Bulletin of Volcanology

, Volume 73, Issue 10, pp 1455–1486 | Cite as

Geochemical homogeneity of a long-lived, large silicic system; evidence from the Cerro Galán caldera, NW Argentina

  • Chris B. FolkesEmail author
  • Shanaka L. de Silva
  • Heather M. Wright
  • Raymond A. F. Cas
Research Article


By applying a number of analytical techniques across a spectrum of spatial scales (centimeter to micrometer) in juvenile components, we show that the Cerro Galán volcanic system has repeatedly erupted magmas with nearly identical geochemistries over >3.5 Myr. The Cerro Galán system produced nine ignimbrites (∼5.6 to 2 Ma) with a cumulative volume of >1,200 km3 (DRE; dense rock equivalent) of calc-alkaline, high-K rhyodacitic magmas (68–71 wt.% SiO2). The mineralogy is broadly constant throughout the eruptive sequence, comprising plagioclase, quartz, biotite, Fe–Ti oxides, apatite, and titanite. Early ignimbrite magmas also contained amphibole, while the final eruption, the most voluminous Cerro Galán ignimbrite (CGI; 2.08 ± 0.02 Ma) erupted a magma containing rare amphibole, but significant sanidine. Each ignimbrite contains two main juvenile clast types; dominant “white” pumice and ubiquitous but subordinate “grey” pumice. Fe–Ti oxide and amphibole-plagioclase thermometry coupled with amphibole barometry suggest that the grey pumice originated from potentially hotter and deeper magmas (800–840°C, 3–5 kbar) than the more voluminous white pumice (770–810°C, 1.5–2.5 kbar). The grey pumice is interpreted to represent the parental magmas to the Galán system emplaced into the upper crust from a deeper storage zone. Most inter-ignimbrite variations can be accounted for by differences in modal mineralogy and crystal contents that vary from 40 to 55 vol.% on a vesicle-free basis. Geochemical modeling shows that subtle bulk-rock variations in Ta, Y, Nb, Dy, and Yb between the Galán ignimbrites can be reconciled with differences in amounts of crystal fractionation from the “grey” parent magma. The amount of fractionation is inversely correlated with volume; the CGI (∼630 km3) and Real Grande Ignimbrite (∼390 km3) return higher F values (proportion of liquid remaining) than the older Toconquis Group ignimbrites (<50 km3), implying less crystal fractionation took place during the upper-crustal evolution of these larger volume magmas. We attribute this relationship to variations in magma chamber geometry; the younger, largest volume ignimbrites came from flat sill-like magma chambers, reducing the relative proportion of sidewall crystallization and fractionation compared to the older, smaller-volume ignimbrite eruptions. The grey pumice clasts also show evidence of silicic recharge throughout the history of the Cerro Galán system, and recharge days prior to eruption has previously been suggested based on reversely zoned (OH and Cl) apatite phenocrysts. A rare population of plagioclase phenocrysts with thin An-rich rims in juvenile clasts in many ignimbrites supports the importance of recharge in the evolution and potential triggering of eruptions. This study extends the notion that large volumes of nearly identical silicic magmas can be generated repeatedly, producing prolonged geochemical homogeneity from a long-lived magma source in a subduction zone volcanic setting. At Cerro Galán, we propose that there is a zone between mantle magma input and upper crustal chambers, where magmas are geochemically “buffered”, producing the underlying geochemical and isotopic signatures. This produces the same parental magmas that are delivered repeatedly to the upper crust. A lower-crustal MASH (melting, assimilation, storage, and homogenization) zone is proposed to act as this buffer zone. Subsequent upper crustal magmatic processes serve only to slightly modify the geochemistry of the magmas.


Ignimbrites Central Andes Crystal-rich rhyodacite Fractionation Magma chamber 



This research was funded by an Australian Research Council Discovery Program Grant DP0663560 to the research team led by R. Cas. Partial support for this work came from NSF grant EAR 0710545 to S. de Silva that is gratefully acknowledged. We thank Monash University, Oregon State University and Salta University, Argentina for access to the various facilities required to undertake this research. Journal reviews from Olivier Bachmann and Eric Christiansen and suggestions from the editors for this special issue helped to improve this manuscript.

