BIOCLASTIC SHORE DEPOSITS - INDICATORS OF LATE QUATERNARY HIGH SEA INSAURASHTRA, WESTERN INDIA

The high energy coastal segment between Okha and Diu in Western Sauras htra is characterised by typical,kind of raised bioclastic shore depos its. These occur up to 15 m (max.) above present day mean sea level an d about 5 km inland. Variously described as ''coast fringing rocks'', ''Chaya Formation'', ''ancient beach rocks'', ''shell limestones'', et c., these possess poorly sorted allochems and lithic fragments of coar se sand to gravel size, mostly cemented by aragonitic micrite and occa sionally fibrous aragonitic and high magnesian calcite, their pores be ing infilled by second generation of low magnesian sparry caf cite cem ent On the western coast of Saurashtra, they underlie coastal dunes an d skeets of miliolitic limestone and form gently seaward dipping sheet s and their surfacial exposures are encountered southward only up to K adwar, near Diu. However, they occur at the base of deep quarries of m iliolitic limestone between Kadwar and Mahuva. Looking at the availabl e reliable Th-230/U-234 and ESR dates of fossil shells from these depo sits, they represent a higher sea level during the oxygen-isotope sub- stage 5e. On the South Saurashtra coast, the high coastal cliffs of mi liolitic limestone exhibit presence of raised shore platforms and notc hes which may be related to this high sea after considering the influe nce of tectonism.