Compositional variations and magma mixing in the 1991 eruptions of Hudson volcano, Chile

  • David J Kratzmann
  • Steven Carey
  • Roberto Scasso
  • Jose-Antonio Naranjo
Research Article


The August 1991 eruptions of Hudson volcano produced ~2.7 km3 (dense rock equivalent, DRE) of basaltic to trachyandesitic pyroclastic deposits, making it one of the largest historical eruptions in South America. Phase 1 of the eruption (P1, April 8) involved both lava flows and a phreatomagmatic eruption from a fissure located in the NW corner of the caldera. The paroxysmal phase (P2) began several days later (April 12) with a Plinian-style eruption from a different vent 4 km to the south-southeast. Tephra from the 1991 eruption ranges in composition from basalt (phase 1) to trachyandesite (phase 2), with a distinct gap between the two erupted phases from 54–60 wt% SiO2. A trend of decreasing SiO2 is evident from the earliest part of the phase 2 eruption (unit A, 63–65 wt% SiO2) to the end (unit D, 60–63 wt% SiO2). Melt inclusion data and textures suggest that mixing occurred in magmas from both eruptive phases. The basaltic and trachyandesitic magmas can be genetically related through both magma mixing and fractional crystallization processes. A combination of observed phase assemblages, inferred water content, crystallinity, and geothermometry estimates suggest pre-eruptive storage of the phase 2 trachyandesite at pressures between ~50–100 megapascal (MPa) at 972 ± 26°C under water-saturated conditions (log fO2 –10.33 (±0.2)). It is proposed that rising P1 basaltic magma intersected the lower part of the P2 magma storage region between 2 and 3 km depth. Subsequent mixing between the two magmas preferentially hybridized the lower part of the chamber. Basaltic magma continued advancing towards the surface as a dyke to eventually be erupted in the northwestern part of the Hudson caldera. The presence of tachylite in the P1 products suggests that some of the magma was stalled close to the surface (<0.5 km) prior to eruption. Seismicity related to magma movement and the P1 eruption, combined with chamber overpressure associated with basalt injection, may have created a pathway to the surface for the trachyandesite magma and subsequent P2 eruption at a different vent 4 km to the south-southeast.


Hudson volcano Magma mixing Calc-alkaline magmas Andean volcanism Explosive eruptions 



The authors thank Alejandro Bande for assistance during fieldwork in 2005. Many thanks go to JD Devine, CW Mandeville, KA Kelley, NA Hamidzada & M Lytle for assistance and expertise during data collection. The manuscript was significantly improved by the detailed and thorough reviews of J McPhie, R Price & J Davidson. This research was supported by NSF grant EAR-0337023 to Carey and Scasso.

Supplementary material

445_2008_234_MOESM1_ESM.xls (28 kb)
Table S1 Sample locations, date sampled, coordinates, eruption sampled (if applicable), and sample collection numbers. (XLS 28.0 KB)
445_2008_234_MOESM2_ESM.xls (21 kb)
Table S2 Major element compositions of andesites used in experimental work and bulk rock analyses of 1991 Hudson trachyandesite. Data normalized to 100% and pre-recalculation LOI given where applicable. (XLS 21.0 KB)


