Microfacies Analysis of Samana Suk Formation, Shah Alla Ditta, Islamabad

Abstract

Fossils give information that unveil the geologic past including paleoenvironment, paleogeographic conditions and depositional settings. Samana Suk Formation is well exposed near Shah Alla Ditta in Islamabad. It is section of Margalla Hill ranges which is the part of lesser Himalayas. It is located in western margin of Main Boundary Thrust. The Samana Suk Formation consists of medium to thick bedded limestone with intercalations of calcareous shale. The limestone contains fragments of Brachiopods, Bivalves, Ammonoids, Gastropods and Crinoids fauna. The petrographic study revealed different microfacies including bioclastic facies, dolomitic facies and quartz rich dolomitic facies. These microfacies were identified on the basis of faunal content e.g., bivalve fragments, ooids, peloids, intraclasts, algae and other sedimentological characteristics. The identified microfacies are consistent with the lagoonal to middle ramp depositional setting.