²¹⁰Pb method for estimating the rate of carbonate sand sedimentation

The plot of ²¹⁰Pb 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 ²¹⁰Pb activity caused by the decay of unsupported ²¹⁰Pb and ²²⁶Ra is followed by increasing activity as a result of ²¹⁰Pb achieving equilibrium with in growing ²³⁰Th. 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 ease of ²¹⁰Pb activity determinations makes this procedure an attractive method in obtaining carbonate sand accumulation rates.