Weichselian

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Jan Mangerud - One of the best experts on this subject based on the ideXlab platform.

  • amino acid ratios in quaternary molluscs and foraminifera from western norway correlation geochronology and paleotemperature estimates
    Boreas, 2008
    Co-Authors: Gifford H Miller, Jan Mangerud, Hans Petter Sejrup, Bjorn G Andersen
    Abstract:

    Isoleucine epimerization (alle/Ue) ratios in the pelecypod Mya truncata and benthic foraminifer Cibicides lobalulus from emerged marine units in western Norway allow construction of a regional relative chronostratigraphy for the Ecmian and Weichselian. Two in situ interglacial sections are considered correlative by the similar biostratigraphy and alle/Ile ratios in C. lobalulus. Overlying sediments at the two sites are of both marine and glacial origin. Neither site contains a complete Weichselian record, but allelic ratios, lithostratigraphy and fauna! changes suggest at least four stadial and three interstadial events occurred along the western Norwegian coast during Early and Middle Weichselian time. Kinetic data defining the relationship between the isoleucine epimerization rate constant and temperature for the species studied allow the estimation of paleotemperatures for samples of known age. Accepting published age estimates for the Eemian interglacial beds, the average Weichselian temperature in western Norway is calculated to have been ca. 4°C below the average Holocene temperature, whereas the last interglacial was 1 to 2°C warmer that the Holocene. The limited temperature depression over this region during the Weichselian implies that coastal western Norway was ice-covered only about 30% of this period, and that Atlantic water, although not necessarily in a warm surface current as today, entered the Norwegian Sea during much of marine isotope stage 5 and intermittently during stage 3. Interpolated amino acid ages date interstadial events at ca. 94 ka, 78 ka and 52 ka, B.P., whereas glacial events are dated ca. 103 ka and bracketed by limiting dates between 78 and 89 ka, between 52 and 63 ka and less than 36 ka B.P.

  • Weichselian stratigraphy and palaeoenvironments at Bellsund, western Svalbard
    Boreas, 2008
    Co-Authors: Jon Y Landvik, Jan Mangerud, Magne Bolstad, Anne Katrine Lycke, Hans Petter Sejrup
    Abstract:

    A coastal cliff facing the ocean at the west coast of Spitsbergen has been studied, and seven formations of Weichselian and Holocene age have been identified. A reconstruction of the palaeoenvironment and glacial history shows that most of the sediments cover isotope stage 5. From the base of the section, the formation 1 and 2 tills show a regional glaciation that reached the continental shelf shortly after the Eemian. Formation 3 consists of glacimarine to marine sediments dated to 105,000–90,000 BP. Amino acid diagenesis indicates that they were deposited during a c. 10,000-year period of continuous isostatic depression, which indicates contemporaneous glacial loading in the Barents Sea. Foraminifera and molluscs show influx of Atlantic water masses along the west coast of Svalbard at the same time. Local glaciers advanced during the latter part of this period, probably due to the penetration of moist air masses, and deposited formation 4. A widespread weathering horizon shows that the glacial retreat was succeeded by subaerial conditions during the Middle Weichselian. Formation 5 is a till deposited during the Late Weichselian glacial maximum in this area. The glaciation was dominated by ice streams from a dome over southern Spitsbergen, and the last deglaciation of the outer coast is dated to 13,000 BP. A correlation of the events with other areas on Svalbard is discussed, and at least two periods of glaciation in the Barents Sea during the Weichselian are suggested.

  • Thermoluminescence dates of Weichselian sediments in western Norway
    Boreas, 2008
    Co-Authors: Högne Jungner, Jon Y Landvik, Jan Mangerud
    Abstract:

    Thermoluminescence dating has been carried out on feldspar sand grains from the distal sandur of the Godoya Formation and correlated sediments at Sunnmore, western Norway. The accumulated dose was determined by the regeneration method. The Godoya Formation, which was earlier assumed to be of Middle Weichselian age, was dated to 105–130 ka and is now assumed to postdate immediately the Eemian interglacial. Dates of sediments previously correlated to the Godoya Formation yielded ages in the ranges of 70–90 and 40–50 ka, thus indicating at least three Weichselian ice-free periods predating the Alesund interstadial in the area.

