Volcanic plumbing filters on ocean-island basalt geochemistry

Abstract Ocean-island basalts (OIBs) are considered to be messengers from the deep mantle, yet filtering effect of plumbing systems that bring OIB melts surface remains poorly assessed. We investigated volcanic products El Hierro island (Canary Islands) textural and chemical perspectives. The majority geochemical data cluster at relatively fractionated basaltic compositions 5 wt% MgO. Compositions ≥10 MgO porphyritic whole rocks accumulate mafic minerals. Near-primary do not erupt. Instead, we show carrier (crystal-free rocks, glasses, melt inclusions) consistently buffered low-MgO during passage through system. tested our model fractionation crystal accumulation on a global compilation OIBs. Similar Hierro, evolved (alkaline) 7 (tholeiitic). Modeling parental melts, with 50% crystallization, reach reduced density, increased volatile content, overall low viscosity, becoming positively buoyant relative wall highly eruptible when reaching saturation depths around crust-mantle boundary. Under these conditions, “sweet spot” propelled erupt carrying an assortment recycled crystals. This mechanism is consistent petrography chemistry erupted suggests volcanoes dominated by melts.