1

Types of volcanoes

Christoph Breitkreuz,

TU Bergakademie Freiberg

Fig. 3.1 Types of volcaniclandforms. Vertical exaggeration 2 to 1 (polygenetic) and 4 to 1 (monogenetic). Relative sizes areonly approximate (From Orton1996, after Simkin et al., 1981).

Monogenetic and complex volcanoes

Scoria cones: most abundant volcanic land form- high viscosity, basaltic (high microlith content!)

Stromboli 2001

2

Mt. Tarawera, New Zealand

Typical eruption styles: - strombolian fallout- minor phreatomagmatic fallout and surge- small lava flows

Schmincke 1988

4 km

Typical horse shoe shape due to erosion by lava

3

Maar – tuff ring – tuff cone:typical land forms of phreatomagmatic eruptions of SiO2-poor magma

Ukinrek maar (formed 1977; Lorenz)

Malha Maar, Meidob Hills, NW Sudan

4

Lorenz 2004

Phreatic tuff breccia, Neogene, Eifel, W Germany

Southern Slovakia: Neogene Diatreme Field

5

Bedded diatreme facies

Unbedded diatreme facies

6

Urach diatreme field, Neogene SW Germany

Iceland 1995

7

Litoral cones, Myvatn, Iceland

Rootless phreatic land forms

Mt. St. Helens volcanic ring plain

Rootless phreatic craters in 1980 tuff deposit

Mt. Pelee, Martinique, 1902/3

SiO2-rich Lava flows and domes

8

Mt. St. Helens, 1980 - 82More about this in the next lecture…

Shield volcanoes:- low-viscosity

basaltic magma- longlasting magma

production at one place

Olympus Mons, Mars

Complex volcanoes

Isabela, Galapagos

9

SW Tenerife: cross section through a Cenozoic shield volcano:Lava pile cross cut by numerous dykes

SW Tenerife: cross section through a Cenozoic shield volcano:Two overlapping scoria cones preserved

10

SiO2-rich lava flowsand lava domes

Importance of volcanotopographic hiati:Spacially differentiated!

PhD project Marion Geißler

Drilling Angermünde (Am) 1/68

?

* = core segments

sediments of aplaya-environment,

with anhydritic blasts

sandstones andmostly andesiticconglomerates

andesite lava flows,mostly vesicular;with interbedded

"block-lava", brecciasand few paleo-soils

vitric rhyodacitic tuff

Carbonif. sedimentsconglomerates

conglomerates and?sandstones

with rhyodacite(?andesite) fragmentsand interbedded tuff

= ?ignimbrite(no cores available)

}

Profile (this project)

rhyodacitic sequenceof massflows

(ignimbrite) and tuffs

sediments of aplaya-environment,

with anhydritic blasts

thin conglomeratehorizont and sandst.

several intermediatelava flows,

partly vesicular

Carbonif. sediments

conglomerates

ash fall deposits

andesite lava flows,mostly vesicular;with interbedded

brecciasand paleo-soils

*

* = core segments

CS

B-Tuff

B-Tuff

B-TuffLava

Lava

Lava

Lava

B-Tuff

4750

4500

4250

4000

Depth[m]

?

?

?

Profile(this project) Lithology

Time

post-variscan flat landscape, covered by tuff and ignimbrite

Mg-andesite shield volcanoes create a high topography

flat landscape, covered by playa sedimentsDrilling Oranienburg (Ob) 1/68

4500

4250

4000

3750

4750

Depth[m] CS

*

Fig.1: Schematic modell of thevolcano-sedimentary evolutionof the area NE of Berlin(from the well Ob 1/68 in theSW through Grüneberg (Gür) 3/76to Am 1/68 in the NE)

x xx

x xx

x xx

xx

xx

pre-ignimbriticporphyric

rhyodaciticlava, lava dome

or sill-intrusionA

B

C

coarse grained clasticsof the Parchim Fm. lake and fan deposits

of the Grüneberg Fm.

sandflat, mudflat and playa lake deposits

E Gür 3/76 E Am 1/68E Ob 1/68

aktive strike-slip (NW-SE) faultingunder slightly extensional (N-S) regime

aktive extrusive and intrusive volcanism,andesitic and rhyolithic (e.g. in well Tuchen 1/74)developement of paleosoils

at the top of andesite lava flows

developementof paleosoils

last rhyodaciticash fall activities

SW

SW

SW NE

NE

NE

conglomerate exclusively withclasts of Carboniferous sediments

Mg-andesite shield volcano complex in Brandenburg

L.Rotlieg.

U.R

otlieg.

PhD projectMarion Geißler

Katzung 1995

„Inundation“ of shield volcano topographyby playa sediments during Upper Rotliegend II

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Plateau basaltsAlias trapp basalt or flood basalt

Typically hot spot-relatedTypically fissure eruptions Iguazú Cascades

Stratovolcanoes:- longlasting intermediate to SiO2-rich magmatism

Lincancabur, N Chile

Mt. Shasta, California

12

Cone facies - volcanic ring plain facies

Mt. Egmont, New Zealand

Sector collapse: oversteepening, hydrothermal alteration, incompetent substrate, active faulting, earthquakes, eruption

Mt. Egmont, debris avalanche deposit

13

Mt. St. Helens

Socompa, N ChileSector collapse

Fig. 3.4 General calderacycle (after Lipman, 1984). Stage 1 –precaldera volcanismdevelops clusters of smallintermediatestratovolcanoes, Stage 2 –eruption of zoned magmachamber develops caldera. Ash flow tuffs interfinger with caldera collapsebreccia whereas a thinoutflow sheet extendsoutward from the caldera, Stage 3 – postcalderadeposition of volcanicsand sediment and resurgent doming (FromOrton 1996).

Mik

e Br

anne

y

Main CALDERA types:- piston (SiO2-rich and –poor!)- trap door- piece meal

- resurgent- non-resurgent

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Non-resurgent caldera

Crater Lake, Oregon

Cerro GalanNW Argentina

Valles Caldera, JemezMtns, New Mexico

Resurgent calderas

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Fig. 3.5 Evolution of Scafell Caldera, English Lake District (after Branney & Kokelaar, 1994). The caldera developed atop basaltic to andesitic lavas (e.g. Lingcove Fm.) that formed a composite low-profile shield-like volcano. Schematic section from the Langdale area showsrelative thickness of facies from the variousstages. These are: A emplacement of Whorneyside ignimbrite and initial subsidence; Binundation of vent leads to phreatoplinianeruptions of Whorneyside bedded tuff; C onset of widespread piecemeal subsidence and eruption of Long Top Tuffs; D continued subsidence and deformation of hot ignimbrites; E eruption of high-grade ignimbrites of Crinkle Crags tuffs; Fdevelopment of a caldera lake, with subaqueousvolcaniclastic sediments and tuffs, and intrusionof rhyolite domes (From Orton 1996).

Piece meal CalderaOrdovicianLake district, W England