Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the h... more 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.
Geografiska Annaler: Series A, Physical Geography, 2014
ABSTRACT Glaciolacustrine kames in the Bielsk Podlaski area (eastern Poland) exhibit a unique reg... more 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.
A b stract. Pleistocene glaciolacustrine sediments o f the Kleszczów Graben near Bełchatów-silts ... more A b stract. Pleistocene glaciolacustrine sediments o f the Kleszczów Graben near Bełchatów-silts and clays with numerous sand intercalations-record the development and decay o f a glacial lake in a subsiding basin. The sediments were classified in eight genetic facies. These facies present a wide scope o f sediments o f subaqueous redeposition and deposition in the basin-from dense mass flows o f debris-flow type, through liquefied flows and turbidity currents, to low-energy bottom currents. The facies make the ground for identification o f subenvironments and environm ents in the Pleistocene glacial lake. The individual complexes correspond to various environments w ithin the lake: inclined lake bottom dominated by dense mass flows and fluidal flows, open lake with fine-grained parapelagic deposition, deepened axial part o f the basin with weak bottom currents, marginal part o f the lake with distal turbidity currents generated by liver supply. Markov chain statistical analysis was used to determine the succession o f sedimentary processes in the different lake environments. Vertical sequences o f facies proved that the dense mass flows gradually evolved to more diluted Newtonian flows. The sequences typical o f turbidites were noted as well as those o f weak underflows generated by river inflows. The frequency and nature o f the coarse-grained lake sediments formed by mass flows and turbidity currents testify to tectonically controlled style o f sedimentation. Processes o f violent redeposition were caused mainly by seismic tremors in the active Kleszczów Graben. A b strak t. Plejstoceńskie osady glacilimniczne rowu Kleszczowa (odkrywka bełchatowska) odzw ierciedlają rozwój i zanik jeziora glacjalnego w warunkach subsydencji podłoża. Są to muły i iły z licznymi przewarstwieniami piaszczystymi. Wśród nich wyróżniono osiem facji genetycznych prezentujących szeroki w achlarz typów podwodnej redepozycji grawitacyjnej-od gęstych spływów masowych typu debris flow, przez spływy uwodnio nego materiału i prądy turbiditowe, do niskoenergetycznych prądów dennych. W yróżnione facje są podstawą identyfikacji subśrodowisk i środowisk w plejstoceńskim jeziorze. Kolejne analizowane kompleksy osadowe odpow iadają różnym środowiskom w zbiorniku. Podwodny skłon jeziora zdominowany był przez gęste spływy masowe i spływy uwodnionego materiału, natomiast otwarty zbiornik-przez depozycję parapelagiczną, w przeglębionej, osiowej części basenu przeważały niskoenergetyczne prądy denne, a w marginalnej części jeziora dystalne prądy zawiesinowe generowane dopływem rzecznym. Statystyczna metoda łańcuchów M arkowa została zastosowana, by w yróżnić następstwo facji i procesów sedymentacyjnych w różnych środowiskach jeziora. W yróżnione dzięki tej metodzie pionowe następstwo facji reprezentuje stopniowe przejście od gęstych spływów masowych do przepływów hydraulicznych. Notowano również sekwencje typowe dla tuibiditów oraz dla słabych prądów dennych powodowanych dopływami rzecznymi. Charakter gruboziarnistych osadów jeziornych, będą cych rezultatem spływów masowych i prądów turbiditowych, wskazuje na tektoniczne uwarunkowania sedy mentacji limnoglacjalnej. Procesy redepozycji wzbudzane były najprawdopodobniej przez wstrząsy sejsmiczne w aktywnym rowie Kleszczowa.
Well developed NE-SW trending corridors of outwash in NE Poland are associated with a series of l... more 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.
Varved layers in the partly consolidated glaciolacustrine Early Saalian deposits exposed in the B... more 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.
A structure in the Enköping esker in southern Sweden appears to result from a series of deformati... more 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.
The Quaternary overburden of Bełchatów outcrop contains five glaciolacustrine units. The three mo... more 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.
Upper Saalian (Illinoian) glaciolacustrine deposits in central Poland, preserved in a tectonic gr... more Upper Saalian (Illinoian) glaciolacustrine deposits in central Poland, preserved in a tectonic graben, were exposed in an opencast lignite mine and investigated using sedimentological and micro-paleontological methods. The extraglacial lake sediments provide the first records of late Saalian cladoceran communities in central Europe, recovered from glaciolacustrine deposits. Sedimentation was dominated by a supply of clastics that fluctuated with the seasons, forming rhythmites. In addition to seasonal cyclicity, sedimentary and environmental conditions changed every several years to decades, with periods of increased inflow to the lake delivering sandy material, and periods of almost stagnant water dominated by suspension settling. The sediments contain Cladocera assemblages that indicate the lake was initially deep, oligotrophic, and filled with moderately cold water. Changes in Cladocera community composition and abundance were perhaps responses to climate seasonality. Zones without Cladocera were associated with seasons of higher inflow and sediment supply, and directly or indirectly, with tectonic activity in the graben. Earthquakes, documented by the presence of seismites, caused not only deformation of unconsolidated lake-bottom sediments, but possibly also changes in habitat characteristics. Combined sedimentological and biological data were used to infer the lake's history and show that deposits of glaciolacustrine lakes can be used as indicators of past ecological and climate changes.
