Limestone and the problem of radiocarbon dating of land-snail shell carbonate

Geology ◽  
1983 ◽  
Vol 11 (10) ◽  
pp. 575 ◽  
Author(s):  
Glenn A. Goodfriend ◽  
Jerry J. Stipp
Keyword(s):  
Radiocarbon Dating ◽  
Land Snail ◽  
Snail Shell ◽  
Shell Carbonate

scholarly journals Carbon Isotope Analysis of Land Snail Shells: Implications for Carbon Sources and Radiocarbon Dating

Radiocarbon ◽  
1983 ◽  
Vol 25 (3) ◽  
pp. 810-830 ◽  
Author(s):  
Glenn A Goodfriend ◽  
Darden G Hood
Keyword(s):  
Exchange Rate ◽  
Organic Carbon ◽  
Radiocarbon Dating ◽  
Activity Patterns ◽  
Isotope Analysis ◽  
Carbon Sources ◽  
Isotopic Fractionation ◽  
Land Snail ◽  
Land Snails ◽  
Shell Carbonate

13C and 14C analyses were performed on a series of modern Jamaican land snails in order to quantitatively determine the sources of shell carbon. A model of these carbon sources, the pathways by which carbon reaches the shell, and the fractionation processes involved are presented. The contribution of limestone to shell carbonate is variable but may comprise up to 33% of the shell. About 25–40% of shell carbonate is derived from plants and about 30–60% from atmospheric CO2. Variation among populations and species with respect to 13C and 14C is attributed to the effects of limestone incorporation, snail size (as it affects CO2 exchange rate), physiological characteristics (presence of urease, respiration rate), and activity patterns of the snails. A formula for correction for isotopic fractionation of 14C of shell carbonate, based on 13C measurements, is derived. Bicarbonate-aragonite fractionation is apparently very minimal. Shell organic carbon appears to be derived largely from plants but also to a lesser extent from inorganic hemolymph carbon. This introduces the possibility of a small age anomaly of shell organic 14C due to limestone incorporation.

Diet control on carbon isotopic composition of land snail shell carbonate

2007 ◽  
Vol 52 (3) ◽  
pp. 388-394 ◽  
Author(s):  
ZongXiu Liu ◽  
ZhaoYan Gu ◽  
NaiQin Wu ◽  
Bing Xu
Keyword(s):  
Isotopic Composition ◽  
Carbon Isotopic Composition ◽  
Land Snail ◽  
Snail Shell ◽  
Carbon Isotopic ◽  
Diet Control ◽  
Shell Carbonate

Holocene Trends in 18O in Land Snail Shells from the Negev Desert and Their Implications for Changes in Rainfall Source Areas

1991 ◽  
Vol 35 (3-Part1) ◽  
pp. 417-426 ◽  
Author(s):  
Glenn A. Goodfriend
Keyword(s):  
Atmospheric Circulation ◽  
Source Region ◽  
Circulation Pattern ◽  
Land Snail ◽  
Negev Desert ◽  
Eastern Africa ◽  
Air Masses ◽  
Stable Pattern ◽  
North Eastern ◽  
Shell Carbonate

AbstractThe δ18O value of the carbonate of land snail shells is related to the 18O content of precipitation, which in turn relates to the source region and trajectory of the rain-bearing air masses. Analyses of 18O of the shell carbonate of 76 radiocarbon-dated Holocene samples of the land snail Trochoidea seetzeni from the northern Negev Desert in southern Israel were carried out and the results were compared to modern snails from the same region. Early Holocene δ18O values are similar to modern but during the period centered around 6500-6000 yr B.P., a depletion of some 2%. below modern is observed. A change in the atmospheric circulation pattern for this period is thus indicated, most likely an increase in the frequency of storm systems reaching the region from north-eastern Africa. By 3500 yr B.P., δ18O values had reached modern levels and indicate a stable pattern of atmospheric circulation since that time.

Mid-Holocene rainfall in the Negev Desert from 13C of land snail shell organic matter

Nature ◽  
1988 ◽  
Vol 333 (6175) ◽  
pp. 757-760 ◽  
Author(s):  
Glenn A. Goodfriend
Keyword(s):  
Organic Matter ◽  
Land Snail ◽  
Negev Desert ◽  
Snail Shell

Validity of Radiocarbon Dates on Terrestrial Snail Shells

1970 ◽  
Vol 35 (1) ◽  
pp. 94-100 ◽  
Author(s):  
M. A. Tamers
Keyword(s):  
Stable Isotope ◽  
Radiocarbon Dating ◽  
The State ◽  
Archaeological Sites ◽  
Radiocarbon Dates ◽  
Snail Shell ◽  
Terrestrial Snail ◽  
Different Characteristics

AbstractRadiocarbon dating of terrestrial snail shells is examined. Three groups of samples, two from archaeological sites of Venezuela and one from the state of Texas, were taken as examples. The true ages were determined from radiocarbon dates on associated charcoal, and measurements on the snail shells allowed the errors to be determined. The groups showed completely different characteristics: 15 samples from Texas all had ages falsely old, 12 specimens of one Venezuelan group produced all correct dates, and another Venezuelan type with five samples gave dates all too recent. This study defines the directions and extents of errors for each group of snail shells, permitting them to be used as relatively reliable datable objectives in excavations where better materials are not available.The possibility of correcting the radiocarbon dates using carbon-13 concentrations is considered, and 24 measurements are presented. It is concluded that more than one factor can influence the stable isotope concentrations in each case, and, therefore, carbon-13 is not useful for the improvement of the accuracy of snail shell dates.

scholarly journals Land Snail Shell Beads in the Sub-Saharan Archaeological Record: When, Where, and Why?

2018 ◽  
Vol 35 (3) ◽  
pp. 347-378 ◽  
Author(s):  
Jennifer M. Miller ◽  
Elizabeth A. Sawchuk ◽  
Amy L. R. Reedman ◽  
Pamela R. Willoughby
Keyword(s):  
Land Snail ◽  
Archaeological Record ◽  
Snail Shell ◽  
Shell Beads ◽  
Sub Saharan

Radiocarbon Dating and Paleoclimatic Significance of Subfossil Limicolaria in Northwestern Sudan

1987 ◽  
Vol 28 (1) ◽  
pp. 86-99 ◽  
Author(s):  
C. Vance Haynes ◽  
Albert R. Mead
Keyword(s):  
Radiocarbon Dating ◽  
Land Snail ◽  
Convincing Evidence ◽  
Annual Rainfall ◽  
Organic Fraction ◽  
Northern Limit ◽  
Middle Holocene ◽  
Latitudinal Shift ◽  
Paleoclimatic Significance ◽  
East West

AbstractThe discovery, identification, and radiocarbon dating of the large achatinid land snail Limicolaria kambeul chudeaui at six places in northwestern Sudan, north of the 100-mm isohyet, provide convincing evidence that at least 300 mm annual rainfall existed there 6000 yr ago. Since then the rainfall north of ca. 20°N lat in the eastern Sahara has certainly been <300 mm and probably <200 mm. Accelerator mass spectrometry has allowed the organic fraction, presumably conchiolin, to be accurately radiocarbon dated whereas carbonate fractions are ca. 600 yr too old. Comparative studies show the subfossil form, L. k. chudeaui, to be the most primitive in its species complex and to occupy a narrow east-west belt across Africa north of 15°N and west of 35°E. The northern limit of living forms lies within the southern part of the Sahelian zone in forest or forest-savanna. They cannot live in open grassland. Therefore, the distribution of L. k. chudeaui marks the former northern position of this zone during the middle Holocene, indicating a latitudinal shift of at least 5° (500 km).

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