caldera betydelse and definition

Exempel på caldera

• A small, possibly ephemeral caldera lake is a likely source.

• Cooling units and composite sheets in relation to caldera structure.

• Eruption of the ignimbrites is envisaged as a series of poorly expanded flows possibly with incorporated fall material generated by foundering of a caldera floor.

• The sedimentary breccias were probably formed from talus and/or other types of colluvium that were shed from the ring-fracture fault scarp of the caldera.

• These minerals may have formed by recrystallization of pre-existing weak advanced-argillic alteration at the southern margin of the caldera structure.

• This suggests that eruptive hiatuses in the extracaldera record may reflect effusive activity and stratovolcano or shield-building phases within the summit caldera.

• A caldera lake is occasionally established in the present caldera following snowmelt.

• It is possible that this embayment is a caldera or lateral collapse structure.