"Geochimica delle rocce magmatiche dei Colli Euganei (PD) e dei Monti Berici (VI)"

Abstract

The Tertiary Magmatic Province of Veneto, in the North-East of Italy represents the most important magmatic province of the Adria Plate and is composed of the Marosticano, Lessini Hills, Berici Hills and Euganei Hills. Interestingly, only in the Euganean zone, trachitic, rhyolitic and latitic rocks were produced. For this project, specimens have been collected from both open and closed quarries, localized in the whole Euganei Hills, and from the eastern and southern part of the Berici Hills in order to reconstruct the age, origin and evolution of the Euganean magmas. Using optical microscopy together with XRF and ICP-MS spectrometers, the following rock-types have been identified: basanite, basalt, basaltic andesite, basaltic trachyandesite, trachyandesite, trachyte e rhyolite. 40Ar/39Ar radioisotopic dating showed that all the magmas were emplaced at about 32 Ma. Moreover, Sr-Nd-Pb isotope analysis showed that the basaltic specimens display DMM and HIMU signatures (this latter is more important in alkaline basalts). According to the geochemical configuration, already analyzed by Beccaluva and collaborators (Beccaluva et al., 2007), it has been thought that the lithospheric mantle of the Adria plate had been enriched by metasomatizing agents with HIMU isotopic signatures. Therefore, the sub-lithospheric originated metasomatizing component may have accumulated with more efficiency in the lower lithosphere. EC-AFC modeling shows that trachitic, rhyolitic and latitic magmas (i.r., the evolved ones) could be the result of a contamination of the initial magma with continental crustal rocks.