It is for that reason that in the members of the U-238 series (fig.2) the thorium isotope Th-230 is practically absent in the speleothem- forming dripping waters of the cave, whereas U-238 and U-234 are present and get into the growing calcite formations.Age determination via Th-23O/U-234 is usually started by cutting a layered speieothem into several sections along visible growth layers.
FREUNDLICH ** * Institut fiir Kernchemie der Universitat zu Koln , Zulpicher Strate 47 D - 5000 KOLN 1 , GERMANY *"*Institut fîir Ur- und Friihgeschichte der Universitat zu Koln , Weyertal 125 , D - 5000 KOLN 41 , GERMANY Because prehistoric men frequently used limestone caves as their domicile or shelter, today many remains of their life are covered by subsequently precipitated calcite formations.
Figure 1 shows the basis of U-series dating via the activity ratio of Th-230/U-234: The trace element uranium is easily dissolved and transported by karstic, carbonate-rich waters seeping through the limestone rock.
Thorium, however, is tightly adsorbed by clay minerals always present in the hair-cracks and crevices of the roof limestone.
In: 91 URANIUM SERIES DATING OF CALCITE FORMATIONS IN CAVES : RECENT RESULTS AND A COMPARATIVE STUDY ON AGE DETERMINATIONS VIA Th-230/U-234 , C-I4 , TL and ESR by G. A few other methods have been applied, but of these only C-14, thermoluminescence and electron spin resonance proved to be quite successful as well.
Uranium series dating of calcite formations in caves : recent results and a comparative study on age determinations via ²³⁰Th/²³⁴U, ¹⁴C, TL and ESR. Uranium series dating seems to be a most reliable and rather frequently used technique to determine the formation age of such speleothems.