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

A wide range of relatively undifferentiated lavas, ranging in composition f rom quartz tholeiites to ankaratrites, were erupted in the Iblean area (SE Sicily) during the Upper Miocene-Lower Pleistocene. New Sr-Nd-Pb isotope an alyses, presented in this paper, have been used to constrain the petrogenes is of the Iblean magmas, and to characterise their sources. The results (Sr -87/Sr-86: 0.70271-0.70328; Nd-143/Nd-144: 0.51325-0.51291; Pb-206/Pb-204: 19.25-20.00) indicate that the Iblean lavas are mantle-derived anorogenic m elts, involving DM+HIMU mantle components. Isotope and trace element data s uggest that magmas formed from a heterogeneous mantle source that equilibra ted in the spinel-peridotite field; the Iblean melts were thus formed withi n the subcontinental lithosphere. The mantle source region, was originally characterised by a depleted isotopic signature (DM), and was repeatedly and variably impregnated (refertilized) by metasomatic agents of sublithospher ic origin characterised by a HIMU signature.