Mineralogical and Geochemical Compositions of Modern Bivalve Shells from The Mediterranean Coast Of Egypt

Abstract

The stable isotopic (8 ^C and 8^O) and elemental (Sr and Mg) compositions are presented for marine mollusc Carditacea and Solenacea shells collected off the Mediterranean coast of Egypt. Based on shell microstructures and mineralogy, the bivalve shells are preserved in their original mineralogy and chemistry. The Sr and Mg concentrations of the bivalve shells have mean values of 1960 ppm and 226 ppm; respectively. The stable isotopic composition generally show high values of 818O and 8'3C. The 818O values range from +0.1 to -1.8%o PDB and most shells are highly enriched in 13C; averaging +2.5%c PDB. These elemental and isotopic signatures are similar to those of modern marine bivalves from other localities. The oxygen and carbon isotopic compositions, together with the calculated temperatures, suggest that the aragonitic bivalve shells were precipitated in isotopic equilibrium from warm marine waters.