scholarly journals 14C Dating of Plant Macrofossils in Lake Sediment

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 411-416 ◽  
Author(s):  
Michael Andree ◽  
Hans Oeschger ◽  
Ulrich Siegenthaler ◽  
Trudi Riesen ◽  
Markus Moell ◽  
...  
Keyword(s):  
Aquatic Plant ◽  
Hard Water ◽  
Late Glacial ◽  
Plant Macrofossils ◽  
Water Effect ◽  
Terrestrial Plants ◽  
14C Dating ◽  
Pollen Zone ◽  
Swiss Plateau ◽  
Terrestrial Material

Macrofossils of terrestrial plants have been picked from a sediment core taken in Lake Lobsigen, a small lake on the Western Swiss Plateau. The sediments were previously analyzed for pollen composition, plant and animal macrofossils, and stable isotopes. Plant macrofossils were selected near pollen zone boundaries in Late Glacial and early Postglacial sediment for 14C dating by AMS. In the same lake carbonate and gyttja (aquatic plant) samples were dated by decay counting. The dates on terrestrial material are generally younger than those on carbonate and gyttja, ie, material reflecting the 14C/C ratio of dissolved bicarbonate in lake water. This is probably due to a contribution of dissolved limestone carbonate and thus a somewhat reduced 14C/C ratio in the lake's water (hard water effect).

Accelerator-Mass Spectrometer Ages for Late-Glacial Events at Ballybetagh, Ireland

1989 ◽  
Vol 31 (3) ◽  
pp. 377-380 ◽  
Author(s):  
Les C. Cwynar ◽  
W. A. Watts
Keyword(s):  
Mass Spectrometer ◽  
Organic Material ◽  
Younger Dryas ◽  
Hard Water ◽  
Late Glacial ◽  
Water Effect ◽  
Vegetation Development ◽  
Terrestrial Plant ◽  
Plant Remains ◽  
Accelerator Mass Spectrometer

AbstractAlthough the character of late-glacial vegetation development in Ireland is well known, the dating is weak for a number of reasons. We report six accelerator-mass spectrometer (AMS) 14C dates of hand-picked organic material from Ballybetagh. Several of the dates are based on terrestrial plant remains, thus eliminating the commonly encountered problem associated with Irish sites of errors due to the hard-water effect. The two most significant indicate that (1) the Rumex-Salix zone, which represents the initial establishment of vegetation following deglaciation, began about 12,600 yr B.P. and (2) the classic Younger Dryas began at 10,600 yr B.P., somewhat younger than the traditionally accepted age of 11,000 yr B.P.

scholarly journals Comparing Continental Carbonates with Other Materials in Dating a Paleolake

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 619-625 ◽  
Author(s):  
J. F. Garcia ◽  
J. S. Mestres ◽  
Gemma Rauret
Keyword(s):  
Organic Matter ◽  
Aquatic Plants ◽  
Radiocarbon Dating ◽  
Hard Water ◽  
Water Effect ◽  
Terrestrial Plants ◽  
Continental Carbonates ◽  
Age Shift ◽  
Apparent Age

We have studied the application of carbonates and organic matter to the radiocarbon dating of a paleolake. The results show a systematic apparent age shift of these materials with respect to contemporary wood. The apparent age of carbonates is evidently due to the hard-water effect, whereas the apparent age of organic matter, systematically younger than carbonates, is attributed to aquatic plants, which metabolize dissolved CO2. Terrestrial plants that deposit organic matter also cause apparent age discrepancies between carbonates and organic matter.

The DeKalb mounds of northeastern Illinois as archives of deglacial history and postglacial environments

2010 ◽  
Vol 74 (1) ◽  
pp. 82-90 ◽  
Author(s):  
B. Brandon Curry ◽  
Michael E. Konen ◽  
Timothy H. Larson ◽  
Catherine H. Yansa ◽  
Keith C. Hackley ◽  
...  
Keyword(s):  
Aquatic Plant ◽  
Lake Michigan ◽  
Plant Macrofossils ◽  
Terrestrial Plants ◽  
Type Region ◽  
Plant Fossils ◽  
Type Area ◽  
Sand And Gravel ◽  
Topographic Inversion

