Gwal Fm
Type Locality and Naming
Khanozai Gr – lower formation: Holotype section: Trakai-Gwal section, Axial Belt. 60 km NE of Quetta. Author: M. Anwar et al., 1993. Reference section: None.
Lithology and Thickness
Pelagic marl. The formation is composed of variegated shale and limestone interbeds with marl intercalations and occasional mafic intrusions in the Trakai-Gwal area. The shale is dark grey to olive, maroon, greenish grey, silty, friable and fissile. The limestone is grey to dark grey, weathering brownish grey, micritic, dense, platy to thin bedded, at places dolomitized. It contains beds of basaltic lavas and exotic blocks of Permian fossiliferous limestone. The formation includes a thin- to medium-bedded micritic limestone unit in the upper part, which the authors have correlated with Narmia and Mittiwali members of the Mittiwali Formation of the Salt Range.
Thickness: More than 350 m thick in the type section.
Relationships and Distribution
Lower contact
The base of the formation is not exposed.
Upper contact
Disconformably overlain by Wulagai Fm . Its upper contact with Wulagai Fm is sharp where a fossiliferous gritty limestone with limestone boulders is present; this bed contains spiriferinids and crinoidal debris. According to authors, its age is Middle Triassic and indicates a disconformity.
Regional extent
Widely distributed in Zhob Valley in Axial Belt, between Gwal and Qila Saifullah and further east.
GeoJSON
Fossils
Ammonites: Meekoceras, Owenite, Anakashmirites, Ana sibirites, Durgaites, Hemiprionetes etc.
Age
Depositional setting
Similar to the overlying Wulagai Fm, it is composed of clastic and carbonates turbidites of deep-water origin and is found in thrust sheets.
Additional Information