Bioclastic Shore Deposits: Indicators of Late Quaternary High Sea in Saurashtra, Western India

The high energy coastal segment between Okha and Diu in Western Saurashtra is characterised by typical kind of raised bioclastic shore deposits. These occur up to 15 m (max.) above present day mean sea level and about 5 km inland. Variously described as "coast fringing rocks", "Chaya Formation", "ancient beach rocks", "shell limestones", etc., these possess poorly sorted allochems and lithic fragments of coarse sand to gravel size, mostly cemented by aragonitic micrite and occasionally fibrous aragonitic and high magnesian calcite, their pores being infilled by second generation of low magnesian sparry calcite cement. On the western coast of Saurashtra, they underlie coastal dunes and sheets of rniliolitic limestone and form gently seaward dipping sheets and their surfacial exposures are encountered southward only up to Kadwar, near Diu. However, they occur at the base of deep quarries of miliolitic limestone between Kadwar and Mahuva. Looking at the available reliable Th²³⁰/U²³⁴ and ESR dates of fossil shells from these deposits, they represent a higher sea level during the oxygen-isotope sub-stage 5e. On the South Saurashtra coast, the high coastal cliffs of miliolitic limestone exhibit presence of raised shore platforms and notches which may be related to this high sea after considering the influence of tectonism.