PROTOACTINIUM-231 DATING OF CARBONATES BY THERMAL IONIZATION MASS-SPECTROMETRY - IMPLICATIONS FOR QUATERNARY CLIMATE-CHANGE

Measurement of protactinium-231 (Pa-231) in carbonates by thermal ioni zation mass spectroscopy yields Pa-231 ages that are more than 10 time s more precise than those determined by decay counting. Carbonates bet ween 10 and 250,000 years old can now be dated with Pa-231 methods. Ba rbados corals that have identical Pa-231 and thorium-230 (Th-230) ages indicate that the timing of sea level change over parts of the last g lacial cycle is consistent with the predictions of the Astronomical Th eory. Two Devils Hole calcite subsamples record identical Pa-231 and T h-230 ages, suggesting that the chronology of this climate record is a ccurate.