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Achim Brauer - One of the best experts on this subject based on the ideXlab platform.
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The first Holocene Varve chronology for the UK: Based on the integration of Varve counting, radiocarbon dating and tephrostratigraphy from Diss Mere (UK)
Quaternary Geochronology, 2021Co-Authors: Celia Martin-puertas, Simon P.e Blockley, Poppy Harding, George E. Biddulph, Adrian Palmer, Amy Walsh, Arne Ramisch, Achim BrauerAbstract:Abstract The British Isles lack long high-precision and independent chronologies to reconstruct Holocene environmental and climatic conditions at sub-decadal timescales. This paper reports the first Holocene Varved chronology for the lacustrine sediment record of Diss Mere in the UK. The record of Diss Mere is 15 m long, and shows 4.2 m of finely-laminated sediments, which are present between ca. 9 and 13 m of core depth. The microfacies analysis identified three major seasonal patterns of deposition (microfacies 1–3), which corroborate the annual nature of sedimentation throughout the whole interval. The sediments are diatomaceous organic and carbonate Varves with an average thickness of 0.45 mm. Microfacies 1 consists of a pale layer of authigenic calcite crystals and diatom frustules, and a dark layer composed of a planktonic diatoms and filaments of organic matter. Microfacies 2 is similar but includes a mono-specific diatom bloom layer preceding the calcite layer. Microfacies 3 consists of Varves with an occasional very thin calcite layer and mono-specific diatom blooms in spring and autumn. A total of 8473 Varves were counted with maximum counting error of up to 40 Varves by the bottom of the Varved sequence. To tie the resulting floating Varve chronology to the IntCal20 radiocarbon timescale, we used a Bayesian Deposition model (P_Sequence with outlier detection) on all available chronological data from the core. The data included five radiocarbon dates, two known tephra layers (Glen Garry and OMH-185) with calendar ages based on Bayesian modelling of sequences of radiocarbon ages, and the relative Varve counts between dated points. The resulting age-depth model (DISSV-2020) dates the Varved sequence between ca. 2100 and 10,300 cal BP and age uncertainties are decadal in scale. The immediate implication of this new UK Holocene chronology is the updated precise ages for the Glen Garry tephra at 2073 ± 39 cal BP and the OMH-185 tephra at 2617 ± 29 cal BP. DISSV-2020 will also enable Holocene research at high time resolution and comparisons to other annually-resolved records on absolute timescales supporting climatic investigations at the regional level.
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hypolimnetic oxygen conditions influence Varve preservation and δ13c of sediment organic matter in lake tiefer see ne germany
Journal of Paleolimnology, 2019Co-Authors: Nadine Dräger, Birgit Plessen, Arne Ramisch, Michal Slowinski, Rik Tjallingii, Ulrike Kienel, Sylvia Pinkerneil, Achim BrauerAbstract:Stable carbon isotopes of sediment organic matter (δ13COM) are widely applied in paleoenvironmental studies. Interpretations of δ13COM, however, remain challenging and factors that influence δ13COM may not apply across all lakes. Common explanations for stratigraphic shifts in δ13COM include changes in lake productivity or changes in inputs of allochthonous OM. We investigated the influence of different oxygen conditions (oxic versus anoxic) on the δ13COM values in the sediments of Lake Tiefer See. We analysed (1) a long sediment core from the deepest part of the lake, (2) two short, sediment–water interface cores from shallower water depths, and (3) OM in the water column, i.e. from sediment traps. Fresh OM throughout the entire water column showed a relatively constant δ13COM value of approximately − 30.5‰. Similar values, about − 31‰, were obtained for well-Varved sediments in both the long and short, sediment–water interface cores. In contrast, δ13COM values from non-Varved sediments in all cores were significantly less negative (− 29‰). The δ13COM values in the sediment–water interface cores from different water depths differ for sediments of the same age, if oxygen conditions at the time of deposition were different at these sites, as suggested by the state of Varve preservation. Sediments deposited from AD 1924 to 1980 at 62 m water depth are Varved and exhibit δ13COM values around − 31‰, whereas sediments of the same age in the core from 35 m water depth are not Varved and show less negative δ13COM values of about − 29‰. The relation between Varve occurrence and δ13COM values suggests that δ13COM is associated with oxygen conditions because Varve preservation depends on hypolimnetic anoxia. A mechanism that likely influences δ13COM is selective degradation of OM under oxic conditions, such that organic components with more negative δ13COM are preferably decomposed, leading to less negative δ13COM values in the remaining, undegraded OM pool. Greater decomposition of OM in non-Varved sediments is supported by lower TOC concentrations in these deposits (~ 5%) compared to well-Varved sediments (~ 15%). Even in lakes that display small variations in productivity and terrestrial OM input through time, large spatial and temporal differences in hypolimnetic oxygen concentrations may be an important factor controlling sediment δ13COM.
