Geochemistry and tectonic setting of triassic magmatism from the Lercara Basin (Sicily, Italy)

Abstract

Petrological and geochemical data of Triassic magmatic rocks from Lercara Basin (Central Sicily), provide new information about the intraplate volcanism related to the Pangea break up. The magmatic rocks crop out as subvolcanic bodies and are packed in several Lower Triassic clayey lithologies correlated to the sedimentation inside the Imerese and Sicano domains. The samples are splitted in two groups: the first includes transitional to alkaline basalts, with sub-ophitic texture; the second includes more altered rocks, with porphyritic texture, showing alkali basaltic to phonolitic compositions. Major and trace element data of single groups show small variations indicating fractional crystallization processes. Abundances and ratios of incompatible trace elements indicate that rocks were formed in an intraplate continental environment from different mantle sources with E-MORB to OIB-type compositions. Low partial melting degrees at the transition between spinel and garnet lherzolite fields can be hypothesized for parental magmas of the Lercara Basin. We propose that magma batches moved toward the surface along lithospheric fractures originated by flexure and uplift of the Mesozoic Pangea supercontinent.