  1. Andersen DJ, Lindsley DH (1988) Internally consistent solution models for Fe-Mg-Mn-Ti oxides: Fe-Ti oxides. Am Mineral 73(7–8):714–726Google Scholar
  2. Andersen DJ, Lindsley DH, Davidson PM (1993) QUILF: a Pascal program to assess equilibria among Fe-Mg-Mn-Ti oxides, pyroxenes, olivine, and quartz. Comp Geosci 19:1333–1350CrossRefGoogle Scholar
  3. Araujo MA (1993) Participacion del INPRES en el monitoreo sismologico de volcanes. I Jorn Nac Vilcan Med Amb Def Civ Actas 157–160Google Scholar
  4. Bacon CR, Hirschmann MM (1988) Mg/Mn partitioning as a test for equilibrium between coexisting Fe-Ti oxides. Am Mineral 73:57–61Google Scholar
  5. Barclay J, Rutherford MJ, Carroll MR, Murphy MD, Devine JD, Gardner JE, Sparks RSJ (1998) Experimental phase equilibria constraints on pre-eruptive storage conditions of the Soufrière Hills magma. Geophys Res Lett 25(18):3437–3440CrossRefGoogle Scholar
  6. Bitschene PR, Fernández MI (1995) Volcanology and petrology of fallout ashes from the August 1991 eruption of the Hudson Volcano (Patagonian Andes). In: Bitschene PR, Mendia J (eds) The August 1991 eruption of the Hudson Volcano (Patagonian Andes); a thousand days after. Cuvillier, Göttingen, pp 27–54Google Scholar
  7. Bitschene PR, Fernández MI, Arias N, Arizmendi A, Griznik M, Nillni A (1993) Volcanology and environmental impact of the August 1991 eruption of the Hudson volcano (Patagonian Andes, Chile). Zbl Geol Palaont Teil I H 1/2:165–177Google Scholar
  8. Blake S (1984) Volatile oversaturation during the evolution of silicic magma chambers as an eruption trigger. J Geophys Res 89(B10):8237–8244CrossRefGoogle Scholar
  9. Carr M (2005) Igpet for Windows. CD-ROMGoogle Scholar
  10. Davidson J, Hassanzadeh J, Berzins R, Stockli DF, Bashukooh B, Turrin B, Pandamouz A (2004) The Geology of Damavand Volcano, Alborz Mountains, Northern Iran. Bull Geol Soc Am 116:16–29CrossRefGoogle Scholar
  11. Davidson JP, Morgan DJ, Charlier BLA, Harlou R, Hora JM (2007) Microsampling and isotopic analysis of igneous rocks: implications for the study of magmatic systems. Ann Rev Earth Planet Sci 35(1):273–311CrossRefGoogle Scholar
  12. Devine JD, Gardner JE, Brack HP, Layne GD, Rutherford MJ (1995) Comparison of microanalytical methods for estimating H2O contents of silicic volcanic glasses. Am Mineral 80:319–328CrossRefGoogle Scholar
  13. Eichelberger JC (1975) Origin of andesite and dacite: evidence of mixing at Glass Mountain in California and at other Circum-Pacific volcanoes. Geol Soc Am Bull 86:1381–1391CrossRefGoogle Scholar
  14. Eichelberger JC, Izbekov PE (2000) Eruption of andesite triggered by dyke injection: contrasting cases at Karymsky Volcano, Kamchatka and Mt Katmai, Alaska. Phil Trans R Soc Lond 358:1465–1485CrossRefGoogle Scholar
  15. Forsythe RD, Nelson EP (1985) Geological manifestations of ridge collision: evidence from the Golfo de Penas-Taitao basin, southern Chile. Tectonics 4:477–495CrossRefGoogle Scholar
  16. Gutiérrez F, Gioncada A, Gonzalez-Ferran O, Lahsen A, Mazzuoli R (2005) The Hudson volcano and surrounding monogenetic centres (Chilean Patagonia): an example of volcanism associated with ridge-trench collision environment. J Volcanol Geotherm Res 145:207–233CrossRefGoogle Scholar
  17. Hammer JE, Rutherford MJ (2002) An experimental study of the kinematics of decompression-induced crystallization in silicic melt. J Geophys Res 107(B1):1–24CrossRefGoogle Scholar
  18. Huppert HE, Sparks RSJ, Turner JS (1982) Effects of volatiles on mixing in calc-alkaline magma systems. Nature 297:554–557CrossRefGoogle Scholar
  19. Irvine TN, Baragaar WRA (1971) A guide to the chemical classification of the common volcanic rocks. Can J Earth Sci 8(5):523–548 doi: 10.1139/e71–055 CrossRefGoogle Scholar
  20. Izbekov PE, Eichelberger JC, Patino LC, Vogel TA, Ivanov BV (2002) Calcic cores of plagioclase phenocrysts in andesite from Karymsky volcano: evidence for rapid introduction by basaltic replenishment. Geology 30(9):799–802CrossRefGoogle Scholar
  21. Kelley KA, Plank T, Ludden J, Staudigel H (2003) Composition of altered oceanic crust at ODP Sites 801 and 1149. Geochemistry, Geophysics, Geosystems 4(6):8910 doi: 10.1029/2002GC000435
  22. Lautze NC, Houghton BF (2005) Physical mingling of magma and complex eruption dynamics in the shallow conduit at Stromboli volcano, Italy. Geology 33(5):425–428 doi: 10.1130/G21325.1 CrossRefGoogle Scholar
  23. Luhr JF (1990) Experimental phase relations of water- and sulfur-saturated arc magmas and the 1982 eruptions of El Chichón volcano. J Petrol 31(5):1071–1114CrossRefGoogle Scholar