Supplementary material

445_2011_511_MOESM1_ESM.pdf (363 kb)
ESM 1 (PDF 362 kb)


  1. Allmendinger RW, Jordan TE, Kay SM, Isacks BL (1997) The evolution of the Altiplano-Puna plateau of the Central Andes. Annu Rev Earth Planet Sci 25:139–174CrossRefGoogle Scholar
  2. Anders E, Ebihara M (1982) Solar system abundances of the elements. Geochim Cosmochim Acta 46:2363–2380CrossRefGoogle Scholar
  3. Andersen JL (1996) Status of thermobarometry in granitic batholiths. Trans R Soc Edin 87:125–138CrossRefGoogle Scholar
  4. Andersen JL, Lindsley DH (1988) Internally consistent solution models for the Fe-Mg-Mn-Ti oxides, Fe-Ti oxides. Am Mineral 73:714–726Google Scholar
  5. Anderson JL, Smith DR (1995) The effects of temperature and fO2 on the Al-in-hornblende barometer. Am Mineral 80:549–559Google Scholar
  6. Annen C, Blundy JD, Sparks RSJ (2006) The genesis of intermediate and silicic magmas in deep crustal Hot zones. J Petrol 47(3):505–539CrossRefGoogle Scholar
  7. Bachmann O, Bergantz GW (2004) On the origin of crystal-poor rhyolites: extracted from batholithic crystal mushes. J Petrol 45:1565–1582CrossRefGoogle Scholar
  8. Bachmann O, Dungan MA, Lipman PW (2002) The Fish Canyon magma body, San Juan volcanic field, Colorado: rejuvenation and eruption of an upper-crustal batholith. J Petrol 43:1469–1503CrossRefGoogle Scholar
  9. Bachmann O, Dungan MA, Bussy F (2005) Insights into shallow magmatic processes in large silicic magma bodies: the trace element record in the Fish Canyon magma body, Colorado. Contrib Mineral Petrol 149:338–349CrossRefGoogle Scholar
  10. Bacon CR, Druitt TH (1988) Compositional evolution of the zoned, calcalkaline magma chamber of Mount Mazama, Crater Lake, Oregon. Contrib Mineral Petrol 98:224–256CrossRefGoogle Scholar
  11. Bacon CR, Hirschmann MM (1988) Mg/Mn partitioning as a test for equilibrium between coexisting Fe-Ti oxides. Am Mineral 73:57–61Google Scholar
  12. Bacon CR, Metz J (1984) Magmatic inclusions in rhyolites, contaminated basalts, and compositional zonation beneath the Cosa volcanic field, California. Contrib Mineral Petrol 85:346–365CrossRefGoogle Scholar
  13. Blundy JD, Cashman K (2001) Ascent-driven crystallisation of dacite magmas at Mount St. Helens, 1980–1986. Contrib Mineral Petrol 140:631–650CrossRefGoogle Scholar
  14. Blundy J, Cashman K (2008) Petrologic reconstruction of magmatic system variables and processes. Rev Mineral Geochem 69:179–239CrossRefGoogle Scholar
  15. Blundy JD, Cashman K, Humphreys M (2006) Magma heating by decompression-driven crystallization beneath andesite volcanoes. Nature 443:76–80CrossRefGoogle Scholar
  16. Tuttle OF, Bowen NL (1958) Origin of granite in the light of experimental studies in the system NaAlSi3O8-KAlSi3O8-SiO2-H2O. Geol Soc Am Mem 74:153Google Scholar
  17. Boyce JW, Hervig RL (2008) Magmatic degassing histories from apatite volatile stratigraphy. Geology 36(1):63–66CrossRefGoogle Scholar
  18. Brenan J (1993) Kinetics of fluorine, chlorine, and hydroxyl exchange in fluorapatite. Chem Geol 110:195–210CrossRefGoogle Scholar
  19. Charlier BLA, Bachmann O, Davidson JP, Dungan MA, Morgan DJ (2007) the upper crustal evolution of a large silicic magma body: evidence from crystal-scale Rb-Sr isotopic heterogeneities in the Fish Canyon Magmatic System, Colorado. J Petrol 48(10):1875–1894CrossRefGoogle Scholar
  20. Chesner CA (1998) Petrogenesis of the Toba Tuffs, Sumatra, Indonesia. J Petrol 39(3):397–438CrossRefGoogle Scholar
  21. Chmielowski J, Zandt G, Haberland C (1999) The central Andean Altiplano-Puna magmatic body. Geophys Res Lett 26:783–786CrossRefGoogle Scholar
  22. Christiansen RL (1983) Yellowstone magmatic evolution; Its bearing on understanding large volume explosive volcanism. In: Boyd FR (ed) Explosive volcanism. National Academy of Sciences, U.S, pp 84–95Google Scholar