  • the extent of the late Weichselian ice sheet in the southeastern barents sea
    Grid and Pervasive Computing, 2001
    Co-Authors: Valery Gataullin, Jan Mangerud, John Inge Svendsen
    Abstract:

    Abstract We have compiled a large number of seismic records and descriptions of sediment cores obtained from the southeastern Barents Sea (Pechora Sea) by former Soviet Union institutions. Five major seismostratigraphic units (SSU-I–V) were recognized. The oldest till (SSU-V) is mainly confined to the southernmost area and is covered by a 100–150-m-thick wedge of Middle Weichselian marine sediments (SSU-IV) distal to the mouth of the Pechora River. Three Late Weichselian ice sheet margins are identified on the Pechora Sea shelf. The oldest is named the Kolguev Line and it marks the southern limit of the youngest till sheet (SSU-III) in the Barents Sea as well as the northern, erosional limit of SSU-IV and -V. The Kolguev Line marks the maximum extension of the Barents Ice Sheet during the Late Weichselian. The Kurentsovo Line, which is located 50–100 km further to the north, is much more expressed than the Kolguev Line and corresponds with long ice-pushed bedrock ridges and till ridges. Up to 100-m-thick accumulations of glaciomarine sediments (SSU-II) were mapped on the southern side of the Kolguev Line whereas less than 10–20 m where found on the northern side of the inferred ice sheet margin, indicating that the ice front remained at this position for considerable time. The youngest line is the southern continuation of the Admiralty Banks moraines, which have previously been mapped along the western margin of Novaya Zemlya. The Kolguev and Kurentsovo lines were both formed by an ice sheet centered in the Barents Sea, whereas the Admiralty Banks moraines were deposited from an ice sheet over Novaya Zemlya during the final stage of the Late Weichselian, possibly during the Younger Dryas. Submerged shorelines of Late Weichselian/Early Holocene ages have been identified on the shelf down to a water depth of 50–70 m indicating a modest glacio-isostatic depression that partly compensated the sea-level fall during the last glacial maximum.

  • maximum extent of the eurasian ice sheets in the barents and kara sea region during the Weichselian
    Boreas, 1999
    Co-Authors: John Inge Svendsen, Julian A. Dowdeswell, Valery Astakhov, Igor Demidov, Valery Gataullin, Christian Hjort, D Bolshiyanov, H W Hubberten, Eiliv Larsen, Jan Mangerud
    Abstract:

    Based on field investigations in northern Russia and interpretation of offshore seismic data, we have made a preliminary reconstruction of the maximum ice-sheet extent in the Barents and Kara Sea region during the Early/Middle Weichselian and the Late Weichselian. Our investigations indicate that the Barents and Kara ice sheets attained their maximum Weichselian positions in northern Russia prior to 50 000 yr BP, whereas the northeastern flank of the Scandinavian Ice Sheet advanced to a maximum position shortly after 17000 calendar years ago. During the Late Weichselian (25 000–10000 yr BP), much of the Russian Arctic remained ice-free. According to our reconstruction, the extent of the ice sheets in the Barents and Kara Sea region during the Late Weichselian glacial maximum was less than half that of the maximum model which, up to now, has been widely used as a boundary condition for testing and refining General Circulation Models (GCMs). Preliminary numerical-modelling experiments predict Late Weichselian ice sheets which are larger than the ice extent implied for the Kara Sea region from dated geological evidence, suggesting very low precipitation.

Tore O. Vorren - One of the best experts on this subject based on the ideXlab platform.

