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Wolfram Lemke - One of the best experts on this subject based on the ideXlab platform.
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the littorina transgression in the southwestern baltic sea new insights based on proxy methods and radiocarbon dating of sediment cores
Boreas, 2011Co-Authors: Doreen Rosler, Matthias Moros, Wolfram LemkeAbstract:Rosler, D., Moros, M. & Lemke, W. 2010: The Littorina transgression in the southwestern Baltic Sea: new insights based on proxy methods and radiocarbon dating of sediment cores. Boreas, 10.1111/j.1502-3885.2010.00180.x. ISSN 0300-9483. The Littorina transgression is one of the most pronounced environmental events in the Holocene history of the Baltic Sea. It changed the hydrographic system from the freshwater Ancylus Lake into the brackish-marine Littorina Sea. Here, 18 cores from two western Baltic basins, Mecklenburg Bay and the Arkona Basin, were analysed. We show that, besides biological indicators, sedimentary organic carbon, C/N ratio, bulk δ13C isotope values and carbonate content display clearly the transition from Ancylus Lake to the Littorina Sea. The first appearances of benthic foraminifers, marine molluscs and ostracods represent the onset of brackish-marine conditions in the bottom waters. Central Arkona Basin sediments display more abrupt shifts in geochemical parameters and microfossil records at the transition from Ancylus Lake to the Littorina Sea than those from Mecklenburg Bay. Mixing of reworked Ancylus material with Littorina Sea stage material was stronger in Mecklenburg Bay, resulting in less pronounced proxy parameter changes and older bulk material dates. Radiocarbon dating of both calcareous material (benthic foraminifers, mollusc shells) and bulk fractions at the transgression horizon shows large age discrepancies. Based on calcareous fossil dates it appears that marine waters began to enter Mecklenburg Bay c. 8000 cal. a BP. In the Arkona Basin the first marine signals are recorded approximately 800 years later, c. 7200 cal. a BP. This indicates a transgression pathway via the Great Belt into Mecklenburg Bay and then into the Arkona Basin.
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Early Holocene history of the southwestern Baltic Sea: the Ancylus Lake stage
Boreas, 2008Co-Authors: Jφrn Bo Jensen, Wolfram Lemke, Ole Bennike, Andrzej Witkowski, Antoon KuijpersAbstract:One of the most discussed stages in the history of the Baltic Sea is the Ancylus Lake phase. This paper presents detailed information from the Darss Sill threshold area as well as the adjacent basins, i.e. the Mecklenburg Bay and Arkona Basin located in the southwesternmost Baltic. The threshold area was transgressed at the Baltic Ice Lake maximum phase and during the following regression about 10.3 ka BP a river valley was incised in the Darss Sill to a level of 23–24 m below present sea level (b.s.l.). Preboreal sediments in the study area show lowstand basin deposition in the Arkona Basin and the existence of a local lake in Mecklenburg Bay. The lowstand system is followed by the Ancylus Lake transgression that reached a maximum level of 19 m b.s.l. Thus, at the maximum level the water depth was about 5 m over the threshold, and the shore level fall during the Ancylus Lake regression must be in the same range. The Darss Sill area is the key area for drainage of the Ancylus Lake, and if the previously suggested regression of 8–10 m in southeastern Sweden is to be achieved, isostatic rebound must also play a role. The existence of the so-called Dana River in the Darss Sill area cannot be supported by our investigations. We observed no signs of progressive erosion of the Darss Sill area in the Early Holocene, and there are no prograding systems in Mecklenburg Bay that can be related to the Ancylus Lake regression. On the contrary, local lakes developed in Mecklenburg Bay and in the Darss Sill threshold area. In the Darss Sill area, marl was deposited in a lake in the valley that developed after the final drainage of the Baltic Ice Lake. Studies of diatoms and macrofossils, combined with seismic interpretation and radiocarbon dating, provide detailed information about the chronology and the relative shore level of these lake phases as well as about environmental conditions in the lakes.
