OOIDS AND PELOIDS IN THE CONTINENTAL-SHELF OFF KACHCHH, WEST-COAST OFINDIA - INFERENCES TO PALAEOSEALEVEL OSCILLATIONS

Grey ooids (0.05 to 0.125 mm size) around 60 m depth, white ooids (0.1 25 to 0.0625 mm size) around 110 m depth and pale brown peloids (0.125 to 0.0625 mm size) around 90 m depth occur in the continental shelf o ff Kachchh. In cross sections, grey ooids with five and white ooids wi th three concentric growth rings are observed. In grey ooids an intern al black growth ring with Fe and S as revealed by EMP studies suggest pyritization after regression. White ooids do not show any elemental v ariation. Peloids contain organic matter. The following inferences are drawn (1) grey ooids are considered older. than the white ooids thoug h they occur at shallow depth or (2) few reversals of sea level took p lace around 60 m level during Holocene, which caused formation and pyr itization of ooids.