Bulletin of Volcanology

, Volume 54, Issue 6, pp 504–520 | Cite as

A reappraisal of ignimbrite emplacement: progressive aggradation and changes from particulate to non-particulate flow during emplacement of high-grade ignimbrite

  • Michael J Branney
  • Peter Kokelaar
Article

Abstract

We propose a mechanism by which massive ignimbrite and layered ignimbrite sequences — the latter liable to have been previously interpreted as multiple flow units-form by progressive aggradation during sustained passage of a single particulate flow. In the case of high-temperature eruptive products the mechanism simplifies interpretation of problematic deposits that exhibit pronounced vertical and lateral variations in texture, including between non-welded, eutaxitic, rheomorphic (lineated) and lava-like. Agglutination can occur within the basal part of a hot density-stratified flow. During initial incursion of the flow, agglutinate chills and freezes against the ground. During sustained passage of the flow, agglutination continues so that the non-particulate (agglutinate) layer thickens (aggrades) and becomes mobile, susceptible to both gravity-induced motion and traction-shear imparted by the overriding particulate part of the flow. The particulate to non-particulate (P-NP) transition occurs in and just beneath a depositional boundary layer, where disruptive collisions of hot viscous droplets give way, via sticky grain interactions, to fluidal behavior following adhesion. Because they have different rheologies, the particulate and non-particulate flow components travel at different velocities and respond to topography in different ways. This may cause detachment and formation of two independent flows. The P-NP transition is controlled by factors that influence the rheological properties of individual erupted particles (strain rate, temperature, and composition including volatiles), by cooling and volatile exsolution during transport, and by the particle-size population and concentration characteristics of the depositional boundary layer. At any one location along the flow path one or more of these can change through time (unsteady flow). Thus the P-NP transition can develop momentarily or repeatedly during the passage of an unsteady flow, or it can occur continuously during the passage of a quasi-steady flow supplied by a sustained explosive eruption. Vertical facies successions developed in the deposit (high-grade ignimbrite) reflect temporal changes in flow steadiness and in material supplied at source. The P-NP transition is also influenced by factors that affect flow behaviour, such as topography. It may occur at any location laterally between a proximal site of deflation (e.g. a fountain-fed lava) and a flow's distal limit, but it most commonly occurs throughout a considerable length of the flow path. Up-sequence variations in welding-deformation fabric (between oblate uniaxial to triaxial and prolate) reflect evolving characteristics of the depositional boundary layer (e.g. fluctuations from direct suspension-sedimentation to deposition via traction carpets or traction plugs), as well as possible modifications resulting from subsequent, post-depositional hot loading and slumping. Similar processes can also account for lateral lithofacies gradations in conduits and vents filled with welded tuff. Our consideration of high-grade ignimbrites has implications for ignimbrite emplacement in general, and draws attention to the limitations of the widely accepted models of emplacement involving mainly high-concentration non-turbulent transport and en masse ‘freezing’ of high-yield-strength plug flows.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Almond DC (1971) Ignimbrite vents at Sabaloka Cauldron, Sudan. Geol Mag 186:159–176Google Scholar
  2. Baker BH (1976) Geology and geochemistry of the Ol Doinyo Nyokie Trachyte Ignimbrite Vent Complex, South Kenya Rift Valley. Bull Volcanol 39:420–440Google Scholar
