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Experimental phase equilibria of a Mount St. Helens rhyodacite: a framework for interpreting crystallization paths in degassing silicic magmas

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Abstract

We present isothermal (885 °C) phase equilibrium experiments for a rhyodacite from Mount St. Helens (USA) at variable total pressure (25–457 MPa) and fluid composition (XH2Ofl = 0.6–1.0) under relatively oxidizing conditions (NNO to NNO + 3). Run products were characterized by SEM, electron microprobe, and SIMS. Experimental phase assemblages and phase chemistry are consistent with those of natural samples from Mount St. Helens from the last 4000 years. Our results emphasize the importance of pressure and melt H2O content in controlling phase proportions and compositions, showing how significant textural and compositional variability may be generated in the absence of mixing, cooling, or even decompression. Rather, variations in the bulk volatile content of magmas, and the potential for fluid migration relative to surrounding melts, mean that magmas may take varied trajectories through pressure–fluid composition space during storage, transport, and eruption. We introduce a novel method for projecting isothermal phase equilibria into CO2–H2O space (as conventionally done for melt inclusions) and use this projection to interpret petrological data from Mount St. Helens dacites. By fitting the experimental data as empirical functions of melt water content, we show how different scenarios of isothermal magma degassing (e.g., water-saturated ascent, vapor-buffered ascent, and vapor fluxing) can have quite different textural and chemical consequences. We explore how petrological data might be used to infer degassing paths of natural magmas and conclude that melt CO2 content is a much more useful parameter in this regard than melt H2O.

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Notes

  1. We have used hyperbolic functions as they better describe the tendency of the experimental data to asymptote at high or low values without the arbitrary inflexion point that bedevils more commonly used third-order polynomial fits.

References

  • Andersen D, Lindsley D (1988) Internally consistent solution models for Fe–Mg–Mn–Ti oxides: Fe–Ti oxides. Am Mineral 73:714–726

    Google Scholar 

  • Baker D, Alletti M (2012) Fluid saturation and volatile partitioning between melts and hydrous fluids in crustal magmatic systems: the contribution of experimental measurements and solubility models. Earth Sci Rev 114:298–324

    Article  Google Scholar 

  • Berlo K, Blundy J, Turner S, Hawkesworth C (2007) Textural and chemical variation in plagioclase phenocrysts from the 1980 eruptions of Mount St. Helens, USA. Contrib Mineral Petrol 154:291–308

    Article  Google Scholar 

  • Berndt J, Liebske C, Holtz F, Freise M, Nowak M, Ziegenbein D, Hurkuck W, Koepke J (2002) A combined rapid-quench and H2-membrane setup for internally heated pressure vessels: description and application for water solubility in basaltic melts. Am Mineral 87:1717–1726

    Google Scholar 

  • Blank J, Stolper E, Carroll M (1993) Solubilities of carbon dioxide and water in rhyolitic melt at 850 °C and 750 bars. Earth Planet Sci Lett 119:27–36

    Article  Google Scholar 

  • Blundy J, Cashman K (2001) Ascent-driven crystallization of dacite magmas at Mount St. Helens, 1980–1986. Contrib Mineral Petrol 140:631–650

    Article  Google Scholar 

  • Blundy J, Cashman K (2005) Rapid decompression-driven crystallization recorded by melt inclusions from Mount St. Helens volcano. Geology 33:793–796

    Article  Google Scholar 

  • Blundy J, Cashman K (2008) Petrologic reconstruction of magmatic system variables and processes. Rev Mineral Geochem 69:197–239

    Article  Google Scholar 

  • Blundy J, Cashman K, Humphreys M (2006) Magma heating by decompression-driven crystallization beneath andesite volcanoes. Nature 443:76–80

    Article  Google Scholar 

  • Blundy J, Cashman K, Berlo K (2008) Evolving magma storage conditions beneath Mount St. Helens inferred from chemical variations in melt inclusions from the 1980–1986 and current (2004–2006) eruptions. In: Sherrod D, Scott W, Stauffer P (eds) A volcano rekindled: the renewed eruption of Mount St. Helens, 2004–2006, USGS Prof Pap 1750, pp 755–790

  • Blundy J, Cashman K, Rust A, Witham F (2010) A case for CO2-rich arc magmas. Earth Planet Sci Lett 290:289–301

    Article  Google Scholar 

  • Botcharnikov R, Almeev R, Koepke J, Holtz F (2008) Phase relations and liquid lines of descent in hydrous ferrobasalt: implications for the Skaergaard intrusion and Columbia River flood basalts. J Petrol 49:1687–1727

