Cretaceous volcanism of the southern Tuscany: Record of volcanic bodies from Tuscan succession of Rapolano Terme

Volcanic and subvolcanic rocks occur in the Rapolano Terme (Siena) as detrital blocks together with Lower Cretaceous limestones whole inserted in the middle-upper Eocene Scaglia toscana succession (Tuscan Domain). Other similar igneous rocks outcrop in other places in southern Tuscany, and were previously classified as alkaline lamprophyres. These occur as pillow lavas and sills within Lower Cretaceous shaly-limestone successions of the External Ligurian Domain (Castiglioncello del Trinoro, Murci, Senna Creek, Ripiglio Creek). Volcanic and subvolcanic rocks of the Rapolano Terme area show strong similarity with the other of Southern Tuscany, even if the geological setting is quite different. Geochemical data obtained for the Rapolano Terme and Castiglioncello del Trinoro volcanic rocks (the latter for comparison), show an overall alkaline affinity, but with slight geochemical differences. They all are considered to belong to the same magmatic context, originated between the end of the opening of the Piedmont-Ligurian ocean and the beginning of the Alpine orogenesis. Geochemical and petrological features of these volcanic rocks corroborate to within-plate magmatic processes linked to an aborted rift in the External Ligurian Domain.