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constraining the time span between the early holocene hasseldalen and askja s tephras through Varve counting in the lake czechowskie sediment record poland
Journal of Quaternary Science, 2016Co-Authors: Florian Ott, Sabine Wulf, Johanna Serb, Michal Slowinski, Milena Obremska, Rik Tjallingii, Miroslaw Blaszkiewicz, Achim BrauerAbstract:We report the first findings of coexisting early Holocene Hasseldalen and Askja-S cryptotephras in a Varved sediment record in Lake Czechowskie (Poland). A time span of 152 +11/−8 Varve years between the two tephras has been revealed by differential dating through Varve counting. This is in agreement within the uncertainties with calculations from radiocarbon-based age models from the non-Varved Hasseldala port record in southern Sweden, but shorter than assumed from the non-Varved lake record on the Faroe Islands. We discuss possible reasons for the observed differences in duration between the two tephras and provide a revised absolute age for the Askja-S tephra of 11 228 ± 226 cal a BP based on anchoring our floating Varve chronology to the absolute timescale by using the Hasseldalen Tephra as dated in the Hasseldala port sediments (11 380 ± 216 cal a BP). This age agrees with radiocarbon age models with larger uncertainty ranges, but is slightly older than radiocarbon-based age models with narrow uncertainty bands and is even 200–300 years older than the age reported from the Faroe Islands record. In addition to these chronological issues we discuss the possible response of the Czechowskie sediment record to the Preboreal climate oscillation.
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combined µ xrf and microfacies techniques for lake sediment analyses
2015Co-Authors: Peter Dulski, Achim Brauer, Clara MangiliAbstract:This contribution presents an evaluation of still unexplored potentials, limitations and technical details of µ-XRF element scanning particularly for Varved sediment analyses using the vacuum device EAGLE III XL. For this case study a 33 cm long interval of exceptionally well-preserved sub-millimetre scale calcite Varves of the interglacial lake deposits from Pianico has been selected. In addition to the demonstration of the very good repeatability of XRF element scans, one focus of this paper is on discussing a suitable scanner resolution in terms of a compromise between short analyses times and a resolution that allows capturing the geochemical signature even of seasonal sub-layers. By combining scanner data with microscopic sediment inspection geochemical signatures of various micro-facies as, for example, Varves, detrital layers and matrix-supported and clay layers are explored. The potential of counting Varves using the seasonal signature of specific elements is discussed and potential error sources are disclosed by comparison with microscopic Varve counts. Detailed grid- µXRF-scanning provides for the first time an insight into the internal structure of Varves presented as high-resolution 3D-images. Finally, an approach of calibrating scanner data through comparison with ICP-MS analyses is introduced. Sensitivity factors for each element have been defined as ratios between mean count rates and bulk element concentrations.
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Integration of the Old and New Lake Suigetsu (Japan) Terrestrial Radiocarbon Calibration Data Sets
Radiocarbon, 2013Co-Authors: Richard A. Staff, Gordon Schlolaut, Michael H. Marshall, Charlotte L. Bryant, Hiroyuki Kitagawa, Johannes Van Der Plicht, Achim Brauer, Fiona Brock, Christopher Bronk Ramsey, Henry F. LambAbstract:The Varved sediment profile of Lake Suigetsu, central Japan, offers an ideal opportunity from which to derive a terrestrial record of atmospheric radiocarbon across the entire range of the 14C dating method. Previous work by Kitagawa and van der Plicht (1998a,b, 2000) provided such a data set; however, problems with the Varve-based age scale of their SG93 sediment core precluded the use of this data set for 14C calibration purposes. Lake Suigetsu was re-cored in summer 2006, with the retrieval of overlapping sediment cores from 4 parallel boreholes enabling complete recovery of the sediment profile for the present "Suigetsu Varves 2006" project (Nakagawa et al. 2012). Over 550 14C determinations have been obtained from terrestrial plant macrofossils picked from the latter SG06 composite sediment core, which, coupled with the core's indepen- dent Varve chronology, provides the only non-reservoir-corrected 14C calibration data set across the 14C dating range. Here, physical matching of archive U-channel sediment from SG93 to the continuous SG06 sediment profile is presented. We show the excellent agreement between the respective projects' 14C data sets, allowing the integration of 243 14C determina- tions from the original SG93 project into a composite Lake Suigetsu 14C calibration data set comprising 808 individual 14C determinations, spanning the last 52,800 cal yr.
