relict of komatiite cinder cone - mikrobittikomati.mbnet.fi/sattasvaara.cindercone.pdf · cinder...
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Relict of komatiite cinder cone
High viscosity in komatiites required high cooling rate due to near-surface magma chamber
Google Earth: Sattasvaara, hill, Finland
Team Pulkkinen & Saverikko
Eruptive crater at top hill
Google Earth 3D
Goal in future
Lava fountains from final eruptions
Result and origin of lava fountain YouTube: Kilauea lava spatter cones
Crater rims of previous explosions
Sattasvaara – typical cinder cone
Extraordinary relict of Archean komatiite cone may be pre- served by the crustal overthrust associated with rotation of the Kola megablock. Allochthonous cap is eroded wholly.
YouTube: Cinder cone formation
Cinder cone and volcanic morphology
Cinder cone and lava flows
Block lavas of viscous komatiite magma
Microscopic texture with tiny clinkers is similar to aa-lavas’ structures (next page).
Block lavas are typical to fel-sic magma but form also in mafic one cooled enough.
Aa-lavas from insitu differentiated magma
Viscous flowing type of aa-lavas
YouTube: Kilauea a’a Shield Flow June 1, 2010
Sattasvaara volcano as a whole
Mainly pyroclastic amph.-chlorite rock
Near-surface magma chamber
http://gtkdata.gtk.fi/mdae/ ”Bouguer anomaly map” and ”Shaded elevation map”
Isolated mantle dome Sattanen, emplaced at junction of the shield-wide Kuolajärvi-Vygozero fracture and the fault scarp of Oraniemi aulacogen.
Satellite of Kittilä caldera-volcano
Source: Geol. Surv. Finland, Rep. Invest. 209
Kittilä megacaldera = Supervolcano
Extensive volcanic plain on the mantle plume
Volcanic outpourings large enough to form calderas instead of cones
Enormous explosions of komatiite magma
YouTube: Caldera Formation
Clinkers of differentiated aa-lava