Uranium-series dating of the Pleistocene reef tracts of Barbados, West Indies

Detailed studies of reef-tract stratigraphy in the southwestern part of Barbados have revealed nine, seven, and ten reef tracts in the Christ Church, Clermont Nose, and Saint George's Valley sections, respectively. The reefs have been projected onto standard traverses, and present elevations are reported for each reef crest.

To date the reef crests by Th²³⁰/U and He⁴/U methods, the U²³⁴/U²³⁸ and Th²³⁰/U²³⁴ activity ratios and U and He⁴ concentrations were determined in about 35 unrecrystallized coral samples. Discordant U²³⁴/U²³⁸, Th²³⁰/U, and He⁴/U ages for many samples indicate that both U²³⁴ and Th²³⁰ have been diagenetically added to the samples. He⁴/U ages are corrected by subtracting the He⁴ added due to the presence of “open system” U-series nuclides; the correction ranges from 0% to 10%.

The reef-tract ages and present elevations as projected on the standard traverse show that prior to 125,000 B.P., the uplift rate of the Christ Church section was much greater than the rate after 125,000 B.P. Paleo-sea levels inferred from Saint George's Valley reef tract ages and elevations cluster about the present datum, which suggests that throughout the Brunhes epoch, minimum interglacial continental ice volume was comparable to the present value.

Within the uncertainty of the age and paleo—sea-level estimates, the Brunhes sea-level history inferred from Barbados reef-tract chronostratigraphy is consistent with that inferred by Shackleton and Opdyke from the oxygen isotope record of core V28-238.