide, a size that has previously not been described from unconsolidated sediments. Two nearby, somewhat smaller load casts consisting mainly of sand also have dimensions of over 2 m, indicating that the formation of huge load casts was apparently a feature related to the special conditions under which loading could develop at this site. The second remarkable feature is that not only is a till present in the succession above the load cast, thus indicating re-advance of the ice, but deposits overlying this till are also deformed by glacitectonism, proving that at least a second phase of ice re-advance must have occurred. This situation has not previously been documented. It is concluded that the varying differential overburden of sediment and particularly the retreating and re-advancing ice in this area were responsible for the formation of the extremely large load casts, possibly triggered by seismic shocks related to isostatic adjustment caused by oscillations of the ice front.

Varved layers in the partly consolidated glaciolacustrine Early Saalian deposits exposed in the Bełchatów mine (central Poland), show specific types of deformations. Two types dominate: half-varve deformations constituting the uppermost, clayey part of a single varve, and multi-varve deformations affecting a few varves. The latter are found either as clast-supported breccia beds with varve fragments in a quasi-horizontal position within a clayey matrix, or as deformed beds resulting from subsequent plastic deformation and folding. The deformed beds are interpreted as seismites derived from earthquakes related to the deep graben structure. The magnitudes of the earthquakes have determined the type of deformations. The seismites are thought to have originated intraformationally.

Grawitacyjnie redeponowane osady glacilimniczne rowu Kleszczowa (pleistocen centralna Polska) Pleistocene glaciolacustrine sediments of the Kleszczow Graben near Belchatow - silts and clays with numerous sand intercalations - record the development and decay a glacial lake in a subsiding basin. The sediments were classified in eight genetic facies. These facies present a wide scope sediments subaqueous redeposition and deposition in the basin - from dense mass flows debris-flow type, through liquefied flows and turbidity currents, to low-energy bottom currents. The facies make the ground for identification of subenvironments and environments in the Pleistocene glacial lake. The individual complexes correspond to various environments within the lake: inclined lake bottom dominated by dense mass flows and fluidal flows, open lake with fine-grained parapelagic deposition, deepened axial part the basin with weak bottom currents, marginal part the lake with distal turbidity currents gene...

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 lowermost and the uppermost 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 lacking. The environment is interpreted as a low-energy 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-induced wet and dry intervals. The upper unit reflects a low-energy meandering river 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...

A substantial glaciolacustrine unit in northern Poland, between the valleys of the Vistula and Wierzyca rivers, was deposited in glacial Lake Gniew during the climatic amelioration of the Late Vistulian. It covers an area of 35 km2 and has an average thickness of 7 m, but locally reaches over 20 m. Four sedimentary facies are distinguished. The silty/clayey rhythmites of facies A are interpreted as varves from the central lake bottom. They represent the initial stage of lake development. Facies B is formed by a single sand layer that is interpreted as a turbidite originating during lake shallowing due to self-drainage. Facies C consists of massive clay with dropstones and dump structures. Two hypothesis regarding its genesis are put forward: the first assumes sedimentation in a shallow basin with a high input of homogenous fine-grained suspended sediment, whereas the second explains the facies as a result of a muddy jokulhlaup, pouring into Lake Gniew and being sourced from another ...

Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the hydraulic conditions for their formation, development and sedimentary records are different. The present review discusses the results of previously published studies of fan deltas (Gilbert-type deltas) and subaqueous fans of lacustrine and glaciolacustrine environments. The depositional mechanisms of deltas and subaqueous fans, textural and structural features of the lithofacies associations and their typical lithofacies are presented. The characteristics of subaqueous fans, which are still relatively poorly understood and are often overlooked in sedimentological interpretations of lacustrine sedimentary successions, receive particular attention. The palaeoenvironmental and lithological differences between deltas and sub-aqueous fans are highlighted.

The Ekeby site, south of Stockholm, has been chosen to elucidate glaciofluvial sedimentation processes soon after the end of the Younger Dryas. Detailed lithofacies and grain-size analyses of gravel, sand and fine sediment sequences in a gravel pit reflect changes in the ...

Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the hydraulic conditions for their formation, development and sedimentary records are different. The present review discusses the results of previously published studies of fan deltas (Gilbert-type deltas) and subaqueous fans of lacustrine and glaciolacustrine environments. The depositional mechanisms of deltas and subaqueous fans, textural and structural features of the lithofacies associations and their typical lithofacies are presented. The characteristics of subaqueous fans, which are still relatively poorly understood and are often overlooked in sedimentological interpretations of lacustrine sedimentary successions, receive particular attention. The palaeoenvironmental and lithological differences between deltas and subaqueous fans are highlighted.

Glaciolacustrine kames in the Bielsk Podlaski area (eastern Poland) exhibit a unique regular pattern. Three representative morphological kame types were chosen for detailed sedimentological analyses, specifically: isolated, isometric mounds; isolated, elongated hills; and branching ridges. All types comprised fine-grained sandy and sandy/silty deposits. Lithofacies analysis resulted in the distinction of several lithofacies associations. Associations dominated by medium- or large-scale, massive or horizontally laminated sands are interpreted as proximal subaqueous fans; associations dominated by medium- or small-scale lithofacies of ripple-drift cross-laminated sand are interpreted as distal subaqueous fans; and those dominated by sandy/silty, silty or silty/clayey lithofacies with horizontal lamination are interpreted as lake bottomsets. Rates of sediment accumulation appear to have been fast, resulting in syndepositional and metadepositional deformation structures of two types: water-escape structures, and slumps on subaqueous slopes.
After the ice-walled lake basins filled with sediment,
glaciofluvial erosion and deposition alternated, resulting in
erosional channels of up to 1 m deep, later filled with gravel
or gravely sand. The results indicate that kames developed in
a supraglacial environment within a topography of ice-cored
moraines containing ice-walled lakes that persisted due to
the presence of permafrost. Pauses during retreat of the ice
walls resulted in ice-contact deformations at the edges of the
kames. Kame formation is therefore consistent with a continental climate and this may explain the increased abundance of this type of kame system in Eastern Europe.

