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Relict clinopyroxenes from within-plate metadolerites of the Petroi Metabasalt, the New England Fold Belt, Australia

  • Deepanker Asthana (a1)

Relict clinopyroxenes from metadolerites of the Early Permian Petroi Metabasalt formation, studied by electron microprobe, show a limited compositional range near the diopside-augite boundary in the pyroxene quadrilateral. Clinopyroxene analyses from three metadolerites, grouped in approximately equal Fs contents, define an overall smooth trend between Fs10 and Fs16. This is typical of clinopyroxenes from mildly alkaline basic magmas. Pyroxene stoichiometry suggests high Fe3+ contents (0.04 to 0.20 a.f.u.), which with high Al (0.10 to 0.31 a.f.u.) and Ti (0.03 to 0.08 a.f.u.) implies that CaTiAl2O6 and CaFe3+AlSiO6 are important ‘other components’. Relative Al z in CaFe3+AlSiO6 decreases and consequently CaTiAl2O6 increases with progressive fractionation. This, with the Fe2+:Fe3+ ratios in the Petroi clinopyroxenes, suggests falling ƒ O2 in the magma with fractionation. The ƒ O2 controlled entry of Al z , Ti y and Na x into the clinopyroxenes and hence the Petroi clinopyroxene trend.

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Akasaka, M. and Onuma, K. (1980) The join CaMg-Si2Of)-CaFeAlSiO6,-CaTiAl2O6 and its bearing on the Ti-rich fassaitic pyroxenes. Contrib. Mineral. Petrol, 71, 30112.
Aoki, K.-I. (1964) Clinopyroxenes from alkaline rocks of Japan. Am. Mineral, 49, 1199223.
Asthana, D. (1984) Intermediate, Mafic, and Vltramafic rocks from the eastern part of the New England Fold Belt: geochemistry, relict mineralogy, magmatic affinities and tectonic significance. Ph.D. thesis. University of Sydney (unpubl.).
Asthana, D. (1990) Petrogenetic significance of relict clinopyroxenes from Early Permian ocean-floor mafic rocks of the McGraths Hump Metabasalt, The New England Fold Belt, Australia. (Submitted) J. Petrol.
Asthana, D. and Leitch, E. C. (1985) Petroi Metabasalt: alkaline within-plate mafic rocks from the Nambucca Slate Belt, northeastern New South Wales. Austral. J. Earth. Sci., 32, 26177.
Barberi, F., Bizouard, H., and Varet, J. (1971) Nature of the clinopyroxene and iron enrichment in alkalic and transitional basaltic magmas. Contrib. Mineral. Petrol., 33, 93107.
Basaltic Volcanism Study Project (1981) Basaltic vol-canism on the Terrestrial Planets. Pergamon, New York, 1286 pp.
Brown, G. M. (1957) Pyroxenes from the early and middle stages of fractionation of the Skaergaard intrusion, east Greenland. Mineral. Mag., 31, 51143.
Brown, G. M. (1967) Mineralogy of basaltic rocks. In Basalts Vol. 1 (Hess, H. H. and Poldervaart, A., eds.), Interscience Publishers, New York, 103-63.
Carmichael, I. S. E. (1967) The mineralogy of Thingmuli, a Tertiary volcano in eastern Iceland. Am. Mineral, 52, 18151.
Coleman, R. G. (1977) Ophiolites: Ancient oceanic lithosphere? Springer-Verlag, New York.
Coombs, D. S. (1963) Trends and affinities of basaltic magmas and pyroxenes as illustrated on the diopside-olivine-silica diagram. Mineral. Soc. Am., Spec. Pap., 1, 22750.
Cundari, A. and Salviulo, G. (1989) Ti solubility in diopsidic pyroxene from a suite of New South Wales leucitites (Australia). Lithos, 22, 1918.
Faraone, D., Molin, G., and Zanazzi, P. F. (1988) Clinopyroxenes from Vulcano (Aeolian Islands, Italy): crystal chemistry and cooling history. Lithos, 22, 11326.