  23. Christiansen RL (2001) The Quaternary and Pliocene Yellowstone Plateau volcanic field of Wyoming, Idaho, and Montana. US Geol Surv Prof Pap 729-G, 145 p., 3 plates, scale 1:125,000Google Scholar
  24. Christiansen EH (2005) Contrasting processes in silicic magma chambers: evidence from very large volume ignimbrites. Geol Mag 142(6):669–681CrossRefGoogle Scholar
  25. Davidson J, Turner S, Handley H, Macpherson C, Dosseto A (2007) Amphibole "sponge" in arc crust? Geology 35(9):787–790CrossRefGoogle Scholar
  26. de Silva SL (1989a) Altiplano-Puna volcanic complex of the Central Andes. Geology 17:1102–1106CrossRefGoogle Scholar
  27. de Silva SL (1989b) The origin and significance of crystal rich inclusions in pumices from two Chilean ignimbrites. Geol Mag 126(2):159–175CrossRefGoogle Scholar
  28. de Silva SL (1991) Styles of zoning in central Andean ignimbrites; insights into magma chamber processes. In: Harmon SR, Rapela CW (eds) Andean Magmatism and its Tectonic Setting. Geological Society of America Special Paper, pp 217–232Google Scholar
  29. de Silva SL, Francis PW (1989) Correlation of large ignimbrites; two case studies from the Central Andes of northern Chile. J Volcanol Geotherm Res 37:133–149CrossRefGoogle Scholar
  30. de Silva SL, Gosnold WD (2007) Episodic construction of batholiths: insights from the spatiotemporal development of an ignimbrite flare-up. J Volcanol Geotherm Res 167:320–335CrossRefGoogle Scholar
  31. de Silva SL, Wolff JA (1995) Zoned magma chambers: the influence of magma chamber geometry on sidewall convective fractionation. J Volcanol Geotherm Res 65:111–118CrossRefGoogle Scholar
  32. de Silva SL, Zandt G, Trumbull R, Viramonte JG, Salas G, Jimenez N (2006) Large ignimbrite eruptions and volcano-tectonic depressions in the Central Andes: a thermomechanical perspective. In: Troise C, de Natale G, Kilburn CRJ (eds) Mechanisms of activity and unrest at large caldera. Geological Society, London, Special Publications, pp 47–63Google Scholar
  33. de Silva SL, Salas G, Schubring S (2008) Triggering explosive eruptions—The case for silicic magma recharge at Huaynaputina, southern Peru. Geology 36:387–390CrossRefGoogle Scholar
  34. Deer WA, Howie RA, Zussman J (1992) An introduction to the rock-forming minerals. 2nd edition. Prentice Hall, p 696Google Scholar
  35. Elston W (1984) Subduction of young oceanic lithosphere and extensional orogeny in southwestern North America during mid-Tertiary time. Tectonics 3:229–250CrossRefGoogle Scholar
  36. Ersoy Y, Helvaci C (2010) FC-AFC-FCA and mixing modeler: A Microsoft Excel spreadsheet program for modeling geochemical differentiation of magma by crystal fractionation, crustal assimilation and mixing. Comput Geosci 36:383–390CrossRefGoogle Scholar
  37. Folkes CB, Wright HM, Cas RAF, de Silva SL, Lesti C, Viramonte JG (2011) A re-appraisal of the stratigraphy and volcanology of the Cerro Galán volcanic system, NW Argentina. In:Cas RAF, Cashman K (eds) The Cerro Galan Ignimbrite and Caldera: characteristics and origins of a very large volume ignimbrite and its magma system. Bull Volcanol doi: 10.1007/s00445-011-0459-y
  38. Francis PW, O'Callaghan LJ, Kretschmar GA, Thorpe RS, Sparks RSJ, Page RN, de Barrio RE, Gillou G, Gonzalez OE (1983) The Cerro Galan ignimbrite. Nature 301:51–53CrossRefGoogle Scholar
  39. Francis PW, Sparks RSJ, Hawkesworth CJ, Thorpe RS, Pyle DM, Tait SR, Mantovani MS, McDermott F (1989) Petrology and geochemistry of volcanic rocks of the Cerro Galan caldera, northwest Argentina. Geol Mag 126(5):515–547CrossRefGoogle Scholar
  40. Friedman J, Heiken G (1977) Report in: Skylab explores the Earth. In: N.A.S.A. Publication 380: pp. 137–170Google Scholar
