Lithofacies and Palynostratigraphy of Some Cretaceous and Paleocene Rocks, Surghar and Salt Range Coal Fields, Northern Pakistan
By Peter D. Warwick, Shahid Javed, S. Tahir A. Mashhadi, Tariq Shakoor, Asrar M. Khan, and A. Latif Khan
Indigenous coal has been a minor part of Pakistan's energy budget since the late 19th century, but as modern, large, coal-fired electric-power generation facilities are brought online, coal will become an important component of Pakistan's energy budget. Consequently, detailed geologic studies such as this report on a coal-bearing area in northern Pakistan are warranted. This report reviews the coal-bearing Cretaceous Lumshiwal and Paleocene Hangu Formations of the Surghar Range and of the western part of the Salt Range in north-central Pakistan (figures 1, 2). The paper defines the stratigraphic relation between the Lumshiwal (and its minor coal occurrences) and the Hangu (and its economically important coal deposits). The various lithologies within the Lumshiwal and Hangu and associated palynological data are discussed, along with the chemical and physical characteristics of Hangu coal samples. The report also includes interpretations of the depositional environments of the Lumshiwal and Hangu rocks.
The Shinghar and Surghar Ranges constitute the northernmost part of the Trans Indus Mountains (figure 1). The Makarwal Gula Khel coal field, as described by Ahmed and others (1986), is located in the north-trending southern part of the Surghar Range and lies along the border of the Punjab and the North-West Frontier Province (NWFP). The coal-mining town of Makarwal is the center of mining activities. The Kurd coal field (Ahmed and others, 1986) is located in the east-trending part of the Surghar Range west of Kalabagh and south of the Kohat Plateau (figure 1). In this report, the Makarwal-Gula Khel and Kurd coal fields are referred to as the Surghar Range coal fields.
The rocks exposed in the Surghar Range vary in age from Triassic(?) to Quaternary (figure 2). The stratigraphic relation between the Hangu and the underlying Lumshiwal Formation is not clear, and in outcrop the contact is difficult to define. The upper part of the Lumshiwal and the lower part of the Hangu are dominated by sandstone, and both formations contain carbonaceous shale and coal beds. Danilchik and Shah (1987) define the contact between the formations as occurring at the base of a prominent coal bed that is developed in the southern part of the field. Where the coal bed is absent, the contact has been placed at the base of a thin lateritic mudstone that Danilchik and Shah (1987) interpreted to represent the base of the Paleocene. Studies in the Salt Range, located southeast of the Surghar Range (figure 1), by Warwick and Shakoor (1988; in press) reported that such lateritic beds do not represent major disconformities and are common in the lower part of the Hangu in that area. These stratigraphic problems led us to collect a series of stratigraphic samples for paleontologic analysis. The results of these paleontological studies, along with measured stratigraphic sections through the Lumshiwal and the Hangu Formations and coal quality data, are presented and discussed in this paper.
The strata in the Surghar Range are deformed by folds and faults and commonly dip 30\xb0 or more to the west or northwest (figures 3A, B). The structural setting of the Surghar Range and the >750 m of overburden above the Hangu Formation (figure 3) have prevented the extensive exploration drilling programs that normally precede coal-field development. The Makarwal coal bed and a few other minor coal beds crop out along the cliff face of the Surghar Range (figures. 2, 3). The Makarwal coal bed is the primary bed mined in the area; however, near the town of Makarwal, a second bed, called the upper coal, is also mined. In the western part of the Salt Range, the Lumshiwal and Hangu Formations are very thin or absent, and only the Hangu has a few minor carbonaceous shale beds.
The regional characteristics of the Lumshiwal and Hangu Formations have been reviewed by Fatmi (1973), Shah (1977), and Wells (1984). Earlier workers who described the occurrences of coal in the Surghar Range include Wynne (1880), Simpson (1904), Gee (1938, 1941, 1948, 1949), Khan (1949), and Warwick and Husain (1990). Landis and others (1971) described the chemical and physical characteristics of nine coal samples collected from four different mines of, presumably, the Makarwal coal bed of the Surghar Range. Their study reported that this coal bed ranges in apparent rank from high-volatile B to high-volatile C bituminous. Warwick and Javed (1990) described the geochemical characteristics of various Pakistani coals, including those from the Surghar Range. Detailed investigations were undertaken by Danilchik and Shah (1987) to map the structure and geology of the Makarwal-Gula Khel coal field at 1:50,000 and 1:6,000 scales. Faruqi (1980, 1983) also worked on the structural details of the mining area. Ghaznavi (1988) described the petrographic characteristics and geologic setting of the Surghar Range coal deposits. Davies and Pinfold (1937), Haque (1956), Fatmi (1972), Köthe (1988), Frederiksen (1992), and Frederiksen and others (in press) have provided paleontological age determinations for the Lumshiwal and Hangu Formations.
A detailed assessment of the coal resources of the Hangu, defining reserve categories such as measured, indicated, and inferred, was not undertaken in this study because such estimates have been presented in Ahmed and others (1986) and Danilchik and Shah (1987). These authors suggest that the coal reserves of the Surghar Range are 16 million to 19 million tons of coal.
This report is a product of a cooperative program between the Geological Survey of Pakistan (GSP) and the U.S. Geological Survey (USGS) and was sponsored by the Government of Pakistan and the U.S. Agency for International Development (USAID). Funding was provided by USAID through Project 391-0478 (Energy Planning and Development Project, Coal Resource Assessment Component 2a; Participating Agency Service Agreement (PASA) No. 1PK-0478-P-IC-5068-00.
We are thankful to the Pakistan Mineral Development Corporation (PMDC) for providing some of the data that were used in this study and for providing access to their mines in the Surghar Range. We are also grateful to the many privately owned mining companies in the Surghar Range who provided coal thickness data and access to their mines for sampling
We acknowledge Patricia A. Hawk for her help in retyping appendix III.
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