Mantle sources of the Cenozoic Iblean volcanism (SE Sicily, Italy): Sr-Nd-Pb isotopic constraints

摘要

A wide range of relatively undifferentiated lavas,ranging in composition from quartz-tholeiites to ankaratrites, wereerupted in the Iblean area (SE Sicily) during the Upper Miocene-Lower Pleistocene. New Sr-Nd-Pb isotope analyses, presented inthis paper, have been used to constrain the petrogenesis of theIblean magmas, and to characterise their sources. The results(87Sr/86Sr: 0.70271-0.70328; 143Nd/144Nd: 0.51325-0.51291;206Pb/204Pb: 19.25-20.00) indicate that the Iblean lavas are mantle-derived anorogenic melts, involving DM+HIMU mantlecomponents. Isotope and trace element data suggest that magmasformed from a heterogeneous mantle source that equilibrated inthe spinel-peridotite field; the Iblean melts were thus formedwithin the subcontinental lithosphere. The mantle source region,was originally characterised by a depleted isotopic signature (DM),and was repeatedly and variably impregnated (refertilized) bymetasomatic agents of sublithospheric origin characterised by a HIMU signature.