Petrochemistry of asbestos bearing rocks from Skhakot-Qila Ultramafic Complex, northern Pakistan
Abstract
This study has been carried out to map asbestos deposits of the Skhakot-Qila Ultramafic Complex around Peshawar valley and to describe their petrochemical characteristics. Dunite, peridotite, serpentinite, chromitite, and mafic rocks are the main types of the complex while tremolite, talc-carbonate, steatite, and chlorite wall rocks are found in the form of irregular to pod-like, elongated or tabular masses and veins transacting the ultramafic rocks along shear zones. The serpentine in the complex is classified as chrysotile and has grown along shear zones as fibrous asbestos. Asbestiform tremolite occurs locally at Newe Killi, Hero Shah, and Behram Dehri and has most probably grown from the deformation of pyroxenite.
The data indicate that rocks of the Skhakot-Qila Ultramafic Complex represent an ophiolite segment of the Thetyan ocean crust and are classified as a partly metamorphosed mafic-ultramafic complex. Igneous crystallization and fractionation and accumulation of olivine, pyroxenes, and chromite have led to the development of mafic and ultramafic rocks. Tectonic emplacement has caused the deformation and metamorphism of these rocks transforming dunite and peridotite into serpentine. Local variation in P-T condition during tectonic deformation and metamorphism caused the recrystallization of various minerals with serpentine as an essential constituent and brucite, forsterite, magnetite, magnesite, talc, and carbonate associated in various proportions.
References
Ahmed, Z., 1978. Petrology of the Taghma area, Swat District, N.W.F.P., Pakistan. Geological Bulletin, University of Punjab, 15, 25-29.
Ahmed, Z., Hall, A., 1982a. Nickeliferous opaque minerals associated with chromite alteration in the Skhakot-Qila complex, Pakistan, and their compositional variation. Lithos, 15, 39-47.
Ahmed, Z., Hall, A., 1982b. Alteration of chromite from the Skhakot-Qila ultramafic complex, Pakistan. Chemei der Erde, 40, 309-339.
Ahmed, Z., 1982. Porphyritic, nodular, nodular, and orbicular chrome ores from the Skhakot-Qila complex, Pakistan, and their chemical variation. Mineralogical Magazine, 45, 167-178.
Arif, M., 1994. Studies of ultramafic rocks from Swat, North Western Pakistan: Genesis of emerald and nickeliferous phases. Unpublished Ph.D. thesis, University of Leicester, U.K.
Asrarullah, Ahmed, Z., Abbas, S. G., 1979. Ophiolites in Pakistan: An introduction. Special Issue, Geological Bulletin, University of Peshawar, 13, 181-92.
Cawthorn, R. G., O’Hara, M. J., 1976. Amphibole fractionation in calc-alkaline magma genesis. American Journal of Science, 276, 309-329.
Coleman, R.G., Kieth, K. E., 1971. A chemical study of serpentinization, Burro Mountain, California. Journal of Petrology, 12, 311-28.
Cox, K.G., Bell, J.D., Pankhurst, R.J., 1979. The interpretation of igneous rocks. George Allen and Unwin, London.
Desio, A., 1964. Geological Tentative map of the Western Karakoram, scale 1:500,000. Institute of Geology, University of Milan, Italy.
DiPietro, J. A., Isachsen, C. E., 2001. U-Pb zircon ages from the Indian plate in northwest Pakistan and their significance to Himalayan and pre-Himalayan geologic history. Tectonics, 20, 510-525.
Grove, T.L., Gerlach, D.C., Sando, T.W., 1982. Origin of calc-alkaline series lavas at Medicine Lake volcano by fractionation, assimilation, and mixing. Contributions to Mineralogy and Petrology, 80, 160-182.
Hamidullah, S., Bowes, D.R., 1987. Petrogenesis of the appinite suite, Appin district, western Scotland. Acta Universities Carolinae-Geologica, 4, 295-396.
