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Bulletin of Volcanology

, Volume 74, Issue 10, pp 2363–2381 | Cite as

Transitions between fall phases and pyroclastic density currents during the AD 79 eruption at Vesuvius: building a transient conduit model from the textural and volatile record

  • Thomas SheaEmail author
  • Lucia Gurioli
  • Bruce F. Houghton
Research Article

Abstract

The magmatic phase of the AD 79 eruption of Vesuvius produced alternations of fall and pyroclastic density current (PDC) deposits. A previous investigation demonstrated that the formation of several PDCs was linked with abrupt increases in the proportion of denser juvenile clasts within the eruptive column. Under the premise that juvenile clast density is controlled by vesiculation processes within the conduit, we investigate the processes responsible for these variations at or close to fragmentation levels. Pumice textures (vesicle sizes, numbers, and connectivity combined with crystal textures) from the AD 79 PDC deposits are compared to those from interbedded fall samples. Both PDC and fall deposits preserve textures that represent a full spectrum of degassing and outgassing processes, from bubble nucleation to collapse. Combining the textural and volatile (groundmass H2O) data, we derive a conduit model that satisfies all the textural and physical observations made for this phase of the eruption: lateral vesicularity/density stratifications are produced by maturing of bubble textures with superimposed localized shearing of bubble-rich magmas, which enhance outgassing of H2O. The incorporation of denser slower-moving magma from the conduit margins (“lateral magma density gradient”) is likely to be responsible for the higher abundances of dense juvenile pumice that triggered partial column collapses. We also illustrate how variations in the fragmentation depth (tapping a “vertical magma density gradient”) can be responsible for variations in erupted clast density distributions, and potentially in the extent of degassing/outgassing.

Keywords

Vesuvius Pumice density Vesicle and crystal textures Volatiles in glass Strain localization 

Notes

Acknowledgments

The authors acknowledge NSF grant EAR-0537950. We thank Thomas Giachetti and Cyrille Galven for their help with He-pycnometer measurements. We thank Raffello Cioni, Kathy Cashman, Julia Hammer, Tim Druitt, Sarah Fagents, and John Allen for informal comments and discussions. Alain Burgisser, an anonymous reviewer and Jim Gardner are acknowledged for their constructive formal reviews. This is Laboratory of Excellence ClerVolc contribution n°38.

Supplementary material

445_2012_668_MOESM1_ESM.doc (60 kb)
ESM 1 (DOC 59 kb)

