Abstract

There are two widely used models of sediment production on carbonate shelves: (1) production varying with depth, and (2) production as a function of depth and distance from the platform margin. Here we recalculate carbonate production on Great Bahama Bank west and northwest of Andros Island using Broecker and Takahashi's (1966) pioneering geochemical study. In the calculations, residence time and depth are used to calculate yearly carbonate production based on equilibrium thermodynamics of CaCO3 loss from water over the banks. Whereas Broecker and Takahashi assumed a uniform depth of 4.5 m in their work, here we use realistic depths and residence times interpolated over the bank. Our results suggest that sediment production is on the order of 4-5 kg/m2/y on the bank margins and that production rapidly drops off into the platform, approaching zero in the shallowest, innermost parts of the platform. Thus, for a large platform such as Great Bahama Bank with long residence times, the shallowest areas of the platform may become sinks, not sources, of sediment.

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