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Previous studies in the Florida-Bahamas region have shown that organic constituents of modern shallow-water carbonate sediments vary systematically and predictably with sediment grain size, submarine topography, areal geography, and hydrography, so that persistent associations of certain facies tracts and dominant organisms now are well known. Although such dominant organic constituents generally are segregated into gross taxonomic groups (coral, coralline algae, forams, mollusks), the present study shows that similar systematic variation also can be observed within a single gross taxon (Foraminiferida). Such variation produces 5 faunas that reflect 5 major environments (forereef slope, shelf margin, open shelf, interior shelf, restricted shelf) of the shallow-marine carb nate realm, as well as local depositional features, such as mudbanks and patch reefs. Sediment classes and foraminiferal faunas are probably only indirectly related, but they are remarkably congruent. Transport of Foraminiferida by currents affects distribution locally, but does not materially affect the 5 major faunas.
Lateral successions in foraminiferal faunas are present in the ancient rock record just as they are in modern sediments and can be used as a predictive tool, but for comparison with ancient faunas, recent death assemblages are more meaningful than living faunas.
Many previous studies of modern forams have emphasized water depth as the dominant environmental parameter, but most modern carbonates are forming in very shallow water so that possible range in water depth is necessarily small. Accordingly, circulation of oceanic waters supersedes water depth as the dominant environmental control of forams in the carbonate realm.
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