Björn Holmquist - One of the best experts on this subject based on the ideXlab platform.
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An 800‐year long, radiocarbon‐dated Varve chronology from south‐eastern Sweden
Boreas, 2008Co-Authors: Barbara Wohlfarth, Göran Possnert, Svante Björck, Björn HolmquistAbstract:More than 50 Varve-thickness diagrams, which were established from glacial Varved clays in south-eastern Sweden were correlated with each other to form an 800-year long floating Varve chronology. AMS C-14 measurements on terrestrial macrofossils from the
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an 800 year long radiocarbon dated Varve chronology from south eastern sweden
Boreas, 2008Co-Authors: Barbara Wohlfarth, Göran Possnert, Svante Björck, Björn HolmquistAbstract:More than 50 Varve-thickness diagrams, which were established from glacial Varved clays in south-eastern Sweden were correlated with each other to form an 800-year long floating Varve chronology. AMS C-14 measurements on terrestrial macrofossils from the
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the relationship between annual Varve thickness and maximum annual discharge 1909 1971
Journal of Hydrology, 2002Co-Authors: Mikkel Sander, Lars Bengtsson, Björn Holmquist, Barbara Wohlfarth, Ingemar CatoAbstract:Annually laminated (Varved) sediments from the River Angermanalven, mid-central Sweden, have been used to construct an annual 2000-year long record of Varve thickness. Maximum daily annual discharge and mean Varve thickness for the years 1909-1971 are significantly correlated (r = 0.87). A relationship between maximum daily annual discharge for the observed period (1909-1971) and Varve thickness was determined. The return time of two exceptionally thick Varves in the 2000-year long record at the years 658 and 492 AD were estimated and their likelihood estimated based on a Gumbel frequency analysis. (C) 2002 Elsevier Science B.V. All rights reserved.
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The relationship between annual Varve thickness and maximum annual discharge (1909–1971)
Journal of Hydrology, 2002Co-Authors: Mikkel Sander, Lars Bengtsson, Björn Holmquist, Barbara Wohlfarth, Ingemar CatoAbstract:Annually laminated (Varved) sediments from the River Angermanalven, mid-central Sweden, have been used to construct an annual 2000-year long record of Varve thickness. Maximum daily annual discharge and mean Varve thickness for the years 1909-1971 are significantly correlated (r = 0.87). A relationship between maximum daily annual discharge for the observed period (1909-1971) and Varve thickness was determined. The return time of two exceptionally thick Varves in the 2000-year long record at the years 658 and 492 AD were estimated and their likelihood estimated based on a Gumbel frequency analysis. (C) 2002 Elsevier Science B.V. All rights reserved
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An evaluation of the Late Weichselian Swedish Varve chronology based on cross-correlation analysis
GFF, 1998Co-Authors: Björn Holmquist, Barbara WohlfarthAbstract:Abstract The Swedish Varve chronology is based on the correlation of overlapping Varve-thickness diagrams. The traditional visual match between single diagrams has been based on, e.g., significant yearly thickness variations or specific marker Varves, but attempts to verify these correlations by statistical methods are rare. To test if these visual correlations can be regarded as correct, i.e. statistically significant, we applied cross-correlation measures to overlapping Varve diagrams from two local Varve chronologies established in southeastern Sweden. Out of a total of 363 analysed connections, only 78 were found to fulfill the statistical requirements for a perfect match. In 96 cases the statistical measures suggested alternative placements to the published links. However, we found that for 179 correlations the published Varve-diagram connections are statistically not valid and that in 11 cases the overlap between diagrams is too short to allow for valid cross-correlation analysis. This large number ...
Tiit Hang - One of the best experts on this subject based on the ideXlab platform.