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Late-glacial and early Postglacial finds of Ancylus fluviatilis from the southwestern Baltic Sea
GFF, 2001Co-Authors: Ole Bennike, Wolfram LemkeAbstract:Abstract The small limpet Ancylus fluviatilis is reported from two sediment cores from the south-western Baltic Sea. One of the occurrences, from Mecklenburg Bay, is dated to the late-glacial, corresponding to the Baltic Ice Lake stage of the Baltic Sea. The other occurrence, from the south-western part of the Bornholm Basin, is dated to the earliest Holocene, corresponding to the Yoldia Sea stage. These appear to be the first reports of Ancylus fluviatilis shells from submarine deposits from the Baltic Sea.
Ole Bennike - One of the best experts on this subject based on the ideXlab platform.
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Early Holocene estuary development of the Hesselø Bay area, southern Kattegat, Denmark and its implication for Ancylus Lake drainage
Geo-Marine Letters, 2017Co-Authors: Carina Bendixen, Jorn Bo Jensen, Ole Bennike, Lars Ole Boldreel, Christian Hübscher, Ole Rønø ClausenAbstract:High-resolution shallow seismic data, sediment core information, radiocarbon dating and sequence stratigraphy have been used to interpret the late glacial to early Holocene geological evolution of Hesselø Bay in the southern Kattegat, Denmark. A reconstruction of the early Holocene coastal environment and a description of coastal processes associated with a river outlet into the bay are presented. Weichselian glacial deposits form the lowermost interpreted unit, covered by late glacial (LG) and postglacial (PG, Holocene) sediments. A funnel-shaped estuary existed at the mouth of channels in the period 10.3–9.2 cal. ka BP; the channels drained water from south to north. The early PG is characterised by estuarine and coastal deposits. The early Holocene bars that developed in the estuary are preserved as morphological features on the present-day seabed, possibly as a result of rapid relative sea-level rise. The estuary existed simultaneously with the occurrence and drainage of the Ancylus Lake. The drainage of this lake occurred through the Dana River (palaeo-Great Belt channel) into the southern Kattegat and then into the study area. The level of the Ancylus Lake in the Baltic Sea region dropped significantly at about 10.2 cal. ka BP at the same time as the estuary developed in the Kattegat region. One outcome of the present study is an enhanced understanding of the Ancylus Lake drainage path. No evidence of major erosion is seen, which indicates non-catastrophic continuous water flow from the south without major drainage events of the Ancylus Lake to the southern Kattegat. During the Littorina transgression, coastal estuarine conditions characterized the Hesselø Bay area where elongated ridges formed a bar system. As the Littorina transgression continued, back-stepping of the bar system and coastline occurred. When the transgression breached the Great Belt threshold, flooding caused major erosion throughout the study area.
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the holocene great belt connection to the southern kattegat scandinavia Ancylus lake drainage and early littorina sea transgression
Boreas, 2017Co-Authors: Jorn Bo Jensen, Ole Bennike, Carina Bendixen, Lars Ole Boldreel, Ole Rønø Clausen, Maritsolveig Seidenkrantz, Johan Nyberg, Christian HübscherAbstract:Late- and postglacial geological evolution of the southern Kattegat connection to the Great Belt was investigated from high-resolution seismic data and radiocarbon-dated sediment cores in order to elucidate the Ancylus Lake drainage/Littorina Sea transgression. It was found that glacial deposits form the acoustic basement and are covered by Lateglacial (LG) marine sediments and postglacial (PG; Holocene) material. The LG deposits form a highstand systems tract, whereas the PG deposits cover a full depositional sequence, consisting of a lowstand systems tract (PG I), transgressive systems tract (PG II; subdivided into three parasequences) and finally a highstand systems tract (PG III). PG I sand deposits (11.7–10.8 cal. ka BP) are found in a major western channel and in a secondary eastern channel. PG II (10.8–9.8 cal. ka BP) consists of estuarine and coastal deposits linked to an estuary located at the mouth of the channels. Both channels drained fresh water from south to north. The PG III, that is younger than 9.8 cal. ka BP, represents the threshold marine flooding at the southeastern branch of the palaeo-Great Belt channel. At 9.3 cal. ka BP, fully marine conditions were established, shortly before the flooding of the threshold to the northern part of the Great Belt. These early Holocene spits and sand bars are preserved as features on the present seabed, probably as a result of the rapid sea-level rise that led to back-stepping of the early Holocene palaeo-coast system. This study shows no evidence of major erosion or delta deposition linked to the emptying of the Ancylus Lake, which suggests that continuous water flow from the south characterized the area, without any major drainage event of the Ancylus Lake impacting the southwestern Kattegat.
