210Pb method for estimating the rate of carbonate sand sedimentation

Abstract

The plot of 21~ activity against depth in carbonate sands on the Virgin Island Bank is a negative asymmetric hyperbolic curve. As depth increases, an initial rapid decrease in 21~ activity caused by the decay of unsupported 21~ and 226Ra is followed by increasing activity as a result of 21~ achieving equilibrium with ingrowing 23~ As this curve is time dependent, an estimate of the relative ages in carbonate sequences and the rates of net carbonate accumulation can be made. The base of 21~ activity determinations makes this procedure an attractive method in obtaining carbonate sand accumulation rates.