Hamidullah, S., 1984. Asbestos occurrence in Mohmand Agency: Genesis, economics, and related health hazards. Geological Bulletin, University of Peshawar, 17, 69-73.
Irvine, T.N., Barager, W.R.A., 1971. A guide to the classification of the common volcanic rocks. Canadian Journal of Earth Sciences, 8, 523-49.
Jackson, E. D., Thayer, T. P., 1972. Some criteria for distinguishing between stratiform, concentric and alpine peridotite-gabbro complexes. International Geological Congress 24th, Montreal, 2, 289-296.
Jehan, K., Khan, A. N., 1963. Spheroidal asbestos from Qila, Charsadda Tehsil, Pakistan. Journal of Scientific and Industrial Research, 16, 266-267.
Johannes, W., 1968. Experimental investigation of the reaction forsterite + water = serpentine + brucite. Contributions to Mineralogy and Petrology, 19, 309-15.
Kazmi, A. H., Lawrence, R. D., Daud, H., Snee, L. W., Hussain, S.S., 1984. Geology of the Indus Suture Zone in the Mingora-Shangla area of Swat, north Pakistan. Geological Bulletin University Peshawar, 17, 127-44.
Miyashiro, A., 1973. Metamorphism and Metamorphic Belts. New York, Harper and Row, 514.
Moody, J. B., 1976a. Serpentinization: A review. Lithos, 9, 125-38.
Moody, J. B., 1976b. An experimental study on the serpentinization of iron-bearing olivines. Canadian Mineralogist, 14, 462-78.
O'Hara M.J., 1968. The bearing of phase equilibria studies in the origin and evolution of basic and ultrabasic rocks. Earth Science Reviews, 4, 69-133.
O'Hara M.J., 1976. Data reduction and projection schemes for complex compositions. Experimental Petrology, 103-126. N.E.R.C. Publication Series, D, 6, Manchester.
Powel, C. Mc. A., 1979. A speculative tectonic history of Pakistan and surroundings: Some constraints from the Indian Ocean. In: Farah, A., DeJong, K. A. (Eds), Geodynamics of Pakistan. Geological Survey of Pakistan, Quetta, 5-24.
Qaisar, M.A., Khan A. H., 1967. Mineralogy of asbestos from Kurram agency, Pakistan. Journal of Scientific and Industrial Research, 12, 163-4.
Qaisar, M.A., Ali, M. K., Khan A. H., 1967. Mineralogy of some asbestos from north-west Pakistan. Pakistan Journal of Scientific and Industrial Research, 10, 116-120.
Rafiq, M., Ahmed., I., Tahirkheli, T., 1983. A geological map of the surroundings of the Peshawar plain. Geological Bulletin University of Peshawar, 16, 189.
Rafiq, M., Shah, M. T., Ahmad, I., 1984. Note on tremolite zone from the extension of Sahkakot-Qila ultramafic complex in Utmankhel, Mohmand agency. Geological Bulletin University of Peshawar, 17, 178-9.
Rafiq, M., 1984. Extension of Skhakot Qila ultramafic complex in Utman Khel, Mohmand agency, NWFP, Pakistan. Geological Bulletin University Peshawar, 17, 53-59.
Sato, H., 1977. Nickel content of basaltic magmas: Identification of primary magmas and a measure of the degree of olivine fractionation. Lithos, 10, 113-20.
Shride, A.F., 1973. Asbestos. In: Brobst, D.A., Part, W.P. (Eds), United States Mineral Resources. U.S. Geological Survey Professional Paper, 820, 63-73.
Tahirkheli, R. A. K., Mattaure, M., Proust, F., Tapponnier, P., 1979. The India-Eurasia suture in northern Pakistan: synthesis and interpretation of data on plate scale. In: Farah, A., DeJong, K. A. (Eds), Geodynamics of Pakistan. Geological Survey of Pakistan, 125-130.
Uppal, I. H., 1972. Preliminary account of the Harichand ultramafic complex, Malakand agency, NWFP, Pakistan. Geological Bulletin University of Punjab, 9, 55-63.
