Integrated Facies Analysis and Stratigraphic Correlation of the Wargal Limestone: Insights into Outcrop Data and Depositional Environments along the Paleotethys

Abstract

Problem statement. Wargal Limestone plays a significant role due to its substantial reservoir potential. A more in-depth analysis of this formation can be helpful in identifying elusive geobodies. Wargal limestone is a reservoir rock of Permian age in Pakistan. It has proven the reservoir in the Dhurnal field that proves its reservoir facies. In Pakistan, the Western Salt Range presents a wonderful opportunity to study this Permian limestone.

Purpose. This study aims to examine the facies and depositional environment of late Permian limestone in Upper Indus Basin by characterizing the geological, mineralogical proxies of rock samples collected from various localities. The geobodies and sedimentary architecture of Wargal Limestone was deciphered using field observation.

Methods. Facies analysis, stratigraphic logging, and lithological correlation were used to interpret outcrop data and reconstruct the depositional environments. On the basis of fossils present in lithofacies, its depositional environment is elaborated. Sedimentology was studied using section measurement along with high resolution field photographs were collected using the facies heterogeneity and architecture. The facies were then plotted on high resolution field photographs. The dataset generated includes sedimentological logs, samples, and field photographs to enable reproducibility and future comparative stratigraphic studies.

Results. The common facies are carbonaceous shale, sandy limestone, argillaceous limestone, fossiliferous limestone, and dolomitic limestone. Fossils such as bryozoans, brachiopods, bivalves, gastropods, and trilobites date it to the mid-late Permian Five sections of Wargal limestone have been taken to correlate. Lateral facies changes of these facies shows stratigraphic continuity but with some obvious changes in lithology and thickness. We observed the geobodies in the formation, whether it has reefs, sheets, lenses, or channels. There is a chance to locate zoned reservoirs for potential hydrocarbon extraction because of stratigraphic variations. The diverse depositional environments of this formation, which range from lagoonal to reefal settings, are widely known for representing a highly active and diverse paleotethys system. The paper supports Sustainable Development Goal (SDG) 9 by advancing geological knowledge relevant to resource assessment and sedimentary basin analysis, SDG 13: through improved understanding of climatic and earliest environmental settings.

Conclusions. As the formation is made up of different types of rock, including fossiliferous limestone and porous dolomite, and since it is situated in a Salt Range, it has good potential for oil and gas exploration in the adjacent Potwar, Kohat and Bannu basins. The findings of this study are recommended for analogues as a guide in developing a framework for future studies of comparable carbonate rock successions in the study region.