scholarly journals AMS Radiocarbon Measurements from the Swedish Varved Clays

Radiocarbon ◽  
2000 ◽  
Vol 42 (3) ◽  
pp. 323-333 ◽  
Author(s):  
Barbara Wohlfarth ◽  
Göran Possnert
Keyword(s):  
Mass Spectrometry ◽  
Accelerator Mass Spectrometry ◽  
Time Scale ◽  
Late Glacial ◽  
Plant Macrofossils ◽  
Northern Sweden ◽  
The Baltic Sea ◽  
Varve Chronology ◽  
Scandinavian Ice Sheet ◽  
The Baltic

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 ångermanälven 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.

scholarly journals Towards a Radiocarbon Chronology of the Late-Glacial: Sample Selection Strategies

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 1007-1019 ◽  
Author(s):  
M J C Walker ◽  
C Bryant ◽  
G R Coope ◽  
D D Harkness ◽  
J J Lowe ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Accelerator Mass Spectrometry ◽  
Sample Selection ◽  
Late Glacial ◽  
Plant Macrofossils ◽  
Sampling Strategies ◽  
Radiocarbon Dates ◽  
Selection Strategies ◽  
Beta Counting ◽  
Radiocarbon Chronology

This paper outlines a dating program designed to test the reproducibility of radiocarbon dates on different materials of Late-Glacial age (plant macrofossils, fossil beetle remains, and the “humic” and “humin” chemical fractions of limnic sediments) using a combination of radiometric (beta counting) and accelerator mass spectrometry (AMS) techniques. The results have implications for the design of sampling strategies and for the development of improved dating protocols, both of which are important if a high-precision 14C chronology for the Late-Glacial is to be achieved.

Late-glacial – early Holocene vegetation, climate, and fire at Sutherland Pond, Hudson Highlands, southeastern New York, U.S.A.

1997 ◽  
Vol 75 (3) ◽  
pp. 431-439 ◽  
Author(s):  
Terryanne E. Maenza-Gmelch
Keyword(s):  
Mass Spectrometry ◽  
New York ◽  
Picea Abies ◽  
Accelerator Mass Spectrometry ◽  
Minor Component ◽  
Late Glacial ◽  
Plant Macrofossils ◽  
Rapid Onset ◽  
Hudson Valley ◽  
Early Woodland

Accelerator mass spectrometry dated pollen, plant-macrofossil, and charcoal records from Sutherland Pond (41°23′29″N, 74°02′16″W), located in the Black Rock Forest, provide a detailed account of forest history during the late-glacial – Holocene transition in the Hudson Highlands, lower Hudson Valley, southeastern New York. Pollen assemblages dating more than 12 600 radiocarbon years before present (years BP) are dominated by herbaceous and shrub types (Salix, Betula, Alnus, Ericaceae, Cyperaceae, Gramineae, and Tubuliflorae), with some arboreal types (Pinus and Picea), apparently representing an open landscape possibly with scattered trees. At 12 600 years BP increased organic deposition and pollen influx and the first occurrence of macrofossils indicate dramatic environmental change. Mixed assemblages of boreal and temperate taxa (Picea, Abies, Betula papyrifera, Quercus, Ostrya – Carpinus, and Fraxinus) are evident from 12 600 to 11 200 years BP. Low charcoal influx suggests that fire was a minor component of early woodland development beginning around 12 600 years BP. A Picea–Abies–Alnus assemblage, suggesting a cool climatic episode, dominates between 11 200 and 10 120 years BP, with rapid onset and termination each occurring within 150 years. Fire activity is also low during this colder interval. Warmer conditions, reestablished by 10 120 years BP, are inferred from expansion of Pinus strobus and increasing Quercus and Ostrya–Carpinus, followed by replacement of B. papyrifera by Betula populifolia and increased charcoal influx. Key words: late glacial, pollen, plant macrofossils, fire, accelerator mass spectrometry radiocarbon dating, New York.