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Early Holocene history of the southwestern Baltic Sea: the Ancylus Lake stage
Boreas, 2008Co-Authors: Jφrn Bo Jensen, Wolfram Lemke, Ole Bennike, Andrzej Witkowski, Antoon KuijpersAbstract:One of the most discussed stages in the history of the Baltic Sea is the Ancylus Lake phase. This paper presents detailed information from the Darss Sill threshold area as well as the adjacent basins, i.e. the Mecklenburg Bay and Arkona Basin located in the southwesternmost Baltic. The threshold area was transgressed at the Baltic Ice Lake maximum phase and during the following regression about 10.3 ka BP a river valley was incised in the Darss Sill to a level of 23–24 m below present sea level (b.s.l.). Preboreal sediments in the study area show lowstand basin deposition in the Arkona Basin and the existence of a local lake in Mecklenburg Bay. The lowstand system is followed by the Ancylus Lake transgression that reached a maximum level of 19 m b.s.l. Thus, at the maximum level the water depth was about 5 m over the threshold, and the shore level fall during the Ancylus Lake regression must be in the same range. The Darss Sill area is the key area for drainage of the Ancylus Lake, and if the previously suggested regression of 8–10 m in southeastern Sweden is to be achieved, isostatic rebound must also play a role. The existence of the so-called Dana River in the Darss Sill area cannot be supported by our investigations. We observed no signs of progressive erosion of the Darss Sill area in the Early Holocene, and there are no prograding systems in Mecklenburg Bay that can be related to the Ancylus Lake regression. On the contrary, local lakes developed in Mecklenburg Bay and in the Darss Sill threshold area. In the Darss Sill area, marl was deposited in a lake in the valley that developed after the final drainage of the Baltic Ice Lake. Studies of diatoms and macrofossils, combined with seismic interpretation and radiocarbon dating, provide detailed information about the chronology and the relative shore level of these lake phases as well as about environmental conditions in the lakes.
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Late-glacial and early Postglacial finds of Ancylus fluviatilis from the southwestern Baltic Sea
GFF, 2001Co-Authors: Ole Bennike, Wolfram LemkeAbstract:Abstract The small limpet Ancylus fluviatilis is reported from two sediment cores from the south-western Baltic Sea. One of the occurrences, from Mecklenburg Bay, is dated to the late-glacial, corresponding to the Baltic Ice Lake stage of the Baltic Sea. The other occurrence, from the south-western part of the Bornholm Basin, is dated to the earliest Holocene, corresponding to the Yoldia Sea stage. These appear to be the first reports of Ancylus fluviatilis shells from submarine deposits from the Baltic Sea.
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LATE- AND POSTGLACIAL SHORE LEVEL CHANGES IN THE SOUTHWESTERN BALTIC SEA
Bulletin of The Geological Society of Denmark, 1998Co-Authors: Ole Bennike, Jorn Bo JensenAbstract:Sub-marine deposits in the region of the Arkona Basin, Mecklenburg Bay and Darss Si11 have been studied using a multi-disciplinary approach that includes shallow seismic work, depositional sequence stratigraphy, radiocarbon dating and analyses of diatoms and macrofossils. Models for the relative shore level changes in the two basin areas are proposed. Both in the Mecklenburg Bay basin and in the Arkona Basin maximum shore levels of c. 20 m below present sea level were reached in late Allerad, in Iate Younger Dryas and in late Preboreal. The drainage of the Baltic Ice Lake led to shore level drops, but in Mecklenburg Bay the drop only amounted to around 5 m, because the Darss threshold hindered further regression. In the Arkona Basin, the drop after the final drainage of the Baltic Ice Lake was approximately 20 m, whereas the water level falls after the Allerod drainage of the Baltic Ice Lake and after the Ancylus Lake maximum, have not yet been determined. The Darss Si11 area became a land area with local lakes after the Ancylus Lake drainage; there is no evidence of erosion or fluvial/deltaic sediments in Mecklenburg Bay that could be referred to the proposed so-called Dana River. The evolution of the shore level after the Boreal lowstand is poorly confined by our data, but hydrographic conditions similar to the present were established at c. 7.6 cal. ka BP.
