Skip to main content
SpringerLink
Log in

The Bad Step Tuff: a lava-like rheomorphic ignimbrite in a calc-alkaline piecemeal caldera, English Lake District

  • Published:
Bulletin of Volcanology Aims and scope Submit manuscript

Abstract

Lava-like tuffs are lithologically indistinguishable from lavas, and form part of a temperature-and composition-controlled continuum from low-grade tuffs (which are non-welded or slightly welded), through high-grade (densely welded) tuffs, extremely high-grade tuffs (which may be agglutinated right to their upper and lower contacts), to spatter-fed lava flows. In some high-grade tuffs, a component of nonparticulate flow may postdate emplacement and deposition, but in extremely high-grade tuffs non-particulate deformation normally occurs during emplacement and deposition. In such cases, syn-depositional non-particulate deformation (previously called ‘primary welding’) and non-particulate slumping (previously called ‘secondary flowage’) processes overlap and are continuous, one into the other, so that distinction between them and their resultant structures is unrealistic and inapplicable. Therefore the term ‘rheomorphism’ should be used to embrace all types of non-particulate flow. The Bad Step Tuff is the most lava-like of a sequence of rheomorphic calc-alkaline rhyolitic ignimbrites emplaced during a climactic caldera-forming eruption episode in the English Lake District. It is a ponded sheet, 40 to ≥400 m thick, which comprises a basal crudely stratified heterolithic breccia, a thick flow-laminated and locally vesicular central part, which beomes increasingly flow-folded upwards, and an upper autobreccia. Despite an absence of vitroclastic textures within the main laminated part, field relations show it to be a tuff. Diagnostic criteria are (1) a gradation, within a lithophysal zone, from unambiguous vitroclastic matrix of the basal lithic breccia upwards into the central flow-laminated tuff; (2) only rate autobreccia at the base of the sheet but ubiquitous autobreccia at the top of the sheet; and (3) close textural similarity with localized, intensely rheomorphic parts of associated ignimbrites that widely display unequivocal vitroclastic textures where their rheomorphism is less marked. The extremely high-grade character of the Bad Step Tuff may reflect its proximal setting in a piecemeal-type caldera. High emplacement temperatures resulted from high-rate but low-velocity vent emission from fissures along numerous cross-cutting calderafloor faults, producing very low ‘boil over’ eruption columns and proximal ponding.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Bonnichsen B, Kauffman DF (1987) Physical features of rhyolite lava flows in the Snake River Plain volcanic province, southwestern Idaho. In: Fink JH The emplacement of silicic domes and lava flows. Geol Soc Am Spec Pap 212:119–145

  • Branney MJ (1988a) The subaerial setting of the Borrowdale Volcanic Group, English Lake District. J Geol Soc London 145:887–890

    Google Scholar 

  • Branney MJ (1988b) Subaerial explosive volcanism, intrusion, sedimentation, and collapse in the Borrowdale Volcanic Group, SW Langdale, English Lake District. Unpublished Ph D thesis, University of Sheffield, UK

  • Branney MJ (1991) The eruption and depositional facies of the Whorneyside Tuff Formation, English Lake District: an exceptionally large-magnitude phreatoplinian eruption. Bull Geol Soc Am 103:886–897

    Google Scholar 

  • Branney MJ, Kokelaar BP (1992a) Soft-state deformation and rheomorphism induced by piecemeal volcanotectonic subsidence: Borrowdale Volcanic Group, English Lake District. Bull Volcanol (submitted)

  • Branney MJ, Kokelaar BP (1992b) A reappraisal of ignimbrite emplacement: particulate to non-particulate flow transitions during progressive aggradation of high-grade ignimbrite. Bull Volcanol 54 (in press)

  • Branney MJ, Soper NJ (1988) Ordovician volcano-tectonics in the English Lake District. J Geol Soc London 145:367–376