  • Late Quaternary glaciation in the south‐western Barents Sea
    Boreas, 2008
    Co-Authors: Tore O. Vorren, Yngve Kristoffersen
    Abstract:

    Moraine ridges have been morphologically and seismically identified in the south-western Barents Sea. Some of these ridges were deposited in front of ice lobes from the northern part of the Fennoscandian Ice Sheet, others in front of glaciers located on the southern Barents Sea shelf. The moraine ridges were probably deposited during the Weichselian, possibly the Late Weichselian.

  • Weichselian sediments containing redeposited interstadialhnterglacial fossils at Slettaelva, North Norway
    Boreas, 2008
    Co-Authors: Tore O. Vorren, Geoffrey D. Corner, Jenö Nagy
    Abstract:

    The following stratigraphy was found at Slettaelva, near Tromso (from bottom to top): greenish basal till (unit A), laminated c lay (unit B), fossitiferous basal till (Unit C). Unit A probably derives from an early Weichselin local glaciation, Unit B comprises lacustrine sediments which were apparently deposited in an early Weichselian tundra-like enivironment, Unit C, which contains reworked fossils of moulluscs, palynomorphs and foraminifera, was deposited by a continenntal ice shcet. Amino acid ratios of Mya truncata and plaaeontological evidence indicate that unit Ccontains a mixed fossil assemblage, probably of Eemian and Weichselian interstadial age.

  • Weichselian ice movement in South Norway and adjacent areas
    Boreas, 2008
    Co-Authors: Tore O. Vorren
    Abstract:

    Three main phases of ice-movement pattern in South Norway during the Weichselian are reconstructed. During Phase II (possibly of Middle Weichselian age) the ice divide was located far to the west. Phase III (assumed Middle/Late Weichselian age) had an easterly situated ice divide. During Phase IV (Preboreal age) the ice divide had moved back to the west and had partly fragmented into separate domes. The migration of the ice divide from west to east may be due to glacier surges, whilst the ice-divide migration from Phase III to IV was probably a result of a general reduction in size of the ice sheet.

  • Weichselian and holocene growth of the northern high latitude lofoten contourite drift on the continental slope of norway
    Sedimentary Geology, 2004
    Co-Authors: Jan Sverre Laberg, Tore O. Vorren
    Abstract:

    Abstract The Weichselian and Holocene sediments in the Lofoten Drift comprise six lithofacies: brown sandy mud, olive grey mud, olive grey laminated mud, dark brown mud, massive sand and dark grey sandy mud. During the Weichselian, the sediment input to the Lofoten Drift was from two main sources, i.e., glacimarine sedimentation and ocean current winnowing. During the Holocene, the sediment input was only from winnowing. The sediment source area was the Voring margin and the continental margin further south. The sedimentation rate was 190 cm/ka during the late Weichelian and 9 cm/ka during the Holocene. The Weichselian rates are high compared with the deep-sea contourite drifts comprising highly bioturbated sediments, and probably explain why bioturbation is less pronounced in these slope drift sediments. Drifts on glaciated margins, as exemplified by the Lofoten Contourite Drift, represent areas of high sedimentation rate during glacial maxima. Sediment input was not restricted to glacial maximum periods, for sediments also accumulated during other stadial and interstadial periods.

  • Late Weichselian and Holocene sediment flux and sedimentation rates in Andfjord and Vågsfjord, North Norway
    Journal of Quaternary Science, 2002
    Co-Authors: Liv Plassen, Tore O. Vorren
    Abstract:

