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Sidewall differentiation in an alkalic magma chamber: evidence from syenite xenoliths in tuffs of the Latera caldera, Italy

Published online by Cambridge University Press:  01 May 2009

B. N. Turbeville
B. N. Turbeville
Affiliation:
Department of Geological Sciences, The University of Texas at Austin, Austin, TX 78713, U.S.A.
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Abstract

Feldspathoidal and quartz-bearing syenite xenoliths in c. 235 to 155 ka tuffs surrounding the Latera caldera have textures and mineral assemblages that indicate an origin from the crystalline margins of a shallow magma chamber. This lithic suite exhibits a diversity of plutonic fabrics; unaltered, glass-bearing nodules with undeformed sanidine frameworks coexist with completely crystallized clasts, many of which show evidence of subsolidus modification. The syenites comprise eutectic mineral assemblages with high percentages of titanite, apatite, and melanite garnet as accessory minerals. Ubiquitous reaction textures in syenite accompany progressive changes in mineral assemblages, and they show the decreasing influence of limestone contamination with distance from the contact of syenite and skarn wallrock. Diagnostic mineral assemblages include nepheline rich in calcite inclusions, coexisting titanite and metamorphic perovskite, zircon with baddeleyite inclusions, fluorapatite mantled by a possible carbonate-bearing apatite (francolite), melanite garnet intergrown with clinopyroxene, and interstitial haüyne rich in pyrrhotite inclusions.

At Latera, pumice fragments in the same deposit can exhibit up to ten-fold differences in vesicularity and crystal content (from < 5 to > 50 vol. % phenocrysts). These clasts, in conjunction with glass-bearing syenite and skarn xenoliths, may represent a range of progressively crystallized magmas that were quenched at the instant of their eruptive entrainment. The major element abundances of pumices and syenite reflect the fractionation of plagioclase and sanidine, with lesser amounts of fassaitic diopside, leucite, biotite, apatite, and alkali amphibole. Trace element ratios (e.g. Rb/Sr, Nb/Ta, Zr/Hf, LREE/HREE), on the other hand, are highly variable for crystalline and pumiceous ejecta, and some element variations (e.g. Li, Ta, Nb, Th) cannot be entirely reconciled with simple crystal-liquid fractionation. The syenite clasts span a range of compositions from strongly fractionated assemblages rich in accessory minerals to compositions that more closely approximate quenched reservoir liquids. These features reflect processes that range from pure fractional crystallization to in situ crystallization where fractionated liquid was trapped in the pores of sidewall cumulates along the chamber roof and walls.

Type
Articles
Information
Geological Magazine , Volume 130 , Issue 4 , July 1993 , pp. 453 - 470
Copyright
Copyright © Cambridge University Press 1993