scholarly journals Quality Dating: A Well-Defined Protocol Implemented at ETH for High-Precision 14C-Dates Tested on Late Glacial Wood

Radiocarbon ◽  
2019 ◽  
Vol 62 (4) ◽  
pp. 891-899 ◽  
Author(s):  
Adam Sookdeo ◽  
Bernd Kromer ◽  
Ulf Büntgen ◽  
Michael Friedrich ◽  
Ronny Friedrich ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tree Ring ◽  
High Precision ◽  
Accelerator Mass Spectrometry ◽  
Late Glacial ◽  
Tree Ring Chronology ◽  
Continuous Measurements ◽  
Calibration Curves

ABSTRACTAdvances in accelerator mass spectrometry have resulted in an unprecedented amount of new high-precision radiocarbon (14C) -dates, some of which will redefine the international 14C calibration curves (IntCal and SHCal). Often these datasets are unaccompanied by detailed quality insurances in place at the laboratory, questioning whether the 14C structure is real, a result of a laboratory variation or measurement-scatter. A handful of intercomparison studies attempt to elucidate laboratory offsets but may fail to identify measurement-scatter and are often financially constrained. Here we introduce a protocol, called Quality Dating, implemented at ETH-Zürich to ensure reproducible and accurate high-precision 14C-dates. The protocol highlights the importance of the continuous measurements and evaluation of blanks, standards, references and replicates. This protocol is tested on an absolutely dated German Late Glacial tree-ring chronology, part of which is intercompared with the Curt Engelhorn-Center for Archaeometry, Mannheim, Germany (CEZA). The combined dataset contains 170 highly resolved, highly precise 14C-dates that supplement three decadal dates spanning 280 cal. years in IntCal, and provides detailed 14C structure for this interval.

Misunderstandings Concerning the Significance of AMS Background 14C Measurements

Radiocarbon ◽  
2018 ◽  
Vol 60 (3) ◽  
pp. 727-749
Author(s):  
R E Taylor ◽  
John R Southon ◽  
Guaciara M Santos
Keyword(s):  
Mass Spectrometry ◽  
Accelerator Mass Spectrometry ◽  
Time Scale ◽  
Point Of View ◽  
General Validity ◽  
General Audience ◽  
Background Levels ◽  
Age Determinations

ABSTRACTWe consider one misconception of those who currently reject the general validity of radiocarbon (14C) age determinations older than, at most, 10,000 BP. There is an allegation that the presence of 14C reported by accelerator mass spectrometry (AMS) laboratories in their measurements of 14C infinite age (>100,000 years) organics used to define background levels, support their point of view. This article has been written for a general audience, primarily for those who have questions about the validity of these arguments. However, they may not be familiar with the literature relevant to providing a clear response to the claims of these individuals. We conclude that, in our view, of all of the possible explanations for the reports of the presence of 14C in these background samples, the least probable explanation has been advanced by those rejecting the validity of the 14C time scale in excess of, at most, 10,000 BP.

scholarly journals Population structure of five native sheep breeds of Sweden estimated with high density SNP genotypes

BMC Genetics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Christina Marie Rochus ◽  
Elisabeth Jonas ◽  
Anna M. Johansson
Keyword(s):  
Population Structure ◽  
Snp Array ◽  
Principal Component ◽  
Northern Sweden ◽  
The Baltic Sea ◽  
Sheep Breeds ◽  
The North ◽  
South West ◽  
Branch Lengths ◽  
The Baltic