    Late Weichselian and Holocene sediment flux and sedimentation rates in a continental-shelf trough, Andfjord, and its inshore continuation, Vagsfjord, North Norway, have been analysed. The study is based on sediment cores and high-resolution acoustic data. Andfjord was deglaciated between 14.6 and 13 14C kyr BP (17.5 and 15.6 calibrated (cal.) kyr BP), the Vagsfjord basin before 12.5 14C kyr BP (14.7 cal. kyr BP), and the heads of the inner tributary fjords about 9.7 14C kyr BP (11.2 cal. kyr BP). In Andfjord, five seismostratigraphical units are correlated to a radiocarbon dated lithostratigraphy. Three seismostratigraphical units are recognised in Vagsfjord. A total volume of 23 km3 post-glacial glacimarine and marine sediments was mapped in the study area, of which 80% are of Late Weichselian origin. Sedimentation rates in outer Andfjord indicate reduced sediment accumulation with increasing distance from the ice margin. The Late Weichselian sediment flux and sedimentation rates are significantly higher in Vagsfjord than Andfjord. Basin morphology, the position of the ice front and the timing of deglaciation are assumed to be the reasons for this. Late Weichselian sedimentation rates in Andfjord and Vagsfjord are comparable to modern subpolar glacimarine environments of Greenland, Baffin Island and Spitsbergen. Downwasting of the Fennoscandian Ice Sheet, and winnowing of the banks owing to the full introduction of the Norwegian Current, caused very high sedimentation rates in parts of the Andfjord trough at the Late Weichselian–Holocene boundary. Holocene sediment flux and sedimentation rates in Andfjord are about half the amount found in Vagsfjord, and about one-tenth the amount of Late Weichselian values. A strong bottom current system, established at the Late Weichselian–Holocene boundary, caused erosion of the Late Weichselian sediments and an asymmetric Holocene sediment distribution. Copyright © 2002 John Wiley & Sons, Ltd.

K Eskola - One of the best experts on this subject based on the ideXlab platform.

  • Weichselian sedimentary record and ice-flow patterns in the Sodankylä area, central Finnish Lapland
    Bulletin of the Geological Society of Finland, 2020
    Co-Authors: Annika Katarina Åberg, Anu Kaakinen, K Eskola, Seija Kultti, Velipekka Salonen
    Abstract:

    Three different till units separated by interstadial fluvial deposits were observed in the Sodankylä area in the River Kitinen valley, northern Finland. The interbedded glaciofluvial sediments and palaeosol were dated by OSL to the Early (79±12 to 67±13 ka) and Middle (41±9 ka) Weichselian. A LiDAR DEM, glacial lineations, the flow direction of till fabrics, esker chains and striations were applied to investigate the glacial flow patterns of the Sodankylä, Kittilä and Salla areas. The analysis revealed that the youngest movement of the Scandinavian Ice Sheet is not visible as DEM lineations within the studied areas. The modern morphology in Kittilä and Salla shows streamlined landforms of various dimensions mainly oriented from the NW and NNW, respectively, corresponding to the Early/Middle Weichselian ice-flow directions inferred from till fabrics. The Late Weichselian ice flow has produced an insignificant imprint on the landforms. This study suggests a northern location for the ice-divide zone during the Early/Middle Weichselian, and a more western–southwestern position during the Late Weichselian. The OSL ages of 14±3.3 ka from the aeolian deposits may indicate ice-free areas during the Bølling–Allerod warm period in the vicinity of the River Kitinen.

  • mid Weichselian interstadial in kolari western finnish lapland
    Boreas, 2014
    Co-Authors: Velipekka Salonen, Julien Moreau, Outi Hyttinen, K Eskola
    Abstract:

    Finnish Lapland is known as an area where numerous sites with sediments from Pleistocene glacial and interglacial periods occur. Recent sedimentological observations and dating call for reinterpretation of the record, which shows a complicated Mid-Weichselian ice-sheet evolution within the ice-divide zone. Here, a large, previously unstudied section from a former Hannukainen iron mine was investigated sedimentologically and dated with optically stimulated luminescence (OSL). Ten sedimentary units were identified displaying a variety of depositional environments (glacial, glaciolacustrine, fluvial and aeolian). They are all – except for the lowermost, deeply weathered till – interpreted to be of Mid- or Late Weichselian/Holocene age. Five OSL samples from fluvial sediments give ages ranging from 55 to 35 ka, indicating two MIS 3 ice-free intervals of unknown duration. The Mid-Weichselian interstadial was interrupted by a re-advance event, which occurred later than 35 ka and caused glaciotectonic deformation, folding and stacking of older sediments. This new evidence emphasizes the importance of the Kolari area when unravelling the complex Late Pleistocene glacial history of northern Finland and adjacent regions.