Matthias Moros - One of the best experts on this subject based on the ideXlab platform.
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Environmental evolution of western Baltic Sea in the Holocene in the light of multidisciplinary investigations of sediments cores from Arkona Basin
Quaternary International, 2018Co-Authors: Robert Kostecki, Beata Janczak-kostecka, Michael Endler, Matthias MorosAbstract:Abstract A multidisciplinary investigation performed on gravity cores, supplemented by a new radiocarbon dating of macrofossils, outlined the environmental evolution of Arkona Basin in the Holocene. Studies comprising the analysis of diatoms, geochemistry, grain size, and radiocarbon dating clarified the knowledge about the age and environmental changes during freshwater and marine transgressions and regressions. The acoustic profiling method allowed proper interpretation of the analysis results from sediment cores and created a proper lithostratigraphic model of the investigated basin. Baltic Ice Lake and Yoldia Sea sediment layers were identified acoustically and cores penetrated the final regression surface of the Baltic Ice Lake. The analyses of cores concentrated on Ancylus Lake and Littorina Sea sediments. Two phases of the Ancylus Lake stage were identified. The peaks of loss on ignition in the cores, observed as a strong acoustic reflector, were identified as a marker of Ancylus Lake regression between the first, high-water level phase and the second, shallow-water phase. The age of onset of Littorina transgression was estimated at around 7000–7200 cal BP and was younger than some previous estimations. The retrieved age confirmed the suggestion that the marine environment appeared first in Mecklenburg Bay and then after a few hundred years in Arkona Basin as an intensive transgression. The appearance of Littorina Sea revealed a fast shift of the environment from lacustrine to marine. The first phase of the Littorina stage was recognised as a rapidly increasing water level and high-energy environment; the second showed rapidly increasing salinity in the calmer conditions of sedimentation.
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The evolution of the Mecklenburg Bay environment in the Holocene in the light of multidisciplinary investigations of the sediment cores
Quaternary International, 2015Co-Authors: Robert Kostecki, Beata Janczak-kostecka, Michael Endler, Matthias MorosAbstract:Abstract Multi-proxy studies of the sediment cores and acoustic profiles from Mecklenburg Bay display a more detailed picture of the evolution of the environment in the Holocene. Studies of diatoms, geochemistry, grain size and radiocarbon dating clearly reveal the age and character of freshwater and marine transgressions and regressions. After the final regression of the Baltic Ice Lake, a local lake and swamp environment was recorded by peat gyttja sediments. This environment existed until the Ancylus Lake transgression dated ca 10,500 cal BP. During the Ancylus Lake period, the area remained a shallow-water lake, transitional isolated from the main Baltic Basin. The first slightly brackish marine inflows confirmed by the appearance of planktonic, mesohalobous and halophilous diatoms were identified at the beginning of the Initial Littorina Sea stage and dated ca 8800 cal BP. The boundary between the Ancylus Lake and the Initial Littorina Sea is marked by increasing contents of biogenic silica and iron. The Initial Littorina Sea stage was characterized by increasing mesohalobous and polyhalobous diatom forms and decreasing oligohalobous species. The Initial Littorina Sea environment was recorded as a slightly brackish reservoir sporadically affected by weak marine inflows. The Littorina transgression appeared in the Mecklenburg Bay at ca 7500–7700 cal BP and is reflected by the domination of polyhalobous diatoms, increasing mean grain size, biogenic silica, and calcium and magnesium contents. The Initial Littorina Sea was a 1500-year-long period in Mecklenburg Bay, existing until the Littorina transgression. The main Littorina transgression first appeared in Mecklenburg Bay around 7700 cal BP and after a few hundred years at around 7200 cal BP in the Arkona Basin.
