Mianwali Fm
Type Locality and Naming
Musakhel Gr – lowest formation: Holotype section: Not designated. Hypo: Zaluch Nallah (Western Salt Range) and Tappan Wahan in Khisor Range. Author: M. D.Williams, 1959.
Lithology and Thickness
Shallow-marine marl. The formation consists mainly of marl, limestone, sandstone, siltstone and dolomite. It has been divided into three members:
i. Kathwai Member - dominantly dolomite (oldest). 3.7 m and 2.4 m thick in Zaluch Nallah and Tappan Wahan, respectively. Its base marks the Permo-Triassic boundary.
ii. Mittiwali Member - dominantly greyish shale, silty shale with sandstone and limestone interbeds with a 2-8 m thick limestone bed at the base. 98 m in Zaluch Nallah.
iii. Narmia Member - carbonaceous shale and limestone. 23 m in Zaluch Nallah
Reference section: Lithology same as above.
Thickness: 121-187 m. The formation represents a great wedge of varied facies, which is thickest in the west and wedges out towards the east. Its thickness in Zaluch Nallah is 121 m while in Tappan Wahan section it ranges from 135 to 187 m.
Relationships and Distribution
Lower contact
Underlain by Chhidru Fm across a paraconformity.
Upper contact
Conformably overlain by Tredian Fm in Salt Range and by Chak Jabbi Limestone Fm in Kalachitta Range (Kohat-Margala Province , Ko-MP).
Regional extent
It is exposed in Khisor Range, SuR and the western part of Salt Range; farther eastward, it wedges out as a result of erosion that preceded Tertiary deposition.
GeoJSON
Fossils
Ammonoid fossils are abundant as reported by Fatmi (1977), like Owenites , Anakashmirites, Meekoceras, Ophiceras, Glyptophiceras, Proptychites, Gyronites, Kymatites, Kingites and Ambites. Permian brachiopods are found in the basal part (Kathwai Member) but are assumed to have been re-worked.
Age
Depositional setting
Prodelta to shallow marine.
Additional Information