  • Lithostratigraphy and Optically Stimulated Luminescence age determinations of pre‐Late Weichselian deposits in the Suupohja area, western Finland
    Boreas, 2013
    Co-Authors: Reijo Pitkäranta, Juha Pekka Lunkka, K Eskola
    Abstract:

    The lithostratigraphy of pre-Late Weichselian sediments and OSL-dating results from four localities in the Suupohja area of western Finland, adjacent to the centre of the former Scandinavian glaciations, are presented. The studied sections expose glacifluvial, quiet-water, littoral and aeolian deposits overlain by Middle and/or Late Weichselian tills. Litho- and biostratigraphical results together with seven OSL age determinations on buried glacifluvial sediment at Ravasen (94±15 ka) and on till-covered littoral and aeolian sediments at Risasen, Ravasen, Jatinmaki and Kiviharju (79±10 to 54±8 ka), accompanied by previous datings and interpretations, suggest that the glacifluvial sediments at Risasen were deposited at the end of the Saalian Stage (MIS 6) and those at Risasen were deposited possibly in the Early Weichselian Substage (MIS 5d?). Palaeosol horizons and ice-wedge casts together with the dated littoral and aeolian sediments between the Harrinkangas Formation (Saalian) and the overlying till(s) indicate that western Finland was ice-free during most of the Weichselian time. Littoral deposits, dated to the Middle Weichselian (MIS 4–3), occur at altitudes of 50–90 m a.s.l., which indicates significant glacio-isostatic depression. The depression resulted from expansion of the ice sheet in the west of Finland at that time.

  • Weichselian glacial stage in Murchisonfjorden, Nordaustlandet, Svalbard
    Boreas, 2009
    Co-Authors: Anu Kaakinen, Velipekka Salonen, K Eskola, Frauke Kubischta, Markku Oinonen
    Abstract:

    Compared to the other islands in the Svalbard archipelago, Nordaustlandet offers only limited stratigraphical or sedimentological information on its Quaternary deposits. This article aims to fill the gap by presenting new results from glacial geological, sedimentological and chronological studies in the southern Murchisonfjorden area. Field data include reconnaissance mapping and detailed logging of vertical sections along cliff-face outcrops a few metres high adjacent to the present-day shoreline. Combined with OSL and AMS age determinations, these data provide evidence of three successive Weichselian sequences, each represented by the deposition of till followed by the accumulation of shallow marine deposits. Contrary to earlier conclusions, this study demonstrates that the area was occupied by a Late Weichselian glacier (LWG), although the LWG till is thin and discontinuous. Interstadial sublittoral sand related to the Mid-Weichselian interstadial was dated to 38–40 kyr, and an Early Weichselian interstadial to 76–80 kyr. The preservation of older sediments, multiple striae generations and abundant observations of weathered local bedrock material indicate weak glacial erosion within the study area. We suggest that the Late Weichselian glacier was relatively inactive and remained mainly cold-based until the deglaciation. The Isvika sections can be considered a new key site that offers further potential to improve our understanding of the Weichselian stage within the northwestern sector of the Barents–Kara Ice Sheet.

Jon Y Landvik - One of the best experts on this subject based on the ideXlab platform.

