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Physical Volcanology

Christoph Breitkreuz, TU Bergakademie Freiberg

Structure:– Introduction– Reology and deformation of magma and lava– Eruption processes and types– Volcano forms– Emplacement of lava flows, domes and subvolcanic bodies– Pyroclastic fragmentation– Pyroclasts: Types and classification– Pyroclastic transport und deposition– Subaquatic and phreatomagmatic processes and resulting textures– Cooling textures in SiO2-rich (sub-)volcanic bodies– Volcanic hazards: Assessment and monitoring

exercises: Fridays 7:30 – 9:00h,

GP Osteifel: 20.6.-22.6.08Test 4.7.08

Recommended literatureBRANNEY, M. & KOKELAAR, P. (2002): Pyroclastic density flows and the sedimentation of

ignimbrites.- Geol. Soc. London, Mem., 27, 143 pp.CAS, R.A.F. & WRIGHT, J.V. (1987): Volcanic successions - Modern and ancient.-

Allen & Unwin, London, 528S.CHAPIN, C. E. and ELSTON, W. E. (eds.)(1979): Ash-flow tuffs.- Geol. Soc. Amer.

Spec. Pap. 180, 211S.CHESTER, D.K., DUNCAN, A.M., GUEST, J.E. & KILBURN, C.R.J. (1985): Mount

Etna: Anatomy of a volcano.- Chapman and Hall, London, 404S.DRUITT, T.H. (1999): Santorini volcano.- Geol. Soc. London, Mem. 19, 165 pp.DRUITT, T.H. & KOKELAAR, B.P. (eds.)(2002): The eruption of Soufrière Hills

Volcano, Montserrat, from 1995 to 1999.- Geol. Soc. Mem. 21, 645S.FISHER, R.V. & SCHMINCKE, H.-U. (1984): Pyroclastic rocks.- Springer-Verlag,

Berlin, 472S.FISHER, R.V. and SMITH, G.A. (eds.)(1991): Sedimentation in volcanic settings.-

Soc. Econ. Paleont. Mineral., Vol. 45.FRANCIS, P. (1993): Volcanoes - A planetary perspective.- Oxford Univ. Press,

Oxford, 1-443.FREUNDT, A. & ROSI, M. (Hrsg.)(1998): From magma to tephra – modelling

physical processes of explosive volcanic eruptions.- Developments in Volcanol. 4,Elsevier, 318S.

GIFKINS, C. , HERRMANN, W. & LARGE, R. (2005): Altered Volcanic Rocks: Aguide to description and interpretation.- Univ. Tasmania, Centre for Ore Depositsand Exploration Studies, Hobart, 275S.

LATTER, J. (ed.)(1989): Volcanic hazards.- Springer, 625S.

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LIPMAN, P.W. & MULLINEAUX, D.R. (eds.)(1981): The 1980 eruptions of Mount St.Helens, Wash., USA.- U.S. Geol. Surv. Prof. Pap., 1250, ca. 850S.

MARTÍ, J. & ERNST, G.G. (eds.)(2005): Volcanoes and the environment.- Cambridge University Press, 471 pp.

McCLELLAND, L. et al. (eds.)(1989): Global volcanism, 1975-1985.- Amer. Geophys.Union, Wash. D.C., 655S.

McPHIE, J.M., DOYLE, M. & ALLEN, R. (1993): Volcanic textures - A guide to theinterpretation of textures in volcanic rocks.- Univ. Tasmania, Centre for OreDeposits and Exploration Studies, 1-196, Hobart.

ORTON, G.J. (1996): Volcanic environment. - in: READING, H.G. (Hrsg.):Sedimentary Environments: Processes, facies and stratigraphy. - BlackwellScience, Oxford, 3. Aufl., 485-567.

SCHMINCKE, H.-U. (2004): Volcanism.- Springer, Heidelberg, 324 pp.SIGURDSON, H. et al. (eds.)(1999): Encyclopedia of volcanoes.- Academic Press.SIMKIN, T. and FISKE, R.S. (1983): Krakatau 1883 - The eruption and its effects.-

Smithsonian Inst. Press. 464S.THOMPSON, D. (2000): The volcano cowboys - The rocky evolution of a dangerous science.-

St. Martin‘s Press, New York, 326 pp.WHITE, J.D.L., SMELLIE, J.L. & CLAGUE, D.A. (eds.)(2003): Explosive Subaqueous

volcanism.- Geophys. Monogr., 140, 1-379.

Journal of Volcanology and Geothermal Research (Elsevier)Bulletin of Volcanology (International Association of Volcanology and Chemistry of

the Earths Interior, IAVCEI), www.iavcei.orghttp://vulcan.wr.usgs.gov/home.html

www.geo.tu-freiberg.de/dynamo/Abbildungen_Lehre.htm

Physical volcanologyPetrology Sedimentology

Natural Hazards

Mineral depositse.g. VHMSRaw material

Agriculture

EngineeringGeology

HydrologyHealth

Fields of work and position within Geosciences

History of volcanology –Historic eruptions

Encyclopedia of Volcanoes 1999

AristothelesPlatoA.G. WernerJ. Hutton

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Santorini, Ägäis

Forque 1879

Dietrich, ETH Zürich

1650 B.C...

Encyclopedia of Volcanoes 1999

History of volcanology –Historic eruptions

Vesuv 79 A.D.

