Evolution of Silicic Magma Chambers and their Relationship to Basaltic Volcanism

摘要: Silicic volcanism is commonly preceded by eruption of basalt. Similarly, the earliest phases granitic plutonic complexes are often gabbro or diorite. Basalt magma must play a role in initiation large silicic system, but three lines evidence suggest that basalt also enters chambers and influences their further evolution. These are: contemporaneous vents flank volcanic centers; thermal models bodies heat be replenished to maintain them upper crust for observed life span; petrologic data indicate mafic clots cognate xenoliths common granodiorite andesite represent quenched within active chambers. Phase assemblages rocks bulk composition suites this type show much variation erupted crystallized end products due interaction basaltic rhyolitic magmas. It proposed from mantle provides generating melt lower crust, resulting rhyolite body continues receive injections as it rises through crust. Implications model discussed.