Chemistry of Clinopyroxene from The Deosai Volcanics, Baltistan, N. Pakistan
Abstract
Seventy analyses of clinopyroxene phenocrysts from the Deosai volcanics were obtained and tested for substitutions and other petrogenetic characters. The data show an overall core-margin substitution of xCa+xNa+xFe3+ +xtAl+xTi =xSi +xMg+xFe2 + +xMn type in the phenocrysts, with representing the actual amount of a cation entered or replaced, and which can be determined precisely from its variation along with unit variation of Si. The data also indicate crystallization in a temperature range of 1100-1200 oC, under highly variable pressure, from a basaltic magma of alkaline (but transitional to non-alkaline) characters.
References
Cameron, M. & Papike, J.J., 1981. Structural and chemical variation in clinopyroxene Am. Mineral. 66, 1-50.
Claude, T. H., 1978. Pyroxene geothermometry and geobarometry: experimental and thermodynamic evolution of some subsolidus phase relations involving pyroxenes in the system CaO-MgO-A12O3-SiO2. Geochim. Cosmochim. Acta 42, 945-57.
Deer, W.A., Howie, R.A. & Zussman, J., 1962. An Introduction to Rock Forming Minerals. Longman, London.
Deer, W.A., Howie, R.A. & Zussman, J., 1977. Rock Forming Minerals. Vol. 2A. (2nd ed.): Single chain silicates. Longman, London.
Desio, A., 1978. On the geology of Deosai plateau (Kashmir). Mem. Sc. fisiche, ccc.- 1978 -S. VIII, XV, 1-19.
Dc Terra, H., 1935. Geological studies Northwest Himalayas between Kashmir and Indus Valley. Mem. Connecticut Acad. Arts. Sci. 8, 18-76.
Frank, W., Gansser, A. & Trommsdorff, V., 1977. Geological observations in the Laddakh area (Himalayas), a preliminary report. Mineral. Petrgr. Mitt. 57, 89-113.
Gansser, A., 1964. Ge010L5' of the Himalayas. Wiley Interscience, London.
Gergan, J.T., 1978. Stratigraphic and tectonic studies on the Indus Suture belt between Dras and Kargil unpubl. Ph.D. Thesis, Jammu Univ.
Gupta, R.R., Gergan, J. T. & Surendar, K, 1983. Geochemistry of the volcanic rocks of the North-Western Himalayas and its bearing on tectonics- A review. In: Contemporary geoscientific Research in Himalayas volume Il, (A.K Sinha ed.). Dehra Dun, India, 9-17.
Hamidullah, S. & Bowes, D.R., 1987. Petrogenesis of the appinite suite, Appin district, Western Scotland, Acta, Universitatis Carolinae-Geologica 4, 295-396.
Honncgar, K, Dietrich, V. Frank, W., Gansscr, A., Thoni, M. & Trommsdroff, V. , 1982.
Magmatism and metamorphism in Laddakh Himalayas (the Indus-Tsangpo suture zone). Earth Planet Sci. Lett. 60, 253-92.
Jean-Claude, C. Mercier, 1976. Single pyroxene geothermometry and geobarometry. Am. Min. 61, 603-615.
Jean-Claude, C. Mercier & Naville, L. Carter, 1976. Pyroxene geotherms. J. Geophy. Res., 61, 3349-3362.
Kuno, H., 1959. Origin of Cenozoic petrographic provinces of Japan, and surrounding area. Bull. Volcanol. Soc. Japan 2, 179-89.
Kushiro, 1., 1960. Si-Al relation in clinopyroxene from igneous rocks. Am. J. Sci. 253, 548-54.
Le Bas, M.J., 1962. The role of aluminium in igneous clinopyroxene with relation to their percentage. Am. J. Sci. 260, 267-88.
Leterrier, J., Muarry, R.C., Thonon, P., Girard, D. & Marchal, M., 1982. Clinopyroxene compositions as a method of identification of the magmatic affinities of paleo-volcanic series. Earth Planet. Sci. Lett. 59, 139-154.
