Oxygen isotope constraints on the crustal contribution to the subduction-related magmatism of the Aeolian Islands, southern Italy

摘要: Oxygen isotope data are presented for 37 samples of subduction-related lavas from the Aeolian Islands, southern Italy, that were characterised radiogenic isotopes (Sr, Nd, Pb) and major- trace-element abundances in previous studies. The samples, which all erupted within past 500,000 years, span full compositional range magmatism calc-alkaline basalt-dacite sequence Salina to shoshonites Stromboli potassic leucite-bearing basalt rhyolite series Vulcano, Whole-rock δ18O values +6.3‰ +8.5‰, but some cases (14 samples) 18O enrichment by post-crystallization hydration low-temperature alteration is suspected, an empirical correction excess water yields a primary magmatic +6.1‰ +8.5‰. Variations exhibit dependence, increased characterize evolved various series, δ18O-SiO2 trends steeper than those predicted closed system fractional crystallization. In general, O variations accompanied only small shifts ratios and, while weak correlations between 87Sr/86Sr etc., observed individual fractionation it apparent these much smaller ranges whole set. A two-stage model magma genesis proposed hybridization mantle introduction subducted sediments gave rise at fairly constant δ18O. Subsequently, magmas derived heterogeneous crustal chambers AFC, involving assimilation 18O-rich crust, giving with high δ18O, decreased 206Pb/204Pb, slightly higher lower 143Nd/144Nd.