Petrographic Criteria for Freshwater Diagenesis of Saurashtra Miliolites

The miliolites of Saurashtra Peninsula represent reworked bioclastic sand accumulations under the varying palaeoclimatic conditions during the Late Quaternary period. Their origin, whether marine or aeolian, forms a matter of controversy. These rocks comprise medium to fine grained allochems along with minor amount of detrital grains cemented together by non-ferroan, low magnesian sparry calcite cement exhibiting various ultrastructures. The intragranular porosity, geopetal infilling, dripstone-drapstone, meniscus and dogtoothspar cements suggest vadose condition while the presence of isopacholls rim and blocky void filling cements indicate their formation in phreatic freshwater environment.