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A local clay-Varve chronology of Onega Ice Lake, NW Russia
Quaternary International, 2019Co-Authors: Tiit Hang, Viktor Gurbich, Dmitri Subetto, V. D. Strakhovenko, Maksim Potakhin, Nataliya Belkina, Mikhail ZobkovAbstract:Abstract Onega Ice Lake developed in front of the receding Late Weichselian ice margin in Russian Karelia. Glacial Varves that formed in Onega Ice Lake have been earlier studied by means of Varve counts, palaeomagnetism and 14C AMS dates from small lakes north of modern Lake Onega and from Lake Onega proper. Synchronous changes in magnetic parameters and similar stratigraphy of these Varve records together with the existence of basin-wide marker interval of pink-coloured Varves have been used for core-to-core correlation and palaeogeographic interpretations. Unfortunately, there are missing Varve-to-Varve correlations between these cores. We present a 1155 yr long local Varve chronology based on 3 parallel overlapping cores from two small lakes in the Zaonezhsky Peninsula at the northern coast of Lake Onega. Varve counts and matching of Varve series were made from digital images. Following the textural, structural, colour and thickness changes of Varves within Onega Ice Lake Varve series, six characteristic Varve units are identified. These clay units reflect changing sedimentary conditions at the time of accumulation that in general can be interpreted as a progressively increasing distance to the retreating ice margin. Variations in Varve thickness superimposed on that overall trend, namely two episodes of abrupt and consistent decrease in Varve thickness, do not correspond to known lake-level changes or shifts in outflow directions. AMS chronology for deglaciation of Lake Onega basin gives some evidences for correlation of above intervals of decreased Varve thickness with the GI-1c2 and GI-1B cold events in NGRIP δ 18O event stratigraphy but further age estimations are needed to confirm presented correlations. Interval of reddish-brown Varves – earlier described also as the ‘pink horizon’ – was observed in all studied sequences, and according to Varve correlation, at the same stratigraphical level, which proves its basin-wide synchronous appearance. Ca 100 km south of our study area, Saarnisto and Saarinen (2001) reported ca 200 more Varves compared to our results. Visual correlation of Varve thickness graphs places these extra Varves to the proximal part of the series and indicate a rapid ice recession from the main lake basin to the northern Lake Onega area with the ice recession rate ca 500 m per year.
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Lateglacial cryptotephra detected within clay Varves in Östergötland, south-east Sweden
Journal of Quaternary Science, 2014Co-Authors: Alison Macleod, Tiit Hang, Lars Brunnberg, Stefan Wastegard, Ian MatthewsAbstract:Here we present a 710-year-long floating Varve record from south-east Sweden. Tephra analyses confirm the presence of the rhyolitic Vedde Ash preserved within two consecutive Varve years, confirming the Younger Dryas age of the Varve series. This permits, for the first time, direct correlation of Swedish Varved clay with other records of equivalent resolution which also preserve the Vedde Ash and demonstrates that the potential exists to independently date the Swedish Timescale. This discovery will allow direct comparison of rates, timing and duration of key climatic events across Europe and the North Atlantic region in records of equivalent resolution.
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Glacial Varves at Pärnu, south-western Estonia: a local Varve chronology and proglacial sedimentary environment
GFF, 2013Co-Authors: Tiit Hang, Marko KohvAbstract:A new Varve chronology comprising 584 consecutive Varve years, Varve thickness changes and proglacial sedimentary environment are analysed across the Pandivere–Neva (>13 300 yr BP) belt of ice-recessional formations in coastal Estonia, eastern Baltic. Varved clays in the area have been deposited in the Baltic Ice Lake. All investigated sequences display a normal Varve series with decreasing Varve thickness upwards. According to the Varve correlation, two groups of Varve graphs could be distinguished: those representing sequences from the distal side and from the proximal side of the Pandivere–Neva ice marginal formations. Accumulation of Varved clays started ca. 100 yr earlier in the distal part. A massive clay unit with corresponding 20 silty Varves in some sequences precedes the beginning of Varve formation at the proximal part of the basin and could therefore correspond to a ca. 20 yr long ice-stagnation period during the Pandivere–Neva Stade. Ice proximal conditions on both sides of the recessional fo...
