Sedimentology and Economic Significance of Hangu Formation, Northwest Pakistan

Abstract

The Hangu Formation (Paleocene) consists of sandstone, siltstone, carbonaceous shale, coal and laterite. It is well exposed in the Trans Indus Surghar range and the southern Hazara basin. The sandstone is yellowish brown, fine to coarse grained and medium to thick bedded. The sandstone of the Hangu Formation is classified as quartz arenite on the Q-F-L diagram. It is mostly grain supported and are cemented by silica cement. The study of different stratigraphic sections reveal that Hangu Formation can be sub-divided into a number of lithofacies on the basis of sedimentary structures and lithological variations. These include lateritic lithofacies, coal and carbonaceous shale, cross-bedded sandstone, bioclastic limestone and bioturbated sandstone. All these lithofacies are well-developed in the Baroch Nala section of the Surghar range except the lateritic lithofacies which contains a thin bed of ferruginous clay. In the studied sections of the Hazara basin, the lateritic lithofacies is the only well-developed lithofacies present in the area. The coal occurs at two stratigraphic levels in the Baroch Nala section. The lower coal seam is thick and its chemical study indicates higher calorific value and carbon content than the upper coal seam and with low moisture/ash content. On the basis of the calorific value, the coal of the Hangu Formation is characterized as high volatile bituminous. The degree of laterization is strong in the Langrial and Khanpur sections and moderate in Baroch Nala section.

Hydrocarbon source rock assessment of the shale and coal bearing horizons of the Early Paleocene Hangu Formation in Kala-Chitta Range, Northwest Pakistan

“…1). Conventionally, this formation has acted as a proven resource of bituminous coal in the Upper Indus Basin of Pakistan (Kadri 1995;Ullah et al 2018;Qureshi et al, 2020). However, in this study, it is assumed to act as a potential source rock for hydrocarbon generation to charge the associated reservoirs in the Kala-Chitta Range of Upper Indus Basin, Pakistan.…”

“…The Hangu Formation represents a shallow marine stratigraphic unit of the eastern Tethyan affinity in Pakistan (Shah 2009;Craig et al 2018;Qasim et al 2020). Lithologically, it consists of light grey to reddish brown, fine to coarse-grained sandstone, medium to thick-bedded limestone with grey shale intercalations and coal beds (Shah 2009;Qureshi et al 2020). It is widely distributed in Attock-Cherat, Kala-Chitta, Surghar and Salt ranges along with Kohat, Potwar and Hazara basins of Pakistan (Fig.…”

“…It is widely distributed in Attock-Cherat, Kala-Chitta, Surghar and Salt ranges along with Kohat, Potwar and Hazara basins of Pakistan (Fig. 1; Shah 2001, Shah 2009Malkani 2012;Malkani and Manhood 2016;Qureshi et al 2020). It has been studied extensively by several researchers notably Ahmed et al (1986), Shah et al (1993) from stratigraphic, sedimentological, provenance and economic point of view.…”

“…and Qureshi et al (2020) detail sedimentological studies of Hangu Formation indicated that it represents a wide variation in lithology encompassing sandstone, siltstone, limestone, coal and shale intervals. Five distinct lithofacies are distinguished within the Early Paleocene Hangu Formation that include (1) Lateritic/Bauxitic lithofacies, (2) Cross-bedding sandstone lithofacies, (3) Bioclastic limestone lithofacies, (4) Coal, carbonaceous shale lithofacies and (5) Bioturbated quartzose sandstone lithofacies.…”

Geochemical investigation and modes of occurrence of critical elements and minerals in the coal of Akkakhel, Akhorwal, and Sheikhan, KP, Pakistan

“…The coal bed occurs in the form of lenses, stringers, and argillaceous facies in the upper part of the Hangu formation (Shah et al, 1993;Shah, 2001). The age of geological formations in the Akkakhel Bara, Akhorwal, and Sheikhan are ranging from mid-Jurassic to Miocene in which the coal lies at the top of the Paleocene Hangu Sandstone and the bottom of the Lockhart Limestone (Shah, 2001;Ding et al, 2016;Qureshi et al, 2020).…”