MODERN OOIDS OF CLEOPATRA BEACH, GOKOVA (SOUTH AEGEAN SEA) TURKEY - RESULTS FROM PETROGRAPHY AND SCANNING ELECTRON-MICROSCOPY

Modern ooids from the Cleopatra Beach on Island in the Gokova Bay, Sou th Aegean Sea, resemble ooids formed on the Bahamian platform. The con centric coatings of the ooids consist of two or more laminae around a carbonate-or non-carbonate nucleus. The oolite cortex is transparent, whereas the non-transparent portions seem to be the dark fields on the oolitic surfaces. The ooids are mixed with molluscan skeletal debris displaying micritic envelopes. Weakly consolidated ooids have been cem ented by calcite in the form of meniscus cement. According to electron -microscope studies, three kinds of crystal shapes have been distingui shed, as follows: 1 - Micronodules attributed to microboring organisms such as cyanobacteria or coccoids; 2- Tablet-shaped crusts of hemisph eres; likely produced by bacterial activity, 3- Acicular- or elongate crystals precipitated directly from sea water in vacated holes of the microborings or as of the tangentially orientated parts of the ooids. Algal- and bacterial processes are thought to have been main sources o f the carbonate that was precipitated to form the ooids.