    Google Scholar 

  • Cas RAF, Wright JV (1987) Volcanic successions: modern and ancient. Allen and Unwin, London, 528 pp

    Google Scholar 

  • 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 Am Spec Pap 180:137–154

  • Christiansen RL, Lipman PW (1966) Emplacement and thermal history of a rhyolite lava flow near Fortymile Canyon, southern Nevada. Geol Soc Am Bull 77:671–684

    Google Scholar 

  • Davis N (1989) The relationship between ignimbrite eruption and caldera collapse in the Borrowdale Volcanic Group of the Central Fells, English Lake District. Unpublished Ph D thesis, University of Sheffield, UK

  • Druitt TH (1985) Vent evolution and lag breccia formation during the Cape Riva Eruption of Santorini, Greece. J Geol 93:439–454

    Google Scholar 

  • Duffield WA (1989) Field guide to the Taylor Creek Rhyolite, Black Range, New Mexico. In: Chapin CE, Zideck J Field excursions to volcanic terranes in the western United States, Volume 1: Southern Rocky Mountain region. NM Bur Mines Miner Res Mem 46:107–110

    Google Scholar 

  • 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 1272:1–76

    Google Scholar 

  • Eichelberger JC, Carrigan CR, Westrich HR, Price RH (1986) Non-explosive silicic volcanism. Nature 323:598–602

    Google Scholar 

  • Ewart A (1979) A review of the mineralogy and chemistry of Tertiary — Recent dacitic, latitic, rhyolitic and related salic volcanic rocks. In: Barker F (ed) Trondhjemites, dacites and related rocks. Elsevier, Amsterdam, pp 13–121

    Google Scholar 

  • Felsche J (1969) Yttrium and Lanthanides: crystal chemistry. In: Wedepohl KH (ed). Handbook of geochemistry. Springer, Berlin Heidelberg New York, pp 39, 57–71/A1–42

    Google Scholar 

  • 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 212:77–88

  • Firman RJ, Lee MK (1986) Age and structure of the concealed English Lake District Batholith and its probable influence on subsequent sedimentation, tectonics, and mineralization. Geology and the real world — the Kingsley Dunham volume. Inst Min Metal, UK pp 117–127

    Google Scholar 

  • Fitton JG (1972) The petrogenesis of the calc-alkaline Borrowdale Volcanic Group, Northern England. Unpublished Ph D thesis, University of Durham, UK

  • Fitton JG, Thirlwall MF, Hughes DJ (1982) Volcanism in the Caledonian belt of Britain. In: Thorpe RS (ed) Andesite: orogenic andesites and related rocks. Wiley, Chichester, UK, pp 611–636

    Google Scholar 

  • Hartley JJ (1932) The volcanic and other igneous rocks of Great and Little Langdale. Proc Geol Assoc 43:32–69

    Google Scholar 

  • 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 212:111–118

  • 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 terranes in the western United States, Volume 1: Southern Rocky Mountain region. NM Bur Mines Miner Res Mem 46:202–230

  • Hutton DHW (1987) Strike-slip terranes and a model for the evolution of the British and Irish Caledonides. Geol Mag 124:405–425

    Google Scholar 

  • Leat PT, Jackson SE, Thorpe RS, Stillman CJ (1986) Geochemistry of bimodal basalt — subalkaline/peralkaline rhyolite provinces within the Southern British Caledonides. J Geol Soc London 143:259–276

    Google Scholar 

  • Lipman PW (1976) Caldera-collapse breccias in the western San Juan Mountains, Colorado. Geol Soc Am Bull 87:1397–1410

    Google Scholar 

  • Lipman PW (1984) Roots of ash-flow calderas in western North America: windows into the tops of granitic batholiths. J Geophys Res 89:B10, 8801–8841

    Google Scholar 

  • Mahood GA (1984) Pyroclastic rocks and calderas associated with strongly peralkaline volcanic rocks. J Geophys Res 89:8540–8552