References

  1. Adams NK, Houghton BF, Fagents SA, Hildreth W (2006) The transition from explosive to effusive eruptive regime: the example of the 1912 Novarupta eruption. Alaska Geol Soc Am Bull 118:620–634CrossRefGoogle Scholar
  2. Balcone-Boissard H, Boudon G, Villemant B (2011) Textural and geochemical constraints on eruptive style of the 79 AD eruption at Vesuvius. Bull Volcanol 73:279–294CrossRefGoogle Scholar
  3. Barberi F, Cioni R, Rosi M, Santacroce R, Sbrana A, Vecci R (1989) Magmatic and phreatomagmatic phases in explosive eruptions of Vesuvius as deduced by grain-size and compositional analysis of pyroclastic deposits. J Volcanol Geotherm Res 38:287–307CrossRefGoogle Scholar
  4. Blower JD, Keating JP, Mader HM, Phillips JC (2002) The evolution of bubble size distributions in volcanic eruptions. J Volcanol Geotherm Res 120:1–23CrossRefGoogle Scholar
  5. Burgisser A, Gardner JE (2005) Experimental constraints on degassing and permeability in volcanic conduit flow. Bull Volcanol 67:42–56CrossRefGoogle Scholar
  6. Burgisser A, Arbaret L, Druitt TH, Giachetti T (2011) Pre-explosive conduit conditions of the 1997 Vulcanian explosions at Soufrière Hills Volcano, Montserrat: II. depth and overpressure distributions. J Volcanol Geotherm Res 199:193–205Google Scholar
  7. Carey S, Sigurdsson H (1987) Temporal variations in column height and magma discharge rate during the 79 A.D. eruption of Vesuvius. Geol Soc Am Bull 99:303–314CrossRefGoogle Scholar
  8. Cioni R (2000) Volatile content and degassing processes in the 79 AD magma chamber at Vesuvius (Italy). Contrib Mineral Petrol 140:40–54CrossRefGoogle Scholar
  9. Cioni R, Marianelli P, Sbrana A (1992) Dynamics of the AD 79 eruption: stratigraphic, sedimentological and geochemical data on the successions from the Somma-Vesuvius southern and eastern sectors. Acta Vulcanol 2:109–123Google Scholar
  10. Cioni R, Civetta L, Marianelli P, Metrich N, Santacroce R, Sbrana A (1995) Compositional layering and syn-eruptive mixing of periodically refilled shallow magma chamber: the A.D. 79 Plinian eruption of Vesuvius. J Petrol 36:739–776CrossRefGoogle Scholar
  11. Cioni R, Gurioli L, Lanza R, Zanella E (2004) Temperatures of A.D. 79 pyroclastic density currents deposits (Vesuvius, Italy). J Geophys Res 109:B02207CrossRefGoogle Scholar
  12. Clarke AB, Stephens S, Teasdale R, Sparks RSJ, Diller K (2007) Petrologic constraints on the decompression history of magma prior to Vulcanian explosions at the Soufriere Hills volcano, Montserrat. J Volcanol Geotherm Res 161:261–274CrossRefGoogle Scholar
  13. Di Muro A, Villemant B, Montagnac G, Scaillet B, Reynard (2006) Quantification of water content and speciation in natural silicic glasses (phonolite, dacite, rhyolite) by confocal microRaman spectrometry. Geochim Cosmochim Acta 70:2868–2884CrossRefGoogle Scholar
  14. Formenti Y, Druitt TH (2003) Vesicle connectivity in pyroclasts and implications for the fluidization of fountain-collapse pyroclastic flows, Montserrat (West Indies). Earth Planet Sci Lett 214:561–574CrossRefGoogle Scholar
  15. Gaonac’h H, Lovejoy S, Stix J, Scherzter D (1996) A scaling growth model for bubbles in basaltic lava flows. Earth Planet Sci Lett 139:395–409CrossRefGoogle Scholar
  16. Gardner JE (2012) Surface tension and bubble nucleation in phonolitic magmas. Geochim Cosmochim Acta 76:93–102CrossRefGoogle Scholar
  17. Gardner JE, Hilton M, Carroll MR (1999) Experimental constraints on degassing of magma: isothermal bubble growth during continuous decompression from high pressure. Earth Planet Sci Lett 168:201–218CrossRefGoogle Scholar
  18. Giachetti T, Druitt TH, Burgisser A, Arbaret L, Galven C (2010) Bubble nucleation, growth and coalescence during the 1997 Vulcanian explosions of Soufriere Hills Volcano, Montserrat. J Volcanol Geotherm Res 193:215–231CrossRefGoogle Scholar
  19. Gonnermann HM, Manga M (2007) The fluid mechanics inside a volcano. Ann Rev Fluid Mech 39:321–356CrossRefGoogle Scholar
  20. Gurioli L, Cioni R, Sbrana A, Zanella E (2002) Transport and deposition from pyroclastic flows over densely inhabited areas: Ercolano, Italy. Sedimentology 46:1–26Google Scholar
  21. Gurioli L, Houghton BF, Cashman KV, Cioni R (2005) Complex changes in eruption dynamics during the 79 AD eruption of Vesuvius. Bull Volcanol 67:144–159CrossRefGoogle Scholar
  22. Hale AJ, Mühlhaus H-B (2007) Modelling shear bands in a volcanic conduit: Implications for over-pressures and extrusion rates. Earth Planet Sci Lett 263:74–87CrossRefGoogle Scholar
  23. Houghton BF, Wilson CJN (1989) A vesicularity index for pyroclastic deposits. Bull Volcanol 51:451–462CrossRefGoogle Scholar
  24. Houghton BF, Carey RJ, Cashman KV, Wilson CJN, Hobden BJ, Hammer JE (2010) Diverse patterns of ascent, degassing, and eruption of rhyolite magma during the 1.8 ka Taupo eruption, New Zealand: evidence from clast vesicularity. J Volcanol Geotherm Res 195:31–47CrossRefGoogle Scholar