    Article  Google Scholar 

  • Brugger C, Hammer J (2010) Crystallization kinetics in continuous decompression experiments: implications for interpreting natural magma ascent processes. J Petrol 51:1941–1965

    Article  Google Scholar 

  • Burnham C, Jahns R (1962) A method for determining the solubility of water in silicate melts. Am J Sci 260:721–745

    Article  Google Scholar 

  • Cashman K (1992) Groundmass crystallization of Mount St. Helens dacite, 1980–1986: a tool for interpreting shallow magmatic processes. Contrib Mineral Petrol 109:431–449

    Article  Google Scholar 

  • Cashman K, Blundy J (2013) Petrological cannibalism: the chemical and textural consequences of incremental magma body growth. Contrib Mineral Petrol 166:703–729

    Article  Google Scholar 

  • Cashman K, McConnell S (2005) Multiple levels of magma storage during the 1980 summer eruptions of Mount St. Helens, WA. Bull Volcanol 68:57–75

    Article  Google Scholar 

  • Castro J, Dingwell D (2009) Rapid ascent of rhyolitic magma at Chaiten volcano, Chile. Nature 461:780–784

    Article  Google Scholar 

  • Cichy S, Botcharnikov R, Holtz F, Behrens H (2011) Vesiculation and microlite crystallization induced by decompression: a case study of the 1991–1995 Mt. Unzen eruption (Japan). J Petrol 52:1469–1492

    Article  Google Scholar 

  • Cooper K, Reid M (2003) Re-examination of crystal ages in recent Mount St. Helens lavas: implications for magma reservoir processes. Earth Planet Sci Lett 213:149–167

    Article  Google Scholar 

  • Couch S, Sparks R, Carroll M (2003) The kinetics of degassing-induced crystallization at Soufriere Hills Volcano, Montserrat. J Petrol 44:1477–1502

    Article  Google Scholar 

  • Devine J, Gardner J, Brack H, Layne G, Rutherford M (1995) Comparison of microanalytical methods for estimating H2O contents of silicic volcanic glasses. Am Mineral 80:319–328

    Google Scholar 

  • Di Carlo I, Pichavant M, Rotolo S, Scaillet B (2006) Experimental crystallization of a high-K arc basalt: the golden pumice, Stromboli volcano (Italy). J Petrol 47:1317–1343

    Article  Google Scholar 

  • Dixon J, Stolper E, Holloway J (1995) An experimental study of water and carbon dioxide solubilities in mid ocean ridge basaltic liquids 1. Calibration and solubility models. J Petrol 36:1607–1631

    Google Scholar 

  • Ebadi A, Johannes W (1991) Beginning of melting and composition of first melts in the system Qz–Ab–Or–H2O–CO2. Contrib Mineral Petrol 106:286–295

    Article  Google Scholar 

  • Eggler D, Burnham C (1973) Crystallization and fractionation trends in the system andesite–H2O–CO2–O2 at pressures to 10 kb. Geol Soc Am Bull 84:2517–2532

    Article  Google Scholar 

  • Gaetani G, O’Leary J, Shimizu N, Bucholz C, Newville M (2012) Rapid reequilibration of H2O and oxygen fugacity in olivine-hosted melt inclusions. Geology 40:915–918

    Article  Google Scholar 

  • Gardner J, Carey S, Rutherford M, Sigurdsson H (1995a) Petrologic diversity in Mount St. Helens dacites during the last 4000 years: implications for magma mixing. Contrib Mineral Petrol 119:224–238

    Article  Google Scholar 

  • Gardner J, Rutherford M, Carey S, Sigurdsson H (1995b) Experimental constraints on pre-eruptive water contents and changing magma storage prior to explosive eruptions of Mount St. Helens volcano. Bull Volcanol 57:1–17

    Article  Google Scholar 

  • Geschwind C, Rutherford M (1992) Cummingtonite and the evolution of the Mount St. Helens (Washington) magma system: an experimental study. Geology 20:1011–1014

    Article  Google Scholar 

  • Gonnermann H, Manga M (2005) Nonequilibrium magma degassing: results from modeling of the ca. 1340 AD eruption of Mono Craters, California. Earth Planet Sci Lett 238:1–16

    Article  Google Scholar 

  • Halliday A, Fallick A, Dickin A, Mackenzie A, Stephens W, Hildreth W (1983) The isotopic and chemical evolution of Mount St. Helens. Earth Planet Sci Lett 63:241–256

    Article  Google Scholar 

  • Hammer J (2008) Experimental studies of the kinetics and energetics of magma crystallization. Rev Mineral Geochem 69:9–59

