ABSTRACT

The British Honduras carbonate depositional province contains a relatively narrow, deep, back-reef lagoon in which Recent fine-grained carbonate sediments are accumulating.

Examination of the finer fractions of these lagoonal muds by optical and scanning electron microscopy reveals that a large proportion of the sediment (as much as 20 percent) is composed of coccoliths and coccolith fragments. Eight nannoplankton species have been described. Matthews (1965, 1966) failed to describe coccoliths and other fine-grained constituents in his study of British Honduran muds because he did not petrographically examine grains smaller than 20 microns. Thus comparisons between his data and the finer muds of Florida. the Bahamas. and other areas must be undertaken with caution because of the differences in grain sizes examined.

The lagoonal, coccolith-rich carbonate muds of British Honduras which surround coralgal pinnacle reefs provide an excellent Recent analog for a number of ancient carbonates, including the Solnhofen Limestone. They also indicate that coccolith-rich sediments need not indicate deep-water deposition or unrestricted circulation far from land masses or major hydrographic barriers.