230Th-234U and 14C ages obtained by mass spectrometry on corals

Abstract

New AMS and TIMS results presented here confirm the precision and accuracy of the U-Th geochronometer applied to scleractinian corals. As shown before, the 14C ages are systematically younger than true ages during most of the 14C range except for the brief period between 500 and 2500 cal BP. This sets the relative duration of the Holocene between 11 200 and 11 500 cal yr, and the Younger Dryas chronozome corresponds to c10 000-1600 cal yr. The AMS 14C age of the early Bolling δ18O shift varies between 12 700 and 12 5000 BP which corresponds to U-Th ages between 14 700 and 14 500 BP. Broecker has proposed that this benchmark could be used to correlate records but problems may result because 12 700 14C yr BP corresponds to another radiocarbon age plateau. -K.Clayton