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the littorina transgression in the southwestern baltic sea new insights based on proxy methods and radiocarbon dating of sediment cores
Boreas, 2011Co-Authors: Doreen Rosler, Matthias Moros, Wolfram LemkeAbstract:Rosler, D., Moros, M. & Lemke, W. 2010: The Littorina transgression in the southwestern Baltic Sea: new insights based on proxy methods and radiocarbon dating of sediment cores. Boreas, 10.1111/j.1502-3885.2010.00180.x. ISSN 0300-9483. The Littorina transgression is one of the most pronounced environmental events in the Holocene history of the Baltic Sea. It changed the hydrographic system from the freshwater Ancylus Lake into the brackish-marine Littorina Sea. Here, 18 cores from two western Baltic basins, Mecklenburg Bay and the Arkona Basin, were analysed. We show that, besides biological indicators, sedimentary organic carbon, C/N ratio, bulk δ13C isotope values and carbonate content display clearly the transition from Ancylus Lake to the Littorina Sea. The first appearances of benthic foraminifers, marine molluscs and ostracods represent the onset of brackish-marine conditions in the bottom waters. Central Arkona Basin sediments display more abrupt shifts in geochemical parameters and microfossil records at the transition from Ancylus Lake to the Littorina Sea than those from Mecklenburg Bay. Mixing of reworked Ancylus material with Littorina Sea stage material was stronger in Mecklenburg Bay, resulting in less pronounced proxy parameter changes and older bulk material dates. Radiocarbon dating of both calcareous material (benthic foraminifers, mollusc shells) and bulk fractions at the transgression horizon shows large age discrepancies. Based on calcareous fossil dates it appears that marine waters began to enter Mecklenburg Bay c. 8000 cal. a BP. In the Arkona Basin the first marine signals are recorded approximately 800 years later, c. 7200 cal. a BP. This indicates a transgression pathway via the Great Belt into Mecklenburg Bay and then into the Arkona Basin.
Beata Janczak-kostecka - One of the best experts on this subject based on the ideXlab platform.
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Environmental evolution of western Baltic Sea in the Holocene in the light of multidisciplinary investigations of sediments cores from Arkona Basin
Quaternary International, 2018Co-Authors: Robert Kostecki, Beata Janczak-kostecka, Michael Endler, Matthias MorosAbstract:Abstract A multidisciplinary investigation performed on gravity cores, supplemented by a new radiocarbon dating of macrofossils, outlined the environmental evolution of Arkona Basin in the Holocene. Studies comprising the analysis of diatoms, geochemistry, grain size, and radiocarbon dating clarified the knowledge about the age and environmental changes during freshwater and marine transgressions and regressions. The acoustic profiling method allowed proper interpretation of the analysis results from sediment cores and created a proper lithostratigraphic model of the investigated basin. Baltic Ice Lake and Yoldia Sea sediment layers were identified acoustically and cores penetrated the final regression surface of the Baltic Ice Lake. The analyses of cores concentrated on Ancylus Lake and Littorina Sea sediments. Two phases of the Ancylus Lake stage were identified. The peaks of loss on ignition in the cores, observed as a strong acoustic reflector, were identified as a marker of Ancylus Lake regression between the first, high-water level phase and the second, shallow-water phase. The age of onset of Littorina transgression was estimated at around 7000–7200 cal BP and was younger than some previous estimations. The retrieved age confirmed the suggestion that the marine environment appeared first in Mecklenburg Bay and then after a few hundred years in Arkona Basin as an intensive transgression. The appearance of Littorina Sea revealed a fast shift of the environment from lacustrine to marine. The first phase of the Littorina stage was recognised as a rapidly increasing water level and high-energy environment; the second showed rapidly increasing salinity in the calmer conditions of sedimentation.