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A local clay‐Varve chronology and proglacial sedimentary environment in glacial Lake Peipsi, eastern Estonia
Boreas, 2008Co-Authors: Tiit HangAbstract:Ten cores consisting of Varved clay from the northern part of Lake Peipsi in eastern Estonia have been correlated using Varve thickness variations and specific marker Varves into a 375-year floating Varve chronology. Continuous sedimentation during gradual ice recession is concluded from a clear transition from proximal to distal Varves. Cyclic variations in Varve thickness are caused mainly by thickness changes of clayey winter layers. This is interpreted to indicate increased influx of finer material due to faster melting of the glacier. The cyclic pattern of thickness change is explained by alternating periods of increased and decreased melting of the ice. Simultaneous accumulation of Varved clay in glacial Lake Peipsi and in the Luga and Neva basins of Russia is concluded from the good visual correlation between the mean Varve thickness diagrams for the three chronologies. Because the Varve chronologies from northwestern Russia have been tentatively correlated to the Swedish Varve chronology, the timing of the clay accumulation in glacial Lake Peipsi is placed between c. 13500 and 13100 Varve years BP.
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correlation of stadial and interstadial events in the south swedish glacial Varves with the grip oxygen isotope record
Boreas, 2003Co-Authors: Bertil Ringberg, Jonas Bjorck, Tiit HangAbstract:A number of correlated Varve sequences from the local Varve chronology in southeastern Sweden have been selected to make a 1040 Varve years long mean Varve thickness curve. Pollen analyses were carried out over an interval of 373 Varve years in the northern part of the study area. The pollen stratigraphical data have been divided into local pollen assemblage zones which have been correlated with the radiocarbon-dated regional pollen assemblage zones. Based on variations in herb and tree pollen content of the analysed Varve sequences, it has been possible to identify well-documented lateglacial pollen zones for southern Sweden, i.e. the Bolling interstadial (GI-1e), the Older Dryas cold event (GI-1d) and the early part of the Allerod interstadial (GI-1c). The event stratigraphy in this study, based on varying Varve thicknesses and the composition of the pollen flora in the Varves, has been correlated with the oxygen isotope stratigraphy of the GRIP ice-core on Greenland between 13600 and 14400 GRIP ice-core years BP. It is concluded that five decadal warm events and one centennial warm event (15–60 and 100 Varve years long, respectively) occur in the clay Varve record along with one centennial cold event (150 Varve years long), the Older Dryas (GI-1d).
Barbara Wohlfarth - One of the best experts on this subject based on the ideXlab platform.
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An 800‐year long, radiocarbon‐dated Varve chronology from south‐eastern Sweden
Boreas, 2008Co-Authors: Barbara Wohlfarth, Göran Possnert, Svante Björck, Björn HolmquistAbstract:More than 50 Varve-thickness diagrams, which were established from glacial Varved clays in south-eastern Sweden were correlated with each other to form an 800-year long floating Varve chronology. AMS C-14 measurements on terrestrial macrofossils from the
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an 800 year long radiocarbon dated Varve chronology from south eastern sweden
Boreas, 2008Co-Authors: Barbara Wohlfarth, Göran Possnert, Svante Björck, Björn HolmquistAbstract:More than 50 Varve-thickness diagrams, which were established from glacial Varved clays in south-eastern Sweden were correlated with each other to form an 800-year long floating Varve chronology. AMS C-14 measurements on terrestrial macrofossils from the
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the relationship between annual Varve thickness and maximum annual discharge 1909 1971
Journal of Hydrology, 2002Co-Authors: Mikkel Sander, Lars Bengtsson, Björn Holmquist, Barbara Wohlfarth, Ingemar CatoAbstract:Annually laminated (Varved) sediments from the River Angermanalven, mid-central Sweden, have been used to construct an annual 2000-year long record of Varve thickness. Maximum daily annual discharge and mean Varve thickness for the years 1909-1971 are significantly correlated (r = 0.87). A relationship between maximum daily annual discharge for the observed period (1909-1971) and Varve thickness was determined. The return time of two exceptionally thick Varves in the 2000-year long record at the years 658 and 492 AD were estimated and their likelihood estimated based on a Gumbel frequency analysis. (C) 2002 Elsevier Science B.V. All rights reserved.
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The relationship between annual Varve thickness and maximum annual discharge (1909–1971)
Journal of Hydrology, 2002Co-Authors: Mikkel Sander, Lars Bengtsson, Björn Holmquist, Barbara Wohlfarth, Ingemar CatoAbstract:Annually laminated (Varved) sediments from the River Angermanalven, mid-central Sweden, have been used to construct an annual 2000-year long record of Varve thickness. Maximum daily annual discharge and mean Varve thickness for the years 1909-1971 are significantly correlated (r = 0.87). A relationship between maximum daily annual discharge for the observed period (1909-1971) and Varve thickness was determined. The return time of two exceptionally thick Varves in the 2000-year long record at the years 658 and 492 AD were estimated and their likelihood estimated based on a Gumbel frequency analysis. (C) 2002 Elsevier Science B.V. All rights reserved
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AMS radiocarbon measurements from the Swedish Varved clays.
