A-Type Granites of Warsak, Khyber Agency, N. Pakistan: Rift- Related Acid Magmatism in the Indian Plate
Abstract
Three varieties of granite from Warsak have been analysed for their geochemical composition, particularly trace elements. Two of the three varieties contain aegirine and riebeckite and are thus peralkaline. The third variety comprises biotite and muscovite with rare garnet, and varies between meta- and peraluminous compositions. Irrespective of these differences in mineralogical and major-element characteristics, there is a close match in incompatible trace elements between all the three varieties of granite from the studied area. A close scrutiny of the trace-element composition reveals A-type nature of the Warsak granites. Pnlaeozoic fragmentation of Gondwana, involving breakaway of India, may be responsible for the generation of the Warsak A-type granites and other similar granites in the Peshawar plain at Ambela, Shewa-Shahbazgarhi, Malakand, and Tarbela.
References
Ahmad, M., Ali, K.S.S., Khan, B., Shah, M.A. & Ullah, I., 1969. The geology of' warsak arc; Peshawar, Pakistan. Geol. Bull. Univ. Peshawar 4, 44-73.
Ahmad, M.I., 1961. Report on the Warsak Hydro-electric project. Govt. of Pakistan.
Anderson, J.L., 1923. Proterozoic anorogenic granite plutonism of North America. In: Medaris, L. G., Byers, C. W., Nickelson, D. M., Shanks, W. C. (eds). Proterozoic Geology. Geol. Soc. Amer. Mem. 161, 133-154.
Anderson, J.L. & Thomas, W.M., 1925. Proterozoic anorogenic two-mica granites: Silver Plume and St Vrain batholiths of Colorado. Geology 13, 177-120.
Brodie, K., & Rutter, E.H., 1926. On the relationship between deformation and metamorphism, with reference to the behavior of basic rocks. In: A.B. Thompson and D. C. Rubie (eds.). Advances in Physical Geochemistry, 4, Springer Verlag, N. Y., 132-179.
Barker, F., Wones, D.R., Sharp, D.N. & Desborough, G.A., 1975. The Pikes Peak Batholith, Colorado Front Rang, and a model for the origin of the gabbro-anorthosite-syenitepotassic granite suite. Precambrian Res. 2, 97-160.
Butt, KA., Chaudhry, M.N. & Ashraf, M., 1980. An introduction of petrotectonic assemblage, West of N. W. Himalayan Syntaxis in Dir district and adjoining areas, Northern Pakistan.
Geol. Bull. Univ. Peshawar 13, 79-86.
Cleman, J.D., Halloway, J.R. & White, A.J.R., 1926. Origin of an A-type granite: experimental constraints. Amer. Mineral. 71, 317-324.
Collins, W.J., Beams, S.D., White, A.J.R. & Chappell, B.W., 1922. Nature and origin of A-type granites with particular reference to south-eastern Australia. Contrib. Mineral. Petrol. 80, 189-200.
Coulson, A.L., 1936. A Soda granite suite in the North-West Frontier Province. Proc. Nat. Inst. Soci. Ind. 2, 103-111.
De La Roche, H., Leterrier, J., Grandeluec, P. & Marchal, M., 1990. A classification of volcanic and plutonic rocks using R1-R2 diagram and major-element analyses--its relationships with current nomenclature. Chem. Geol. 29, 183-210.
Haris, N.B.W. & Marriner, G.F., 1?'10. Geochemistry and petrogenesis of peralkaline granite complex from the Midian mountains, Saudi Arabia. Lithos 13, 325-327.
Jan, M.Q. & Karim, A., 1990. Continental magmatism related to Late Paleozoic-Early Mesozoic rifting in northern Pakistan and Kashmir. Geol. Bull. Univ. Peshawar 23, 1-25.
Khan, S.R., Khan, M.A., Karim, T. & Nawaz, R., 1990. Stratigraphic control for the age of Peshawar-plain magmatism, northern Pakistan. Geol. Bull. Univ. Peshawar 23, 253-263.
Kempe, D.R.C., 1973. Petrology of Warsak alkaline granites of Pakistan and their relationship to the other alkaline rocks of the region. Geol. Mag. 110, 385-404.
Kempe, D.R.C., 1923A. Alkaline granites, syenites and associated rocks of the Peshawar plain. In: Granites of Himalayas, Karakoram and Hindukush: (F. A. Shams, cd.). Inst. Geol. Punjab Univ. Lahore, pp. 143-169.
Kempe, D.R.C. & Jan, M.Q., 1970. An alkaline igneous province in the North-West Frontier Province, West Pakistan. Geol. Mag. 107, 395-398.
Kempe, D.R.C. & Jan, M.Q., 1990. The Peshawar plain alkaline igneous Province, NW Pakistan, Geol. Bull. Univ. Peshawar (special issue) 13, 71-77.
Le Bas, M.J., Mian., I. & Rex, D.C., 1976. Age and nature of carbonatite emplacement in the north Pakistan. Geol. Rundschau, 317-323.
Le Fort, P., 1921. Manaslu leucogranite: a collision signature of the Himalaya, a model for its genesis and emplacement. J. Geophys. Res. 26, 10545-10562.
Le Fort, P., Michard, A., Sonet, J. & Zimmermann., 1983. Petrography, geochemistry, and geochronology of some samples from the Karakoram axial batholith, N. Pakistan. In: Granites of Himalayas, Karakoram, and Hindukush (F.A. Shams, ed.). Inst. Geol. Punj. Univ. Lahore, pp. 377-327.
Loiselle, M.C. & Wones, D.R., 1979, Characteristics of anorogenic granites. Geol. Soc. Amer. Abs. with Prog. 11, 468.
Mian, I., 1987. he mineralogy and geochemistry of the carbonatites, syenites, and fenites of N. W. F. P. Pakistan. Ph. D. Thesis, Univ. Leicester, U. K, p 320.
Pearce, J.A., Harris, N.B.W & Tindle, A.G., 1984. Trace element discrimination diagrams for tectonic interpretation of granitic rocks. J. Petrology. 26, 956-923.
Petterson, M.G. & Windley, B.F., 1985. Rb-Sr dating of the Kohistan arc-batholith in the Trans-Himalaya of north Pakistan, and tectonic implications. Earth Planet. Sci. Lett. 74, 45-67.
Rafiq, M., 1917. Petrology and geochemistry of the Ambela granitic complex, NWFP, Pakistan. Unpublished Ph. D. thesis., Univ. Peshawar, 272p.
Whalen, J.B., Kurrie, KL. & Chappell, B.W., 1917. A-type granites: geochemical characteristics, discrimination and petrogenesis. Contrib. Mineral. Petrol. 95, 437-419.
