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.

• This northern caldera was formed in the 21 000 year explosive eruption.

• This igneous activity was focused on the southwest margin of the dormant caldera.

• Fractionation was repeatedly interrupted by eruption of material from the roof zone such that seven stages of caldera development have been identified.

• They have been interpreted to represent part of a caldera-related succession, possibly intra-caldera.

• The caldera has chemical characteristics that could result in ambiguous or incorrect tectonic discrimination if the entire rock suite was not considered as a whole.

• Many of the major eruptions recorded by the extensive lithic brecciabearing ignimbrite sheets may have involved caldera collapse.

• The caldera is partially filled and surrounded by crystal-rich ignimbrite (f).