Recognition of a relationship between depth and macroboring distribution in growth framework reef cavities, Bonaire, Netherlands Antilles

Samples of reef rock collected from the back wall of growth framework reef cavities on the forereef slope of Bonaire, Netherlands Antilles, over the depth range 1.5 m to 33.5 m, contain large numbers of macroborings. The number of borings per unit area show a correlation with depth. The highest correlations, established by using linear regression, are the mean cross-sectional area of boreholes with depth, and the standard deviation of the cross-sectional areas with depth. The regression of standard deviation on mean borehole cross-sectional area and on mean cross-sectional area and depth also indicates a relationship. This shows that in Bonaire reef framework cavities, macroborings show a decrease in their mean size and a decrease in variability in borehole size with increasing depth.

By using the regression of depth on mean area and standard deviation, a model can be developed that may permit the prediction of relative water depth in ancient reefs from the size distribution of populations of macroborings in growth framework cavities. Although there is a relationship to water depth, the practical difficulty of measuring these parameters of populations of boreholes in reef cavity substrates means that this relationship would be difficult to apply as a paleobathymetric tool in a fossil reef.