AbstractThe “type” DeKalb mounds of northeastern Illinois, USA (42.0°N, −88.7°W), are formed of basal sand and gravel overlain by rhythmically bedded fines, and weathered sand and gravel. Generally from 2 to 7 m thick, the fines include abundant fossils of ostracodes and uncommon leaves and stems of tundra plants. Rare chironomid head capsules, pillclam shells, and aquatic plant macrofossils also have been observed.Radiocarbon ages on the tundra plant fossils from the “type” region range from 20,420 to 18,560 cal yr BP. Comparison of radiocarbon ages of terrestrial plants from type area ice-walled lake plains and adjacent kettle basins indicate that the topographic inversion to ice-free conditions occurred from 18,560 and 16,650 cal yr BP. Outside the “type” area, the oldest reliable age of tundra plant fossils in DeKalb mound sediment is 21,680 cal yr BP; the mound occurs on the northern arm of the Ransom Moraine (−88.5436°W, 41.5028°N). The youngest age, 16,250 cal yr BP, is associated with a mound on the Deerfield Moraine (−87.9102°W, 42.4260°N) located about 9 km east of Lake Michigan. The chronology of individual successions indicates the lakes persisted on the periglacial landscape for about 300 to 1500 yr.

scholarly journals 14C Dating of Terrestrial Moss in Tern Lake Deposits, Antarctica

Radiocarbon ◽  
1997 ◽  
Vol 40 (2) ◽  
pp. 849-854 ◽  
Author(s):  
Chengde Shen ◽  
Tungsheng Liu ◽  
Weixi Yi ◽  
Yanmin Sun ◽  
Mantao Jiang ◽  
...  
Keyword(s):  
Liquid Scintillation ◽  
Hard Water ◽  
14C Dating ◽  
Environment Effect ◽  
Terrestrial Moss ◽  
Glacial Epoch ◽  
Latitude Effect ◽  
Drill Holes ◽  
Lake Deposits ◽  
The Last Glacial

Accurate radiocarbon ages were obtained from terrestrial moss from two drill holes in Tern Lake deposits, Antarctica, using liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS). The results show that the lake deposits have been accumulating since the end of the last glacial epoch ca. 12,600 cal BP at the rate of 0.13–1.1 mm a-1. We discuss the validity of 14C ages of Antarctic lake deposits, with respect to the latitude effect of 14C productivity, the reservoir effect, the environment effect and the hard-water effect.

scholarly journals Atmospheric Radiocarbon at the End of the Last Glacial: An Estimate Based on AMS Radiocarbon Dates on Terrestrial Macrofossils From Lake Sediments

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 795-804 ◽  
Author(s):  
Hugo Zbinden ◽  
Michael Andree ◽  
Hans Oeschger ◽  
Brigitta Ammann ◽  
Andre Lotter ◽  
...  
Keyword(s):  
Mass Spectroscopy ◽  
Calibration Curve ◽  
Hard Water ◽  
Sedimentation Rates ◽  
Local Effects ◽  
Data Set ◽  
Radiocarbon Dates ◽  
Pollen Zone ◽  
Plant Remains ◽  
The Last Glacial

The main purpose of this work is to reconstruct the atmospheric Δ 14C in the glacial-postglacial transition, 14,000 – 10,000 BP, a range not covered by the tree-ring calibration curve. We measured 14C/12C ratios on series of terrestrial macrofossils from sediments of two Swiss lakes. We selected exclusively plant remains of recognizable terrestrial origin that are not affected by hard water and thus reflect atmospheric 14C concentration. Due to the scarcity of such material, we used accelerator mass spectroscopy. Cores of two lakes were measured to eliminate local effects and to check the reproducibility of results. This required a reliable, 14C-independent correlation of the cores, obtained through local pollen zone boundaries 14C ages were obtained as a function of the depth in the cores. If sedimentation rates are known ages can be converted into Δ 14C values. We also attempted estimating sedimentation rates; calculations are based on the Swedish varve chronology. Results were combined to form an entire data set. The Δ 14C curve shows an increase with time during the Allerød and decreases during Preboreal and Bølling periods. Probabilities for these 14C variations are discussed.