  24. Mandeville CW, Webster JD, Rutherford MJ, Taylor BE, Timbal A, Faure K (2002) Determination of molar absorptivities for infrared absorption bands of H2O in andesitic glasses. Am Mineral 87:813–821CrossRefGoogle Scholar
  25. Maria A, Carey S, Sigurdsson H, Kincaid C, Helgadottir G (2000) Source and dispersal of jökulhaup sediments discharged to the sea following the 1996 Vatnajökull eruption. Geol Soc Am Bull 112(10):1507–1521CrossRefGoogle Scholar
  26. Martel C, Pichavant M, Holtz F, Scaillet B, Bourdier J-L, Traineau H (1999) Effects of fO2 and H2O on andesite phase relations between 2 and 4 kbar. J Geophys Res 104(B12):29,453–429,470 doi: 10.1029/1999JB900191 CrossRefGoogle Scholar
  27. Martel C, Radadi Ali A, Poussineau S, Gourgard A, Pichavant M (2006) Basalt-inherited microlites in silicic magmas: evidence from Mount Pelée (Martinique, French West Indies). Geology 34(11):905–908 doi: 10.1130/G22672A.1 CrossRefGoogle Scholar
  28. Moore G, Carmichael ISE (1998) 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. Contrib Mineral Petrol 130:304–319 doi: 10.1007/s004100050367 CrossRefGoogle Scholar
  29. Moore G, Vennemann T, Carmichael ISE (1998) An empirical model for the solubility of H2O in magmas to 3 kilobars. Am Mineral 83:36–42CrossRefGoogle Scholar
  30. Murphy MD, Sparks RSJ, Barclay J, Carroll MR, Lejeune A-M, Brewer TS, Macdonald R, Black S, Young SR (1998) The role of magma mixing in triggering the current eruption at the Soufrière Hills volcano, Montserrat, West Indies. Geophys Res Lett 25(18):3433–3436CrossRefGoogle Scholar
  31. Naranjo JA, Moreno H, Banks N (1993) La erupción del Volcán Hudson en 1991 (46°S), Región XI, Aisén. Chile Boletin 44:1–50Google Scholar
  32. Naranjo JA, Stern CR (1998) Holocene explosive activity of Hudson Volcano, southern Andes. Bull Volcanol 59:291–306 doi: 10.1007/s004450050193 CrossRefGoogle Scholar
  33. Orihashi Y, Naranjo JA, Motoki A, Sumino H, Hirata D, Anma R, Nagao K (2004) Quaternary volcanic activity of Hudson and Lautaro volcanoes, Chilean Patagonia: new constraints from K-Ar ages. Rev Geol Chile 31(2):207–224CrossRefGoogle Scholar
  34. Pallister JS, Hoblitt RP, Reyes AG (1992) A basalt trigger for the 1991 eruptions of Pinatubo volcano? Nature 356:426–428 doi: 10.1038/356426a0 CrossRefGoogle Scholar
  35. Scasso RA, Carey S (2005) Morphology and formation of glassy volcanic ash from the August 12–15, 1991 eruption of Hudson Volcano, Chile. Lat Am J Sedimentol Bas Anal 12(1):3–21Google Scholar
  36. Scasso RA, Corbella H, Tiberi P (1994) Sedimentological analysis of the tephra from the 12–15 August 1991 eruption of Hudson volcano. Bull Volcanol 56:121–132 doi: 10.1007/BF00304107 CrossRefGoogle Scholar
  37. Sparks RSJ, Sigurdsson H, Wilson L (1977) Magma mixing: a mechanism for triggering acid explosive eruptions. Nature 267:315–318CrossRefGoogle Scholar
  38. Stern CR (1991) Mid-Holocene tephra on Tierra del Fuego (54°S) derived from the Hudson Volcano (46°S): evidence for a large explosive eruption. Rev Geol Chile 18(2):139–146Google Scholar
  39. Stern CR (2004) Active Andean volcanism: its geologic and tectonic setting. Rev Geol Chile 31(2):161–206CrossRefGoogle Scholar
  40. Stern CR, Futa K, Muehlenbachs K (1984) Isotope and trace element data for orogenic andesites from the Austral Andes. In: Harmon RS & Barreiro BA (eds) Andean magmatism: chemical and isotopic constraints. Shiva Geology Series, pp 31–46Google Scholar
  41. Taddeucci J, Pompolio M, Scarlato P (2004) Conduit processes during the July–August 2001 explosive activity of Mt. Etna (Italy): inferences from glass chemistry and crystal size distribution of ash particles. J Volcanol Geotherm Res 137:33–54 doi: 10.1016/j.jvolgeores.2004.05.011 CrossRefGoogle Scholar
  42. Tepley FJ III, Davidson JP, Tilling RI, Arth JG (2000) Magma mixing, recharge and Eruption Histories Recorded in Plagioclase Phenocrysts from El Chichón Volcano, Mexico. J Petrol 41(9):1397–1411CrossRefGoogle Scholar
  43. Venezky DY, Rutherford MJ (1999) Petrology and Fe-Ti oxide reequilibration of the 1991 Mount Unzen mixed magma. J Volcanol Geotherm Res 89(1–4):213–230 doi: 10.1016/S0377–0273(98)00133–4 CrossRefGoogle Scholar
  44. Wilson M (1989) Igneous Petrogenesis. Kluwer Academic Publishers, Boston, MACrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • David J Kratzmann
    • 1
    • 4
  • Steven Carey
    • 1
    • 4
  • Roberto Scasso
    • 2
  • Jose-Antonio Naranjo
    • 3
  1. 1.GSO/Univ. of Rhode IslandNarragansettUSA
  2. 2.Dpto. de Cs. Geologicas, FCENUniv. de Buenos Aires Cuidad Univ.Buenos AiresArgentina
  3. 3.Serv. Nacional Geol. y MineriaCasillaChile
  4. 4.Graduate School of OceanographyNarragansettUSA

Personalised recommendations