  3. Bates RL, Jackson JA (eds) (1980) Glossary of geology. Amer Geol Inst, Falls Church, Virginia, USA, pp 1–175Google Scholar
  4. Bond A, Sparks RSJ (1976) The Minoan eruption of Santorini, Greece. J Geol Soc London 131:1–16Google Scholar
  5. Bonnichsen B (1982) Rhyolite lava-flows in the Bruneau-Jar-bridge eruptive center, southwestern Idaho. In: Bonnichsen B, Breckenridge RM (eds) Cenezoic geology of Idaho. Idaho Bur Mines Geol Bull 26:283–320Google Scholar
  6. Bonnichsen B, Kauffman DF (1987) Physical features of rhyolite lava flows in the Snake River Plain volcanic province, southwestern Idaho. In: Fink JH (ed) The emplacement of silicic domes and lava flows. Geol Soc Am Spec Pap 212:118–145Google Scholar
  7. Branney MJ (1988) Subaerial explosive volcanism, intrusion, sedimentation, and collapse in the Borrowdale Volcanic Group, SW Langdale, English Lake District. Unpubl PhD thesis, Sheffield Uni, UK, p 1–235Google Scholar
  8. Branney MJ, Kokelaar BP, McConnell BJ (1992) The Bad Step Tuff: a lava-like rheomorphic ignimbrite in a calc-alkaline piecemeal caldera, English Lake District. Bull Volcanol 54:187–199Google Scholar
  9. Bristow CM (1962) Kenya ignimbrites. Nature 196:364–365Google Scholar
  10. Buesch DC, Valentine GA (1989) Thickness and flow dynamics as factors controlling welding variations in ignimbrites (abstract). IAVCEI General Assembly on Continental Magmatism, Santa Fe. New Mexico Bur Mines Mineral Resources Bull 131:32Google Scholar
  11. Cas RAF, Wright JV (1987) Volcanic successions: modern and ancient. Allen & Unwin, London, pp. 1–528Google Scholar
  12. Carey SN (1991) Transport and deposition of tephra by pyroclastic flows and surges. In: Fisher RV, Smith GA (eds) Sedimentation in volcanic settings SEPM Spec Publ 45:39–57Google Scholar
  13. Chapin CE, Lowell GR (1979) Primary and secondary flow structures in ash-flow tuffs of the Gribbles Run Palaeovalley, central Colorado. In: Chapin CE, Elston WE (eds) Ash flow tuffs. Geol Soc Amer Spec Pap 180:137–154Google Scholar
  14. Christiansen RL, Lipman PW (1966) Emplacement and thermal history of a rhyolite lava flow near Fortymile Canyon, southern Nevada. Geol Soc Am Bull 77:671–684Google Scholar
  15. Cook EF (ed) (1966) Tufflavas and ignimbrites: a survey of Soviet studies. Elsevier Publishing Co, NY, pp 1–212Google Scholar
  16. Davis N (1989) The relationship between ignimbrite eruption and caldera collapse in the Central Fells, English Lake District. Unpubl PhD thesis, Sheffield Uni, UK, p 1–153Google Scholar
  17. Druitt TH (1992) Emplacement of 18 May 1980, lateral blast ENE of Mount St. Helens, Washington. Bull Volcanol (in press)Google Scholar
  18. Druitt TH, Bacon CR (1986) Lithic breccia and ignimbrite erupted during the collapse of Crater Lake caldera, Oregon. J Volcanol Geotherm Res 25:1–32Google Scholar
  19. Druitt TH, Sparks RSJ (1982) A proximal ignimbrite breccia facies on Santorini, Greece. J Volcanol Geotherm Res 13:147–171Google Scholar
  20. du Bray EA, Pallister JS (1991) An ash flow caldera in cross section: ongoing field and geochemical studies of the Mid-Tertiary Turkey Creek caldera, Chiricahua Mountains, SE Arizona. J Geophys Res 96:13435–13457Google Scholar
  21. Duffield WA (1990) Eruptive fountains of silicic magma and their possible effects on the tin content of fountain-fed lavas, Taylor Creek Rhyolite, New Mexico. In: Stein HJ, Hannah JL (eds) Ore-bearing granite systems: petrogenesis and mineralizing processes: Geol Soc Am Spec Pap 246:251–261Google Scholar
  22. Eichelberger JC, Carrigan CR, Westrich HR, Price RH (1986) Non-explosive silicic volcanism. Nature 323:598–602Google Scholar
  23. Ekren EB, McIntyre DH, Bennet EH (1984) High-temperature large-volume, lavalike ash-flow tuffs without calderas in southwestern Idaho. US Geol Surv Prof Pap 1272:1–76Google Scholar
