Growth and evolution of long-lived, large volcanic clusters in the Central Andes: The Chachani Volcano Cluster, southern Peru

In the Central Andes, large (> 500 km2) and long-lived (1–5 Ma) volcanic clusters (LVCs) are less explored their eruptive history magmatic regimes understood than smaller, short-lived (<0.5 Ma), individual stratocones. The Chachani-large cluster (C-LVC) sizeable volume (c. 290 km3) consists of twelve edifices forming 1.06–0.64 Ma group stratovolcanoes 0.46–0.05 domes coulees block-lava flow fields. Both groups overlie pre-Chachani lavas tuffs 1.02–1.27 Ma, together they have buried nested craters or a caldera associated with c. 1.62–1.66 Arequipa Airport ignimbrite. C-LVC evolved from: (i) homogeneous compositions Chachani basal units to (ii) relatively wide compositional variations (53–67 wt% SiO2) between mafic andesite dacite at moderate rates (0.27–0.41 km3/ka) for ‘Old Edifice’ group, finally (iii) narrower (57–64 andesitic coinciding extrusive activity 2.5 times lower (0.12–0.15 ‘Young group. in Old Edifice related strongly contrasting resident recharge magma hybridized lavas. contrast, narrow range eruption rate during second half represent trend towards more homogeneous, composition time. Mineral texture studies provide evidence disequilibrium mixing shallow (5–20 km depth range) reservoirs. These temporal changes document that transcrustal systems matured time by combination processes: fractional crystallization, crustal contamination mixing/mingling variable recharge. This resulted shift steady state, monotonous (andesite) regime as result coupling parameters thermal conditions, density constraints, viscosity/crystallinity erupted magmas.