Origin of green clinopyroxene cores of lavas from the garrotxa volcanic field (spain)

Abstract

Volcanism of the Garrotxa area is part of the Neogene volcanism of NE Spain (NE Spain volcanic province, NESVP). This volcanism is a manifestation of the magmatic activity consequence of the rift-type extensional tectonics that affect the eastern margin of Iberia since late Oligocene and that involved the opening of the Valencia trough. Volcanic activity in the NESVP started weakly in the Cadaqués zone 15 Ma ago, (C. Lewis, personal communication), followed by the Empordà (9 to 12 Ma in Alt Empordà, 6 Ma in Baix Empordà), La Selva field (5 to 7 Ma) and the Tordera fault system (2 Ma). Finally, activity took place at the Garrotxa volcanic field (GVF) from 300,000 to 10,000 years ago, with an eruptive episode every 15,000 to 20,000 years approximately (C. Lewis personal communication).