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Zoning in highly alkaline magma bodies

Published online by Cambridge University Press:  01 May 2009

John A. Wolff  and
Michael Storey
John A. Wolff
Affiliation:
Geology Department, Imperial College, Prince Consort Road, London SW7 2BP, U.K.
Michael Storey
Affiliation:
Geology Department, Bedford College, Regent's Park, London NW1 4NS, U.K.
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Abstract

We present chemical data on magmatically heterogeneous pyroclastic deposits of late Quaternary age erupted from zoned magma systems underlying Tenerife (Canary Islands), Sao Miguel and Faial (Azores), and Vesuvius. The most fractionated magmas present at each centre are respectively Na-rich phonolite, trachyte, and K-rich phonolite. Within any one deposit, chemical variation is either accompanied by changes in the phenocryst assemblage (petrographic zonation) or is largely manifested in trace element abundances, unaccompanied by any petrographic change (occult zonation). Zoning is analogous to that in calc-alkaline systems where the most fractionated products are high-silica rhyolites. When a range of magma types are considered, a correlation emerges between roofward depletion of trace elements (especially REE) in the zoned system and compatability of those same trace elements in the accessory phenocryst phases present. Thus, allanite- or chevkinite-bearing rhyolitic systems are light-REE depleted roofwards, the sphene-bearing Tenerife system is middle-REE depleted roofwards, the melanite-bearing Vesuvius system is heavy-REE depleted roofwards, while the Azores systems, which lack these phases, display roofward REE enrichment. Therefore, the behaviour of trace elements may in each case be explained by fractionation of observed phenocryst assemblages. The resemblance between features of zoned magma systems and published work on the dynamic consequences of cooling saturated aqueous solutions prompts us to suggest that sidewall crystallization and consequent boundary-layer uprise to form a capping layer at top of the system may be a plausible mechanism for the generation of both petrographic and occult zonation. Reverse zoning occurs among the first-erupted tephra of some deposits, demonstrating that the most highly differentiated magma available is not always the first to be tapped during an eruption from a zoned system.

Type
Articles
Information
Geological Magazine , Volume 121 , Issue 6 , November 1984 , pp. 563 - 575
Copyright
Copyright © Cambridge University Press 1984