    Google Scholar 

  • Manley CR, Fink JH (1987) Internal textures of rhyolite flows as revealed by research drilling. Geology 15:549–552

    Google Scholar 

  • Mathieson (1986) Geology, structure and geochemistry of the Ordovician Succession in SW Cumbria. Unpublished Ph D thesis, University of Sheffield, UK, pp 1–141

  • McConnell BJ, Stillman C, Hertogen J (1991) An Ordovician basalt to peralkaline rhyolite fractionation series from Avoca, Ireland. J Geol Soc London 148:711–718

    Google Scholar 

  • Millward D (1976) Petrology, structure and geochemistry of the Ordovician volcanics of the English Lake District. Unpublished Ph D thesis, University of Birmingham, UK

  • Moseley F, Millward D (1982) Ordovician volcanicity in the English Lake District. In: Sutherland DS (ed) Igneous rocks of the British Isles. Wiley, Chichester, UK pp 93–111

    Google Scholar 

  • Oliver RL (1961) The Borrowdale Volcanic and associated rocks of the Scafell area, English Lake District. Q J Geol Soc London 117:377–417

    Google Scholar 

  • Pearce JA (1980) Geochemical evidence for the genesis and eruptive setting of lavas from Tethyan ophiolites. Proc Int Ophiol Symp Nicosia, Cyprus 261–272

  • Pichler H (1981) Italienische Vulkan-Gebiete III: Lipari, Vulcano, Stromboli, Tyrrenisches Meer. Samml Geol Führer 69:233

    Google Scholar 

  • Reedman AJ, Park KH, Merriman RJ, Kim SE (1987) Welded tuff infilling a volcanic vent at Weolseong, Republic of Korea. Bull Volcanol 49:541–546

    Google Scholar 

  • Ringwood AE (1977) Petrogenesis in island-arc systems. In: Talwani M, Pitman WC III (eds) Island-arcs, deep sea trenches and back-arc basins. Maurice Ewing Series 1, American Geophysical Union, Washington DC, 355–365

    Google Scholar 

  • Schmincke H-U (1974) Volcanological aspects of peralkaline silicic welded ash-flow tuffs. Bull Volcanol 38:594–636

    Google Scholar 

  • Schmincke H-U, Swanson DA (1967) Laminar viscous flowage structures in ash-flow tuffs from Gran Canaria, Canary Islands. J Geol 75:641–664

    CAS  Google Scholar 

  • Sparks RSJ (1976) Grain size variations in ignimbrites and implications for the transport of pyroclastic flows. Sedimentology 23:147–188

    Google Scholar 

  • Walker GPL (1983) Ignimbrite types and ignimbrite problems. J Volcanol Geothermal Res 17:65–88

    Google Scholar 

  • Walker GPL (1985) Origin of coarse lithic breccias near ignimbrite source vents. J Volcanol Geothermal Res 25:157–171

    Google Scholar 

  • Walker GW, Swanson DA (1968) Laminar flowage in a Pliocene soda rhyolite ash-flow tuff, Lake and Harney counties, Oregon. US Geol Surv Prof Pap 600-B:37–47

    Google Scholar 

  • Wolff JA, Wright JV (1981) Rheomorphism of welded tuffs. J Volcanol Geothermal Res 10:13–34

    Google Scholar 

  • 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 51:299–310

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Earth Sciences, The University of Liverpool, Brownlow Street, PO Box 147, L69 3BX, Liverpool, UK

    Michael J Branney, B Peter Kokelaar & Brian J McConnell

Authors
  1. Michael J Branney
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. B Peter Kokelaar
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Brian J McConnell
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Branney, M.J., Kokelaar, B.P. & McConnell, B.J. The Bad Step Tuff: a lava-like rheomorphic ignimbrite in a calc-alkaline piecemeal caldera, English Lake District. Bull Volcanol 54, 187–199 (1992). https://doi.org/10.1007/BF00278388

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00278388

Keywords

Search

Navigation