Pompei

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Encyclopedia of Volcanoes 1999

History of volcanology –Historic eruptions

Krakatau 1883 in Indonesia: Tsunami caused by a shallow marine calderaeruption: 36 000 fatalities

Encyclopedia of Volcanoes 1999

History of volcanology –Historic eruptions

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Lacroix 1904

Mt. Pelee, Martinique: 1902-3

St. Pierre

Lassen Peak, 1915,California

Encyclopedia of Volcanoes 1999

History of volcanology –Historic eruptions

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Mt. St. Helens, WashingtonJune 1980

Pinatubo 1991

Smithsonian Institute

Schmincke 1986

Bahlburg & Breitkreuz 2004

Plate tectonics and magma generation

Irvine & Baragar 1971

Geochemicalclassification

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older classifications

Requiered: Norm calculation(e.g. CIPW)

Al2O3 content

Reology and Deformation of Magma

and Lava

Christoph Breitkreuz,

TU Bergakademie Freiberg

Sill, Estratos El Bordo, Chile

Mt. St. Helens

Glass Mtns, California

welded ignimbrite, St. Francis Mtns, Missouri, Proterozoic

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Reology, deformation and fragmentation are controlled bymany parameters. The following are important:

- Ambient pressure (in the magmatic conduitsystem, in subaquatic environment)

- Viscosity of Magma/Lava

- Density of Magma/Lava

- Temperature

- Deformation rate

- Magma ascent rate

Just to remember…

Types of fluids:Newtonian Fluid: water, certain pyroclastic flows

Bingham Fluid:(with yield strength)Debris flows, lava / magmacertain pyroclastic flows

Fig. 1.1 Relationship between viscosityand temperature for some magmas. Therhyolite was glassy or liquid through theentire temperature range (From Cas & Wright 1987, after Murase & McBirney1973).

VISCOSITY depends on:

- composition(SiO2 , Al2O3 ↑)(H2O, other volatiles, Na, K etc. ↓)

- temperature

- phenocryst content- microlith content,- vesicle content

Table 1.1 Estimates of eruption temperatures for some common magmas (After Cas & Wright 1987).

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Fig. 1.2 The effect of H2O on the viscosityof (a) granitic and (b) basaltic melts at varying temperatures (From Cas & Wright 1987, after Murase 1962).

H2O content and Viscosity:

e.g. foaming up of magma during ascent(first boiling)

Basalt

Rhyolite

Fig. 1.3 Densities of some molten volcanicrocks with varying temperature at atmosphericpressure (From Cas & Wright 1987, afterMurase & McBirney 1973).

Density depends on:compositiontemperaturepressurecontent of phenocrysts and vesicles

Fig. 1.5 Relation between super cooling (∆T) and crystal nucleation and growth rate in a granitic melt(Swanson et al. 1989)

∆T = supercooling(below liquidus)

Formation of crystals and vesicles depends on:- temperature- presuure- time (Nucleation and diffusion!)

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Fig. 1.6 Bubble growth and water oversaturation in an ascending rhyolitic magma. The curvesdefine oversaturation in % as a function of the depth in the system during magma ascent. Thelabels on the curves refer to the ascent or rise rates. The initial conditions are 4 km (a) and 1 km (b), which correspond to initial water concentrations dissolved in the magma of 3.72 and 1.86 wt.%, respectively. Reproduced from Proussevitch and Sahagian (1996) (From Dingwell 1998).

FIRST BOILING:- ascent rate- supersaturation (e.g., with respect to H2O)

(m)

Embayments in quartz phenocrysts

Embayments form by:- growth impediment- skeletal growth

(quenching)

Growth zonation

Cathodoluminescenceimage of a quartzphenocryst

Quartz broken during first boiling

Ignimbrite with crystal fragments

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Fig. 1.4 Relation between deformation rate and deformation style of magma or lava dependingon temperature; Tg = glass transition temperature

Fig. 1.7 Temperature profiles of the Ben Lomondflow at different time steps as derived by numericalmodelling with the emplacement temperature of 850°C; Tg = glass transition temperature, FVP = finely vesicular pumice, U.OBS = upper obsidian, TZ = transition zone, RHY = stony rhyolite, L.OBS = lower obsidian, BRX = breccia (from Stevenson et al. 2001)

Land surface

Tg = glass transition temperaturec. 2/3 of the liquidus temperature

Glass (above Tg) oozes out of a fracture plain

Panum Crater, Mono Lake, California

Soweit so gut!