MICROFACIES AND DIAGENETIC ANALYSIS OF AMB FORMATION WESTERN PART OF CENTRAL SALT RANGE, PAKISTAN

Abstract

An almost 76m thick deposit of Amb Formation of Zaluch Group at its type locality, in Warchha Gorge near Amb village in western part of Central Salt Range Pakistan, is divided into three prominent lithological units, i.e. lower sandstone, middle calcareous sandstone with sandy limestone and upper sandstone with shale unit. In this study, 29 samples were studied from different levels of Amb Formation at its type locality which were used for microfacies analysis. Ten microfacies were identified and their salient features are discussed in this paper. Some diagenetic processes, such as compaction, cementation, dolomitization and bioturbation, were also observed in Amb Formation. Different types of fauna, observed in the formation, include brachiopods, bryozoans, crinoids, bivalves and foraminifera (fusulinids). On the basis of fusulinids (first foraminifera appearing in Pakistan in Amb Formation) and different sedimentary structures observed, it is considered that Amb Formation of Central Salt Range, Pakistan was deposited in a shallow marine environment during Late Permian (Artinskian).