The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Peter Trimborn - One of the best experts on this subject based on the ideXlab platform.
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a stable isotope tree ring timescale of the Late Glacial holocene boundary
Nature, 1991Co-Authors: Bernd Becker, Bernd Kromer, Peter TrimbornAbstract:Late Glacial and Holocene tree-ring chronologies, like deep-sea sediments or polar ice cores, contain information about past environments. Changes in tree-ring growth rates can be reLated to past climate anomalies and changes in the isotope composition of tree-ring cellulose reflect changes in the composition of the atmosphere and the hydrosphere. We have established a 9,928-year absolutely dated dendrochronological record of Holocene oak (Quercus robur, Quercus petraea)—and a 1,604-year floating Late Glacial and Early Holocene chronology of pine (Pinus sylvestris) from subfossil tree remnants deposited in alluvial terraces of south central European rivers. The pine sequence provides records of dendro-dated 14C, 13C and 2H patterns for the Late Younger Dryas and the entire Preboreal (10,100–9,000 yr BP). Through the use of dendrochronology, radiocarbon age calibration and stable isotope analysis, we suggest that the Late Glacial/Holocene transition may be identified and dated by 13C and 2H tree-ring chronologies.
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A stable-isotope tree-ring timescale of the Late Glacial/Holocene boundary
Nature, 1991Co-Authors: Bernd Becker, Bernd Kromer, Peter TrimbornAbstract:Late Glacial and Holocene tree-ring chronologies, like deep-sea sediments or polar ice cores, contain information about past environments. Changes in tree-ring growth rates can be reLated to past climate anomalies and changes in the isotope composition of tree-ring cellulose reflect changes in the composition of the atmosphere and the hydrosphere. We have established a 9,928-year absolutely dated dendrochronological record of Holocene oak (Quercus robur, Quercus petraea)—and a 1,604-year floating Late Glacial and Early Holocene chronology of pine (Pinus sylvestris) from subfossil tree remnants deposited in alluvial terraces of south central European rivers. The pine sequence provides records of dendro-dated 14C, 13C and 2H patterns for the Late Younger Dryas and the entire Preboreal (10,100–9,000 yr BP). Through the use of dendrochronology, radiocarbon age calibration and stable isotope analysis, we suggest that the Late Glacial/Holocene transition may be identified and dated by 13C and 2H tree-ring chronologies.
Ian R. Walker - One of the best experts on this subject based on the ideXlab platform.
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Richness, diversity and succession of Late-Glacial chironomid assemblages in New Brunswick, Canada
Journal of Paleolimnology, 1996Co-Authors: André J. Levesque, Les C. Cwynar, Ian R. WalkerAbstract:Chironomid analysis was performed on Late-Glacial sediment from four New Brunswick lakes in order to gain basic ecological information regarding the richness and diversity of Late-Glacial chironomid assemblages, and to compare the pattern of succession at each site. At all sites, the richness and diversity of the larval assemblages were lowest immediately following deglaciation and during the Younger Dryas, corresponding to the coldest times of the Late-Glacial period. Although cold-stenothermous taxa are characteristic of sediments deposited immediately following deglaciation, as well as during the Killarney Oscillation and Younger Dryas cooling events, the constituent taxa are different at each site. During the intervening warm periods, the larval assemblages at each site are also dissimilar, with the more southern sites containing a greater variety of temperate littoral taxa. This raises the possibility that a north-south temperature gradient existed during the warm intervals of the Late-Glacial period in New Brunswick.
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Wisconsinan Late-Glacial environmental chage in New Brunswick: A regional synthesis
Journal of Quaternary Science, 1994Co-Authors: Les C. Cwynar, André J. Levesque, Francis E. Mayle, Ian R. WalkerAbstract:A synthesis is presented of the history of deglaciation, vegetation cover and climate in New Brunswick, Canada, during that part of the Wisconsinan Late-Glacial period (12-9 ka BP) for which detailed records exist. Curves of inferred temperature variations in the region during this period are presented based upon qualitative interpretations of plant records and quantitative estimates based upon fossil chironomid assemblages.
André F. Lotter - One of the best experts on this subject based on the ideXlab platform.
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Late Glacial radiocarbon and palynostratigraphy on the swiss pLateau
Boreas, 2008Co-Authors: Brigitta Ammann, André F. LotterAbstract:A detailed Late-Glacial radiocarbon stratigraphy for the Swiss PLateau has been established on the basis of over 90 accelerator 14C dates on terrestrial plant macrofossils. Two pLateaux of constant.,14C age were observed, occurring at 12,700 B.P. and at 10,000 B.P. The consequences of these pLateaux for palaeo-ecological investigations are threefold: (1) a more refined 14C dating within the pLateaux is not possible, (2) in teleconnections between different sites (if based on 14C dating and concerning the periods around 12,700 B.P. and 10,000 B.P.) events are considered synchronous which are only synchronous within a pLateau of constant age, and (3) exact time-depth relationship and therefore influx calculations are made impossible during these pLateau periods. A comparison of the radiocarbon ages derived from terrestrial, telmatic and limnic material at different sites on the Swiss PLateau yields a proposal for modifying the zonation system of Welten for the Late-Glacial. By retaining the limits of chronozones (at 13, 12, 11 and 10ka B.P.) and by refining the palynostratigraphic criteria for the limits of biozones, a separation between chrono- and biozonation at the beginning of the Belling and at the beginning of the Younger Dryas becomes obvious.
