Kaleem Akhtar Qureshi and Ali Nasir Fatmi
Geological Survey of Pakistan, 16-G, Model Town, Lahore, Pakistan
Riaz Ahmed Sheikh and Aftab Ahmad Butt
Institute of Geology, Punjab University, Lahore – 54590, Pakistan
Microfacies analysis and ammonite biostratigraphy of the Mianwali Formation of the Kala Chitta Range were worked out on the basis of stratigraphic sections from Chak Jabbi and Bagh. Four microfacies were identified from the Chak Jabbi section while ammonite biostratigraphy was studied from both the sections.
Filamentous bivalves in micrite deposited along a shelf margin below normal wave base represent the first microfacies. The second microfacies contains bioclastic wackestone deposited in an open marine environment of normal salinity. The third microfacies consists of lime mudstone formed in a stressed environment of lagoonal conditions, whereas the fourth microfacies of dolomitised carbonate mudstone was formed by the diagenetic dolomitisation of the third microfacies.
The new collection of ammonites includes Arctoceras tuberculatum, Anakashmirites aff. evolutus, Meekoceras gracilitatis, Stephanites sp., Pseudoceltites sp., Subvishnuites aff. welteri, Arnautoceltites sp., Owenites sp. indet, Subvishnuites aff. enveris, Pseudosageceras sp. indet, Paranannites sp., Subcolumbites sp., Anasibrites sp., and Pseudaspidites sp. confirming the already known Sctythian age of the Mianwali Formation.