Microfacies Analysis of Wargal Formation Exposed In Nammal Gorge, Western Salt Range, Upper Indus Basin, Pakistan

Abstract

The carbonates of Middle-Late Permian age Wargal limestone constitute important petroleum reservoirs in the Salt Range area. Permian rocks are the most important HC reservoirs in Pakistan. These reservoirs are productive throughout the Indus Basin predominantly in the Upper Indus Basin. Somewhere else, e.g. in the North Sea Basin in the use of outcrop data and microfacies techniques for constructing the dynamic depositional model has significantly increased the knowledge to characterize reservoir rocks. In this study the outcrop data and microfacies from the key study section Le Nammal Gorge of Western Salt Range have been used for understanding the depositional dynamics and biostratigraphic properties of Wargal Limestone. The presence of reef-forming organisms (Bryzones, foraminifers, echinoderms and bivalves) supports the model. The thickness of the formation in the Nammal Gorge section is 75m. On the basis of outcrop and petrographic data four microfacies are identified. These microfacies are WF-1 (Packstone-Grainstone Microfacies), WF-2 (Peloidal Packstone-Grainstone Microfacies), WF-3 (Wackstone-Packstone Microfacies), and WF-4 (Medium Bedded Mudstone Microfacies). The microfacies type of Wargal Limestone is suggested to be deposited in the inner to middle shelf environment.