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Evolution of Arkona Basin environment in the Holocene in the light of diatom research
Landform Analysis, 2015Co-Authors: Beata Janczak-kosteckaAbstract:This article presents the results of diatom studies from three cores taken from the Arkona Basin. The main stages of the Baltic Sea evolution in the Holocene - Ancylus Lake, Mastogloia Sea, Littorina Sea, and Post-Littorina Sea - were identified in diatom assemblages. The transition stage between Ancylus Lake and Littorina Sea, called Mastogloia Sea, was not such a long period as in the Mecklenburg Bay but was essential in the evolution of the Baltic Sea. The most pronounced feature of this period was an increase in the number of halophilous species, which reflected the existence of the littoral environment at the onset of this stage. The appearance and development of halophilous species was stimulated by stepwise inflows of saline waters. The composition of diatom assemblages reflected natural eutrophication of the Baltic Sea during the Littorina Sea stage.
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The evolution of the Mecklenburg Bay environment in the Holocene in the light of multidisciplinary investigations of the sediment cores
Quaternary International, 2015Co-Authors: Robert Kostecki, Beata Janczak-kostecka, Michael Endler, Matthias MorosAbstract:Abstract Multi-proxy studies of the sediment cores and acoustic profiles from Mecklenburg Bay display a more detailed picture of the evolution of the environment in the Holocene. Studies of diatoms, geochemistry, grain size and radiocarbon dating clearly reveal the age and character of freshwater and marine transgressions and regressions. After the final regression of the Baltic Ice Lake, a local lake and swamp environment was recorded by peat gyttja sediments. This environment existed until the Ancylus Lake transgression dated ca 10,500 cal BP. During the Ancylus Lake period, the area remained a shallow-water lake, transitional isolated from the main Baltic Basin. The first slightly brackish marine inflows confirmed by the appearance of planktonic, mesohalobous and halophilous diatoms were identified at the beginning of the Initial Littorina Sea stage and dated ca 8800 cal BP. The boundary between the Ancylus Lake and the Initial Littorina Sea is marked by increasing contents of biogenic silica and iron. The Initial Littorina Sea stage was characterized by increasing mesohalobous and polyhalobous diatom forms and decreasing oligohalobous species. The Initial Littorina Sea environment was recorded as a slightly brackish reservoir sporadically affected by weak marine inflows. The Littorina transgression appeared in the Mecklenburg Bay at ca 7500–7700 cal BP and is reflected by the domination of polyhalobous diatoms, increasing mean grain size, biogenic silica, and calcium and magnesium contents. The Initial Littorina Sea was a 1500-year-long period in Mecklenburg Bay, existing until the Littorina transgression. The main Littorina transgression first appeared in Mecklenburg Bay around 7700 cal BP and after a few hundred years at around 7200 cal BP in the Arkona Basin.
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Holocene environmental changes in the south-western Baltic Sea reflected by the geochemical data and diatoms of the sediment cores
Journal of Marine Systems, 2012Co-Authors: Robert Kostecki, Beata Janczak-kosteckaAbstract:Abstract Marine sediment cores from the Pomeranian Bay and Arkona Basin were analysed in terms of geochemical composition, diatom assemblages and radiocarbon dating, in order to evaluate the characteristics of the Littorina transgression, on the environment of the south Baltic basin. The data show that this transgression had a strong influence on the evolution of the hydrographic system, which has changed substantially from the Ancylus Lake to the Littorina Sea. The beginning of the period of the Littorina Sea was estimated at 7400–8000 cal BP, but culmination of the marine ingression appeared a few hundred years afterwards in the western cores from the Arkona Basin, and almost 2000 years later in the eastern cores from the Pomeranian Bay. In this study we present a new look at the evolution of the Baltic Sea during the Holocene, based on the statistical analysis of relations between geochemical composition and diatom occurrence. Canonical correlation analysis clearly describes Ancylus and Littorina environments. The Ancylus Lake was characterised as a cold lacustrine environment with poor nutrient availability and high mineral matter inflow, probably from adjacent rivers, while the Littorina Sea environment was much warmer, with a high inflow of nutrients that favoured biogenic production.
