Page 98 - Caldera Volcanism Analysis, Modelling and Response

Pyroclastic Density Currents 73

granular aggrada- ash cloud an regime

(a) from sketch of a stratigraphic fully turbulent PDC; without development of from fallout modi¢ed).
regimes. deposits (c) (e) base of ¢ne ash direct

four depositional at the £ow fully turbulent settling of Gentle in the deposited Branney and Kokelaar, 2002;

PDC for deposits over a £at surface; aggradation of thick pulses; development of thin pulses dilute, (l) (h); ¢ne ash (after

same stacked regime with (f ) (h) current; at point of £ow-boundary zone

aggradation of di¡erent pulses within the pulses that generate of aggradation £ow £uid-escape regime; £uid escape by of a traction-dominated current described deposits left by the deposits of massive, accretionary lapilli-bearing four types of the

for stepwise (b) deposits); (d) (valley-pond of di¡erent pulses dominated base at the cross-strati¢ed stacked (m) relative ¢elds

model aggradation of thick pulses; a valley (i) very base; regime; fallout conceptualisation of the

Sedimentological in aggradation deposits left by aggradation of thin pulses at the by a direct

7 regime with of di¡erent pulses from pulses dominated (n) point l);
Figure £ow tion column (g) granular of