Lindsley, D. H., 1983. Pyroxene thermometry. Am. Mineral. 68,477-93.
Marcelet, G., Muaty, R.C. & Le Fevre, C., 1983. Mineralogy of Erromango lavas (New Hebrides): Evidencc of an early stage of fractionation in island arc basalts. Lithos. 16, 135-51.
Misch, P., 1936. Einiges Zur metamorphose des Nanga Parbat. Geol. Rdseh. 27, 79-81.
Morimoto, M., Fabrics, J., Furguson, A. K., Ginzburg, I. V., Ross, M., Seifert, F. A, Zussman, J., Aoki, & Gottardi, G., 1988. Nomenclature of Pyroxene: Subcommittee on pyroxenes, Commission on new minerals and mineral names, International Mineralogical Association. Am. Min. 73, 1123-33.
Nisbet, E.G., & Pearce, JA, 1977. Clinopyroxene compositions in mafic lavas from different tectonic settings. Cont. Mineral. Petrol. 63, 149-60.
Papike, JJ., 1982. Pyroxene mineralogy of the moon and meteorite. In: Review in mineralogy pyroxene (C.T. Prewitt, ed.). Min. Soc. Am. Spec. Pub. 7, 495-525.
Papike, J. J., Cameron, K. L. & Baldwin, K., 1974. Amphiboles and pyroxenes: Characterization of OTHER than QUAD components and estimates of ferric iron for microprobe data. Geol. Soc. Am. Abst. with programs 6, 1053-1054.
Pemberton, J. W. & Offler, R., 1985. Significance of clinopyroxene compositions from the Cudgegong volcanics and Toolamanang volcanics; Cudgegong-Mudgee district, NSW, Australia. Min. Mag. 49, 591-99.
Petterson M. G. & Windley B. F., 1991. Changing source regions of magmas and crustal growth in the Trans-Himalayas: Evidence from the Chalt volcanics and Kohistan Batholith, North Pakistan. Earth Planet Sci. Lett. 102, 326-341.
Raiverman, V. & Mishra, V.M., 1974. Suru tectonic axis, Laddakh area. Geol. Min. Met. Soc. Ind. Golden Jubilee Symp. (Abst.).
Schairer, J. F. & Yoder, H. S., 1962. Pyroxenes: the system diopside-enstatitc-silica. Carnegie Inst. Washington, Ann. Rept. Dir. Geophys. Lab. 62, 75-82.
Schairer, J. F. & Yoder, H. S., 1970. Critical planes and flow sheets for a portion of the system CaO-MgO-A1203-Si02, having petrological implications. Carnegie Inst. Washington, Ann. Rcpt. Dir. Geophys. Lab. 68, 202-214.
Shah, S.K & Gergan, J. T., 1978. Geochemistry of Dras volcanics and its tectonics significance. 9th. Him. Geol. Sim. Abst.
Shah, S.K, Sharma, M.I., Gergan, J.T. & Tara, C. S., 1976. Stratigraphy and structure of the Western part of the Indus suture belt. Laddakh, Northwest Himalayas. Him. Geol. 6, 534-56.
Sugimura, A, 1973. Multiple correlation between composition of volcanic rocks and depth of earthquake foci. In: The western Pacific island arcs, marginal seas and geochemistry (P. Coleman ed.) Perth, Western Australia University Press, 471-482.
Wadia, D.N., 1937. The Cretaceous volcanic series of Astor; Deosai, Kashmir and its intrusions Rec. Geol. Surv. India 51, 185-370.
Wilson, M., 1989. Igneous Petrogenesis. Unwin Hyman, London.
Yoder, H. S., 1965. Diopside-Anorthite-Water at five and ten kilobars and its bearing on explosive volcanism. Carnegie Inst. Washington, Ann. Rcpt. Dir. Geophys. Lab. 64, 82-89.