  41. Ghiorso MS, Evans BW (2008) Thermodynamics of rhombohedral oxide solid solutions and a revision of the Fe-Ti two-oxide geothermometer and oxygen barometer. Am J Sci 308:957–1039CrossRefGoogle Scholar
  42. Giordano D, Russell JK, Dingwell DB (2008) Viscosity of magmatic liquids: a model. Earth Planet Sci Lett 271:123–134CrossRefGoogle Scholar
  43. Grunder AL, Boden DR (1987) Comment on '…Magmatic Conditions of the Fish Canyon Tuff, Central San Juan Volcanic Field, Colorado' by Whitney and Stormer, 1985. J Petrol 28:737–746Google Scholar
  44. Harmon RS (1981) Petrogenesis of Andean andesites from combined Sr-O isotope relationships. Nature 290:396–399CrossRefGoogle Scholar
  45. Heit B (2005) Teleseismic tomographic images of the Central Andes at 21° S and 25.5° S: an inside look at the Altiplano and Puna Plateaus. In: Freie Universitat. Berlin, p 137Google Scholar
  46. Hildreth W (1981) Gradients in silicic magma chambers: implications for lithospheric magmatism. J Geophys Res 86:10153–10192CrossRefGoogle Scholar
  47. Hildreth W (2004) Volcanological perspectives on Long Valley, Mammoth Mountain, and Mono Craters: several contiguous but discrete systems. J Volcanol Geotherm Res 136:169–198CrossRefGoogle Scholar
  48. Hildreth W, Moorbath S (1988) Crustal contributions to arc magmatism in the Andes of Central Chile. Contrib Mineral Petrol 98:455–489CrossRefGoogle Scholar
  49. Hildreth W, Halliday AN, Christiansen RL (1991) Isotopic and chemical evidence concerning the genesis and contamination of basaltic and rhyolitic magma beneath the Yellowstone Plateau volcanic field. J Petrol 31(1):63–138Google Scholar
  50. Holland T, Blundy J (1994) Non-ideal interactions in calcic amphiboles and their bearing on amphibole-plagioclase thermometry. Contrib Mineral Petrol 116:433–447CrossRefGoogle Scholar
  51. Housh TB, Luhr JF (1991) Plagioclase-melt equilibria in hydrous systems. Am Mineral 76:477–492Google Scholar
  52. Huber C, Bachmann O, Manga M (2009) Homogenization processes in silicic magma chambers by stirring and mushification (latent heat buffering). Earth Planet Sci Lett 283:38–47CrossRefGoogle Scholar
  53. Isacks BL (1988) Uplift of the central Andean plateau and bending of the Bolivian orocline. J Geophys Res 7614:3325–3346Google Scholar
  54. Jellinek AM, DePaolo DJ (2003) A model for the origin of large silicic magma chambers: precursors of caldera-forming eruptions. Bull Volcanol 65:363–381CrossRefGoogle Scholar
  55. Johannes W, Holtz F (1996) Petrogenesis and experimental petrology of granitic rocks. Springer, Berlin, p 335CrossRefGoogle Scholar
  56. Johnson MC, Rutherford MJ (1989a) Experimental calibration of the aluminium-in-hornblende geobarometer with application to Long Valley Caldera (California) volcanic rocks. Geology 17:837–841CrossRefGoogle Scholar
  57. Johnson MC, Rutherford MJ (1989b) Experimentally determined conditions in the Fish Canyon Tuff, Colorado, Magma Chamber. J Petrol 30(3):711–737Google Scholar
  58. Johnson DM, Hooper PR, Conrey RM (1999) XRF analysis of rocks and minerals for major and trace elements on a single low dilution Li-tetraborate fused bead. Advances in X-ray Analysis 41:843–867Google Scholar
  59. Jordan TE, Isacks BL, Allmendinger RW, Brewer JA, Ramos VA, Ando CJ (1983) Andean tectonics related to geometry of the subducted Nazca plate. Geol Soc Am Bull 94:341–361CrossRefGoogle Scholar
  60. Kay SM, Mpodozis C, Coira B (1999) Neogene magmatism, tectonism, and mineral deposits of the central Andes (22° to 33°S latitude). In: Skinner BJ, Holland R (eds) Geology and Ore Deposits of the Central Andes. Society of Economic Geologists Special Publications, pp 27–59Google Scholar