    Article  Google Scholar 

  • Hammer J, Rutherford M (2002) An experimental study of the kinetics of decompression-induced crystallization in silicic melt. J Geophys Res 107:1–23

    Google Scholar 

  • Hammer J, Rutherford M (2003) Petrologic indicators of preeruption magma dynamics. Geology 31:79–82

    Article  Google Scholar 

  • Hammer J, Rutherford M, Hildreth W (2002) Magma storage prior to the 1912 eruption at Novarupta, Alaska. Contrib Mineral Petrol 144:144–162

    Article  Google Scholar 

  • Harris D, Rose W (1996) Dynamics of carbon dioxide emissions, crystallization, and magma ascent: hypotheses, theory, and applications to volcano monitoring at Mount St. Helens. Bull Volcanol 58:163–174

    Article  Google Scholar 

  • Hauri E, Wang J, Dixon J, King P, Mandeville C, Newman S (2002) SIMS analysis of volatiles in silicate glasses 1. Calibration, matrix effects, and comparisons with FTIR. Chem Geol 183:99–114

    Article  Google Scholar 

  • Heliker C (1995) Inclusions in Mount St. Helens dacite erupted from 1980 through 1983. J Volcanol 66:115–135

    Google Scholar 

  • Hoblitt R, Harmon R (1993) Bimodal density distribution of cryptodome dacite from the 1980 eruption of Mount St. Helens, Washington. Bull Volcanol 55:421–437

    Article  Google Scholar 

  • Holloway J, Blank J (1994) Application of experimental results to C–O–H species in natural melts. Rev Mineral 30:187–230

    Google Scholar 

  • Holtz F, Pichavant M, Barbey P, Johannes W (1992) Effects of H2O on liquidus phase relations in the haplogranite system at 2 and 5 kbar. Am Mineral 77:1223–1241

    Google Scholar 

  • Holtz F, Sato H, Lewis J, Behrens H, Nakada S (2005) Experimental petrology of the 1991–1995 Unzen dacite, Japan. Part I: phase relations, phase composition and pre-eruptive conditions. J Petrol 46:319–337

    Article  Google Scholar 

  • Humphreys M, Menand T, Blundy J, Klimm K (2008) Magma ascent rates in explosive eruptions: constraints from H2O diffusion in melt inclusions. Earth Planet Sci Lett 270:25–40

    Article  Google Scholar 

  • Ihinger P, Hervig R, Mcmillan P (1994) Analytical methods for volatiles in glasses. Rev Mineral 30:67–121

    Google Scholar 

  • Johnson E, Wallace P, Cashman K, Granados H, Kent AJ (2008) Magmatic volatile contents and degassing-induced crystallization at Volcán Jorullo, Mexico: implications for melt evolution and the plumbing systems of monogenetic volcanoes. Earth Planet Sci Lett 269:478–487

    Article  Google Scholar 

  • Kress V, Carmichael I (1991) The compressibility of silicate liquids containing Fe2O3 and the effect of composition, temperature, oxygen fugacity and pressure on their redox states. Contrib Mineral Petrol 108:82–92

    Article  Google Scholar 

  • Lees J (1992) The magma system of Mount St. Helens: non-linear high-resolution P-wave tomography. J Volcanol 53:103–116

    Google Scholar 

  • Lepage L (2003) ILMAT: an Excel worksheet for ilmenite–magnetite geothermometry and geobarometry. Comput Geosci 29:673–678

    Article  Google Scholar 

  • Lesne P, Kohn S, Blundy J, Witham F, Botcharnikov R, Behrens H (2011) Experimental simulation of closed-system degassing in the system basalt–H2O–CO2–S–Cl. J Petrol 52:1737–1762

    Article  Google Scholar 

  • Lloyd A, Plank T, Ruprecht P, Hauri E, Rose W (2013) Volatile loss from melt inclusions in pyroclasts of differing sizes. Contrib Mineral Petrol 165:129–153

    Article  Google Scholar 

  • Mangan M, Sisson T (2000) Delayed, disequilibrium degassing in rhyolite magma: decompression experiments and implications for explosive volcanism. Earth Planet Sci Lett 183:441–455

    Article  Google Scholar 

  • Martel C (2012) Eruption dynamics inferred from microlite crystallization experiments: application to plinian and dome-forming eruptions of Mt. Pelee (Martinique, Lesser Antilles). J Petrol 53:699–725

    Article  Google Scholar 

  • Merzbacher C, Eggler D (1984) A magmatic geohygrometer: application to Mount St. Helens and other dacitic magmas. Geology 12:587–590