  24. Ellwood BB (1982) Estimates of flow directions for calc-alkaline welded tuffs and palaeomagnetic data reliability from anisotropy of magnetic susceptibility measurements: Central San Juan Mountains, southwest Colorado. Earth Planet Sci Lett 59:303–314Google Scholar
  25. Elston WE, Smith EI (1970) Determination of flow direction of rhyolitic ash-flow tuffs from fluidal textures. Geol Soc Bull 81:3393–3406Google Scholar
  26. Fink JH, Manley CR (1987) Origin of pumiceous and glassy textures in rhyolite flows and domes. In: Fink JH (ed) The emplacement of silicic domes and lava flows. Geol Soc Am Spec Pap 212:77–88Google Scholar
  27. Fisher RV (1966) Mechanism of deposition from pyroclastic flows. Am J Sci 264:350–363Google Scholar
  28. Fisher RV (1986) Systems of transport and deposition within pyroclastic surges: evidence from Mount St. Helens, Washington. EOS Trans Am Geophys Union 67:1246Google Scholar
  29. Fisher RV (1990) Transport and deposition of a pyroclastic surge across an area of high relief: the 18 May 1980 eruption of Mount St. Helens, Washington. Geol Soc Am Bull 102:1038–1054Google Scholar
  30. Fisher RV, Schmincke H-U (1984) Pyroclastic rocks. Springer-Verlag, Berlin 472 ppGoogle Scholar
  31. Freundt A, Schmincke H-U (1990) The densely welded basaltic ignimbrite P1 on Gran Canaria (Abstract). Abstr IAVCEI Int Volcanol Congr Mainz (FDR), Sept, 1990Google Scholar
  32. Gay NC (1968) Pure shear and simple shear deformation of inhomogeneous viscous fluids. 1. Theory. Tectonophys 5:211–234Google Scholar
  33. Gibson IA (1970) A pantellerite welded ash-flow tuff from the Ethiopian Rift Valley. Contrib Mineral Petrol 28:89–111Google Scholar
  34. Gluckman MJ, Yerushalmi J, Squires AM (1976) Defluidization characteristics of sticky or agglomerating beds. In: Keairns DL (ed) Fluidization Technology vol 2. McGraw-Hill, NY, pp 395–422Google Scholar
  35. Hargrove HR, Denver P-L, Sheridan MF (1984) Welded tuffs deformed into megarheomorphic folds during collapse of the McDermitt caldera, Nevada-Oregon. J Geophys Res 89:8629–8638Google Scholar
  36. Hausback BP (1987) An extensive, hot, vapour-charged rhyodacite flow, Baja California, Mexico. In: Fink JH (ed) The emplacement of silicic domes and lava flows. Geol Soc Am Spec Pap 212:111–118Google Scholar
  37. Hay RL, Hildreth W, Lambe RN (1979) Globule ignimbrite of Mount Suswa, Kenya. In: Chapin CE, Elston WE (eds) Ash flow tuffs. Geol Soc Am Spec Pap 180:167–175Google Scholar
  38. Henry CD, Price GJ, Parker DF, Wolff JA (1989) Mid-Tertiary silicic alkalic magmatism of Trans-Pecos Texas: rheomorphic tuffs and extensive silicic lavas. In: Chapin CE, Zidek J (eds) Field excursions to volcanic terrances in the western United States, Vol 1: Southern Rocky Mountain region. New Mexico Bur Mines Mineral Resources Mem 46:202–230Google Scholar
  39. Henry CD, Price JG, Rubin JN, Laubach SE (1990) Case study of an extensive silicic lava: the Bracks Rhyolite, Trans-Pecos Texas. J Volcanol Geotherm Res 43:113–132Google Scholar
  40. Hildreth W (1981) Gradients in silicic magma chambers: implications for lithospheric magmatism. J Geophys Res 86:10153–10192Google Scholar
  41. Hillhouse JW, Wells RE (1991) Magnetic fabric, flow directions, and source area of the Lower Miocene Peach Springs Tuff in Arizona, California, and Nevada. J Geophys Res 96:12443–12460Google Scholar
  42. Hiscott RN, Middleton GV (1980) Fabric of coarse deep-water sandstones, Tourelle Formation, Quebec, Canada. J Sed Petrol 50:703–721Google Scholar
  43. Holloway JR, Jakobsson S (1986) Volatile solubility in magmas: transport of volatiles to planet surfaces. J Geophys Res 91:505–508Google Scholar
  44. Jaupart C, Allègre CJ (1991) Gas content, eruption rate and instabilities of eruption regime in silicic volcanoes. Earth Planet Sci Lett 102:413–429Google Scholar
  45. Johnson AM (1970) Physical processes in geology. Freeman Cooper, San Francisco, California, pp 1–577Google Scholar
