Abstract:
The Eocene age Kohat Formation exposed in karat hills, district Karak was studied to analyze its detailed biostratigraphy and mechanical properties on the basis of fossils assemblages and laboratory work.The studied formation is mainly composed of limestone and laminated shale with thin calcareous fossiliferous beds. The studied formation records a thickness of only 20-40 meters.The Kohat Formation
lies conformably over Kuldana Formation and upper contact is unconformable with the Kamlial Formation of the Rawalpindi group that marks unconformity. On the basis of microscopic study of the thin sections different type of fossils and their species were recognized to construct biostratigraphy of the Kohat Formation. The idntified fossils includes; Nummulitessubirregularis, Nummulitesglobulus,Nummulitesatacicus and Nummulitesmammillatus, Assilinaexponens and Assilinagranulosa,Alveolinastercusmeris and Alveolinaelliptica with dispersed distribution of Gastropods and Bioclasts. The idnetified fossils suggest that the Kohat Formation is a carbonate sequence containing diagnostic larger foraminiferas that confirm the Middle Eocene age. The Formation represents shallow shelf deposits because of the presence of larger foraminifera’s i-e Nummulites,.Alveolina and Assilina. The mechanical tests carried out suggest that the limestone of the kohat Formation can be preferably used for light constructions like small bridges, small dams and other small construction projects.