Fodor, R. V., Keil, K., and Bunch, T. E. (1975) Contributions to the mineral chemistry of the Haw-aiian rocks. IV. Pyroxene in rocks from Haleakala and West Maui Volcanoes, Maui, Hawaii. Contrib. Mineral. Petrol, 50, 17395.
Fodor, R. V., Berkley, J. L., Keil, K., Husler, J. W., Ma, M.-S., and Schmitt, R. A. (1980) Petrology of basalt drilled from the Galapagos Spreading Centre, DSDP leg 54. In Initial Reports of the DSDP 54, (Rosendahl, B. R. and Hekinian, R., eds.) pp. 737-49. U.S. Govt. Printing Office, Washington D.C.
Foit, F. F. Jr., Hooper, R. L., and Rosenberg, P. E. (1987) An unusual pyroxene, melilite and iron oxide mineral assemblage in a coal-fire buchite from Buffalo, Wyoming. Am. Mineral, 72, 13447.
Garcia, M. O. (1978) Criteria for the identification of ancient volcanic arcs. Earth. Sci. Review, 14, 14765.
Ghose, S., Okamura, F. P., and Ohashi, H. (1986) The crystal structure of CaFe3+SiAlO6 and the crystal chemistry of Fe3+Al3+ substitution in calcium Tscher-mak's pyroxene. Contrib. Mineral. Petrol, 92, 5305.
Gibb, F. G. F. (1973) The zoned clinopyroxenes of the Shiant Isles sill, Scotland. J. Petrol. 14, 20330.
Gupta, A. K., Onuma, K., Yagi, K., and Lidiak, E. G. (1973) Effects of silica concentration on the diopside pyroxenes in the system diopside- CaTiAl2O6-SiO2. Contrib. Mineral. Petrol, 41, 33344.
Himmelberg, G. R., Loney, R. A., and Nabelek, P. I. (1987) Petrogenesis of gabbronorite at Yakobi and northwest Chichagof Islands, Alaska. Geol. Soc. Am. Bull, 98, 26579.
Huckenholz, H. G., Lindhuber, W., and Springer, J. (1974) The join CaSiO3-Al2O3-Fe2O3 of the CaO-Al2O5-Fe2O3-SiO2 quarternary system and its bearing on the formation of granditic garnets and fassiate pyroxenes. Neues Jahrb. Mineral. Abh., 121, 161207.
Huebner, J. S. (1980) Pyroxene phase equilibria at low pressure. In Pyroxenes (Prewitt, C. T., ed.), 213-8 Mineral. Soc. Amer, Reviews in Mineralogy, 7.
Kushiro, I. (1960) Si-Al relation in clinopyroxenes from igneous rocks. Am. J. Sci., 258, 54854.
Larsen, L. M. (1976) Clinopyroxenes and coexisting mafic minerals from the alkaline Ilimaussaq Intru-sion, South Greenland. J. Petrol, 17, 25890.
Laverne, C. (1987) Unusual occurrences of aegirine-augite, fassaite and melanite in oceanic basalts. (DSDP Hole 504 B). Lithos, 20, 13551.
LeBas, N. J. (1962) The role of aluminium in igneous clinopyroxenes with relation to their parentage. Am. J. Sci., 260, 26788.
Leitch, E. C. (1976) Zonation of low-grade regional metamorphic rocks, Nambucca Slate Belt, north-eastern New South Wales. J. Geol Soc. Austral, 22, 41322.
Leitch, E. C. (1978) Structural succession in a Late Palaeozoic slate belt and its tectonic significance. Tectonophysics, 47, 31123.
Leitch, E. C. and Asthana, D. (1986) Rhyolite, alkali basalt and ocean floor mafic rocks in the Early Permian Barnard Basin, Southern New England Fold Belt, Australia. Internal. Volcanol Congress, New Zealand (abstr.), p. 176.
Leitch, E. C. and McDougall, I. (1979) The age of orogenesis in the Nambucca Slate Belt: a K-Ar study of low-grade regional metamorphic rocks. J. Geol. Soc. Austral, 26, 1119.
