Corrections for initial isotopic disequilibrium in the speleothem U-Pb dating method

Abstract

The accuracy of ages produced by the U-Pb speleothem chronometer is influenced by initial disequilibrium effects resulting from weathering and transit of water through the epikarst. If some residual disequilibrium remains at the time of measurement, corrections can be made. However, once the system reaches equilibrium, the initial state has to be estimated thus propagating significant uncertainty into the age calculation. As an alternative approach, here we explore the possibility of calculating [234U/238U]i initial values by forcing concordance in the 238U to 206Pb and 235U to 207 Pb decay schemes. Whether this method can be successfully implemented relies heavily on the quality of the line..