Carina Bendixen - One of the best experts on this subject based on the ideXlab platform.
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Early Holocene estuary development of the Hesselø Bay area, southern Kattegat, Denmark and its implication for Ancylus Lake drainage
Geo-Marine Letters, 2017Co-Authors: Carina Bendixen, Jorn Bo Jensen, Ole Bennike, Lars Ole Boldreel, Christian Hübscher, Ole Rønø ClausenAbstract:High-resolution shallow seismic data, sediment core information, radiocarbon dating and sequence stratigraphy have been used to interpret the late glacial to early Holocene geological evolution of Hesselø Bay in the southern Kattegat, Denmark. A reconstruction of the early Holocene coastal environment and a description of coastal processes associated with a river outlet into the bay are presented. Weichselian glacial deposits form the lowermost interpreted unit, covered by late glacial (LG) and postglacial (PG, Holocene) sediments. A funnel-shaped estuary existed at the mouth of channels in the period 10.3–9.2 cal. ka BP; the channels drained water from south to north. The early PG is characterised by estuarine and coastal deposits. The early Holocene bars that developed in the estuary are preserved as morphological features on the present-day seabed, possibly as a result of rapid relative sea-level rise. The estuary existed simultaneously with the occurrence and drainage of the Ancylus Lake. The drainage of this lake occurred through the Dana River (palaeo-Great Belt channel) into the southern Kattegat and then into the study area. The level of the Ancylus Lake in the Baltic Sea region dropped significantly at about 10.2 cal. ka BP at the same time as the estuary developed in the Kattegat region. One outcome of the present study is an enhanced understanding of the Ancylus Lake drainage path. No evidence of major erosion is seen, which indicates non-catastrophic continuous water flow from the south without major drainage events of the Ancylus Lake to the southern Kattegat. During the Littorina transgression, coastal estuarine conditions characterized the Hesselø Bay area where elongated ridges formed a bar system. As the Littorina transgression continued, back-stepping of the bar system and coastline occurred. When the transgression breached the Great Belt threshold, flooding caused major erosion throughout the study area.
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the holocene great belt connection to the southern kattegat scandinavia Ancylus lake drainage and early littorina sea transgression
Boreas, 2017Co-Authors: Jorn Bo Jensen, Ole Bennike, Carina Bendixen, Lars Ole Boldreel, Ole Rønø Clausen, Maritsolveig Seidenkrantz, Johan Nyberg, Christian HübscherAbstract:Late- and postglacial geological evolution of the southern Kattegat connection to the Great Belt was investigated from high-resolution seismic data and radiocarbon-dated sediment cores in order to elucidate the Ancylus Lake drainage/Littorina Sea transgression. It was found that glacial deposits form the acoustic basement and are covered by Lateglacial (LG) marine sediments and postglacial (PG; Holocene) material. The LG deposits form a highstand systems tract, whereas the PG deposits cover a full depositional sequence, consisting of a lowstand systems tract (PG I), transgressive systems tract (PG II; subdivided into three parasequences) and finally a highstand systems tract (PG III). PG I sand deposits (11.7–10.8 cal. ka BP) are found in a major western channel and in a secondary eastern channel. PG II (10.8–9.8 cal. ka BP) consists of estuarine and coastal deposits linked to an estuary located at the mouth of the channels. Both channels drained fresh water from south to north. The PG III, that is younger than 9.8 cal. ka BP, represents the threshold marine flooding at the southeastern branch of the palaeo-Great Belt channel. At 9.3 cal. ka BP, fully marine conditions were established, shortly before the flooding of the threshold to the northern part of the Great Belt. These early Holocene spits and sand bars are preserved as features on the present seabed, probably as a result of the rapid sea-level rise that led to back-stepping of the early Holocene palaeo-coast system. This study shows no evidence of major erosion or delta deposition linked to the emptying of the Ancylus Lake, which suggests that continuous water flow from the south characterized the area, without any major drainage event of the Ancylus Lake impacting the southwestern Kattegat.