Pleistocene glaciolacustrine sediments of the Kleszczow Graben the Bełchatow outcrop, central Pol... more Pleistocene glaciolacustrine sediments of the Kleszczow Graben the Bełchatow outcrop, central Poland record théó rigin, 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 Kleszczoẃ 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.
Gruszka B. and Zieliñski T. (2008)-Ev i dence for a very low-en ergy flu vial sys tem: a case stu... more Gruszka B. and Zieliñski T. (2008)-Ev i dence for a very low-en ergy flu vial sys tem: a case study from the di no saur-bear ing Up per Trias sic rocks of South ern Po land. Geol. Quart., 52 (3): 239-252. Warszawa. The Up per Tri as sic suc ces sion in S Po land in which di no saur bones have been found con sists pre dom i nantly of siltstones and claystones. Three units are dis tin guished. The low er most and the up per most units re flect an al lu vial en vi ron ment, whereas the mid dle one rep re sents lac us trine fa cies. The lower al lu vial unit is in ter preted as a re cord of ephem eral, sin u ous, sus pended-load chan nels with rapid ver ti cal accre tion. Chan nel barforms are lack ing. The en vi ron ment is in ter preted as a low-en ergy anastomosing flu vial sys tem. The clayey mid dle unit is in ter preted as hav ing formed in a wide long-lived lake. The top of the lac us trine de pos its shows signs of vertisol-type pedogenesis, most prob a bly un der sub trop i cal con di tions, with sea son ally-in duced wet and dry in ter vals. The up per unit re flects a low-en ergy me ander ing river sys tem. Silty point bars were abun dant and the chan nels mi grated freely. The en ergy level of this flu vial sys tem was slightly higher than that of the ear lier one, which is in ter preted as an ef fect of base-level low er ing in com bi na tion with an in creas ingly hu mid climate. The al most ex clu sively silty/clayey al lu vial de pos its rep re sent an ex cep tion ally rare fa cies. The drain age ba sin must have been an ex tremely flat low land. The pres ence of ver te brate bones within the anastomosing and me an der ing river de pos its in di cates that low-energy al lu vial plains were ap par ently fa vour able hab i tats for both rep tiles and am phib i ans dur ing the Late Tri as sic: un der the sub trop i cal, sea son ally dry con di tions, the an i mals must have pre ferred moist low ar eas, i.e. the flood bas ins and aban doned chan nels on the flat valley floors.
The results of a sedimentological study of a branching esker system near Uniszki, north-central P... more The results of a sedimentological study of a branching esker system near Uniszki, north-central Poland, provide a deeper insight into the depositional processes that took place within a subglacial tunnel formed during the Wartanian (= Late Saalian) glaciation. The internal structure of the esker deposits is complex, and coarse-grained debris intercalates with silt and clay layers. Ten main lithofacies types are recognized, including one formed in a tunnel-mouth environment; and three other lithofacies, which must have been deposited in a truly subglacial environment. A "subglacial-tunnel association" is defined. Fluctuations in meltwater discharge through the tunnels resulted in cyclicity in the sedimentary succession. Deposition of fine-grained facies took place during low discharge, whereas boulder and gravel lithofacies formed in the tunnel-mouth during high discharge. Changes in the hydrostatic conditions finally resulted in the collapse of the tunnel roof, so that the succession became covered with supraglacial deposits. The Uniszki deposits record deposition under highly variable sedimentary hydrostatic conditions, which is typical of environments in the Polish Lowlands. The results of the present study provide some criteria for the interpretation of subglacial meltwater debris and thus may contribute to the current discussion on subglacial-tunnel sedimentation.
The Ekeby site, south of Stockholm, has been chosen to elucidate glaciofluvial sedimentation proc... more 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.
A substantial glaciolacustrine unit in northern Poland, between the valleys of the Vistula and Wi... more 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 lo-cally 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 struc-tures. Two hypothesis regarding its genesis are put forward: the first assumes sedimentation in a shallow basin with a high input of ho-mogenous fine-grained suspended sediment, whereas the second explains the facies as a result of a muddy jökulhlaup, pouring into Lake Gniew and being sourced from anoth...
Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the h... more 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.
Abstract A well-exposed section in an esker near Ryssjon (S Sweden), strongly affected by several... more 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.
Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the h... more 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.
Geografiska Annaler: Series A, Physical Geography, 2014
ABSTRACT Glaciolacustrine kames in the Bielsk Podlaski area (eastern Poland) exhibit a unique reg... more 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.
A b stract. Pleistocene glaciolacustrine sediments o f the Kleszczów Graben near Bełchatów-silts ... more A b stract. Pleistocene glaciolacustrine sediments o f the Kleszczów Graben near Bełchatów-silts and clays with numerous sand intercalations-record the development and decay o f a glacial lake in a subsiding basin. The sediments were classified in eight genetic facies. These facies present a wide scope o f sediments o f subaqueous redeposition and deposition in the basin-from dense mass flows o f debris-flow type, through liquefied flows and turbidity currents, to low-energy bottom currents. The facies make the ground for identification o f subenvironments and environm ents in the Pleistocene glacial lake. The individual complexes correspond to various environments w ithin the lake: inclined lake bottom dominated by dense mass flows and fluidal flows, open lake with fine-grained parapelagic deposition, deepened axial part o f the basin with weak bottom currents, marginal part o f the lake with distal turbidity currents generated by liver supply. Markov chain statistical analysis was used to determine the succession o f sedimentary processes in the different lake environments. Vertical sequences o f facies proved that the dense mass flows gradually evolved to more diluted Newtonian flows. The sequences typical o f turbidites were noted as well as those o f weak underflows generated by river inflows. The frequency and nature o f the coarse-grained lake sediments formed by mass flows and turbidity currents testify to tectonically controlled style o f sedimentation. Processes o f violent redeposition were caused mainly by seismic tremors in the active Kleszczów Graben. A b strak t. Plejstoceńskie osady glacilimniczne rowu Kleszczowa (odkrywka bełchatowska) odzw ierciedlają rozwój i zanik jeziora glacjalnego w warunkach subsydencji podłoża. Są to muły i iły z licznymi przewarstwieniami piaszczystymi. Wśród nich wyróżniono osiem facji genetycznych prezentujących szeroki w achlarz typów podwodnej redepozycji grawitacyjnej-od gęstych spływów masowych typu debris flow, przez spływy uwodnio nego materiału i prądy turbiditowe, do niskoenergetycznych prądów dennych. W yróżnione facje są podstawą identyfikacji subśrodowisk i środowisk w plejstoceńskim jeziorze. Kolejne analizowane kompleksy osadowe odpow iadają różnym środowiskom w zbiorniku. Podwodny skłon jeziora zdominowany był przez gęste spływy masowe i spływy uwodnionego materiału, natomiast otwarty zbiornik-przez depozycję parapelagiczną, w przeglębionej, osiowej części basenu przeważały niskoenergetyczne prądy denne, a w marginalnej części jeziora dystalne prądy zawiesinowe generowane dopływem rzecznym. Statystyczna metoda łańcuchów M arkowa została zastosowana, by w yróżnić następstwo facji i procesów sedymentacyjnych w różnych środowiskach jeziora. W yróżnione dzięki tej metodzie pionowe następstwo facji reprezentuje stopniowe przejście od gęstych spływów masowych do przepływów hydraulicznych. Notowano również sekwencje typowe dla tuibiditów oraz dla słabych prądów dennych powodowanych dopływami rzecznymi. Charakter gruboziarnistych osadów jeziornych, będą cych rezultatem spływów masowych i prądów turbiditowych, wskazuje na tektoniczne uwarunkowania sedy mentacji limnoglacjalnej. Procesy redepozycji wzbudzane były najprawdopodobniej przez wstrząsy sejsmiczne w aktywnym rowie Kleszczowa.
Well developed NE-SW trending corridors of outwash in NE Poland are associated with a series of l... more 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.
Varved layers in the partly consolidated glaciolacustrine Early Saalian deposits exposed in the B... more 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.
A structure in the Enköping esker in southern Sweden appears to result from a series of deformati... more 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.
The Quaternary overburden of Bełchatów outcrop contains five glaciolacustrine units. The three mo... more 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.
Upper Saalian (Illinoian) glaciolacustrine deposits in central Poland, preserved in a tectonic gr... more Upper Saalian (Illinoian) glaciolacustrine deposits in central Poland, preserved in a tectonic graben, were exposed in an opencast lignite mine and investigated using sedimentological and micro-paleontological methods. The extraglacial lake sediments provide the first records of late Saalian cladoceran communities in central Europe, recovered from glaciolacustrine deposits. Sedimentation was dominated by a supply of clastics that fluctuated with the seasons, forming rhythmites. In addition to seasonal cyclicity, sedimentary and environmental conditions changed every several years to decades, with periods of increased inflow to the lake delivering sandy material, and periods of almost stagnant water dominated by suspension settling. The sediments contain Cladocera assemblages that indicate the lake was initially deep, oligotrophic, and filled with moderately cold water. Changes in Cladocera community composition and abundance were perhaps responses to climate seasonality. Zones without Cladocera were associated with seasons of higher inflow and sediment supply, and directly or indirectly, with tectonic activity in the graben. Earthquakes, documented by the presence of seismites, caused not only deformation of unconsolidated lake-bottom sediments, but possibly also changes in habitat characteristics. Combined sedimentological and biological data were used to infer the lake's history and show that deposits of glaciolacustrine lakes can be used as indicators of past ecological and climate changes.