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References

Anderson, A. T. 1976. Magma mixing: petrological process and volcanological tool. Journal of Volcanology and Geothermal Research 1, 3–33.Google Scholar
Bacon, C. R. 1983. Eruptive history of Mount Mazama and Crater Lake Caldera, Cascade Range, U.S.A. Journal of Volcanology and Geothermal Research 18, 57–115.CrossRefGoogle Scholar
Barberi, F., Bizouard, H., Clochiatti, R. Metrich, N., Santacroce, R. & Sbrana, A. 1981. The Somma-Vesuvius magma chamber: A petrological and volcanological approach. Bulletin Volcanologique 44, 295–315.CrossRefGoogle Scholar
Berlin, R. & Henderson, C. M. B. 1969. The distribution of Sr and Ba between alkali feldspar, plagioclase and groundmass phases of porphyritic trachytes and phonolites. Geochimica et Cosmochimica Acta 33, 247–55.CrossRefGoogle Scholar
Blake, S. 1981. Eruptions from zoned magma chambers. Journal of the Geological Society of London 138, 281–7.Google Scholar
Booth, B. 1973. The Granadilla Pumice Deposit of southern Tenerife, Canary Islands. Proceedings of the Geologists' Association 84, 353–70.CrossRefGoogle Scholar
Booth, B., Croasdale, R. & Walker, G. P. L. 1978. A quantitative study of five thousand years of volcanism on Sao Miguel, Azores. Philosophical Transactions of the Royal Society of London A 288, 271–319.Google Scholar
Booth, B. & Walker, G. P. L. in preparation. Products of explosive volcanism on Tenerife, Canary Islands.Google Scholar
Borley, G. D. 1974. Aspects of the volcanic history and petrology of the island of Tenerife, Canary Islands. Proceedings of the Geologists Association 85, 259–79.Google Scholar
Chen, C. F. & Turner, J. S. 1980. Crystallisation in a double-diffusivesystem. Journal of Geophysical Research 85, 2573–93.CrossRefGoogle Scholar
Clague, D. A. 1978.Theoceanic basalt-trachyte association: an explanation of the Daly Gap. Journal of Geology 86, 739–43.Google Scholar
Crecraft, H. R., Nash, W. P. & Evans, S. H. Jr., 1981. Late Cenozoic volcanism at Twin Peaks, Utah: geology and petrology. Journal of Geophysical Research 86, 10303–20.Google Scholar
Cullers, R. L. & Medaris, G. Jr. 1977. Rare earth elements in carbonatites and cogenetic alkaline rocks: examples from Seabrook Lake and Callander Bay, Ontario. Contributions to Mineralogy and Petrology 65, 143–53.CrossRefGoogle Scholar
Eggleston, E. L., Osburn, G. R. & Chapin, C. E. 1983. Reversely zoned Hells Mesa Tuff and Socorro Cauldron. EOS, Transactions of the American Geophysical Union 64, 884.Google Scholar
Fuster, J. M., Arana, V., Brandle, J. L., Navarro, M., Alonso, U. & Aparicio, A. 1968. Geology and Volcanology of the Canary Islands: Tenerife, 218 pp. Institute ‘Lucas Mallada’, Madrid.Google Scholar
Green, T. H. & Pearson, N. J. 1983. Effect of pressure on rare earth element partition coefficients in common magmas. Nature 305, 414–16.Google Scholar
Hellman, P. L. & Green, T. H. 1979. The role of sphene as an accessory phase in the high-pressure partial melting of hydrous mafic compositions. Earth and Planetary Science Letters 42, 191–201.Google Scholar
Hildreth, W. 1979. The Bishop Tuff: evidence for the origin of compositional zonation in silicic magma chambers. In Ash-flow Tuffs (eds. Chapin, C. E & Elston, W. E), pp. 43–75. Geological Society of America Special Paper no. 180.CrossRefGoogle Scholar
Hildreth, W. 1981. Gradients in silicic magma chambers: implications for lithospheric magmatism. Journal of Geophysical Research 86, 10153–92.Google Scholar
Hildreth, W. 1983. Chemical differentiation of the Bishop Tuff and other high-silica magmas through crystallization processes: comment. Geology 11, 622–3.2.0.CO;2>CrossRefGoogle Scholar
Huppert, H. E. & Sparks, R. S. J. 1980. The fluid dynamics of a basaltic magma chamber replenished by influx of hot, dense ultrabasic magma. Contributions to Mineralogy and Petrology 75, 279–89.CrossRefGoogle Scholar
Huppert, H. E., Sparks, R. S. J. & Turner, J. S. 1982. Effects of volatiles on mixing in calc-alkaline magma systems. Nature 297, 554–7.Google Scholar
Huppert, H. E., Turner, J. S. & Sparks, R. S. J. 1982. Replenished magma chambers: effects of compositional zonation and input rates. Earth and Planetary Science Letters 57, 345–57.Google Scholar
Larsen, L. M. 1979. Distribution of REE and other trace elements between phenocrysts and peralkaline under-saturated magmas, exemplified by rocks from the Gardar igneous province, South Greenland. Lithos 12, 303–15.Google Scholar
Laughton, A. S. & Whitmarsh, R. B. 1975. The Azores-Gibraltar plate boundary. In Geodynamics of Iceland and the North Atlantic Area (ed. Kristjansson, L.). Dordrecht: D. Reidel.Google Scholar
