▁These ▁contain ▁phen oc ry st s ▁of ▁pl agi oc l ase ▁and ▁py ro x ene , ▁with ▁additional ▁micro phen oc ry st s ▁of ▁il men ite ▁and ▁magnet ite . ▁ ▁Based ▁on ▁the ▁composition , ▁it ▁has ▁been ▁infer red ▁that ▁the ▁mag ma ▁res er voir ▁of ▁Qu et rup ill án ▁contained ▁a ▁m ush ▁of ▁cry st als , ▁from ▁which ▁mag ma ▁was ▁repeatedly ▁mobil ized ▁following ▁the ▁injection ▁of ▁fresh ▁mag mas ▁that ▁re he ated ▁the ▁m ush . ▁Fra ction al ▁cry st all ization ▁of ▁bas al ts ▁generated ▁tra ch yt ic ▁mel ts . ▁ ▁E rupt ive ▁history ▁▁ ▁E rupt ive ▁activity ▁at ▁Qu et rup ill án ▁comm enced ▁before ▁the ▁ice ▁ages . ▁The ▁first ▁phase ▁of ▁activity ▁involved ▁the ▁formation ▁of ▁cal der as ▁and ▁strat ov ol cano es ; ▁later ▁during ▁the ▁ice ▁ages ▁la va ▁flows ▁and ▁ign imb rit es ▁were ▁emp la ced . ▁Finally , ▁the ▁present ▁strat ov ol cano ▁with ▁its ▁cal der a ▁was ▁emp la ced ▁towards ▁the ▁end ▁of ▁gla ci ation ; ▁par as it ic ▁v ents ▁formed ▁even ▁later ▁and ▁produced ▁la va ▁flows . ▁ ▁Qu et rup ill án ▁has ▁er upt ed ▁py ro cl ast ics , ▁which ▁have ▁formed ▁flow ▁and ▁p um ice ▁depos its ▁east ▁of ▁the ▁vol cano . ▁Several ▁phases ▁of ▁vol can ic ▁activity ▁have ▁been ▁infer red