Pleistocene glaciolacustrine sediments of the Kleszczow Graben the Bełchatow outcrop, central Pol... more Pleistocene glaciolacustrine sediments of the Kleszczow Graben the Bełchatow outcrop, central Poland record théó rigin, 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 Kleszczoẃ 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.
Gruszka B. and Zieliñski T. (2008)-Ev i dence for a very low-en ergy flu vial sys tem: a case stu... more Gruszka B. and Zieliñski T. (2008)-Ev i dence for a very low-en ergy flu vial sys tem: a case study from the di no saur-bear ing Up per Trias sic rocks of South ern Po land. Geol. Quart., 52 (3): 239-252. Warszawa. The Up per Tri as sic suc ces sion in S Po land in which di no saur bones have been found con sists pre dom i nantly of siltstones and claystones. Three units are dis tin guished. The low er most and the up per most units re flect an al lu vial en vi ron ment, whereas the mid dle one rep re sents lac us trine fa cies. The lower al lu vial unit is in ter preted as a re cord of ephem eral, sin u ous, sus pended-load chan nels with rapid ver ti cal accre tion. Chan nel barforms are lack ing. The en vi ron ment is in ter preted as a low-en ergy anastomosing flu vial sys tem. The clayey mid dle unit is in ter preted as hav ing formed in a wide long-lived lake. The top of the lac us trine de pos its shows signs of vertisol-type pedogenesis, most prob a bly un der sub trop i cal con di tions, with sea son ally-in duced wet and dry in ter vals. The up per unit re flects a low-en ergy me ander ing river sys tem. Silty point bars were abun dant and the chan nels mi grated freely. The en ergy level of this flu vial sys tem was slightly higher than that of the ear lier one, which is in ter preted as an ef fect of base-level low er ing in com bi na tion with an in creas ingly hu mid climate. The al most ex clu sively silty/clayey al lu vial de pos its rep re sent an ex cep tion ally rare fa cies. The drain age ba sin must have been an ex tremely flat low land. The pres ence of ver te brate bones within the anastomosing and me an der ing river de pos its in di cates that low-energy al lu vial plains were ap par ently fa vour able hab i tats for both rep tiles and am phib i ans dur ing the Late Tri as sic: un der the sub trop i cal, sea son ally dry con di tions, the an i mals must have pre ferred moist low ar eas, i.e. the flood bas ins and aban doned chan nels on the flat valley floors.
The results of a sedimentological study of a branching esker system near Uniszki, north-central P... more The results of a sedimentological study of a branching esker system near Uniszki, north-central Poland, provide a deeper insight into the depositional processes that took place within a subglacial tunnel formed during the Wartanian (= Late Saalian) glaciation. The internal structure of the esker deposits is complex, and coarse-grained debris intercalates with silt and clay layers. Ten main lithofacies types are recognized, including one formed in a tunnel-mouth environment; and three other lithofacies, which must have been deposited in a truly subglacial environment. A "subglacial-tunnel association" is defined. Fluctuations in meltwater discharge through the tunnels resulted in cyclicity in the sedimentary succession. Deposition of fine-grained facies took place during low discharge, whereas boulder and gravel lithofacies formed in the tunnel-mouth during high discharge. Changes in the hydrostatic conditions finally resulted in the collapse of the tunnel roof, so that the succession became covered with supraglacial deposits. The Uniszki deposits record deposition under highly variable sedimentary hydrostatic conditions, which is typical of environments in the Polish Lowlands. The results of the present study provide some criteria for the interpretation of subglacial meltwater debris and thus may contribute to the current discussion on subglacial-tunnel sedimentation.
The Ekeby site, south of Stockholm, has been chosen to elucidate glaciofluvial sedimentation proc... more 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.
A substantial glaciolacustrine unit in northern Poland, between the valleys of the Vistula and Wi... more 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 lo-cally 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 struc-tures. Two hypothesis regarding its genesis are put forward: the first assumes sedimentation in a shallow basin with a high input of ho-mogenous fine-grained suspended sediment, whereas the second explains the facies as a result of a muddy jökulhlaup, pouring into Lake Gniew and being sourced from anoth...
Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the h... more 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.
Abstract A well-exposed section in an esker near Ryssjon (S Sweden), strongly affected by several... more 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.
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