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Late‐Glacial radiocarbon‐ and palynostratigraphy on the Swiss PLateau
Boreas, 2008Co-Authors: Brigitta Ammann, André F. LotterAbstract:A detailed Late-Glacial radiocarbon stratigraphy for the Swiss PLateau has been established on the basis of over 90 accelerator 14C dates on terrestrial plant macrofossils. Two pLateaux of constant.,14C age were observed, occurring at 12,700 B.P. and at 10,000 B.P. The consequences of these pLateaux for palaeo-ecological investigations are threefold: (1) a more refined 14C dating within the pLateaux is not possible, (2) in teleconnections between different sites (if based on 14C dating and concerning the periods around 12,700 B.P. and 10,000 B.P.) events are considered synchronous which are only synchronous within a pLateau of constant age, and (3) exact time-depth relationship and therefore influx calculations are made impossible during these pLateau periods. A comparison of the radiocarbon ages derived from terrestrial, telmatic and limnic material at different sites on the Swiss PLateau yields a proposal for modifying the zonation system of Welten for the Late-Glacial. By retaining the limits of chronozones (at 13, 12, 11 and 10ka B.P.) and by refining the palynostratigraphic criteria for the limits of biozones, a separation between chrono- and biozonation at the beginning of the Belling and at the beginning of the Younger Dryas becomes obvious.
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The Würmian Late-Glacial in lowland Switzerland
Journal of Quaternary Science, 1994Co-Authors: Brigitta Ammann, André F. Lotter, U. Eicher, Marie-josé Gaillard, Barbara Wohlfarth, Wilfried Haeberli, G. Lister, Max Maisch, F. Niessen, Christian SchlüchterAbstract:A synthesis is provided of Late-Glacial (14-9 ka BP) environmental changes in lowland Switzerland (the 'Swiss PLateau'). The chronology of deglaciation and subsequent developments in vegetation cov ...
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rates of change and chronological problems during the Late Glacial period
Climate Dynamics, 1992Co-Authors: André F. Lotter, Brigitta Ammann, Michael SturmAbstract:Results of high-resolution AMS 14C dating of terrestrial plant macrofossils from Late-Glacial and early-Holocene lake deposits in Switzerland show three periods with constant radiocarbon ages. These pLateaux of constant age occur at 12700, 10000, and 9500 y BP. A comparison of this radiocarbon chronology with a varve chronology documents discrepancies between the sidereal and the radiocarbon time-scale for the Late-Glacial period. The age-pLateaux and the time-scale discrepancies have a significant impact on the estimation of rates of change during this period: estimates of rates of change can be very misleading if calcuLated on the basis of radiocarbon ages. This is illustrated by an example of estimated rates of Late-Glacial and early Holocene palynological change in Switzerland.
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absolute dating of the Late Glacial period in switzerland using annually laminated sediments
Quaternary Research, 1991Co-Authors: André F. LotterAbstract:Abstract Results of a high-resolution Late-Glacial AMS 14C chronology from Rotsee, central Switzerland, have given evidence that the atmospheric radiocarbon concentration was not constant between 13,000 and 9500 yr B.P. This resulted in three marked phases of constant radiocarbon age: at 12,700, at 10,000, and at 9500 yr B.P. New results of a Late-Glacial varve chronology from Soppensee, central Switzerland, suggest that the younger two phases of constant 14C age each had a duration of ca. 400 calendar years. The length of the Late-Glacial chronozones has been calcuLated on the basis of these replicate varve counts and a comparison with their estimated duration in radiocarbon years shows that the estimated duration of the chronozones Bolling (ca. 800 calendar yr vs 1000 14C yr) and Younger Dryas (ca. 900 calendar yr vs 1000 14C yr) agree with the expected time span, whereas the estimated duration of the Allerod chronozone (ca. 400 calendar yr vs 1000 14C yr) is substantially shorter than expected. Furthermore, a tentative comparison of varve ages and 14C ages suggests that the varve chronology is more than 1000 yr offset toward older ages from the radiocarbon chronology during the Late-Glacial period.
Bernd Becker - One of the best experts on this subject based on the ideXlab platform.
