Further Data on Ortho- and Clinopyroxenes from the Pyroxene Granulites of Swat-Kohistan, Northern Pakistan
Abstract
Microprobe analyses of pyroxenes from the pyroxene granulites of Swat-Kohistan are similar to their wet chemical analysis and the two sets of analysis yield similar temperature estimates. The pyroxenes are exsolved, but the exsolved pyroxene is similar chemistry to its corresponding principal pyroxene, suggesting the attainment of physico-chemical equilibrium. The Mg/(Mg + Fe") ratios for the coexisting pyroxenes have been plotted and the implications of granulite facies metamorphosed noritic teases in the amphibolite belt of Kohistan discussed.
References
Andrews-Speed, C.P. & Brookfield, M.F.., 1982. Middle Palaeozoic and Cenozoic geology and tectonic evolution of the northwestern Himalaya. Tectonophysics 82, 253-275.
Bard, J.P., Maluski, H., Matte, Ph. & Prom, F., 1980. The Kohistan Sequence: crust and mantle of an obducted island arc. Geol. Bull. Univ. Peshawar (Spec. Issue) 13, 87-94.
Chaudhry, M.N. & Chaudhry, A.G., 1974. Geology of Khagram area, Dir district. Geol. Bull. Punjab Univ. 11, 21-43.
Chaudhry, M.N., Kausar, A.B., 8r Lodhi, S.A.K., 1974. Geology of Timurgara-Lal Qila area, Dir district, N.W.F.P. Geol. Bull. Punjab Univ. 11. 53-73.
Coward, M.P., Jan, M.Q., Rex, D., Tarney, J., Thirlwall, M. and Windley, B.F., 1982. Geotectonic framework of the Himalaya of N. Pakistan. Jour. Geol. Soc. Lond. 139, 299-308.
Dahl, P.S., 1980. The thermal-compositional dependence of Fe’’-Mg distributions between coexisting garnet and pyroxene: applications to geothermometry. Amer. Mineral. 65, 854-866.
Ferry, J.M. & Spear, F.S., 1978. Experimental calibration of partitioning of Fe and Mg between biotite and garnet. Contrib. Miieral. Petrol. 66, 113-1 17.
Ganguly, J., 1977. Compositional variables and chemical equilibrium in metomorphism. In "Energetics of Geological Processes" (eds. S.K. Saxena & S. Bhattacharji), Springer-Verlag, 250-284.
Honegger, K., Dietrich, V., Frank, W., Gansser, A., Thoni, M. & Trommsdorff, V., 1982. Magmatism and metamorphism in the Ladakh Himalayas (the Indus-Tsangpo suture zone). Earth Planet. Sci. Letters 60, 253-292.
Jan, M.Q., 1979. Petrography of pyroxene granulites from northern Swat and Kohistan. Geol. Bull. Univ. Peshawar (Spec. Issue) 11, 65-87.
Jan, M.Q., 1980. Petrology of the obducted mafic and ultramafic metamorphites from the southern part of the Kohistan Island arc sequence. Ibid. (Spec, Issue) 13, 95-107.
Jan, M.Q., & Howie, R.A., 1980. Ortho- and clinopyroxenes from the pyroxene granulites of Swat Kohistan, northern Pakistan. Miner. Mag. 43, 7 15-726.
Jan, M.Q., & Howie, R.A., In preparation. Some garnets, epidotes, biotitic nucas, and feldspars from Swat Kohistan, NW Pakistan.
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.
Kretz, R., 1963. Distribution of magnesium and iron between ortho-pyroxene and calcic pyroxene in natural mineral assemblages. J. Geol. 71, 773-785.
Perchuck, L.L., 1966. Temperature dependence of the coefficient of distribution of calcium between coexisting amphibole and plagiodase. Dokl. Acad. Sci, USSR, Earth Sci. Sect. 169, 203-205.
Perchuck, L.L., 1968. Pyroxene-garnet: equilibrium and the depth facies of ecologites, Int. Geol. Rev. 10, 280-318.
Perchuck, L.L., 1969. The effect of temperature and pressure on the equilibrium of natural iron-magnesium minerals. Int. Geol. Rev. 11, 875-901.
Perchuck, L.L., 1977. Thermodynamic control of metamorphic processes. In “Energetics of Geological Processes” (eds. S.K. Saxena & S. Bhattacharji) Springa-Verlag, 285-325.
Perchuck, L.L., & Vaganov, V.I., 1977. Temperature regime of formation of continental volcanic series. Preprint, Inst. Exper. Mineral. Acad. Sci. U.S.S.R. 1-48.
Shams, F.A., 1975. The petrology of the Thak Valley igneous complex, Gilgit Agency, northern Pakistan. Acad. Naz. Lincei, Ser. 8, 59, 453-464.
Spear, F.S., 1980. NaSi CaAl exchange equilibrium between plagioclase and amphibole. Contrib. Mineral. Petrol. 73, 33-41.
Tahirkheli, R.A.K. & Jan, M.Q. (eds.), 1979. Geology of Kohistan, Karakoram. Himalaya, Northern Pakistan. Geol. Bull. Univ. Peshawar (Spec. Issue) 11.
Tahirkheli, R.A.K., Mattauer, M., Proust, F. & Tapponnier, P., 1979. The India-Eurasia suture zone in northern Pakistan: synthesis and interpretation of data at plate scale. In "Geodynamics of Pakistan" (eds. R. Farah and K. De Jong) Geol. Surv. Pakistan, 125-130.
Thompson, A.B., 1976. Mineral reactions in pelitic rocks: II. Calculation of some P-T-X (Fe=Mg) phase relations. Amer. J. Sci. 276, 425-454.
Weawer, B.L., Tarney, J., Windley, B.F., Sugavanam, E.B. & Venkata Rao, V., 1978. Madras granulites: Geochemistry and P-T conditions of crystallization. In 'Archaean Geochemistry' (eds. B.F. Windley and S.M. Naqvi), Elsevier, Amsterdam, 177-204.
Wells, P.R.A., 1977. Pyroxene thermometry in simple and complex systems, Contrib. Mineral. Petrol. 62, 129-139.
Wilson, A.D., 1955. A rapid method for the determination of Ferrous iron in rocks. Bull. Geol. Sum Gt. Br. 9, 56-58.
Wood, B.J. & Banno, S., 1973. Garnet-orthopyroxene and orthopyroxene-clinopyroxene relationships in simple and complex systems. Contrib. Mineral. Petrol. 42, 109-124.