    Article  Google Scholar 

  • Moore G (2008) Interpreting H2O and CO2 contents in melt inclusions: constraints from solubility experiments and modeling. Rev Mineral Geochem 69:333–361

    Article  Google Scholar 

  • Moran S (1994) Seismicity at Mount St. Helens, 1987–1992: evidence for repressurization of an active magmatic system. J Geophys Res 99:4341–4354

    Article  Google Scholar 

  • Mullineaux D (1986) Summary of pre-1980 tephra-fall deposits erupted from Mount St. Helens, Washington State, USA. Bull Volcanol 48:17–26

    Article  Google Scholar 

  • Newman S, Lowenstern J (2002) VolatileCalc: a silicate melt–H2O–CO2 solution model written in Visual Basic for Excel. Comput Geosci 28:597–604

    Article  Google Scholar 

  • O’Neill H, Pownceby M (1993) Thermodynamic data from redox reactions at high temperatures. I. An experimental and theoretical assessment of the electrochemical method using stabilized zirconia electrolytes, with revised values for the Fe–“FeO”, Co–CoO, Ni–NiO and Cu–Cu2O oxygen buffers, and new data for the W–WO2 buffer. Contrib Mineral Petrol 114(3):296–314

    Article  Google Scholar 

  • Pallister J, Rand Hoblitt D, Crandell Mullineaux D (1992) Mount St. Helens a decade after the 1980 eruptions: magmatic models, chemical cycles, and a revised hazards assessment. Bull Volcanol 54:126–146

    Article  Google Scholar 

  • Pallister J, Thornber C, Cashman K, Clynne M, Lowers H, Mandeville C, Brownfield I, Meeker G (2008) Petrology of the 2004–2006 Mount St. Helens lava dome: implications for magmatic plumbing and eruption triggering. US Geol Surv Prof Paper 1750:647–702

    Google Scholar 

  • Papale P, Moretti R, Barbato D (2006) The compositional dependence of the saturation surface of H2O + CO2 fluids in silicate melts. Chem Geol 229:78–95

    Article  Google Scholar 

  • Pichavant M, Martel C, Bourdier J, Scaillet B (2002) Physical conditions, structure, and dynamics of a zoned magma chamber: Mount Pelee (Martinique, Lesser Antilles Arc). J Geophys Res 107:1–29

    Google Scholar 

  • Pichavant M, Costa F, Burgisser A, Scaillet B, Martel C, Poussineau S (2007) Equilibration scales in silicic to intermediate magmas: implications for experimental studies. J Petrol 48:1955–1972

    Article  Google Scholar 

  • Pichavant M, Di Carlo I, Le Gac Y, Rotolo SG, Scaillet B (2009) Experimental constraints on the deep magma feeding system at Stromboli volcano, Italy. J Petrol 50:601–624

    Article  Google Scholar 

  • Portnyagin M, Almeev R, Matveev S, Holtz F (2008) Experimental evidence for rapid water exchange between melt inclusions in olivine and host magma. Earth Planet Sci Lett 272:541–552

    Article  Google Scholar 

  • Putirka K (2008) Thermometers and barometers for volcanic systems. Rev Mineral Geochem 69:61–120

    Article  Google Scholar 

  • Ridolfi F, Renzulli A (2012) Calcic amphiboles in calcalkaline and alkaline magmas: thermobarometric and chemometric empirical equations valid up to 1130 °C and 2.2 GPa. Contrib Mineral Petrol 163:877–895

    Article  Google Scholar 

  • Roberge J, Wallace P, Kent A (2013) Magmatic processes in the Bishop Tuff rhyolitic magma based on trace elements in melt inclusions and pumice matrix glass. Contrib Mineral Petrol 165:237–257

    Article  Google Scholar 

  • Rust A, Cashman K, Wallace P (2004) Magma degassing buffered by vapor flow through brecciated conduit margins. Geology 32:349–352

    Article  Google Scholar 

  • Rutherford M, Devine J (1988) The May 18, 1980, eruption of Mount St. Helens 3. Stability and chemistry of amphibole in the magma chamber. J Geophys Res 93:11949–11959

    Article  Google Scholar 

  • Rutherford M, Devine J (2008) Magmatic conditions and processes in the storage zone of the 2004–2006 Mount St. Helens dacite. US Geol Surv Prof Paper 1750:703–725

    Google Scholar 

  • Rutherford M, Hill P (1993) Magma ascent rates from amphibole breakdown: an experimental study applied to the 1980–1986 Mount St. Helens eruptions. J Geophys Res 98:19667–19685