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a stable isotope tree ring timescale of the Late Glacial holocene boundary
Nature, 1991Co-Authors: Bernd Becker, Bernd Kromer, Peter TrimbornAbstract:Late Glacial and Holocene tree-ring chronologies, like deep-sea sediments or polar ice cores, contain information about past environments. Changes in tree-ring growth rates can be reLated to past climate anomalies and changes in the isotope composition of tree-ring cellulose reflect changes in the composition of the atmosphere and the hydrosphere. We have established a 9,928-year absolutely dated dendrochronological record of Holocene oak (Quercus robur, Quercus petraea)—and a 1,604-year floating Late Glacial and Early Holocene chronology of pine (Pinus sylvestris) from subfossil tree remnants deposited in alluvial terraces of south central European rivers. The pine sequence provides records of dendro-dated 14C, 13C and 2H patterns for the Late Younger Dryas and the entire Preboreal (10,100–9,000 yr BP). Through the use of dendrochronology, radiocarbon age calibration and stable isotope analysis, we suggest that the Late Glacial/Holocene transition may be identified and dated by 13C and 2H tree-ring chronologies.
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A stable-isotope tree-ring timescale of the Late Glacial/Holocene boundary
Nature, 1991Co-Authors: Bernd Becker, Bernd Kromer, Peter TrimbornAbstract:Late Glacial and Holocene tree-ring chronologies, like deep-sea sediments or polar ice cores, contain information about past environments. Changes in tree-ring growth rates can be reLated to past climate anomalies and changes in the isotope composition of tree-ring cellulose reflect changes in the composition of the atmosphere and the hydrosphere. We have established a 9,928-year absolutely dated dendrochronological record of Holocene oak (Quercus robur, Quercus petraea)—and a 1,604-year floating Late Glacial and Early Holocene chronology of pine (Pinus sylvestris) from subfossil tree remnants deposited in alluvial terraces of south central European rivers. The pine sequence provides records of dendro-dated 14C, 13C and 2H patterns for the Late Younger Dryas and the entire Preboreal (10,100–9,000 yr BP). Through the use of dendrochronology, radiocarbon age calibration and stable isotope analysis, we suggest that the Late Glacial/Holocene transition may be identified and dated by 13C and 2H tree-ring chronologies.
Les C. Cwynar - One of the best experts on this subject based on the ideXlab platform.
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A midge-based Late-Glacial temperature reconstruction from southwestern Nova Scotia
Canadian Journal of Earth Sciences, 2005Co-Authors: Bronwen S. Whitney, Jessie H. Vincent, Les C. CwynarAbstract:We present a quantitative reconstruction of the thermal regime spanning the Late-Glacial period of Nova Scotia (14 700 to 11 600 BP) as inferred by analyzing fossil midges from a small lake (Lac a Magie) in southwestern Nova Scotia. The GS-1 event (equivalent to the Younger Dryas, dating from 12 700 to 11 600 BP in Maritime Canada) was marked by a 5 °C decline in inferred mean July surface-water temperatures and a 15% drop in organic content. Previous pollen and plant macrofossil analyses of this site demonstrate a response of vegetation to GS-1 cooling. These data, coupled with a midge-inferred temperature reconstruction from a nearby site, suggest that Late-Glacial climate change was less pronounced in southern Nova Scotia than in other sites in Maritime Canada and adjacent eastern North America.
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Richness, diversity and succession of Late-Glacial chironomid assemblages in New Brunswick, Canada
Journal of Paleolimnology, 1996Co-Authors: André J. Levesque, Les C. Cwynar, Ian R. WalkerAbstract:Chironomid analysis was performed on Late-Glacial sediment from four New Brunswick lakes in order to gain basic ecological information regarding the richness and diversity of Late-Glacial chironomid assemblages, and to compare the pattern of succession at each site. At all sites, the richness and diversity of the larval assemblages were lowest immediately following deglaciation and during the Younger Dryas, corresponding to the coldest times of the Late-Glacial period. Although cold-stenothermous taxa are characteristic of sediments deposited immediately following deglaciation, as well as during the Killarney Oscillation and Younger Dryas cooling events, the constituent taxa are different at each site. During the intervening warm periods, the larval assemblages at each site are also dissimilar, with the more southern sites containing a greater variety of temperate littoral taxa. This raises the possibility that a north-south temperature gradient existed during the warm intervals of the Late-Glacial period in New Brunswick.
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Wisconsinan Late-Glacial environmental chage in New Brunswick: A regional synthesis
Journal of Quaternary Science, 1994Co-Authors: Les C. Cwynar, André J. Levesque, Francis E. Mayle, Ian R. WalkerAbstract:A synthesis is presented of the history of deglaciation, vegetation cover and climate in New Brunswick, Canada, during that part of the Wisconsinan Late-Glacial period (12-9 ka BP) for which detailed records exist. Curves of inferred temperature variations in the region during this period are presented based upon qualitative interpretations of plant records and quantitative estimates based upon fossil chironomid assemblages.