  46. Johnson RW (1968) Volcanic globule rock from Mount Suswa, Kenya. Geol Soc Am Bull 79:647–651Google Scholar
  47. Kamata H, Mimura K (1983) Flow directions inferred from imbrication in the Handa pyroclastic flow deposit in Japan. Bull Volcanol 46:277–282Google Scholar
  48. Knight MD, Walker GPL, Ellwood BB, Diehl JF (1986) Stratigraphy, palaeomagnetism, and magnetic fabric of the Toba Tuffs: constraints on the sources and eruptive styles. J Geophys Res 91:10355–10382Google Scholar
  49. Leat PT (1985) Facies variations in peralkaline ash-flow tuffs from the Kenya Rift Valley. Geol Mag 122:139–150Google Scholar
  50. Lowe DR (1979) Sediment gravity flows: their classification and some problems of application to natural flows and deposits. In: Doyle LJ, Pilkey OH (eds) Geology of continental slopes. SEPM Spec Publ 27:75–82Google Scholar
  51. Lowe DR (1982) Sediment gravity flows: II. Depositional models with special reference to high-density turbidity currents. J Sed Petrol 52:279–297Google Scholar
  52. Lowe DR (1988) Suspended fallout rate as an independent variable in the analysis of current structures. Sedimentol 35:765–776Google Scholar
  53. MacDonald GA (1972) Volcanoes. Prentice-Hall, Englewood Cliffs, NJ, pp 1–510Google Scholar
  54. MacDonald WD, Palmer HC (1990) Flow directions in ash-flow tuffs: a comparison of geological and magnetic susceptibility measurements, Tshirege member (upper Bandelier Tuff), Valles caldera, New Mexico, USA. Bull Volcanol 53:45–59Google Scholar
  55. Mahood GA (1984) Pyroclastic rocks and calderas associated with strongly peralkaline volcanic rocks. J Geophys Res 89:8540–8552Google Scholar
  56. Mahood GA, Hildreth W (1986) Geology of the peralkaline volcano at Pantelleria, Straits of Sicily. Bull Volcanol 48:143–172Google Scholar
  57. Manley CR, Fink JH (1987) Internal textures of rhyolite flows as revealed by research drilling. Geology 15:549–552Google Scholar
  58. Marsella M, Palladino DM, Trigilia R (1987) The Onano pyroclastic Formation (Vulsini Volcanoes): depositional features, distribution and eruptive mechanisms. Per Mineral 56:225–240Google Scholar
  59. McCall GJH (1965) Froth flows in Kenya. Geol Rundsch 54:1148–1195Google Scholar
  60. Mellors RA, Sparks RSJ (1991) Spatter-rich pyroclastic flow deposits on Santorini, Greece. Bull Volcanol 53:327–342Google Scholar
  61. Mimura K (1984) Imbrication, flow direction and possible source areas of the pumice flow tuffs near Bend, Oregon, USA. J Volcanol Geotherm Res 21:45–60Google Scholar
  62. Nemec W (1990) Aspects of sediment movement on steep delta slopes. In: Colella A, Prior DB (eds) Coarse-grained deltas. Spec Publ int Ass Sediment 10:29–73Google Scholar
  63. Noble DC (1968) Laminar viscous flowage structures in ash-flow tuffs from Gran Canaria, Canary Islands: a discussion. J Geol 76:721–723Google Scholar
  64. Orsi G, Sheridan MF (1984) The Green Tuff of Pantelleria: rheoignimbrite or rheomorphic fall? Bull Volcanol 47-3:611–626Google Scholar
  65. Orsi G, Sheridan MF (1986) The Green Tuff of Pantelleria: an example of rheoignimbrite (Abstract). Abstr 1986 IAVCEI Int Volcanol Congr, NZ 67Google Scholar
  66. Orsi G, Ruvo L, Scarpati C (1991) The recent explosive volcanism at Pantelleria. Geol Rundsch 80:187–200Google Scholar
  67. Park KH, Kim SE (1985) Ash-flow tuffs of the Chiselryoung Volcanic Formation and associated welded tuff intrusion, Weolseong District, South Korea. J Korea Inst Mineral Geol 18:357–368Google Scholar
  68. Parkash B, Middleton GV (1970) Downcurrent textural changes in Ordovician Turbidite Greywackes. Sedimentol 14:259–293Google Scholar
  69. Peterson DW (1979) Significance of flattening of pumice fragments in ash-flow tuffs. In: Chapin CE, Elston WE (eds) Ash flow tuffs. Geol Soc Am Spec Pap 180:195–204Google Scholar