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References

Allegre, C. J. & Minster, J. F. 1978. Quantitative models of trace element behaviour in magmatic processes Earth and Planetary Science Letters 38, 1–25.CrossRefGoogle Scholar
Amato, A., Biella, G. & de Franco, R. 1991. Velocity structure of the Vulsinian volcanic complex (Latium, Italy) from seismic refraction data and three-dimensional inversion of travel times Journal of Geophysical Research 96, 517–35.Google Scholar
Barberi, F., Innocenti, F., Landi, P., Rossi, U., Saitta, M., Santacroce, R. & Villa, I. M. 1984. The evolution of Latera Caldera (Central Italy) in the light of subsurface data Bulletin Volcanologique 47, 125–41.Google Scholar
Barker, D. S. 1970. Compositions of granophyre, myrmekite, and graphic granite Geological Society of America Bulletin 81, 3339–50.CrossRefGoogle Scholar
Barker, D. S. 1976. Phase relations in the system NaAlSiO4 SiO2 NaCl-H2O at 400°–800°C and 1 kilobar, and petrologic implications Journal of Geology 84, 97–106.CrossRefGoogle Scholar
Bence, A. E. & Albee, A. L. 1968. Empirical correction factors for the electron microanalysis of silicates and oxides Journal of Geology 76, 382–403.Google Scholar
Boudreau, A. E. & McCallum, I. S. 1989. Investigations of the Stillwater Complex: Part I. Apatites as indicators of evolving fluid composition Contributions to Mineralogy and Petrology 102, 138–53.Google Scholar
Brandeis, G. & Jaupart, C. 1986. On the interaction between convection and crystallization in cooling magma chambers Earth and Planetary Science Letters 77, 354–61.Google Scholar
Brandeis, G. & Marsh, B. 1989. The convective liquidus in a solidifying magma chamber: a fluid dynamic investigation Nature 339, 613–14.Google Scholar
Candela, P. A. 1986. Toward a thermodynamic model for the halogens in magmatic systems: an application to melt-vapor-apatite equilibria Chemical Geology 57, 289–301.Google Scholar
Carmichael, I. S. I., Turner, F. & Verhoogen, J. 1974. Igneous Petrology. New York: McGraw-Hill, 739 pp.Google Scholar
Cavarretta, G., Gianelli, G., Scandiffio, G. & Tecce, F. 1985. Evolution of the Latera geothermal system; II. Metamorphic, hydrothermal mineral assemblages and fluid chemistry Journal of Volcanology and Geothermal Research 26, 337–64.Google Scholar
Conticelli, S., Francalanci, L., Manetti, P., Peccerillo, A. & Santo, A. 1986. Caratteristiche compositizionali dei prodotti dell'apparato di Latera (Monti Vulsini, Lazio Settentrionale) e loro significato vulcanologico Memoria della Societa Geologica d' Italia 35, 345–57.Google Scholar
Conticelli, S., Francalanci, , & Santo, A. 1991. Petrology of final-stage Latera lavas (Vulsini Mts.): mineralogical, geochemical and Sr-isotopic data and their bearing on the genesis of some potassic magmas in central Italy Journal of Volcanology and Geothermal Research 46, 187–212.CrossRefGoogle Scholar
de Silva, S. L. 1989. The origin and significance of crystal rich inclusions in pumices from two Chilean ignimbrites Geological Magazine 126, 159–75.Google Scholar
Dingwell, D. B. & Brearley, M. 1985. Mineral chemistry of igneous melanite garnets from analcite-bearing volcanic rocks, Alberta, Canada Contributions to Mineralogy and Petrology 90, 29–35.Google Scholar
Ferrara, G., Preite-Martinez, M., Taylor, H. P. Jr, Tonarini, S. & Tori, B. 1986. Evidence for crustal assimilation, mixing of magmas, and a 87Sr-rich upper mantle: an oxygen and strontium isotope study of the M. Vulsini volcanic area, Central Italy Contributions to Mineralogy and Petrology 92, 269–80.CrossRefGoogle Scholar
Fudali, R. F. 1963. Experimental studies bearing on the origin of pseudoleucite and associated problems with alkali rock systems Geological Society of America Bulletin 74, 1101–10.CrossRefGoogle Scholar
Ghiorso, M. S. & Carmichael, I. S. E. 1987. Modeling magmatic systems: petrologic applications. In Thermodynamic Modeling of Geological Materials: Minerals, Fluids, and Melts, Reviews in Mineralogy Vol. 7 (eds Carmichael, I. S. E. and Eugster, H. P.), pp. 467–97. Washington: Mineralogical Society of America.Google Scholar