  • Thermoluminescence dates of Weichselian sediments in western Norway
    Boreas, 2008
    Co-Authors: Högne Jungner, Jon Y Landvik, Jan Mangerud
    Abstract:

    Thermoluminescence dating has been carried out on feldspar sand grains from the distal sandur of the Godoya Formation and correlated sediments at Sunnmore, western Norway. The accumulated dose was determined by the regeneration method. The Godoya Formation, which was earlier assumed to be of Middle Weichselian age, was dated to 105–130 ka and is now assumed to postdate immediately the Eemian interglacial. Dates of sediments previously correlated to the Godoya Formation yielded ages in the ranges of 70–90 and 40–50 ka, thus indicating at least three Weichselian ice-free periods predating the Alesund interstadial in the area.

  • Weichselian stratigraphy and palaeoenvironments at Bellsund, western Svalbard
    Boreas, 2008
    Co-Authors: Jon Y Landvik, Jan Mangerud, Magne Bolstad, Anne Katrine Lycke, Hans Petter Sejrup
    Abstract:

    A coastal cliff facing the ocean at the west coast of Spitsbergen has been studied, and seven formations of Weichselian and Holocene age have been identified. A reconstruction of the palaeoenvironment and glacial history shows that most of the sediments cover isotope stage 5. From the base of the section, the formation 1 and 2 tills show a regional glaciation that reached the continental shelf shortly after the Eemian. Formation 3 consists of glacimarine to marine sediments dated to 105,000–90,000 BP. Amino acid diagenesis indicates that they were deposited during a c. 10,000-year period of continuous isostatic depression, which indicates contemporaneous glacial loading in the Barents Sea. Foraminifera and molluscs show influx of Atlantic water masses along the west coast of Svalbard at the same time. Local glaciers advanced during the latter part of this period, probably due to the penetration of moist air masses, and deposited formation 4. A widespread weathering horizon shows that the glacial retreat was succeeded by subaerial conditions during the Middle Weichselian. Formation 5 is a till deposited during the Late Weichselian glacial maximum in this area. The glaciation was dominated by ice streams from a dome over southern Spitsbergen, and the last deglaciation of the outer coast is dated to 13,000 BP. A correlation of the events with other areas on Svalbard is discussed, and at least two periods of glaciation in the Barents Sea during the Weichselian are suggested.

  • Saalian to Weichselian stratigraphy and sedimentation along the Lågjæren – Høgjæren escarpment, southwest Norway
    Journal of Quaternary Science, 1999
    Co-Authors: Knut Stalsberg, Eiliv Larsen, Jon Y Landvik, Hans Petter Sejrup
    Abstract:

    Quaternary sediments along a profile crossing the southern part of the Jaeren escarpment, southwestern Norway, have been investigated with regard to their glacial history and sea-level variations. Deposits from at least three glaciations and two ice-free periods between Oxygen Isotope Stage 6 and the Late Weichselian have been identified. Subglacial till directly overlain by a glaciomarine regressional succession indicates a deglaciation, and amino acid ratios in Elphidium excavatum between 0.083 and 0.118 date this event to Oxygen Isotope Stage 6. Sea-level dropped from 130 to below 110 m a.s.l. Subsequently, a short-lived ice advance deposited a marginal moraine and a sandur locally on the escarpment. Stratigraphical position and luminescence dates around 148 ka BP suggest deposition during the final stage 6 deglaciation. A Late Weichselian till covers most of the surface of Jaeren. In addition to a well documented westerly ice flow, glaciotectonic indications of ice flow towards the north have been found. Ice flow directions and a hiatus between Oxygen Isotope Stage 6 and the Weichselian indicate enhanced erosion along the escarpment and the influence of a Norwegian Channel ice-stream. Copyright © 1999 John Wiley & Sons, Ltd.

