Kohat Fm

Charrat Gr – seventh (and uppermost) formation in Kohat-Margala Province (Ko-MP). Holotype section: Kohat-Khushalgarh Highway section. Author: F.E. Eames, 1952. Reference section: None.

Limestone and Claystone. It consists of interbedded nummulitic limestone and shale, and is subdivided into two members:

Kaladhand Member: It is composed predominantly of limestone, which is light grey, hard, compact and thin bedded with shale intercalations, particularly in the lower part. It contains abundant diagnostic Early Eocene forams, such as Orbitolites complanatus, Alveolina oblonga, Linderina burgesi and Assilina pustulosa. It is essentially a cliff-forming sequence, but in places becomes more shaly and forms steep slopes.

Sadkal Member: It is mainly comprised of greenish grey, calcareous shale with lesser amounts of light grey limestone. It outcrops in northern Kohat, Kalachitta area. In northeastern Kohat the shale dominates, elsewhere the limestone assumes larger proportion and is crowded with larger Nummulites (Meissner et al., 1974 as in Shah, 2009).

Thickness: 37-170 m in western Ko-MP, and only as thin slivers in Kalachitta area. It is 115 m thick at Shekhan Nallah, 37 m at Bahadur Khel, 60 m at Pathan Algad, 111 m at Jozara, 81 m at Dalan-Thal section, 93 m at Doaba-Karbogha section and 70 m at Mardan Khel. It is 130 m at Uch Bazar, 50 m at Mami Khel, 170 m at Chilli Bagh, 90 m at Gumbat, 100 m at Sumeri Payan, and 70 m south of Lachi in Kohat area.

Assilina cabcellata, Dictiyoconides vredenburgi, Fasciolites oblonga, Orbitolites complanatus and various species of Nummulites.

It was deposited during the last marine transgression in Kohat area.