Trace element and isotopic constraints on magmatic evolution at Lassen volcanic center

Magmatic evolution at the Lassen volcanic center (LVC) is characterized by a transition from predominantly andesitic to predominantly silicic volcanism with time. Magmas of the andesitic, or "Brokeoff phase' of volcanism range in composition from basaltic andesite to dacite, whereas those of silicic, or "Lassen phase' range in composition from basaltic andesite to rhyolite. The compositions of magmas from each phase define well organized but distinct variation trends. Magmatic evolution at LVC can be viewed in terms of a series of mantle melting events that subsequently stimulated melting in a progressively increasing volume of the lower crust. -from Authors