  • fluctuations of the svalbard barents sea ice sheet during the last 150 000 years
    Quaternary Science Reviews, 1998
    Co-Authors: Jan Mangerud, John Inge Svendsen, Vagn Mejdahl, Trond Dokken, Dierk Hebbeln, Beathe Heggen, Olafur Ingolfsson, Jon Y Landvik, Tore O. Vorren
    Abstract:

    Abstract On Spitsbergen, western Svalbard, three major glacial advances have been identified during the Weichselian. All three reached the continental shelf west of the Svalbard archipelago. Radiocarbon, luminescence and amino acid dating of interbedded interstadial and interglacial sediments indicate that these glacial advances have Early (Isotope Stage 5d), Middle (Stage 4), and Late Weichselian ages (Stage 2). An additional, more local, advance has been dated to Isotope Stage 5b. The Late Weichselian ice sheet expanded across the entire Barents Sea. However, in the south-western Barents Sea, the Late Weichselian till is the only till above Eemian sediments, indicating that the Early- and Middle Weichselian ice advances were restricted to the Svalbard archipelago and the northern Barents Sea. A major problem with the onshore sites is the dating of events beyond the range of the radiocarbon method. To overcome this, the onshore record has been correlated with marine cores from the continental slope and the deep-sea west of Svalbard, where a chronology has been established by oxygen isotope stratigraphy. Ice rafted detritus (IRD) was used as the main monitor of glaciation. The IRD record closely mirrors the glaciation history as interpreted from the onshore sections. During the Late Weichselian, the largest IRD peak occurred during deglaciation, a pattern also postulated for the earlier events. Given this, the results from the marine cores indicate that the ages for the first glacial advances during the Weichselian were a few thousand years older than interpreted from the onshore stratigraphy.

Juha Pekka Lunkka - One of the best experts on this subject based on the ideXlab platform.

  • Stratigraphy of the Koivusaarenneva exposure and its correlation across central Ostrobothnia, Finland
    Geological Society of Finland, 2016
    Co-Authors: Juha Pekka Lunkka, P. Lintinen, K. Nenonen, P. Huhta
    Abstract:

    A multiple till succession at Koivusaarenneva in Central Ostrobothnia, adjacent to the Gulf of Bothnia, was studied using conventional sedimentological techniques. In addition, a sand-rich unit between two till beds was dated by the Optical Stimulated Luminescence (OSL) method and organic-bearing silt was subjected to pollen analysis. The methods were applied to determine the Pleistocene sedimentation history of the area. The results obtained indicate that the lowest till above the crystalline bedrock at Koivusaarenneva was deposited from the NNW during the Saalian glaciation, whereas the organic-bearing sediments and deformed sand and silt above, were laid down during the Eemian and the Early Weichselian stages. Two till beds above the Early Weichselian sediments indicate that at least two separate Scandinavian Ice Sheet advances took place in the area, most likely in the early Middle Weichselian and the Late Weichselian substages

  • the rautuvaara section western finnish lapland revisited new age constraints indicate a complex scandinavian ice sheet history in northern fennoscandia during the Weichselian stage
    Boreas, 2015
    Co-Authors: Juha Pekka Lunkka, Pertti Sarala, Philip L. Gibbard
    Abstract:

    The Rautuvaara section in northern Finnish Lapland has been widely considered as the stratotype for the northern Fennoscandian late Middle and Late Pleistocene. It exposes four till units interbedded with sorted sediments resting on Precambrian bedrock. In order to shed light on the Scandinavian Ice Sheet (SIS) history and palaeoenvironmental evolution in northern Fennoscandia through time, a chronostratigraphical study was carried out at the Rautuvaara site. The succession was studied using sedimentological methods and different sand-rich units between till units were dated using the Optical Stimulated Luminescence (OSL) method. The results obtained indicate that the whole sediment succession at Rautuvaara was deposited during the Weichselian Stage and there is no indication of older deposits. The SIS advanced across Finnish Lapland to adjacent areas to the east at least once during the Early Weichselian, twice during the Middle Weichselian (∼MIS 4 and MIS 3) and once during the Late Weichselian substages. Glaciolacustrine sediments interbedded between the till units indicate that a glacial lake repeatedly existed after each deglacial phase. The results also suggest that there were two ice-free intervals in northern Fennoscandia during the Middle Weichselian close to the SIS glaciation centre.

