A Hornblende Basalt from Western Mexico: Water-saturated Phase Relations Constrain a Pressure---Temperature Window of Eruptibility

Trachybasalt scoria from a cinder cone near the Mexican volcanic front contain phenocrysts of olivine with chromite inclusions, apatite, augite and hornblende, with microphenocrysts of plagioclase. The water-saturated phase relations reproduce the phenocryst assemblage between 1040 C and 970 C with water contents of between 2 5 and 4 5%(50---150MPa).The absence of biotite phenocrysts in the scoria places a tight constraint on the pressure---temperature conditions of phenocryst equilibration, as there is only a small zone where biotite does not accompany hornblende in the experiments. Diluting the fluid phase with CO2 changes the composition of the olivine, indicating that CO2 was only a minor component of the fluid of the scoria. Hornblende is stable to 1040 C at oxygen fugacities of NNO ‡ 2 (where NNO is the nickel---nickel oxide buffer), but at lower oxygen fugacities, the upper limit is 990 C. There is a progressive increase in crystallinity in experimental runs as both pressure and temperature decrease. Isobaric plots of crystallinity show that the onset of hornblende crystallization involves a reaction relation, and also results in a marked 15---40 vol.% increase in crystallinity. Ascending hydrous magmas intersecting the cooler crust could be trapped there by the large increase in crystallinity accompanying the isobaric crystallization of hornblende.

[1]  I. Carmichael,et al.  Hydrous phase equilibria of a Mexican high-silica andesite:A candidate for a mantle origin? , 2001 .

[2]  B. Scaillet,et al.  Evidence for mantle metasomatism by hydrous silicic melts derived from subducted oceanic crust , 2001, Nature.

[3]  R. Lange,et al.  The Density of Hydrous Magmatic Liquids. , 1999, Science.

[4]  N. Bagdassarov,et al.  Granite rheology: magma flow and melt migration , 1998, Journal of the Geological Society.

[5]  I. Carmichael,et al.  Plagioclase-free andesites from Zitácuaro (Michoacán), Mexico: petrology and experimental constraints , 1998 .

[6]  L. Borg,et al.  The petrogenesis of felsic calc-alkaline magmas from the southernmost Cascades, California: origin by partial melting of basaltic lower crust , 1998 .

[7]  M. Hort.  Abrupt Change in Magma Liquidus Temperature because of Volatile Loss or Magma Mixing: Effects on Nucleation, Crystal Growth and Thermal History of the Magma , 1998 .

[8]  I. Carmichael,et al.  The hydrous phase equilibria (to 3 kbar) of an andesite and basaltic andesite from western Mexico: constraints on water content and conditions of phenocryst growth , 1998 .

[9]  T. Vennemann,et al.  An empirical model for the solubility of H2O in magmas to 3 kilobars , 1998 .

[10]  A. Woods,et al.  Control of magma volatile content and chamber depth on the mass erupted during explosive volcanic eruptions , 1997 .

[11]  T. Grove,et al.  Magmatic processes that generated the rhyolite of Glass Mountain, Medicine Lake volcano, N. California , 1997 .

[12]  Holloway,et al.  Melting Temperature and Partial Melt Chemistry of H2O-Saturated Mantle Peridotite to 11 Gigapascals , 1997, Science.

[13]  T. Sisson,et al.  Hornblende gabbro sill complex at Onion Valley, California, and a mixing origin for the Sierra Nevada batholith , 1996 .

[14]  R. Lange,et al.  The Aurora volcanic field, California-Nevada: oxygen fugacity constraints on the development of andesitic magma , 1996 .

[15]  T. Tingle,et al.  An Improved Mean Atomic Number Background Correction for Quantitative Microanalysis , 1996, Microscopy and Microanalysis.

[16]  R. Rudnick,et al.  Nature and composition of the continental crust: A lower crustal perspective , 1995 .

[17]  P. Richet,et al.  Rheology of crystal-bearing silicate melts : an experimental study at high viscosities , 1995 .

[18]  R. Sparks,et al.  Physical aspects of magma degassing I. Experimental and theoretical constraints on vesiculation , 1994 .

[19]  M. Pownceby,et al.  Thermodynamic data from redox reactions at high temperatures. III. Activity-composition relations in Ni-Pd alloys from EMF measurements at 850–1250 K, and calibration of the NiO+Ni-Pd assemblage as a redox sensor , 1994 .

[20]  W. Bryan,et al.  The influence of water on the petrogenesis of subductionrelated igneous rocks , 1993, Nature.

[21]  S. Miyashita,et al.  Zoned Calc-Alkaline Plutons in Northeastern Kamchatka, Russia: Implications for the crustal growth in magmatic arcs , 1993 .

[22]  J. Tepper,et al.  Petrology of the Chilliwack batholith, North Cascades, Washington: generation of calc-alkaline granitoids by melting of mafic lower crust with variable water fugacity , 1993 .

[23]  T. Sisson,et al.  Experimental investigations of the role of H2O in calc-alkaline differentiation and subduction zone magmatism , 1993 .

[24]  G. Pe‐Piper,et al.  Geochemical variation with time in the Cenozoic high-K volcanic rocks of the island of Lesbos, Greece: significance for shoshonite petrogenesis , 1992 .