Leitch, E. C. and Scheibner, E. (1987) Stratotectonic terranes of the Eastern Australian Tasmanides. In Terrane Accretion and Orogenic Belts (Leitch, E. C. and Scheibner, E., eds.), 1-19. Geodynamic Series 19, Amer. Geophysical Union, Washington, D.C.
Leterrier, J., Maury, R. C., Thonon, P., Girard, D., and Marchal, M. (1982) Clinopyroxene composition as a method of identification of the magmatic affinities of paleo-volcanic series. Earth. Planet. Sci. Lett., 59, 13954.
Lindsley, D. H. (1983) Pyroxene thermometry. Am. Mineral, 68, 47793.
Lindsley, D. H. and Andersen, D. J. (1983) A two-pyroxene thermometer. Proceedings 13th Lunar Planet. Sci. Conf., Part 2. J. Geophys. Res., 88, A887906.
Manning, C. E. and Bird, D. K. (1986) Hydrothermal clinopyroxenes of the Skaergaard intrusion. Contrib. Mineral. Petrol, 92, 43747.
Maruyama, S. and Liou, J. G. (1985) The stability of Ca-Na pyroxene in low-grade metabasites of high-pressure intermediate facies series. Am. Mineral., 70, 1629.
Mattey, D. A. and Muir, J. D. (1980) Geochemistry and mineralogy of basalts from the Galapagos Spreading Centre, DSDP Leg 54. In Initial Report of the DSDP54 (Rosendahl, B. R. and Hekinian, R., eds.), 755-71. U.S. Govt. Printing Office, Washington, D.C.
Mellini, M., Carbonin, S., Dal Negro, A., and Piccirillo, E. M. (1988) Theoleiitic hypabyssal dykes: How many clinopyroxenes? Lithos, 22, 12734.
Morimoto, N., Fabries, J., Ferguson, A. K., Ginzburg, I. V., Ross, M., Seifert, F. A., Zussman, J., Aoki, K., and Gottardi, G. (1988) Nomenclature of pyr-oxenes. Mineral. Mag., 52, 53550.
Morris, P. A. (1988) Volcanic arc reconstruction using discriminant function analyses of detrital clinopyroxenes and amphiboles from the New England Fold Belt, Eastern Australia. Geoi, 96, 299311.
Mueller, R. F. and Saxena, S. K. (1977) Chemical Petrology, Springer-Verlag, New York, 394 pp.
Myers, C. W., Bence, A. E., Papike, J. J., and Ayuso, R. A. (1975) Petrology of an alkali-olivine basalt sill from site 169 of DSDP Leg 17: the Central Pacific Basin. J. Geophys. Res., 80, 80722.
Nabelek, P. I., Lindsley, D. H., and Bohlen, S. R. (1987) Experimental examination of two-pyroxene graphical thermometers using natural pyroxenes with application to meta-igneous pyroxenes from the Adirondack Mountains, New York. Con-trib. Mineral. Petrol, 97, 6671.
Nakamura, Y. and Coombs, D. S. (1973) Clinopyrox-enes in the Tawhiroko tholeitic dolerite at Moeraki, north-eastern Otago, New Zealand. Ibid. 42, 213-28.
Nash, W. P. and Wilkinson, J. F. G. (1970) Shonkin Sag Laccolith, Montana. I. Mafic minerals and estimates of temperature, pressure, oxygen fugacity and silica activity. Ibid. 25, 241-69.
Nisbet, E. G. and Pearce, J. A. (1977) Clinopyroxene composition in mafic lavas from different tectonic settings. Ibid. 63, 149-60.
Onuma, K. (1983) Effect of oxygen fugacity on fassaitic pyroxene. J. Fac. Sci. Hokkaido Univ., Ser. iv, 20, 18594.
Otten, M. T. and Buseck, P. R. (1987) TEM study of the transformation of augite to sodic pyroxene in ecologitised ferrogabbro. Contrib. Mineral. Petrol, 96, 52938.
