Uranium-Thorium Chronology

U-Th dating of carbonate samples can be conducted if the following conditions are met:

  • Formed within the datable range of the U-Th systematics
    (up to 500 ka),
  • Contain sufficient concentrations of the minor
    isotopes 234U and 230Th for high-precision isotope dilution
    analysis,
  • Incorporation of negligible or known amounts of initial
    (excess) 230Th at the time of deposition, and
  • Remained closed with respect to U and Th isotopes since
    primary deposition.

Uranium loss and inherited 230Th in open-system settings can result in erroneous conclusions. Samples with a relatively low initial U/Ca and uranium concentration tend to uptake uranium after deposition and through diagenetic processes – yielding aberrant ages.

More information on sample types

Uranium-Thorium sample selection