  25. Hurwitz S, Navon O (1994) Bubble nucleation in rhyolitic melts: Experiments at high pressure, temperature, and water content. Earth Planet Sci Lett 122:267–280CrossRefGoogle Scholar
  26. Klug C, Cashman KV (1996) Permeability development in vesiculating magmas: implications for fragmentation. Bull Volcanol 58:87–100CrossRefGoogle Scholar
  27. Klug C, Cashman KV, Bacon CR (2002) Structure and physical characteristics of pumice from the climactic eruption of Mt. Mazama (Crater Lake), Oregon. Bull Volcanol 64:486–501CrossRefGoogle Scholar
  28. Larsen JF (2008) Heterogeneous bubble nucleation and disequilibrium H2O exsolution in Vesuvius K-phonolite melts. J Volcanol Geotherm Res 275:278–288CrossRefGoogle Scholar
  29. Le Losq Ch, Neuville DR, Moretti R, Roux J (2012) Water quantification and speciation in silicate melt using Raman spectroscopy. Am Mineral 97:779–790Google Scholar
  30. Lirer L, Pescatore T, Booth B, Walker GPL (1973) Two Plinian pumice-fall deposits from Somma-Vesuvius, Italy. Geol Soc Am Bull 84:759–772CrossRefGoogle Scholar
  31. Martí J, Soriano C, Dingwell DB (1999) Tube pumices as strain markers of the ductile-brittle transition during magma fragmentation. Nature 402:650–653CrossRefGoogle Scholar
  32. Mastin LG (2005) The controlling effect of viscous dissipation on magma flow in silicic conduits. J Volcanol Geotherm Res 143:17–28CrossRefGoogle Scholar
  33. Papale P (1999) Strain-induced magma fragmentation in explosive eruptions. Nature 397:425–428CrossRefGoogle Scholar
  34. Polacci M, Papale P, Rosi M (2001) Textural heterogeneities in pumices from the climactic eruption of Mount Pinatubo, 15 June 1991, and implication for magma ascent dynamics. Bull Volcanol 63:83–97CrossRefGoogle Scholar
  35. Polacci M, Pioli L, Rosi M (2003) The Plinian phase of the Campanian Ignimbrite eruption (Phlegrean Fields, Italy): evidence from density measurements and textural characterization of pumice. Bull Volcanol 65:418–432CrossRefGoogle Scholar
  36. Rust AC, Cashman KV (2004) Permeability and degassing of vesicular silicic magma. Earth Planet Sci Lett 228:93–107CrossRefGoogle Scholar
  37. Sable JE, Houghton BF, Wilson CJN, Carey RJ (2006) Complex proximal geometry of fall deposits from the Tarawera 1886 basaltic Plinian eruption: implications for eruption dynamics. Bull Volcanol 69:89–103Google Scholar
  38. Shea T, Larsen JF, Gurioli L, Hammer JE, Houghton BF, Cioni R (2009) Leucite crystals: surviving witnesses of magmatic processes preceding the 79 AD eruption at Vesuvius, Italy. Earth Planet Sci Lett 281:88–98CrossRefGoogle Scholar
  39. Shea T, Houghton BF, Gurioli L, Cashman KV, Hammer JE, Hobden B (2010a) Textural studies of vesicles in volcanic rocks: an integrated methodology. J Volcanol Geotherm Res 190:271–289CrossRefGoogle Scholar
  40. Shea T, Gurioli L, Larsen JF, Houghton BF, Hammer JE, Cashman KV (2010b) Linking experimental and natural vesicle textures in Vesuvius 79 AD white pumice. J Volcanol Geotherm Res 192:69–84CrossRefGoogle Scholar
  41. Shea T, Gurioli L, Houghton BF, Cashman KV, Cioni R (2011) Column collapse and generation of pyroclastic density currents during the A.D. 79 eruption of Vesuvius: the role of pyroclast density. Geology 39:695–698CrossRefGoogle Scholar
  42. Sigurdsson H, Cashdollar S, Sparks RSJ (1982) The eruption of Vesuvius in AD 79: reconstruction from historical and volcanological evidence. Am J Archaeo 86:39–51CrossRefGoogle Scholar
  43. Sigurdsson H, Carey S, Cornell W, Pescatore T (1985) The eruption of Vesuvius in A.D. 79. Natl Geogr Res 1:332–387Google Scholar
  44. Sparks RSJ, Murphy MD, Lejeune AM, Watts RB, Barclay J, Young SR (2000) Control on the emplacement of the andesite lava dome of the Soufriere Hills volcano, Montserrat by degassing-induced crystallization. Terra Nova 12:14–20CrossRefGoogle Scholar
  45. Thomas R (2000) Determination of water contents of granite melt inclusions by confocal laser Raman microprobe spectroscopy. Am Mineral 85:868–872Google Scholar
  46. Toramaru A (2006) BND (bubble number density) decompression rate meter for explosive volcanic eruptions. J Volcanol Geotherm Res 154:303–316CrossRefGoogle Scholar
  47. Wright HMN, Weinberg RF (2009) Strain localization in vesicular magmas: Implications for rheology and fragmentation. Geology 37:1023–1026CrossRefGoogle Scholar
  48. Wright HMN, Roberts JJ, Cashman KV (2006) Permeability of anisotropic tube pumice: model calculations and measurements. Geophys Res Lett 33:L17316CrossRefGoogle Scholar
  49. Zhang Y (1999) A criterion for the fragmentation of bubbly magma based on brittle failure theory. Nature 402:648–650CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Thomas Shea
    • 1
    Email author
  • Lucia Gurioli
    • 2
    • 3
    • 4
  • Bruce F. Houghton
    • 1
  1. 1.Department of Geology and Geophysics, SOESTUniversity of HawaiiHonoluluUSA
  2. 2.Clermont UniversitéUniversité Blaise Pascal, Laboratoire Magmas et VolcansClermont-FerrandFrance
  3. 3.CNRS, UMR 6524, LMVClermont-FerrandFrance
  4. 4.IRD, R 163, LMVClermont-FerrandFrance

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