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

Petrological and geochemical data of Triassic magmatic rocks from Lercara Basin (Central Sicily), are discussed to 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 into the Imerese and Sicano domains. The samples were divided in two groups. The first group includes transitional to alkaline basalts, with crystalline sub-ophitic texture mainly characterized by plagioclase, clino- and orthopyroxene, and olivine crystals. The second group 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 degrees of partial melting at the transition between spinel and garnet lherzolite fields can be hypothesized for parental magmas of the Lercara Basin. Magmas ascended to the surface as various batches of magmas along lithospheric fractures originated by flexure and uplift of the Mesozoic Pangea supercontinent.