Radiocarbon, 2000Co-Authors: Barbara Wohlfarth, Göran PossnertAbstract:The Swedish Varve chronology, or Swedish Time Scale, is an annual chronology based upon the successive correlation of more than 1000 Varve-thickness diagrams. The Late Glacial-Early Holocene Varved clays were deposited as glaciolacustrine sediments in the Baltic Sea during the recession of the Scandinavian ice sheet. Formation of Varved clays continued throughout the Holocene and is still going on in the estuary of River Angermanalven in northern Sweden. Accelerator mass spectrometry (AMS) radiocarbon measurements, which have been performed on terrestrial plant macrofossils extracted from the Varved clays, show--in comparison with other annual chronologies--that several hundreds of Varve years are missing in the Varve chronology. These findings are supported by, among others, pollen stratigraphic investigations on time-equivalent Varve year intervals. If an effort were undertaken to evaluate the erroneous parts, the Swedish Time Scale would have the potential of becoming a continuous annual chronology.
Göran Possnert - One of the best experts on this subject based on the ideXlab platform.
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An 800‐year long, radiocarbon‐dated Varve chronology from south‐eastern Sweden
Boreas, 2008Co-Authors: Barbara Wohlfarth, Göran Possnert, Svante Björck, Björn HolmquistAbstract:More than 50 Varve-thickness diagrams, which were established from glacial Varved clays in south-eastern Sweden were correlated with each other to form an 800-year long floating Varve chronology. AMS C-14 measurements on terrestrial macrofossils from the
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an 800 year long radiocarbon dated Varve chronology from south eastern sweden
Boreas, 2008Co-Authors: Barbara Wohlfarth, Göran Possnert, Svante Björck, Björn HolmquistAbstract:More than 50 Varve-thickness diagrams, which were established from glacial Varved clays in south-eastern Sweden were correlated with each other to form an 800-year long floating Varve chronology. AMS C-14 measurements on terrestrial macrofossils from the
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Radiocarbon dating of the Goti‐Finiglacial boundary of the Swedish Time Scale
Boreas, 2008Co-Authors: Lars Brunnberg, Göran PossnertAbstract:While working with the revision of the Swedish Time Scale, based on clay-Varve chronology, mollusc shells of Portlandia (Yoldia) arctica were found in the clay at Ekensberg, Stockholm, Sweden, deposited at the beginning of the Finiglacial epoch. The clay-Varves have been connected with the revised Swedish Time Scale and the time for deposition is 10,370 clay-Varve years cal BP. Shells of bivalves, shell fragments and periostracum have been AMS radiocarbon-dated at the The Svedberg Laboratory in Uppsala. The 11 radiometric datings are grouped in two assemblages, one between 10,500 and 11,600 BP (shell carbonate) and one between 8200 and 9100 BP (periostracum). These results are compared with the radiocarbon age obtained for a fish skeleton (Salmo alpinus) found in Varved clay close to Ekensberg during the geological mapping of the area. The age of the fish is 8600 BP, which is in agreement with the periostracum datings. Reservoir effects and calibration of the radiocarbon ages (BP) to sidereal years (cal BP) are discussed.
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AMS radiocarbon measurements from the Swedish Varved clays.
Radiocarbon, 2000Co-Authors: Barbara Wohlfarth, Göran PossnertAbstract:The Swedish Varve chronology, or Swedish Time Scale, is an annual chronology based upon the successive correlation of more than 1000 Varve-thickness diagrams. The Late Glacial-Early Holocene Varved clays were deposited as glaciolacustrine sediments in the Baltic Sea during the recession of the Scandinavian ice sheet. Formation of Varved clays continued throughout the Holocene and is still going on in the estuary of River Angermanalven in northern Sweden. Accelerator mass spectrometry (AMS) radiocarbon measurements, which have been performed on terrestrial plant macrofossils extracted from the Varved clays, show--in comparison with other annual chronologies--that several hundreds of Varve years are missing in the Varve chronology. These findings are supported by, among others, pollen stratigraphic investigations on time-equivalent Varve year intervals. If an effort were undertaken to evaluate the erroneous parts, the Swedish Time Scale would have the potential of becoming a continuous annual chronology.
