A Skarn Rock from Dir, Northwest Pakistan
Abstract
The geology and petrology of a skarn from northwest Pakistan me presented. The chemistry of the rocks and their constituent minerals is discussed briefly and compared with other similar occurrences. The rock chemistry and the abundance of ferrosalite, andradite-rich garnet, and epidote (Fe3+/(Fe3+ + Al) = 0.30) are considered to be due to metasomatism (mainly the introduction of iron, and possibly silica) of the country metasediments or, less likely, volcanic rocks by a biotite-two pyroxene tonalite intrusion.
References
Ashraf. M., Chaudhry, M.N. & Hussain, S.S., 1980. General geology and economic significance of the Lahor granite and rocks of southern ophiolite belt in Allai Kohistan area. Geol. Bull. Univ. Peshawar 13, 207-213.
Bard, J.P., 1953. Metamorphism of an obducted island arc: example of the Kohistan sequence (Pakistan) in the Himalayan collided range. Earth Planet. Sci. Letters 65, 133-144.
Deer, W.A., Howie, R.A. & Zussman, J., 1962. Rock-Forming Minerals, vol. 1. Longmans, London.
Deer, W.A., Howie, R.A. & Zussman, J., 1978. Rock-forming minerals, vol. 2A. Longmans, London.
Einaudi, M.T. & Burt, D.M., 1982. Introduction - terminology, classification, and composition of skarn deposits. Econ. Geol. 77, 745-754.
Eskola, P., 1914. On the petrology of the Orijarvi region in southwestern Finland. Bull. Comm. Geol. Finlande 40, 1-279.
Firman, R.J., 1957. Fissure metasomatism in volcanic rocks adjacent to the Shap granite, Westmorland. Quart. J. Geol. Soc. 113, 205-222.
Hess, H.H., 1949. Chemical composition and optical properties of common clinopyroxenes, Part I. Amer. Min. 34, 621-666.
Jan, M.Q. & Asif, M., 1983. Geochemistry of tonalites and (quartz) diorites of the Kohistan-Ladakh (Transhimalayan) granitic belt in Swat, NW Pakistan. In Granites of Himalayas, Karakoram and Hindukush (F.A. Shams edit.). Inst. of Geol. Punjab Univ., Lahore, Pakistan, 355-376.
Jan, M.Q. & Kempe, D.R.C., 1973. The petrology of the basic and intermediate rocks of Upper Swat, Pakistan. Geol. Mag. 110, 285-300.
Jan, M.Q. & Mian, I., 1971. Preliminary geology and petrography of Swat Kohistan. Geol. Bull. Univ. Peshawar 6, 1-32.
Kempe, D.R.C. & Jan, M.Q., 1980. The Peshawar Plain alkaline igneous province, NW Pakistan. Geol. Bull. Univ. Peshawar 13, 71-77.
Khalil, M.A. and Afridi, A.G.K., 1979. The geology and petrography of Deshai-Diwangar area, Ushu Go1 Valley, Swat Kohistan. Geol. Bull. Univ. Peshawar 11 (spec. issue), 99-111.
Khan, J., 1979. Geology of the Baraul Valley, Dir. Geol. Bull. Univ. Peshawar 11 (spec. issue), 153-162.
Majid, M., 1979. Petrology of diorites from the "Kohistan sequence", Swat, northern Pakistan: A genetic interpretation at plate scale. Geol. Bull. Univ. Peshawar 11 (special issue), 13 1-1 51.
Matsumoto, Y., 1974. Ferrohastingsites from the skarn zone in Japan. Mem. Geol. Soc. Japan 11, 113.
Oliver. R.L., 1958. Andradite from the Island of Jersey. Am. Bull. Soc. Jersiaise 17, 181.
Shams, F.A., 1963. Reactions in and around a calcareous xenolith lying within the granite of gneiss Manglaur, Swat State, West Pakistan. Geol. Bull. Univ. Punjab 3, 7-18.
Sharma, R.S., 1981. Mineralogy of a scapolite-bearing rock from Rajasthan, northwest peninsular India. Lithos 14, 165-172.
Shay, K., 1975. Mineralogical zoning in a scapolite-bearing skarn body on San Gorgonio Mountain, California. Amer. Min. 60, 785-797.
Symes, R.F., Bevan, J.C. & Jan, M.Q., (In prep.) Orbicular rocks near Deshai, Swat Kohistan, Pakistan.
Tahirkheli, R.A.K. & Jan, M.Q. (Eds.1, 1979. The geology of Kohistan, Karakoram Himalaya, northern Pakistan. Geol. Bull. Univ. Peshawar 11 (spec. issue).
Tahirkheli, R.A.K., Mattauer, M., Proust, F. & Tapponnier, P., 1979. The India Eurasia suture zone in northern Pakistan: synthesis and interpretation of recent data at plate scale. In Geodynamics of Pakistan (Farah, A. & DeJong, K.A., eds.). Geol. Sum. Pakistan, Quetta, 125-130.
Temp& H.-G., 1938. Der Einfluss der seltenen Erden and einiger anderer Komponenten auf die physikalischoptischen Eigenschaften innerhalb der Epidotgruppe. Chemie der Erde 11, 525-541.
Turner, F.J. & Verhoogen, J., 1960. Igneous and Metamorphic Petrology. McGraw-Hill, New York.
