Microfacies Analysis and Depositional Environment of Middle Jurassic Samana Suk Formation, Chichali Nala Section, Surghar Range, Pakistan

Abstract

The Middle Jurassic age Samana Suk Formation, exposed in Chichali Nala section of Surghar ranges has been investigated by field work, petrographic study and XRD analysis to understand the microfacies, depositional environment and fault related dolomitization of the Samana Suk Formation. This formation is widely distributed in the upper Indus basin of Pakistan and considered the most prominent stratigraphic unit of the Jurassic period. The project area lies in the Chichali Nala Section of Surghar range (Trans Indus Salt Ranges). In this section, Samana Suk Formation constitutes the lithology of carbonate having CaCo3 as a major mineral, where dolomite is present in minor amount, which is restricted to fluids along fault zone. During the study two major microfacies have been identified including the Grainstone microfacies and Mudstone-Wackestone microfacies. Samana Suk. Formation was formed under stormy influence in the environment of deposition of Formation. Its depositional environment is the inner-middle shelf which suggests the marine shelf depositional environment.