Abstract Background Native Swedish sheep breeds are part of the North European short-tailed sheep group; characterized in part by their genetic uniqueness. Our objective was to study the population structure of native Swedish sheep. Five breeds were genotyped using the 600 K SNP array. Dalapäls and Klövsjö sheep are from the middle of Sweden; Gotland and Gute sheep from Gotland, an island in the Baltic Sea; and Fjällnäs sheep from northern Sweden. We studied population structure by: principal component analysis (PCA), cluster-based analysis of admixture, and an estimated population tree. Results The analyses of the five Swedish breeds revealed that these breeds are five distinct breeds, while Gute and Gotland are more closely related to each other as seen in all analyses. All breeds had long branch lengths in the population tree indicating they’ve been subjected to drift. We repeated our analyses using 39 K SNP and including 50 K SNP genotypes from other European and southwestern Asian breeds from the Sheep HapMap project and 600 K SNP genotypes from a dataset of French sheep. Results arranged breeds into five groups: south-west Asia, south-west Europe, central Europe, north Europe and north European short-tailed sheep. Within this last group, Norwegian and Icelandic breeds, Finn and Romanov sheep, Scottish breeds, and Gute and Gotland sheep were more closely related while the remaining Swedish breeds and Ouessant sheep were distinct from all breeds and had longer branches in the population tree. Conclusions We showed population structure of five Swedish breeds and their structure within European and southwestern Asian breeds. Swedish breeds are unique, distinct breeds that have been subjected to drift but group with other north European short-tailed sheep.

Stages of the Baltic Sea evolution in the geochemical record and radiocarbon dating of sediment cores from the Arkona Basin

2014 ◽  
Vol 43 (3) ◽  
Author(s):  
Robert Kostecki
Keyword(s):  
Baltic Sea ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Late Glacial ◽  
Sudden Increase ◽  
The Baltic Sea ◽  
Geochemical Composition ◽  
Arkona Basin ◽  
The Baltic ◽  
Ancylus Lake

AbstractFour sediment cores from the southern part of the Arkona Basin were analyzed in terms of their geochemical composition, age and stratigraphy. The main stages of the Baltic Sea: the Baltic Ice Lake, the Ancylus Lake and the Littorina Sea were identified in all the analyzed cores. The data confirmed the high water fluctuation and significant environmental changes during the Baltic Sea evolution in the Late-Glacial and the Holocene. The signs of the second regression of the Baltic Ice Lake, dated at around 11 000 cal BP, were identified at a depth of 24 m b.s.l. Regression of the Ancylus Lake, dated at 9300 cal BP, was identified at a depth of 23 m b.s.l. The most pronounced period was the transition stage between the Ancylus Lake and the Littorina Sea. The record of the Littorina Sea onset in the sediments of the Arkona Basin is marked as a sudden increase in loss on ignition, biogenic silica, magnesium, calcium, iron and strontium. The age of the Littorina Sea in the Arkona Basin was estimated as younger than 8200 cal BP.

scholarly journals Accelerator Mass Spectrometry at Arizona: Geochronology of the Climatic Record and Connections with the Ocean

2002 ◽  
Vol 2 ◽  
pp. 1579-1593 ◽  
Author(s):  
J.T. Jull ◽  
G.S. Burr ◽  
J.W. Beck ◽  
D.J. Donahue ◽  
D. Biddulph ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Radioactive Waste ◽  
Environmental Conditions ◽  
Accelerator Mass Spectrometry ◽  
Time Scale ◽  
Southern Oscillation ◽  
Waste Dump ◽  
Short Term ◽  
Millennial Time Scale ◽  
Climatic Record

There are many diverse uses of accelerator mass spectrometry (AMS).14C studies at our laboratory include much research related to paleoclimate, with14C as a tracer of past changes in environmental conditions as observed in corals, marine sediments, and many terrestrial records. Terrestrial records can also show the influence of oceanic oscillations, whether they are short term, such as ENSO (El Niño/Southern Oscillation), or on the millennial time scale. In tracer applications, we have developed the use of129I as well as14C as tracers for nuclear pollution studies around radioactive waste dump sites, in collaboration with IAEA. We discuss some applications carried out in Tucson, AZ, for several of these fields and hope to give some idea of the breadth of these studies.

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