OBSERVATIONS ON SELECTED SALT-MARSH AND SHALLOW-MARINE SPECIES OF AGGLUTINATING FORAMINIFERA - GRAIN-SIZE AND MINERALOGICAL SELECTIVITY

Two species of surface salt-marsh agglutinating foraminifera from site s around Britain have been investigated using SEM/EDX to examine for g rain size and mineralogical selectivity of their adventitious test wal l particles, Grain size and elemental measurements on test constituent s of Trochammina inflata and Jadammina macrescens, from the same sites , when compared with substrate grain size distributions, suggest a hig h degree of grain size and mineralogical selectivity. Trochammina infl ata tests are dominated by relatively small (modal class 1-3 mu m) qua rtz grains, whereas those of J. macrescens are characterized by larger (modal class 4-9 mu m) platy aluminosilicate minerals, In addition, f our species of surface/subsurface agglutinating foraminifera from arou nd Britain and Ireland were examined for mineralogical selectivity, Eg gerelloides scabrus and Ammoscalaria runiana are dominated by quartz, whereas Haplophragmoides wilberti is predominantly composed of alumino silicate minerals, Miliammina fusca does not appear to select grains b y size, shape or mineralogy.