[25]  Harry Pinkerton,et al.  Methods of determining the rheological properties of magmas at sub-liquidus temperatures. , 1992 .

[26]  S. Kay,et al.  The influence of amphibole fractionation on the evolution of calc-alkaline andesite and dacite tephra from the central Aleutians, Alaska , 1992 .

[27]  R. Sparks,et al.  Petrogenesis of mafic inclusions in granitoids of the Adamello Massif, Italy , 1992 .

[28]  P. Wallace,et al.  Alkaline and calc-alkaline lavas near Los Volcanes, Jalisco, Mexico: geochemical diversity and its significance in volcanic arcs , 1992 .

[29]  D. Green,et al.  Possible role of amphibole in the origin of andesite: some experimental and natural evidence , 1992 .

[30]  E. Middlemost,et al.  A classification of igneous rocks and glossary of terms , 1991 .

[31]  G. P. Wyers,et al.  Estimates of P, T, PH2O and FO2 for lavas from Patmos (Greece) and implications for magmatic evolution , 1991 .

[32]  I. Carmichael,et al.  The compressibility of silicate liquids containing Fe2O3 and the effect of composition, temperature, oxygen fugacity and pressure on their redox states , 1991 .

[33]  G. P. Wyers,et al.  Petrology and evolution of transitional alkaline — sub alkaline lavas from Patmos, Dodecanesos, Greece: evidence for fractional crystallization, magma mixing and assimilation , 1986 .

[34]  H. Sigurdsson,et al.  The May 18, 1980, eruption of Mount St. Helens: 1. Melt composition and experimental phase equilibria , 1985 .

[35]  H. Sakai,et al.  Ophiolite-contaminated andesites, trachybasalts, and cognate inclusions of Mount Lamington, Papua New Guinea: anhydrite-amphibole-bearing lavas and the 1951 cumulodome , 1983 .

[36]  J. C. Allen,et al.  The stability of amphibole in andesite and basalt at high pressures , 1983 .

[37]  B. Marsh.  On the crystallinity, probability of occurrence, and rheology of lava and magma , 1981 .

[38]  J. Gill.  Orogenic Andesites and Plate Tectonics , 1981 .

[39]  J. Luhr,et al.  The Colima volcanic complex, Mexico: Part II. Late-quaternary cinder cones , 1981 .

[40]  R. Arculus,et al.  The Petrology of Plutonic Blocks and Inclusions from the Lesser Antilles Island Arc , 1980 .

[41]  A. T. Anderson.  Water in Some Hypersthenic Magmas , 1979, The Journal of Geology.

[42]  R. Arculus,et al.  The Alkalic Rock Suite of Bogoslof Island, Eastern Aleutian Arc, Alaska , 1977, The Journal of Geology.

[43]  R. T. Helz.  Phase Relations of Basalts in their Melting Ranges at PH2O = 5 kb. Part II. Melt Compositions , 1976 .

[44]  H. Sigurdsson,et al.  Amphibole-bearing basalts from the submarine volcano Kick’em-Jenny in the lesser antilles Island arc , 1974 .

[45]  A. T. Anderson.  Chlorine, Sulfur, and Water in Magmas and Oceans , 1974 .

[46]  R. T. Helz.  Phase Relations of Basalts in their Melting Range at PH2O = 5 kb as a Function of Oxygen Fugacity Part I. Mafic Phases , 1973 .

[47]  J. Holloway,et al.  Melting Relations of Basalt with Equilibrium Water Pressure Less Than Total Pressure , 1972 .

[48]  International Mineralogical Association: Commission on New Minerals and Mineral Names , 1971, Mineralogical Magazine.

[49]  J. Holloway.  Melting Temperature and Partial Melt Chemistry of H 2 O-Saturated Mantle Peridotite to 11 Gigapascals Tatsuhiko Kawamoto , 1997 .

[50]  S. Tait,et al.  The dimensions of magmatic inclusions as a constraint on the physical mechanism of mixing , 1997 .

[51]  R. Lange,et al.  Quaternary minettes and associated volcanic rocks of Mascota, western Mexico: a consequence of plate extension above a subduction modified mantle wedge , 1996 .

[52]  I. Carmichael,et al.  Thermodynamic properties of silicate liquids with emphasis on density, thermal expansion and compressibility , 1990 .

[53]  R. W. Le Maitre,et al.  A Classification of igneous rocks and glossary of terms : recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks , 1989 .

[54]  B. Wood,et al.  Simulating the earth : experimental geochemistry , 1988 .

[55]  J. Luhr,et al.  Jorullo Volcano, Michoacán, Mexico (1759–1774): The earliest stages of fractionation in calc-alkaline magmas , 1985 .

[56]  G. Mason.  The mineralogy and textures of the Coastal Batholith, Peru , 1985 .

[57]  J. Nicholls,et al.  XLFRAC: a program for the interactive testing of magmatic differentiation models , 1978 .

[58]  F. Brown,et al.  Quaternary volcanoes of the lake Rudolf Region: 1. The basanite-tephrite series of the Korath range , 1969 .

[59]  R. Howie,et al.  Rock-forming minerals , 1962 .

[60]  R. Howie,et al.  Rock-forming minerals: Vol. 3 : sheet silicates , 1962 .