The age of the Hartman moraine and the Campbell beach of Lake Agassiz in northwestern Ontario

1982 ◽  
Vol 19 (10) ◽  
pp. 1933-1937 ◽  
Author(s):  
Erik Nielsen ◽  
W. Brian McKillop ◽  
James P. McCoy
Keyword(s):  
Water Level ◽  
Hard Water ◽  
High Water ◽  
Water Effect ◽  
Lake Agassiz ◽  
Red Clay ◽  
Radiocarbon Dates ◽  
Freshwater Molluscs ◽  
Northwestern Ontario ◽  
Freshwater Mollusc

Fluctuations in the level of Lake Agassiz are dated at two sites in northwestern Ontario. A radiocarbon date on a modern shell sample indicates dates on freshwater molluscs from the area are about 440 ± 100 years (GSC-3281) too old due to the hard-water effect. An adjustment of 400 years to two fossil freshwater mollusc dates of 11 400 ± 410 (GSC-3114) and 10 400 ± 100 years BP (GSC-2968) makes them compatible with radiocarbon dates on wood from deposits in other parts of the Lake Agassiz basin. The two new dates indicate the beginning of the low-water Moorhead Phase of Lake Agassiz started about 11 000 years BP. The high-water Emerson Phase started when the water level rose to form the Upper Campbell beach approximately 10 000 years BP. The red clay widely distributed throughout northwestern Ontario was deposited during the Emerson Phase when the ice margin lay along the Hartman, Dog Lake, and Marks moraines.

scholarly journals Stepped-Combustion 14C Dating of Sediment: A Comparison with Established Techniques

Radiocarbon ◽  
2001 ◽  
Vol 43 (2A) ◽  
pp. 255-261 ◽  
Author(s):  
J McGeehin ◽  
G S Burr ◽  
A J T Jull ◽  
D Reines ◽  
J Gosse ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Clay Minerals ◽  
Radiocarbon Dating ◽  
Age Determination ◽  
Clay Content ◽  
Plant Macrofossils ◽  
Bulk Sediment ◽  
14C Dating ◽  
Organic Carbon Fractions ◽  
Sediment Age

Radiocarbon dating of bulk sediment has long been used as a method of last resort when reliable wood, charcoal, or plant macrofossils are not available for analysis. Accurate dating of sediment is complicated by the presence of multiple organic carbon fractions, each with a potentially different 14C activity. Additionally, the presence of carbon bound by clay minerals can significantly reduce the accuracy of a sediment age determination, with the oldest 14C ages seen in samples with the highest clay content (Scharpenseel and Becker-Heidmann 1992).

scholarly journals Recent Reservoir Ages for Danish Fjords and Marine Waters

Radiocarbon ◽  
1995 ◽  
Vol 37 (3) ◽  
pp. 875-882 ◽  
Author(s):  
Susanne Heier-Nielsen ◽  
Jan Heinemeier ◽  
H. L. Nielsen ◽  
Niels Rud
Keyword(s):  
Calibration Curve ◽  
Weighted Average ◽  
Hard Water ◽  
Experimental Uncertainty ◽  
Water Effect ◽  
Layer Model ◽  
Marine Waters ◽  
Marine Samples ◽  
The Difference ◽  
Reservoir Age

AMS 14C dates were measured for 28 mollusk shells collected live in Danish waters over the period ad 1885 to 1945. Fourteen samples were from fjords and 14 were marine samples from the Danish Skagerrak-Kattegat coastal area and from the Belts. Reservoir ages were calculated for all samples on the basis of the tree-ring calibration curve. For the marine samples, which cover the period ad 1885–1916, we found a weighted-average reservoir age of 377 ± 16 yr. The marine ∆R values (the difference between the measured 14C age and the age deduced from marine, mixed-layer model calculation of Stuiver, Pearson and Braziunas (1986)) were found to be uniform within the experimental uncertainty with a weighted average of ∆R = 13 ± 16 yr. Based on the observed scatter, the standard deviation is 21 yr. This result shows that it is justified to use the marine calibration curve with standard parameters (∆R = 0) when 14C-dating marine samples from the Danish area. Our value is consistent with the result ∆R = −33 ± 27 yr previously found for the Norwegian and Swedish Skagerrak-Kattegat coasts. In contrast, reservoir ages for Danish fjords were found to vary from 400 to >900 yr, far beyond experimental uncertainty. We ascribe this to varying content of dissolved, old soil carbonate (hard-water effect). Therefore, dating of samples from such fjord environments is expected to be uncertain by several hundred years.

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