  70. Pichler H (1981) Italienische Vulkan-Gebiete III: Lipari, Vulcano, Stromboli, Tyrrenisches Meer. Sammlung Geol Führer 69:pp 1–233Google Scholar
  71. Potter DB, Oberthal CM (1987) Vent sites and flow directions of the Otowi ash-flows (lower Bandelier Tuff), New Mexico. Geol Soc Am Bull 98:66–76Google Scholar
  72. Ragan DH, Sheridan MF (1972) Compaction of the Bishop Tuff, California. Geol Soc Am Bull 83:95–106Google Scholar
  73. Reedman AJ, Park KH, Merriman RJ, Kim SE (1987a) Welded tuff infilling a volcanic vent at Weolseong, Republic of Korea. Bull Volcanol 49:541–546Google Scholar
  74. Reedman AJ, Howells MF, Orton G, Campbell SDG (1987b) The Pitts Head Tuff Formation: a subaerial to submarine welded ash-flow tuff of Ordivician age, North Wales. Geol J 124:427–439Google Scholar
  75. Rees AL, Woodall WA (1975) The magnetic fabric of some laboratory-deposited sediments. Earth Planet Sci Lett 25:121–130Google Scholar
  76. Riehle JR (1973) Calculated compaction profiles of rhyolitic ash-flow tuffs, Geol Soc Am Bull 84:2193–2216Google Scholar
  77. Ross CS, Smith RL (1961) Ash-flow tuffs, their origin, geological relations and identification. US Geol Surv Prof Pap 366:1–77Google Scholar
  78. Ryan MP, Blevins JYK (1987) The viscocity of synthetic and natural silicate melts and glasses at high temperature and 1 Bar (105 Pascals) pressure and at higher pressures. US Geol Surv Bull 1764Google Scholar
  79. Schmincke H-U (1969) Ignimbrite sequence on Gran Canaria. Bull Volcanol 35:1199–1219Google Scholar
  80. Schmincke H-U (1972) Froth blows and globule flows in Kenya. Naturwissensch 11:1–2Google Scholar
  81. Schmincke H-U (1974) Volcanological aspects of peralkaline silicic welded ash-flow tuffs. Bull Volcanol 38:594–636Google Scholar
  82. Schmincke H-U, with contributions by Freundt A, Ferriz H, Kobberger G, Leat P (1990) Geological field guide Gran Canaria 1-202. Pluto Press, Witten FRGGoogle Scholar
  83. Schmincke H-U, Swanson DA (1967) Laminar viscous flowage structures in ash-flow tuffs from Gran Canaria, Canary Islands. J Geol 75:641–664Google Scholar
  84. Scott SC (1980) The geology of Longenot volcano, Central Kenya: a question of volumes. Phil Trans R Soc London Ser A 296:437–465Google Scholar
  85. Seaman SJ, McIntosh WC, Geissman JW, Williams ML, Elston WE (1991) Magnetic fabrics of the Bloodgood Canyon and Shelley Peak Tuffs, southwestern New Mexico: implications for emplacement and alteration process. Bull Volcanol 53:460–476Google Scholar
  86. Self S, Lipman PW (1989) Large ignimbrites and caldera-forming eruptions. Handbook of the IAVCEI Working Group on Explosive Volcanism Field Workshop (11 WA) in Jemez Mountains, New Mexico, and San Juan Mountains, Colorado. 134 ppGoogle Scholar
  87. Shaw HR (1963) Obsidian-H2O viscosities at 1000 and 2000 bars in the temperature range 700° to 900° C. J Geophys Res 68:6337–6343Google Scholar
  88. Sheridan MF (1979) Emplacement of pyroclastic flows: a review. In: Chapin CE, Elston WE (eds) Ash-flow tuffs. Geol Soc Am Spec Pap 180:125–136Google Scholar
  89. Simpson C, Schmid SM (1983) An evaluation of criteria to deduce the sence of movement in sheared rocks. Geol Soc Am Bull 94:1281–1288Google Scholar
  90. Smith RL (1960) Zones and zonal variations in welded ash-flows. US Geol Surv Prof Pap 354-F:149–159Google Scholar
  91. Sparks RSJ (1976) Grain size variations in ignimbrites and implications for the transport of pyroclastic flows. Sedimentol 23:147–188Google Scholar
  92. Sparks RSJ, Wright JV (1979) Welded air-fall tuff. In: Chapin CE, Elston WE (eds) Ash flow tuffs. Geol Soc Am Spec Pap 180:155–166Google Scholar
  93. Sparks RSJ, Francis PW, Hamer RD, Pankhurst RJ, O'Callaghan LO, Thorpe RS, Page R (1985) Ignimbrites of the Cerro Galan Caldera, NW Argentina. J Volcanol Geotherm Res 24:205–248Google Scholar
  94. Sparks RSJ, Wilson L, Hulme G (1978) Theoretical modelling of the generation, movement and emplacement of pyroclastic flows by column collapse. Geophys Res 83:1727–1739Google Scholar
