Takatu Fm
Type Locality and Naming
Holotype section: Dara Manda Nallah. Author: M.D. Williams, 1959. Reference section: None.
Synonym: Chiltan Limestone
Lithology and Thickness
Reef limestone. It is typically a massive, thick to very thick bedded dark limestone that gives a fetid smell on broken surface. The color varies from dark to very light grey and brown to brownish grey; intraformational conglomerates have been found in the Takatu Range. The texture varies from fine grained, sub-lithographic to oolitic. At places the limestone is reefal or biohermal. The massive mound shaped body, which forms the main mass of Takatu Peak represents a bioherm, devoid of bedding and composed largely of algal limestone. At Ziarat the bioherm is composed of algae, sponges and other unidentified skeletal material; recrystalization is common in these bioherms. The overlying about 30 m thick interbedded grey limestone and dark shale was earlier designated as Mazar Drik formation (Arkell, 1965). SCP has now formalized it as Mazar Drik Member of Takatu Fm (Shah, 2009)
Mazar Drik Member (Arkell, 1956): In its type locality near Mazar Drik in Marri Hills (northern Sulaiman Lobe), this unit is less than 30 m thick and consists of interbedded grey limestone and shale. It has early Callovian fauana in the upper part and Bathonian fauna in the lower part. The member is disconformably overlain by Sembar Fm of Early Cretaceous age. It was also reported by Vredenburg (1909) from the axis of Moro anticline in the Kirthar Range, however it is not developed in the Sulaiman Province.
Thickness: 757-1,818 m. (294-1,437 m in subsurface). At the type section Takatu Fm (Chiltan Limestone, HSC, 1960) is 757 m thick, whereas near Quetta it attains a thickness of 1,818 m. In well Jhatpat-1 a total thickness of 1,437 m of Takatu limestone was encountered from 1,555 - 2992 m, and in Zindapir-1 well it has a total thickness of 845 m, and was encountered from 2,165-3,010 m. At Bhadmi-1 (South of Badin) a total thickness of 826 m was encountered from 2,734-3,560 m. at Jiwanwala-1 a total of 294 m was drilled from 1,663-1957 m.
Relationships and Distribution
Lower contact
Conformably underlain by Shirinab Fm in the Axial Belt
Upper contact
Disconformably overlain by Sembar Fm.
Regional extent
The formation is widely distributed in Kirthar Province (KrP) and Sulaiman Province (SP) (both on surface and in subsurface). Around Quetta it forms the peaks of high mountains like Koh-e- Maran, Koh-e-Siah, Chiltan, Murdar Ghar, Takatu, Khilafat and Zardah. Most of these mountains are resistant cores of anticlines. Northern half of Kirthar Range exposes Takatu limestone in the cores of huge anticlines and the Takht-e-Sulaiman in Sulaiman Range also exposes the limestone in the core of the N-W oriented large anticline. It has been encountered in wells drilled in the plains to the east of the ranges, except in the T-CP.
GeoJSON
Fossils
With the exception of fossils from within the Mazar Drik Member no identifiable fossils are found in the formation, which are mostly poorly preserved fragmentary remains.
Age
Depositional setting
Additional Information
EMW: Low oil and gas potential.