Habib Rahi Fm
Type Locality and Naming
Ghazij Gr – fifth formation in Sulaiman Province (SP). Hypo: Near Zam Post. Author: Tainsh et al., 1958. Reference section: None.
Lithology and Thickness
Limestone. It is a grayish brown and buff, hard limestone that weathers white. It is fine grained, thin bedded, dominantly argillaceous, and in few places grades into marl; thin lenticular chert bands are common but are restricted to upper part of the formation. Oil shales have been reported from this unit (as in Kazmi and Abbasi, 2008). The argillaceous limestone and marl in the lower part contain abundant Assilina. At Shinki Post (North Waziristan), the upper part of the formation is pebbly and massive; the middle part is thick bedded while the lower part is again massive. [SEE BELOW ABOUT REGIONAL MEMBERS]
Thickness: 10-200 m. In the eastern Sulaiman Range, its thickness ranges between 10-40 m. However, towards southwest it gradually thickens in the surface exposures, while in subsurface a very thick sequence of 190-200 m was drilled at the Sui gasfield. South of Sui its thickness again reduces to less than 100 m in Kandhkot, Qadirpur and Mari gasfields.
Relationships and Distribution
Lower contact
Conformably underlain by Baska Fm
Upper contact
Conformably overlain by Domanda Fm
Regional extent
The formation is restricted to SP in both subsurface (towards the eastern and southern plains) as well as in the surface exposures to the west. The unit provides a useful marker along Sulaiman Range while interpreting satellite imagery of the area.
Note: Earlier the name Kirthar Formation of Kirthar Province was extended to the Sulaiman Province where it consisted of four members namely, Habib Rahi, Domanda, Pirkoh and Drazinda members belonging to Leutetian-Priabonian stages, while these members are not represented in Kirthar Province. SCP has now upgraded these four members of SP to formation level (Habib Rahi Fm, Domanda Fm, Pirkoh Fm and Drazinda Fm). Kirthar Fm of the Kirthar Province, predominantly limestone, also represents the Lutetian-Priabonian stages, and hence the above four members of Sulaiman Province and the Kirthar Formation (in KrP) are chronostratigraphic equivalent and are being discussed as two chronostratigraphic equivalents occurring in two different geological provinces. Similarly Habib Rahi was extended by some authors up to Kohat area as the upper most member of the Kohat Fm. However, the SCP has now elevated Habib Rahi to formation level and considers it to be restricted largely to Sulaiman Province only (Shah, 2009). According to Kazmi and Abbasi (2008) also, the characteristics of this formation do not correspond to similar beds in upper part of the Kohat Fm.
GeoJSON
Fossils
Large forams are reported and include Assilina papillata, Nummulities cf. mammilatus, Opecrulina aspensis and Lockhartia conditi. This assemblage correlates with A. spira abrardi of Schaub (1981). Nannoplanktonic zone NP16 is assigned to the formation by Muller (2002), whereas Kothe et al. (1988) have placed it in NP14-16. From higher levels of the formation Nummulites beaumonti and Alveolina elliptica have been reported (as in Kazmi and Abbasi, 2008), while abundance of Assilina characterizes the lower part (Shah, 2009). Vertebrate fossils also indicate Middle Eocene age (as in Shah, 2009).
Age
Depositional setting
The formation represents variation in depositional environment from shallow to relatively deep marine, ranging from shelf to middle and outer shelf.
Additional Information
EMW: Gas bearing in Sui, Kandhkot, Qapirpur gasfields where the reserves are not only small but quality is poor. However, farther southeast, the Mari gasfield is a giant with about 7 Tcf reserves, and average heating value of 733 btu/cu.ft.