  61. Kay SM, Coira B, Wörner G, Kay RW, Singer BS (2011) Geochemical, isotopic and single crystal 40Ar/39Ar age constraints on the evolution of the Cerro Galán ignimbrites. In:Cas RAF, Cashman K (eds) The Cerro Galan Ignimbrite and Caldera: characteristics and origins of a very large volume ignimbrite and its magma system. Bull Volcanol doi: 10.1007/s00445-010-0410-7
  62. Kent AJR, Stolper EM, Francis D, Woodhead J, Frei R, Eiler J (2004) Mantle heterogeneity during the formation of the North Atlantic Igneous Province: Constraints from trace element and Sr-Nd-Os-O isotope systematics of Baffin Island picrites. Geochem, Geophys, Geosystems 5(11):1–26CrossRefGoogle Scholar
  63. Knaack C, Cornelius SB, Hooper PR (1994) Trace element analyses of rocks and minerals by ICP-MS. Technical Notes for WSU GeoAnalytical LabGoogle Scholar
  64. Larsen JF (2005) Experimental study of plagioclase rim growth around anorthite seed crystals in rhyodacitic melt. Am Mineral 90:417–427CrossRefGoogle Scholar
  65. Le Maitre RW (1989) A classification of igneous rocks and glossary of terms. Blackwell, OxfordGoogle Scholar
  66. Lindsay JM, Schmitt AK, Trumbull RB, de Silva SL, Siebel W, Emmermann R (2001) Magmatic evolution of the La Pacana Caldera System, Central Andes, Chile: compositional variation of two cogenetic, large-volume felsic ignimbrites. J Petrol 42(3):459–486CrossRefGoogle Scholar
  67. Lipman PW (1984) The roots of ash flow calderas in western north America: windows into the tops of granitic batholiths. J Geophys Res 89(B10):8801–8841CrossRefGoogle Scholar
  68. Lipman PW (2007) Incremental assembly and prolonged consolidation of Cordilleran magma chambers: evidence from the Southern Rocky Mountain volcanic field. Geosph 3:42–70CrossRefGoogle Scholar
  69. Lipman PW, Dungan MA, Bachmann O (1997) Comagmatic granophyric granite in the Fish Canyon Tuff, Colorado; implications for magma-chamber processes during a large ash-flow eruption. Geology 25:915–918CrossRefGoogle Scholar
  70. MacDonald GA, Katsura T (1965) Eruption of Lassen Peak, Cascade Range, California in 1915: example of mixed magmas. Geol Soc Am Bull 76:475–482CrossRefGoogle Scholar
  71. Mantovani MSM, Hawkesworth CJ (1990) An inversion approach to assimilation and fractional crystallisation processes. Contrib Mineral Petrol 105:289–302CrossRefGoogle Scholar
  72. Marsh BD (2000) Magma chambers. In: Sigurdsson H, Houghton BF, McNutt SR, Rymer H, Stix J (eds) Encyclopedia of volcanoes. Academic, San Diego, California, pp 191–206Google Scholar
  73. Mason BG, Pyle DM, Oppenheimer C (2004) The size and frequency of the largest explosive eruptions on Earth. Bull Volcanol 66:735–748CrossRefGoogle Scholar
  74. Maughan LL, Christiansen EH, Best MG, Gromme CS, Deino AL, Tingey DG (2002) The Oligocene Lund Tuff, Great Basin, USA: a very large volume monotonous intermediate. J Volcanol Geotherm Res 113:129–157CrossRefGoogle Scholar
  75. Miller DS, Smith RB (1999) P and S velocity of the Yellowstone volcanic field from local earthquake and controlled-source tomography. J Geophys Res 104:15105–15121CrossRefGoogle Scholar
  76. Naney MT (1983) Phase equilibria of rock-forming ferromagnesian silicates in granitic systems. Am J Sci 283:993–1033CrossRefGoogle Scholar
  77. Pouchou JL, Pichoir F (1985) ‘PAP’ Procedure for improved quantitative microanalysis. Microbeam Analysis Proceedings. In: Armstrong JT (ed) Microbeam Analysis. San Francisco Press, pp 104–106Google Scholar
  78. Putirka KD (2008) Thermometers and barometers for volcanic systems. Rev Mineral Geochem 69:61–120CrossRefGoogle Scholar
  79. Rampino M, Self S (1992) Volcanic winter and accelerated glaciation following the Toba super-eruption. Nature 359:50–52CrossRefGoogle Scholar
