Nammal Fm
Type Locality and Naming
Charrat Gr – lowest formation in Trans Indus-Potwar Province (TrI-PP). Holotype section: Nammal Gorge. Author: E.R. Gee (as in Fermor, 1935, quoted by Shah, 2009). Reference section: None.
Lithology and Thickness
Shallow-marine marl. The formation comprises shale, marl and Nummulite-rich limestone. In the Salt Range, these rocks occur as alternations. The shale is grey to olive green, while the limestone and marl are light grey to bluish grey. The limestone is argillaceous in places. In the Surghar Range, the lower part of the formation is composed of bluish grey marl with subordinate interbedded calcareous shale and minor limestone. The upper part consists of bluish grey limestone with intercalations of marl and shale.
Thickness: 35-130 m. It is 100 m thick in the type section and thins out to 60 m at Khairabad. The formation is 40 m thick in the Khewra-Choa Saidan Shah Road section in Eastern Salt Range. It is 130 m thick in the Chichali Pass and 35 m in Broach Nallah of the Surghar Range.
Relationships and Distribution
Lower contact
Conformably underlain by Patala Fm (transitional).
Upper contact
Conformably overlain by Sakesar Limestone Fm (transitional).
Regional extent
The formation is well developed in Salt Range and Surghar Range. It has been encountered in wells drilled in TrI-PP and the T-CP.
GeoJSON
Fossils
Highly fossiliferous. Forams include Nummulites atacicus, N. lahiri, N. irregularis, Assilina granulose, A. laminose, A. spinosa, Lockhartia tipperi, L. hunti, L. conditi, Operculina nummulitoides, Discocyclina ranikotensis and Fasciolites applinae etc.
Age
Depositional setting
Additional Information
EMW: Gas and oil.