MICROFACIES ANALYSIS OF THE MIDDLE EOCENE KOHAT FORMATION, SHEKHAN NALA, KOHAT BASIN, PAKISTAN

The Kohat Formation from the Shekhan Nala was sampled and measured for detailed stratigraphical and micropalentological studies to determine the age and environment of the formation. The Kohat Formation contains abundant varieties of larger foraminifera belonging to the genera Nummulites, Assilina and Alveolina. On the basis of larger foraminifera Middle Eocene age of the formation has been confirmed The microfacies studies identified the bioclastic wackestone, bioclastic packstone and bioclastic grainstone where the bioclasts are larger foraminiferal species, Nummulites beaumonti, Nummulites mamillatus, Assilina exponens and Alveolina elliptica. The Kohat Formation on the basis of larger foraminifera and micro facies analysis draws attention to the fact that it was deposited in shallow marine environments. The Kohat Formation has been identified into four lithofacies, which are from base to top, TS-l:- Calcareous shale interbedded with fossiliferous limestone. TS 2:- Nummulitic shale and limestone. TS-3:-Highly fossiliferous limestone. TS-4: Massive nodular limestone.