  • The Rautuvaara section, western Finnish Lapland, revisited – new age constraints indicate a complex Scandinavian Ice Sheet history in northern Fennoscandia during the Weichselian Stage
    Boreas, 2014
    Co-Authors: Juha Pekka Lunkka, Pertti Sarala, Philip L. Gibbard
    Abstract:

    The Rautuvaara section in northern Finnish Lapland has been widely considered as the stratotype for the northern Fennoscandian late Middle and Late Pleistocene. It exposes four till units interbedded with sorted sediments resting on Precambrian bedrock. In order to shed light on the Scandinavian Ice Sheet (SIS) history and palaeoenvironmental evolution in northern Fennoscandia through time, a chronostratigraphical study was carried out at the Rautuvaara site. The succession was studied using sedimentological methods and different sand-rich units between till units were dated using the Optical Stimulated Luminescence (OSL) method. The results obtained indicate that the whole sediment succession at Rautuvaara was deposited during the Weichselian Stage and there is no indication of older deposits. The SIS advanced across Finnish Lapland to adjacent areas to the east at least once during the Early Weichselian, twice during the Middle Weichselian (∼MIS 4 and MIS 3) and once during the Late Weichselian substages. Glaciolacustrine sediments interbedded between the till units indicate that a glacial lake repeatedly existed after each deglacial phase. The results also suggest that there were two ice-free intervals in northern Fennoscandia during the Middle Weichselian close to the SIS glaciation centre.

  • Lithostratigraphy and Optically Stimulated Luminescence age determinations of pre‐Late Weichselian deposits in the Suupohja area, western Finland
    Boreas, 2013
    Co-Authors: Reijo Pitkäranta, Juha Pekka Lunkka, K Eskola
    Abstract:

    The lithostratigraphy of pre-Late Weichselian sediments and OSL-dating results from four localities in the Suupohja area of western Finland, adjacent to the centre of the former Scandinavian glaciations, are presented. The studied sections expose glacifluvial, quiet-water, littoral and aeolian deposits overlain by Middle and/or Late Weichselian tills. Litho- and biostratigraphical results together with seven OSL age determinations on buried glacifluvial sediment at Ravasen (94±15 ka) and on till-covered littoral and aeolian sediments at Risasen, Ravasen, Jatinmaki and Kiviharju (79±10 to 54±8 ka), accompanied by previous datings and interpretations, suggest that the glacifluvial sediments at Risasen were deposited at the end of the Saalian Stage (MIS 6) and those at Risasen were deposited possibly in the Early Weichselian Substage (MIS 5d?). Palaeosol horizons and ice-wedge casts together with the dated littoral and aeolian sediments between the Harrinkangas Formation (Saalian) and the overlying till(s) indicate that western Finland was ice-free during most of the Weichselian time. Littoral deposits, dated to the Middle Weichselian (MIS 4–3), occur at altitudes of 50–90 m a.s.l., which indicates significant glacio-isostatic depression. The depression resulted from expansion of the ice sheet in the west of Finland at that time.

  • Weichselian sediment succession at Ruunaa, Finland, indicating a Mid‐Weichselian ice‐free interval in eastern Fennoscandia
    Boreas, 2008
    Co-Authors: Juha Pekka Lunkka, Andrew S. Murray, Kauko Korpela
    Abstract:

    Core material obtained from three boreholes was studied from the Ruunaa area, Finnish northern Karelia, in order to reveal the Late Pleistocene environmental history of eastern Finland. Conventional litho- and biostratigraphical methods were used and suitable sediment samples were dated using quartz optically stimulated luminescence. The results indicate that two till units were deposited by two separate Weichselian ice advances into the area. The first advance took place prior to 52 kyr ago, most likely during the early Middle Weichselian, while the second is thought to have taken place during the Late Weichselian after 25 kyr ago. The sediment succession at Ruunaa therefore indicates a Middle Weichselian ice-free period around 50–25 kyr ago in the eastern part of Fennoscandia.