Lesher, C. E. & Walker, D. 1983. Soret fractionation of high-silica rhyolite magma. EOS, Transactions of the American Geophysical Union 64, 883.Google Scholar
Lirer, L., Pescatore, T., Booth, B. & Walker, G. P. L. 1973. Two plinian pumice fall deposits from Somma-Vesuvius, Italy. Geological Society of America Bulletin 84, 759–72.2.0.CO;2>CrossRefGoogle Scholar
McBirney, A. R. 1968. Compositional variations of the climactic eruption of Mount Mazama. In Andesite Conference Guidebook (ed. Dole, M. H), pp. 53–7. Oregon State Department of Geology and Mineral Industries Bulletin no. 62.Google Scholar
McBirney, A. R. 1980. Mixing and unmixing of magmas. Journal of Volcanology and Geothermal Research 7, 357–71.CrossRefGoogle Scholar
Mahood, G. A. 1981. Chemical evolution of a Pleistocene rhyolitic centre: Sierra La Primavera, Jalisco, Mexico. Contributions to Mineralogy and Petrology 77, 129–49.Google Scholar
Mahood, G. A. & Hildreth, W. 1983. Large partition coefficients for trace elements in high-silica rhyolites. Geochimica et Cosmochimica Acta 47, 11–30.Google Scholar
Marriner, G. F., Norry, M. J. & Gibson, I. L. 1982. The petrology and geochemistry of Agua de Pau volcano, Sao Miguel, Azores. Proceedings of International Symposium on the Activity of Oceanic Volcanoes (IAVCEI), 1980, 159–73.Google Scholar
Michael, P. J. 1983 a. Chemical differentiation of the Bishop Tuff and other high-silica magmas through crystallization processes. Geology 11, 31–4.2.0.CO;2>CrossRefGoogle Scholar
Michael, P. J. 1983 b. Chemical differentiation of the Bishop Tuff and other high-silica magmas through crystallization processes: reply. Geology 11, 623–4.Google Scholar
Miller, C. F. & Mittlefehldt, D. W. 1982. Depletion of light rare-earth elements in felsic magmas. Geology 10, 129–33.2.0.CO;2>CrossRefGoogle Scholar
Mittlefehldt, D. W. & Miller, C. F. 1983. Geochemistry of the Sweetwater Wash Pluton, California: implications for ‘anomalous’ trace element behaviour during differentiation of felsic magmas. Geochimica et Cosmochimica Acta 47, 109–24.Google Scholar
Ridley, W. I. 1970 a. The abundance of rock types on Tenerife, Canary Islands, and its petrogenetic significance. Bulletin Volcanologique 34, 196–204.CrossRefGoogle Scholar
Ridley, W. I. 1970 b. The petrology of the Las Canadas volcanoes, Tenerife, Canary Islands. Contributions to Mineralogy and Petrology 26, 124–60.Google Scholar
Schnetzler, C. C. & Philpotts, J. A. 1970. Partition coefficients of rare earth elements between igneous matrix material and rock-forming mineral phenocrysts. II. Geochimica et Cosmochimica Acta 34, 331–40.Google Scholar
Smith, R. L. 1979. Ash-flow magmatism. In Ash-flow Tuffs (eds. Chapin, C. E, Elston, W. E), pp. 5–27. Geological Society of America Special Paper no. 180.CrossRefGoogle Scholar
Smith, R. L. & Bailey, R. A. 1966. The Bandelier Tuff: a study of ash-flow eruption cycles from zoned magma chambers. Bulletin Volcanologique 29, 83–104.Google Scholar
Sparks, R. S. J., Huppert, H. E. & Turner, J. S. 1984. The fluid dynamics of evolving magma chambers. Philosophical Transactions of the Royal Society of London A310, 511–34.Google Scholar
Storey, M. 1981. Trachytic pyroclastics from Agua de Pau volcano, Sao Miguel, Azores: evolution of a magma body over 4,000 years. Contributions to Mineralogy and Petrology 78, 423–32.CrossRefGoogle Scholar
Sun, S. S. & Hanson, G. N. 1976. Rare earth evidence for differentiation of McMurdo volcanics, Ross Island, Antarctica. Contributions to Mineralogy and Petrology 54, 139–55.Google Scholar
Turner, J. S. & Gustafson, L. B. 1981. Fluid motions and compositional gradients produced by crystallization or melting at vertical boundaries. Journal of Volcanology and Geothermal Research 11, 93–125.Google Scholar
Walker, G. P. L. & Croasdale, R. 1971. Two plinian-type eruptions in the Azores. Journal of the Geological Society of London 127, 17–55.Google Scholar
Wolff, J. A. 1984. Variation in Nb/Ta during differentiation of phonolitic magma, Tenerife, Canary Islands. Geochimica et Cosmochimica Acta 48, 1345–8.Google Scholar
Wood, D. A. 1978. Major and trace element variations in the Tertiary lavas of Eastern Iceland and their significance with respect to the Iceland geochemical anomaly. Journal of Petrology 19, 393–436.CrossRefGoogle Scholar
Wörner, G., Beussen, J. M., Duchateau, N., Gubels, R. & Schmincke, H. U. 1983. Trace element abundances and mineral/melt distribution coefficients in phonolites from the Laacher See Volcano (Germany). Contributions to Mineralogy and Petrology 84, 152–73.Google Scholar
Wright, J. V., Smith, A. L. & Self, S. 1980. A working terminology of pyroclastic deposits. Journal of Volcanology and Geothermal Research 8, 315–36.Google Scholar