Page 234 - Caldera Volcanism Analysis, Modelling and Response

Characterisation of Archean Subaqueous Calderas in Canada 209

Figure 9 Characteristics of the Normetal caldera. Arrow indicates younging direction. (A)
Phase 2 rhyolite £ow with 5--15 cm columnar joints. Scale: ¢eld book 17 cm. (B) Close-up of
columnar-jointed £ow. Scale: pen 13 cm. (C) Lapilli tu¡ (autoclastic) breccia of major caldera
construction phase. Scale: pen 13 cm. (D) Massive quartz-phyric rhyolite of phase 4. Note the
large quartz phenocrysts and the deformation. Scale: pen 6 cm. (E) Volcaniclastic deposits of
phase 5 with lapilli tu¡ breccia, and strati¢ed lapilli tu¡. Scale: pen 13 cm. (F) Basal part of ¢n-
ing-upward sequence with lapilli tu¡ breccia and lapilli tu¡. Scale: ¢eld book 17 cm. (G) Pyro-
clast with abundant calcite-¢lled vesicles. Selected pyroclasts display patchy brown carbonate
alteration. Scale: pen 13 cm. (H) Thin-bedded tu¡ turbidites with parallel-laminated Bouma
T b and crossbedded BoumaT c sedimentary structures. Scale: pen 8 cm. (I) Out-sized tu¡ rip-
up clast in lapilli tu¡ bed. Scale: pen 13 cm.