Ghiorso, M. S. & Kelemen, P. B. 1987. Evaluating reaction stoichiometry in magmatic systems evolving under general thermodynamic constraints: examples comparing isothermal and isenthalpic assimilation. In Magmatic Processes: Physiochemical Principles (ed. Mysen, B. O.), pp. 319–36. Geochemical Society Special Publication no. 1.Google Scholar
Giannetti, B. 1982. Cumulate inclusions from K-rich magmas, Roccamonfina volcano, Italy Earth and Planetary Science Letters 57, 313–35.Google Scholar
Hanson, G. N. 1978. The application of trace elements to the petrogenesis of igneous rocks of granitic composition Earth and Planetary Science Letters 38, 26–43.Google Scholar
Hermes, O. D. & Cornell, W. C. 1983. The significance of mafic nodules in the ultra-potassic rocks from central Italy-reply Journal of Volcanology and Geothermal Research 16, 166–72.Google Scholar
Holm, P. M. & Munksgaard, N. C. 1986. Reply to: a criticism of the Holm-Munksgaard oxygen and strontium isotope study of the Vulsinian District, Central Italy Earth and Planetary Science Letters 78, 454–59.CrossRefGoogle Scholar
Hunter, R. H. & Sparks, R. S. J. 1990. The differentiation of the Skaergaard intrusion. Replies to A. R. MacBirney and H. R. Naslund, S. A. Morse, C. K. Brooks, and T. F. D., Nielsen Contributions to Mineralogy and Petrology 104, 248–54.Google Scholar
Jackson, E. D. 1961. Primary textures and mineral associations in the ultramafic zone of the Stillwater complex, Montana. Geological Survey Professional Paper 358, 106 pp.Google Scholar
Jorgensen, K. A. 1987. Mineralogy and petrology of alkaline granophyric xenoliths from the Thorsmörk ignimbrite, southern Iceland Lithos 20, 153–68.Google Scholar
Jurewicz, S. R. & Watson, E. B. 1985. The distribution of partial melt in a granitic system: the application of liquid phase sintering theory Geochimica et Cosmochimica Acta 49, 1109–21.CrossRefGoogle Scholar
Landi, P. 1987. Un esempio di zonatura composizionale in camere magmatiche superficiali: l'eruzione piroclastica alcalino potassica di Pitgliano (Volcano di Latera) Rendiconti della Societa Mineralogia e Petrologia d' Italia 42, 123–40.Google Scholar
Langmuir, C. H. 1989. Geochemical consequences of in situ crystallization Nature 340, 197–205.Google Scholar
Locardi, E., Lombardi, G., Funiciello, R. & Parotto, M. 1976. The main volcanic groups of Latium, Italy: relations between structural evolution and petrogenesis Geologica Romana 15, 279–300.Google Scholar
Lofgren, G. 1980. Experimental studies on the dynamic crystallization of silicate melts. In Physics of Magmatic Processes (ed. Hargraves, R. B.), pp. 487–551. Princeton: Princeton University Press.Google Scholar
Manning, C. E. & Bird, D. K. 1986. Hydrothermal clinopyroxenes of the Skaergaard intrusion Contributions to Mineralogy and Petrology 92, 437–47.Google Scholar
Marsh, B. D. 1981. On the crystallinity, probability of occurrence, and rheology of lava and magma Contributions to Mineralogy and Petrology 78, 85–98.Google Scholar
Marsh, B. D. 1990. Crystal capture, sorting, and retention in converting magma: a reply Geological Society of America Bulletin 102, 849–50.Google Scholar
Matthews, A. & Nathan, Y. 1977. The decarbonation of carbonate-fluorapatite (francolite) American Mineralogist 62, 565–73.Google Scholar
McArthur, J. M. 1985. Francolite geochemistry-compositional controls during formation, diagenesis, metamorphism and weathering Geochimica et Cosmochimica Acta 49, 23–35.CrossRefGoogle Scholar
Nekvasil, H. 1990. Reaction relations in the granitic system: implications for trachytic and syenitic magmas American Mineralogist 75, 560–71.Google Scholar
Petersen, J. S. 1987. Solidification contraction: another approach to cumulus processes and the origin of igneous layering. In Origins of Igneous Layering (ed. Parsons, I.), pp. 505–26. Dordrecht: D. Reidel.CrossRefGoogle Scholar