  80. Riciputi LR, Johnson CM, Sawyer DA, Lipman PW (1995) Crustal and magmatic evolution in a large multicyclic caldera complex: isotopic evidence from the central San Juan volcanic field. J Volcanol Geotherm Res 67:1–28CrossRefGoogle Scholar
  81. Rollinson H (1993) Using geochemical data. Longman Group, Harlow, pp 1–352Google Scholar
  82. Schmidt MW (1992) Amphibole composition in tonalite as a function of pressure: an experimental calibration of the Al-in-hornblende barometer. Contrib Mineral Petrol 110:304–310CrossRefGoogle Scholar
  83. Schmitt AK (2001) Gas-saturated crystallization and degassing in large-volume, crystal-rich dacitic magmas from the Altiplano-Puna, northern Chile. J Geophys Res 108(B12):30561–30578CrossRefGoogle Scholar
  84. Schmitt AK, Lindsay JM, Emmermann R (1999) Pre-eruptive magma storage conditions and evidence for externally controlled eruption of large-volume central Andean ignimbrites. EOS Trans Am Geophys Union 80:F982–F983CrossRefGoogle Scholar
  85. Schurr B, Asch G, Rietbrock A, Trumbull R, Haberland C (2003) Complex patterns of fluid and melt transport in the central Andean subduction zone revealed by attenuation tomography. Earth Planet Sci Lett 215:105–119CrossRefGoogle Scholar
  86. Singer BS, Dungan MA, Layne GD (1995) Textures and Sr, Ba, Mg, Fe, K, and Ti compositional profiles in volcanic plagioclases: clues to the dynamics of calc-alkaline magma chambers. Am Mineral 80:776–798Google Scholar
  87. Smith RL (1979) Ash-flow magmatism. Geol Soc Am Spec Paper 180:5–27Google Scholar
  88. Smith VC, Blundy JD, Arce JL (2009) A temporal record of magma accumulation and evolution beneath Nevado de Toluc, Mexico, preserved in plagioclase phenocrysts. J Petrol 50:405–426CrossRefGoogle Scholar
  89. Sparks RSJ, Francis PW, Hamer RD, Pankhurst RJ, O'Callaghan LO, Thorpe RS, Page RN (1985) Ignimbrites of the Cerro Galan caldera, NW Argentina. J Volcanol Geotherm Res 24:205–248CrossRefGoogle Scholar
  90. Spera FJ (2000) Physical properties of magma. In: Sigurdsson H, Houghton BF, McNutt SR, Rymer H, Stix J (eds) Encyclopedia of volcanoes. Academic, San Diego, California, pp 171–190Google Scholar
  91. Tepley FJ III, Davidson JP, Tilling RI, Arth JG (2000) Magma mixing, recharge and eruption histories recorded in plagioclase phenocrysts from El Chichon volcano, Mexico. J Petrol 41:1397–1411CrossRefGoogle Scholar
  92. Whitney JA, Stormer JC Jr (1985) Mineralogy, petrology, and magmatic conditions from the Fish Canyon Tuff, central San Juan Volcanic Field, Colorado. J Petrol 26:726–762Google Scholar
  93. Wolff JA (1985) The effect of explosive eruption processes on geochemical patterns within pyroclastic deposits. J Volcanol Geotherm Res 26:189–201CrossRefGoogle Scholar
  94. Wolff JA, Worner G, Blake S (1990) Gradients in physical parameters in zoned felsic magma bodies: implications for evolution and eruptive withdrawal. J Volcanol Geotherm Res 43:37–55CrossRefGoogle Scholar
  95. Wright HMN, Folkes CB, Cas RAF, Cashman KV (2011) Heterogeneous pumice populations in the 2.08 Ma Cerro Galán ignimbrite: implications for magma recharge and ascent preceding a large volume silicic eruption. In:Cas RAF, Cashman K (eds) The Cerro Galan Ignimbrite and Caldera: characteristics and origins of a very large volume ignimbrite and its magma system. Bull Volcanol doi: 10.1007/s00445-011-0525-5
  96. Zandt G, Velasco AA, Beck SL (1994) Composition and thickness of the southern Altiplano crust, Bolivia. Geology 22:1003–1006CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Chris B. Folkes
    • 1
    Email author
  • Shanaka L. de Silva
    • 2
  • Heather M. Wright
    • 1
  • Raymond A. F. Cas
    • 1
  1. 1.School of Geosciences, Building 28Monash UniversityVictoriaAustralia
  2. 2.Department of GeosciencesOregon State UniversityCorvallisUSA

Personalised recommendations