Nari Fm
Type Locality and Naming
Momani Gr – lower formation. Holotype section: Gaj River section. Author: W.T. Blanford, 1876. Reference section: None.
Lithology and Thickness
Sandy limestone. The formation consists of sandstone, shale and subordinate limestone. The lower part, the Nal Member, is predominantly composed of crystalline limestone, which is white to grey, brown and shelly, nodular or rough surfaced, thin to thick bedded and even massive; thin stringers of dark shale are present. The upper part of the formation consists predominantly of sandstone, which is greenish grey, grey brown and white colored, fine- to coarse-grained often gritty and calcareous with subordinate shale, sandstone and varicolored claystone. Beds of conglomerate and ironstone are present either at the base or in the upper part.
Thickness: 150-1,820 m. The formation is 1,400 m thick at the type locality and 1,045 m in the Mazarani area of the Kirthar fold belt. In eastern Sulaiman Range, the thickness ranges from 150 m at Chitarwatta to 300 m at Moghal Kot. It is 200 m thick in Sor Range near Quetta and 600 m in Nal area in the Axial Belt. However, it attains a maximum thickness of 1,820 in KrP as reported by HSC (1960).
Relationships and Distribution
Lower contact
Conformably underlain by Kirthar Fm and Nisai Fm (gradational). In southern Kirthar Province (KrP), it is unconformable underlain by Laki Fm and the Kirthar Fm
Upper contact
Conformably overlain by Gaj Fm in southern Sulaiman Province and Kirthar Province (KrP), or by Hinglaj Fm (or Khojak Fm) in the Arenaceous Zone of the southern Axial Belt. In eastern Sulaiman Range the contact with Siwalik Group is unconformable.
Regional extent
The formation is widely distributed in southern Sulaiman Province, Kirthar Province (KrP) extending up to Quetta and the Axial Belt.
GeoJSON
Fossils
Foraminifers, Nummulites intermedius, N. vascus, N. fichteli, N. clypeus, Lepidocyclina (Eulepidina) dilatata. Bivalves include Crassatella sulcata, Venus (Ventricola) multilamella, V. (Antigona) peepera. Gastropods: Scaphander oligoturritus, Lyria anceps etc.
Age
Depositional setting
The basal part is largely marine while the upper part of the formation represents deposition under mixed marine and continental setting. Major part the clastic sediments were deposited in a delta, which was prograding from north to south.
Additional Information