"A structure in the Enköping esker in southern Sweden appears to result from a series of deformations that followed, essentially, loading because of an unstable density gradient (diamicton on top of water-saturated sands). The more-or-less symmetrical structure, which is in fact a structure within a graben structure, is some 12 m wide at its top, 2.5 m wide at its visible base, and some 13 m high. It shows a variety of both synthetic and antithetic faults. In addition, numerous folds are present so that a complex structure results. Both the structural characteristics and the shape resemble those of the (much smaller) gravifossums that have been described from subrecent lagoonal silty deposits in The Netherlands. It is the first time that a gravifossum has been described from glacigenic deposits and, consequently, also the first time that such a structure has been
found in esker deposits."

"Well developed NE-SW trending corridors of outwash in NE Poland are associated with a series of lakes with a similar direction of elongation. The glaciofluvial corridor under study consists of parallel ridges with associated channels and kames. The deposits are flanked by till and hummocky terrain. The gravel ridges are composed of sand and gravel deposits that are cross-stratified, massive or graded, and that contain cut-and-fill structures and large intra-clasts of sand and gravel. Locally the deposits show normal faults. The succession of one of the ridges is interpreted to reflect the infilling of a braided channel in a crevasse. Sedimentation took place in some phases when the ice-sheet regime changed from active to stagnant. Sandy-gravel ridges occur within this complex perpendicular to the Weichselian icesheet margin.
The corridor is interpreted as an interlobate area in the zone between the Warmia and Mazury ice lobes. The braided-channel deposits are not comparable to typical Polish sandurs. The lithofacies characteristics show higher energy conditions, and the channels are deeper than those typical of Pleistocene lowland sandurs. The sand and gravel ridges are interpreted as interlobate eskers."

The Quaternary overburden of Bełchatów outcrop contains five glaciolacustrine units. The three most widespread are presented.
They originated during the advance of the Sanian (=Elsterian), Odranian (=Drenthian) and Wartanian (=Warthian) ice sheets. The following lake environments are distinguished: lake-bottom plain, tectonically active subaqueous slope, subaqueous fan, terminoglacial subaqueous fan and prodelta fan. The lakes formed under changing conditions; the most significant tectonic activity of the graben took place during the Odranian and the lake deposits from this glaciation represent terminoglacial conditions. The Wartanian lake deposits are the only ones that show a shallow-water facies that has not been eroded, because it has not been overridden by an ice sheet.
Sedimentation conditions changed during the succeeding glaciations. Endogenic factors affecting sedimentation (i.e. tectonic activity of the graben) complemented some exogenic controls, such as the distance from the ice sheet, the thermal conditions of the lake, and the type of sediment supply. Tectonics changed the style of deposition so much that the lakes, although situated in a lowland area, displayed characteristics of deep valleys.

"A substantial glaciolacustrine unit in northern Poland, between the valleys of the Vistula and Wierzyca rivers, was deposited in glacial Lake Gniew during the climatic amelioration of the Late Vistulian. It covers an area of 35 km2 and has an average thickness of 7m, but locally reaches over 20 m. Four sedimentary facies are distinguished. The silty/clayey rhythmites of facies A are interpreted as varves from the central lake bottom. They represent the initial stage of lake development. Facies B is formed by a single sand layer that is interpreted
as a turbidite originating during lake shallowing due to self-drainage. Facies C consists of massive clay with dropstones and dump structures.
Two hypothesis regarding its genesis are put forward: the first assumes sedimentation in a shallow basin with a high input of homogenous fine-grained suspended sediment, whereas the second explains the facies as a result of amuddy jökulhlaup, pouring into Lake Gniew and being sourced from another glacial lake; further research is required to interpret this facies reliably. Facies D consists of thick silty/clayey rhythmites that are interpreted as prodeltaic deposits."

Pleistocene glaciolacustrine sediments of the Kleszczow Graben (the Bełchatow outcrop, central Poland) record the origin, development, and decay of a glacial lake formed in the area of a subsiding basin during the advance of the Elsterian ice sheet. The sediments represent a transition from glaciofluvial to glaciolacustrine facies at the bottom part, and from glaciolacustrine to glacial facies at the top. The glaciolacustrine facies represent a few environments inside the lake basin, from the marginal sub-aqueous slope through the bottom part to the sub-aqueous fan. The contact of the glaciolacustrine facies and the overlying glacial till is erosional, and implies that a considerable part of the shallow-water lake facies was eroded.
The lake existed for not longer than 600 years, but its development proceeded under the conditions of the Kleszczow
Graben subsidence and the approach of the Elsterian ice sheet. Both factors influenced the sedimentation processes. The tectonic and climatic factors were recognised on the basis of facies analysis of lithofacies associations, and of their vertical and lateral changes.

The Ekeby site, south of Stockholm, has been chosen to elucidate glaciofluvial sedimentation processes soon after the end of the Younger Dryas. Detailed lithofacies and grain-size analyses of gravel, sand and fine sediment sequences in a gravel pit reflect changes in the depositional environment. Four main facies assemblages have been distinguished. The lowermost part of the sequence was probably deposited in a subglacial conduit environment. The middle part of the sequence reflects a transition to a proglacial subaqueous environment. The upper part of the latter sequence probably occurred during increased melting of the ice. The sequence was then covered by beach gravel formed during the regression after the drainage of the Baltic Ice Lake.