Maximum sea levels for the last glacial period from U-series ages of submerged speleothems

Abstract

PLEISTOCENE sea levels reflect changes in the surface distribution of land, sea and ice, which in turn significantly influence the Earth's climate1. The most complete record of sea levels for the last glacial cycle has come from raised coral reef terraces of the Huon Peninsula, Papua New Guinea2–4, but interpretation of this record is hampered by relatively large age uncertainties and the possibility of variation in the rate of tectonic uplift. Subaerial speleothems (stalagmites, stalactites and flowstones) from submerged caves in tetonically stable areas provide an alternative source of data5–8, as their growth stops when rising sea levels flood the caves. Previous studies of speleothems have been limited by dating precision5,6 and sample availability5–7. Here we present high-precision thermal- ionization mass-spectrometric 230Th ages9–11 for a comprehensive suite of speleothem samples from the Bahamas. Our results provide a record of maximum elevation of sea levels for the period from 80 to 10 kyr before the present, for much of which sea levels are poorly known. We also find that regional palaeoclimatic change can be an important factor in the termination of speleothem growth.