Dating methods uranium series

Figure 1. Schematic diagram showing a TRU-spec extraction chromatography method for separation of uranium, thorium, protactinium, and radium from a single rock aliquot. Further purification for each element is normally necessary for mass spectrometric analysis. Analysis of a single aliquot reduces sample size requirements and facilitates evaluation of uranium-series dating concordance for volcanic rocks and carbonates. For TIMS work where ionization is negatively influenced by the presence of residual extractant, inert beads are used to help remove dissolved extractant from the eluant.

Rosholt NJ (1967) Open system model for uranium-series dating of Pleistocene samples. In Radioactive Dating and Methods of low-level Counting. 1. A. E. A. Proc Ser Publ, SM-87/50, p 299-311 Rosholt JN, Antal PS (1962) Evaluation of the Pa /U-Th °/U method for dating Pleistocene carbonate rocks. US Geol Survey Prof Paper 450-E 108-lll... 

Blackwell B. A. and H. P. Schwarcz (1995), The uranium series disequilibrium dating methods, in Rutter, N. W. and N. R. Catto (eds.), Dating Methods for Quaternary Deposits, Geotext 2, Geological Association of Canada. 

Smart, P. L. (1991), Uranium series dating, in Smart, P. L. and P. D. Frances (eds.), Quaternary Dating Methods - a Users Guide, Technical Guides Vol. 4, Quaternary Research Association, Cambridge, UK. 

Turkian, K. K., Nelson, E., Uranium series dating of the travertines of Caune de l Arago (France) In Colloque I, Datations Absolute et Analyse Isotopiques en Prehistoire, Methodes et Limites, Union des Sci. Prehist. Protohist. 

In the early stages of dating by nuclear methods, the measurement of He formed by a decay in the natural decay series (9, 6 and 7 He atoms in the uranium series, the thorium series and the actinium series, respectively) has been applied. The preferred method was the U/He method which allows dating of samples with very low concentrations of U of the order of 1 mg/kg. Helium produced by a decay is driven out by heating and measured by sensitive methods, e.g. by MS. However, it is difficult to ensure the prerequisites of dating by the U/He method neither " He nor a-emitting members of the decay series must be lost and no " He atoms must be produced by other processes such as decay of Th and spallation processes in meteorites. 

One of the most important applications of uranium-series methods of age determination has been the dating of fossil corals and other carbonate materials. In contrast to deep-sea sediments, which accumulate excess h and Pa that decay over time, carbonates accumulate uranium by co-precipitation from seawater that is essentially free of °Th and Pa. The radioactive ingrowth of °Th and Pa over time toward secular equilibrium with and is the basis of the two methods. 

Blackwell, B., and Schwarcz, H.P., 1995, The Uranium Series Disequilibrium Dating Methods, in Dating methods for Quaternary deposits, Rutter, N.W., and Catto, N.R., eds.. Geological Association of Canada GEOtext 2, pp. 167-208. 

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