Volcanism and petrogenesis in the S. Venanzo Area (Italy)
SummaryGeological and petrological investigations on the volcanic products of the S. Venanzo area (Central Italy) provided some new data, that allowed to understand its volcanic and petrogenetical history.The volcanic activity in the S. Venanzo zone may be sketched as follows:1)Pian di Celle Volcano. — An initial strongly explosive activity built up a tephra cone. A lava fountain activity followed, emplacing beds of welded scoriae. The volcanic activity ended with a quiet effusion of lava.2)S. Venanzo Volcano. — The activity consisted almost exclusively of ejections and lava fountains, that built up a cinder cone.
The progressive and intensive assimilation of limestones originated, in these volcanites, successive and complex mineral equilibria, with end products of carbonatitic type.Within the limits of the Pian di Celle lava flow such equilibria, together with the high gas content, produced pegmatite-like differentiations.