Papike, J. J. (1980) Pyroxene mineralogy of the Moon and Meteorites. In Pyroxenes (Prewitt, C. T., ed.), pp. 495-525. Mineral. Soc. of Am. Reviews in Mineralogy, 1.
Papike, J. J. Cameron, K. L., and Baldwin, K. (1974) Amphi boles and pyroxenes: characterisation of other than quadrilateral components and estimates of ferric iron from microprobe data. Geol. Soc. Amer. Abstr. with Programs, 6, 10534.
Perfit, M. R. and Fornari, D. J. (1983) Geochemical studies of abyssal lavas recovered by DSRV Alvin from Eastern Galapagos Rift, Inca transform and Ecuador Rift 2. Phase chemistry and crystallisation history. Geophys. Res., 88, 1053050.
Presnall, D. C. and Hoover, J. D. (1984) Composition and depth of origin of primary mid-ocean ridge basalts. Contrib. Mineral. Petrol., 87, 1708.
Schweitzer, E. L., Papike, J. J., and Bence, A. E. (1979) Statistical analysis of clinopyroxenes from deep-sea basalts. Am. Mineral., 64, 50113.
Scott, P. W. (1976) Crystallisation trends of pyroxenes from the alkaline volcanic rocks of Tenerife, Canary Islands. Mineral. Mag., 40, 80516.
Sen, G. (1986) Mineralogy and petrogenesis of the Deccan Trap lava flows around Mahabaleshwar, India. Petrol, 27, 62763.
Shimizu, N. and leRoex, A. P. (1986) The chemical zoning of augite phenocrysts in alkaline basalts from Gaough Island, South Atlantic. Volcanol. Geotherm. Res., 29, 15988.
Smith, D. and Lindsley, D. H. (1971) Chemical variations in pyroxene and olivine from Picture Gorge basalt. Yearb. Carnegie Instn. Wash., 69, 26974.
Thompson, R. N. and Humphris, S. E. (1980) Silicate mineralogy of basalts from the East Pacific Rise, OCP Ridge, and Siqueiros Fracture Zone: Deep Sea Drilling Project Leg 54, In Initial Reports of the DSDP54 (Rosendahl, B. R. and Hekinian, R., eds.), pp. 651-69. U.S. Govt. Printing Office, Washington, D.C.
Tracey, R. J. and Robinson, P. (1977) Zoned titanium augite in alkali olivine basalt from Tahiti and the nature of titanium substitutions in augite. Am. Mineral, 62, 63445.
Vallance, T. G. (1969) Recognition of specific magma-tic character in some Palaeozoic mafic lavas in New South Wales. Proc. Specialists Symposia (Canberra, 1968). Geol. Soc. Aust., Spec. Pub. 2, 163-7.
Vallance, T. G. (1974a) Spilite degradation of a tholeiitic basalt. J. Petrol, 15, 7996.
Vallance, T. G. (1974b) Pyroxenes and the Basalt-Spilite Rela tion. In Spilites and Spilitk Rocks (Amstutz, C. G., ed.), pp. 5968. Springer-Verlag, Berlin.
Verhoogen, J. (1962) Distribution of titanium between silicates and oxides in igneous rocks. Am. J. Sci., 260, 21120.
Vieten, K. (1979) The minerals of the volcanic rock association of the Siebengebirge. I. Clinopyroxenes I. Variation of chemical composition of Ca-rich clinopyroxenes (salites) in dependence of the degree of magma differentiation. Neues. Jahrb. Mineral, Abh., 135, 27086.
Wass, S. Y. (1979) Multiple origins of clinopyroxenes in alkalic basaltic rocks. Lithos, 12, 11532.
Wilkinson, J. F. G. (1956) Clinopyroxenes of alkali-basalt magma. Am. Mineral, 41, 72443.
Wilkinson, J. F. G. (1957) The clinopyroxenes of a differentiated teschenite sill near Gunncdah, New South Wales. Geol. Mag., 94, 12334.
Wilkinson, J. F. G. (1966) Clinopyroxenes from the Square Top intru sion, Nundle, New South Wales. Mineral. Mag., 35, 106170.
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