Santorini volcano magma plumbing system: constraints from a combined experimental and natural products study

摘要: Santorini Volcano constitutes a serious hazard in the Aegean region of Greece. The recent 2011-2012 episode caldera unrest has focussed attention on magma plumbing system volcano, and notably depths storage different batches. We investigated differentiation conditions mafic-intermediate magmas, as well pre-eruptive dacitic-rhyodacitic magmas prior to four largest Plinian eruptions volcano over last 200 ka (Minoan, Cape Riva, Lower Pumice 2, 1). intensive variables (P, T, fO2, volatiles content) were determined by combining laboratory crystallization experiments with study natural products (including melt inclusions). Our results show that is dominated large, long-lived ( ka) at about 8 km depth (2 kb), from which silicic are derived. This fed injections deeper, mafic reservoir located boundary between upper lower crust 15 km; 4 kb). Mantle-derived basalts stall region, where they fractionate basaltic andesite (55 58 wt.% SiO2) 2-3 H2O through 60 oliv, cpx, plag, mt/ilm opx, 1040-1000°C, kbar, fO2 = FMQ-0.5. basaltic-andesitic then ascent either (1) experience equilibration eruption, or (2) produce dacitic rhyodacitic liquids. Prior major eruptions, stored T 850-900°C, under relatively reduced FMQ or, NNO -0.9 -0.1), melts depleted fluorine 500-700 ppm) particularly sulphur (<100 but rich water chlorine (5-6 wt.%, ca. 2500-3500 ppm, respectively) probably co-existing hydrosaline liquid, pressure 2 kbar. fact dacites-rhyodacites have high enough dissolved Cl for be saturated liquid (and maybe vapor) before significant consequences degassing budget, was previously estimated insignificant.