ABSTRACT

Surface sediments from the Bimini Lagoon were analyzed for their major element content (CaO, SrO and MgO), minor element content (Si, Al, Fe, Ba, Cr and Mn), mineralogy (aragonite, high and low magnesium calcite) and petrographic constituents (grain size, intraclasts, pellets, oolites, skeletal material and mud content). The overlying waters were also analyzed and environmental data was collected. Methods of analysis are briefly described. The data was analyzed statistically to discover controls on overall geochemical variation.

Linear product moment correlation coefficients were calculated for all variable pairs. A correlation matrix was generated and used to identify covarying groups of variables. The results of this test allowed a simple interpretation to be made. The physical environment in terms of water quietness (rather than the chemical environment) is shown to govern the organic and inorganic phase constituents of the sediments; these in turn govern the bulk chemistry. Correlation analysis was repeated for the sample population from each of the three water masses in the lagoon (as recognized by Turekian, 1957, in terms of salinity). The same basic control of water quietness is shown to be operative in each area, though in certain localized environments its government of the bulk chemistry and mineral gy is reflected in a different way.

A simple analysis of variance for the sample groups from each water mass showed that the sediments from these three areas of different salinity in the lagoon are also significantly different in bulk constitution. But the salinity (and hence chemistry) of the waters is not simply related to the sediment composition; for the three masses are also distinct in terms of physical environment and it is this which is reflected in the mean sediment composition.