Roelandts, I. & Michel, G. 1986. Sequential inductively coupled plasma determination of some rare-earth elements in five French geostandards Geostandards Newsletters 10, 135–54.CrossRefGoogle Scholar
Rogers, N. W., Hawkesworth, C. J., Parker, R. J. & Marsh, J. S. 1985. The geochemistry of potassic lavas from Vulsini, central Italy and implications for mantle enrichment processes beneath the Roman region Contributions to Mineralogy and Petrology 90, 244–57.Google Scholar
Santacroce, R. 1970. Assimilazione carbonatica negli inclusi lituodi dellepomici di Casa Collina, Pitigliano (Grosseto) Periodicoldi Mineralogica 39, 255–90.Google Scholar
Shapiro, L. 1975. Rapid analysis of silicate, carbonate, and phosphate rocks-revised edition. United States Geological Survey Bulletin no. 1401, 76 pp.Google Scholar
Shaw, H. R. 1965. Comments on viscosity, crystal setting, and convection in granitic magmas American Journal of Science 263, 120–52.CrossRefGoogle Scholar
Sparks, R. S. J. 1975. Stratigraphy and geology of the ignimbrites of Vulsini volcano, Central Italy Geologische Rundschau 64, 497–523.Google Scholar
Storey, M. 1981. Trachytic pyroclasts from Aqua de Pau volcano, Sao Miguel, Azores: evolution of a magma body over 4,000 years Contributions to Mineralogy and Petrology 78, 423–32.Google Scholar
Stormer, J. C. & Carmichael, I. S. E. 1971. The free-energy of sodalite and the behavior of chloride, fluoride, and sulphate in silicate magmas American Mineralogist 56, 291–306.Google Scholar
Tait, S. R. 1988. Samples from the crystallizing boundary layer of a zoned magma chamber Contributions to Mineralogy and Petrology 100, 474–83.Google Scholar
Taylor, B. E. & Liou, J. G. 1978. The low temperature stability of andradite in C-O-H fluids American Mineralogist 63, 378–93.Google Scholar
Tilley, C. E. 1952. Some trends of basaltic magma in limestone anatexis. American Journal of Science, Bowen volume 2, 529–45.Google Scholar
Trial, A. J. & Spera, F. J. 1990. Mechanisms for the generation of compositional heterogeneities in magma chambers Geological Society of America Bulletin 102, 353–67.Google Scholar
Turbeville, B. N. 1992 a. Evidence of ash fountaimng, rheomorphism, and spatter flow during emplacement of the Pitigliano Tuffs, Latera Caldera, Italy Journal of Volcanology and Geothermal Research 53, 309–27.Google Scholar
Turbeville, B. N. 1992 b. 40Ar/39Ar ages and stratigraphy of the Latera caldera, Italy Bulletin of Volcanology 55, 308–27.Google Scholar
Turbeville, B. N. 1993. Petrology and petrogenesis of the Latera caldera, Italy Journal of Petrology 34, 77–123.CrossRefGoogle Scholar
Varekamp, J. C. 1979. Geology and petrology of the Vulsinian volcanic area (Latium, Italy). Utrecht: Geologica Ultraiectina, Rijksuniversiteit, 384 pp.Google Scholar
Varekamp, J. C. 1980. The Geology of the Vulsinian area, Lazio, Italy Bulletin Volcanologique 43, 487–503.CrossRefGoogle Scholar
Varekamp, J. C. & Kalamarides, R. I. 1989. Hybridization processes in leucite tephrites from Vulsini, Italy, and the evolution of the Italian potassic suite Journal of Geophysical Research 94, 4603–18.CrossRefGoogle Scholar
Villemant, B. 1988. Trace element evolution in the Phlegrean Fields (Central Italy): fractional crystallization and selective enrichment Contributions to Mineralogy and Petrology 98, 169–83.Google Scholar
Wager, L. R. & Brown, G. M. 1968. Layered Igneous Rocks. London: Oliver and Boyd, 588 pp.Google Scholar
Wellman, T. R. 1969. The stability of sodalite in a synthetic syenite plus aqueous chloride fluid system Journal of Petrology 11, 49–71.CrossRefGoogle Scholar
Widom, E., Schmincke, H.-U. & Gill, J. B. 1992. Processes and timescales in the evolution of a chemically zoned trachyte: Fogo A, Sao Miguel, Azores Contributions to Mineralogy and Petrology 111, 311–28.CrossRefGoogle Scholar
Wolff, J. A. 1987. Crystallization of nepheline syenite in a subvolcanic magma system: Tenerife, Canary Islands Lithos 20, 207–23.Google Scholar
Wyllie, P. J. 1974. Limestone assimilation. In The Alkaline Rocks (ed. Sorensen, H.), pp. 459–74. New York: John Wiley and Sons.Google Scholar