Relict of komatiite cinder cone - MikroBittikomati.mbnet.fi/Sattasvaara.CinderCone.pdf · Cinder...

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