    Article  Google Scholar 

  • Rutherford M, Sigurdsson H, Carey S, Davis A (1985) The May 18, 1980, eruption of Mount St. Helens 1. Melt composition and experimental phase equilibria. J Geohys Res 90:2929–2947

    Article  Google Scholar 

  • Saunders K, Blundy J, Dohmen R, Cashman K (2012) Linking petrology and seismology at an active volcano. Science 336:1023–1027

    Article  Google Scholar 

  • Scaillet B, Evans B (1999) The 15 June 1991 eruption of Mount Pinatubo I. Phase equilibria and pre-eruption P–T–fO2–fH2O conditions of the dacite magma. J Petrol 40:381–411

    Article  Google Scholar 

  • Scaillet B, Pichavant M, Cioni R (2008) Upward migration of Vesuvius magma chamber over the past 20,000 years. Nature 455:216–239

    Article  Google Scholar 

  • Scandone R, Malone S (1985) Magma supply, magma discharge and readjustment of the feeding system of Mount St. Helens during 1980. J Volcanol 23:239–262

    Google Scholar 

  • Scheidegger K, Federman A, Tallman A (1982) Compositional heterogeneity of tephras from the 1980 eruptions of Mount St. Helens. J Geophys Res 87:861–881

    Google Scholar 

  • Sisson T, Ratajeski K, Hankins W, Glazner A (2005) Voluminous granitic magmas from common basaltic sources. Contrib Mineral Petrol 148:635–661

    Article  Google Scholar 

  • Smith D (1984) The petrology and geochemistry of high cascade volcanics in southern Washington: Mount St. Helens Volcano and the Indian Heaven Basalt Field. Dissertation, Rice University

  • Smith D, Leeman W (1987) Petrogenesis of Mount St. Helens dacitic magmas. J Geophys Res 92:10313–10334

    Article  Google Scholar 

  • Stormer J (1983) The effects of recalculation on estimates of temperature and oxygen fugacity from analyses of multicomponent iron-titanium oxides. Am Mineral 68:586–594

    Google Scholar 

  • Streck M, Broderick C, Thornber C, Clynne M, Pallister J (2008) Plagioclase populations and zoning in dacite of the 2004–2005 Mount St. Helens eruption: constraints for magma origin and dynamics. US Geol Surv Prof Paper 1750:791–808

    Google Scholar 

  • Tamic N, Behrens H, Holtz F (2001) The solubility of H2O and CO2 in rhyolitic melts in equilibrium with a mixed CO2–H2O fluid phase. Chem Geol 174:333–347

    Article  Google Scholar 

  • Tuttle O, Bowen N (1958) Origin of granite in the light of experimental studies in the system NaAlSi3O8–KAlSi3O8–SiO2–H2O. Geol Soc Am Mem 74:1–146

    Article  Google Scholar 

  • Wallace P, Anderson A, Davis A (1999) Gradients in H2O, CO2, and exsolved gas in a large-volume silicic magma system: interpreting the record preserved in melt inclusions from the Bishop Tuff. J Geophys Res 104:20097–20122  

    Article  Google Scholar 

  • Weaver C, Grant W, Malone S, Endo E (1981) Post-May 18 seismicity: volcanic and tectonic implications. USGS Prof Pap 1250:109–121

    Google Scholar 

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Acknowledgments

JMR was supported by a University of Bristol postgraduate scholarship; JDB by European Research Council Advanced Grant CRITMAG; ACR and MCSH by Royal Society URFs; and RB by Deutsche Forschungsgemeinschaft funding. We thank R. Brooker and K. Cashman for helpful discussions. We are also grateful for assistance on the University of Edinburgh ion microprobe from R. Hinton and C.J. de Hoog, and on the University of Bristol electron microprobes and SEM from B. Buse and S. Kearns.

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Authors and Affiliations

  1. School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, UK

    Jenny M. Riker, Jonathan D. Blundy & Alison C. Rust

  2. Institüt fur Mineralogie, Universität Leibniz Hannover, 30167, Hannover, Germany

    Roman E. Botcharnikov

  3. Department of Earth Sciences, Durham University, Durham, DH1 3LE, UK

    Madeleine C. S. Humphreys

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  1. Jenny M. Riker
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Correspondence to Jenny M. Riker.

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Communicated by Timothy L. Grove.

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Riker, J.M., Blundy, J.D., Rust, A.C. et al. Experimental phase equilibria of a Mount St. Helens rhyodacite: a framework for interpreting crystallization paths in degassing silicic magmas. Contrib Mineral Petrol 170, 6 (2015). https://doi.org/10.1007/s00410-015-1160-5

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