Magnetismo paleozoico en el Macizo del Roc de Frausa (Pirineos Orientales)

Abstract

In thc Kock de Frausa Massif two different geochemical types of amphibolites have been described. One type is formed by orthoamphibolites of tholeitic affinity and with composition similar to E-MORB, dcnved froni little evolved magrnas low in potassium. Tbey outcrop as sills interbedded with cambro-ordovician metasediments and are spatially related to augen gneiss levels. A continental marginal basin or continental back-arc is probably the orogenic setting of this magmatism. The second type is formed by high K and Fe amphibolites placed between the Roc de Frausa orthogneises and the metasediments. They are highly deformed and their primary composition has been probably modified by hydrothermal processes acompanying Hercynian fracturation tectonics.