  95. Suzuki K, Ui T (1982) Grain orientation and depositional ramps as flow direction indicators of large-scale pyroclastic flow deposits in Japan. Geology 10:429–432Google Scholar
  96. Tiara A, Scholle PA (1979) Deposition of resedimented sandstone beds in the Pico Formation, Ventura basin, California, as interpreted from magnetic fabrics measurements. Geol Soc Am Bull 90:952–962Google Scholar
  97. Trigilia R, Walker GPL (1986) The Onano Spatter Flow, Italy: evidence for a new ignimbrite depositional mechanism. Abstr Int Volcanol Congr NZ 1986Google Scholar
  98. Ui T, Suzuki-Kamata K, Matsusue R, Fujita K, Metsugi H, Araki M (1989) Flow behaviour of large-scale pyroclastic flows-evidence obtained from petrofabric analysis. Bull Volcanol 51:115–122Google Scholar
  99. Valentine GA (1987) Stratified flow in pyroclastic surges. Bull Volcanol 49:616–630Google Scholar
  100. Valentine GA, Buesch DC, Fisher RV (1989) Basal layered deposits of the Peach Springs Tuff, northwest Arizona, USA. Bull Volcanol 51:395–414Google Scholar
  101. Vernon RH (1987) A microstructural indicator of shear sense in volcanic rocks and its relationship to porphyroblast rotation in metamorphic rocks. J Geol 95:127–134Google Scholar
  102. Villari L (1969) On particular ignimbrites of the island of Pantelleria (Channel of Sicily). Bull Volcanol 33:828–839Google Scholar
  103. Villari L (1974) The island of Pantelleria. Bull Volcanol 38:680–724Google Scholar
  104. Walker GPL (1983) Ignimbrite types and ignimbrite problems. J Volcanol Geotherm Res 17:65–88Google Scholar
  105. Walker GPL, Croasdale R (1972) Characteristics of some basaltic pyroclastics. Bull Volcanol 35:303–317Google Scholar
  106. Walker GPL, Hemming RF, Wilson CJN (1980) Low aspect-ratio ignimbrites. Nature 283:286–287Google Scholar
  107. Walker GPL, Wilson CJN, Froggatt PC (1981) An ignimbrite veneer deposit: the trail marker of a pyroclastic flow. J Volcanol Geotherm Res 8:409–421Google Scholar
  108. Walker GW, Swanson DA (1968) Laminar flowage in a Pliocene soda rhyolite ashflow tuff, Lake and Harney counties, Oregon. US Geol Surv Prof Pap 600-B:37–47Google Scholar
  109. Wilson CJN (1980) The role of fluidization in the emplacement of pyroclastic flows: an experimental approach. J Volcanol Geotherm Res 8:231–249Google Scholar
  110. Wilson CJN (1985) The Taupo eruption, New Zealand. II The Taupo ignimbrite. Phil Trans R Soc Lond 314:229–310Google Scholar
  111. Wilson CJN (1986) Pyroclastic flows and ignimbrites. Sci Prog Oxf 70:172–201Google Scholar
  112. Wilson L, Head JW (1981) Morphology and rheology of pyroclastic flows and their deposits, and guidelines for future observations. In: Lipman PW, Mullineaux DR (eds) The 1980 eruptions of Mount St. Helens, Washington. US Geol Surv Prof Pap 1250:513–524Google Scholar
  113. Wilson L, Huang TC (1979) The influence of shape on the atmosphere settling velocity of volcanic ash particles. Earth Planet Sci Lett 44:311–324Google Scholar
  114. Wolff JA (1986) Welded tuff dykes, conduit closure, and lava dome growth at the end of explosive eruptions. J Volcanol Geotherm Res 28:379–384Google Scholar
  115. Wolff JA, Wright JV (1981) Rheomorphism of welded tuffs. J Volcanol Geotherm Res 10:13–34Google Scholar
  116. Wolff JA, Ellwood BB, Sachs SD (1989) Anisotropy of magnetic susceptibility in welded tuffs: application to a welded-tuff dyke in the Tertiary Trans-Pecos Texas volcanic province, USA. Bull Volcanol 51:299–310Google Scholar
  117. Wright JV, Walker GPL (1981) Eruption, transport and deposition of ignimbrite: a case study from Mexico. J Volcanol Geotherm Res 9:111–131Google Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • Michael J Branney
    • 1
  • Peter Kokelaar
    • 1
  1. 1.Department of Earth SciencesUniversity of LiverpoolLiverpoolUK

Personalised recommendations