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Radiometric Dating of Young and Old Calcrete

Published online by Cambridge University Press:  18 July 2016

Mebus A. Geyh  and
Bernhard Eitel
Mebus A. Geyh
Affiliation:
Niedersächsisches Landesamt für Bodenforschung, P.O. Box 510153, D-30631 Hannover, Germany
Bernhard Eitel
Affiliation:
Niedersächsisches Landesamt für Bodenforschung, P.O. Box 510153, D-30631 Hannover, Germany
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Abstract

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To obtain a better understanding of the relationship between calcrete genesis and the results of different absolute dating methods, thermoluminescence (TL), radiocarbon (14C) and uranium/thorium (U/Th) were applied to coeval sample; take from a very young calcrete profile in Namibia. The methodically different ages reflect the characteristics of the applied dating methods, the genetics of calcrete and different events of calcrete genesis. The conventional 14C ages and the TL dates cover the last 50 ka, while the corresponding U/Th dates of coeval samples are many times larger, Uranium-series dates are not related to the deposition of the host material or to its cementation if the ages are smaller than ca. 120 ka. The TL clock is set to zero during eolian transport and the corresponding radiometric ages of the quartz and feldspar grains date the time of their deposition. The 14C ages of the cement correspond, on the other hand, to a time shortly after the onset of the cementation and long before its termination. In the case of very old calcrete, the mixture of young and old cement results in ambiguous ages if they cannot be confirmed by an independent technique.

Type
Part 2: Applications
Information
Radiocarbon , Volume 40 , Issue 2: 16th International Radiocarbon Conference June 16-20, 1997 Part 2: Applications, Conference Editors: Willem G. Mook Johannes van der Plicht , 1997 , pp. 795 - 802
Copyright
Copyright © The American Journal of Science 

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