Modelización de la fusión parcial en equilibrio en una fuente mantélica metasomatizada. El volcanismo Cuaternario de La Garrotxa (Cataluña)

Abstract

Trace element modelling together with the use of radiogenic and stable isotopic ratios, is a widely used tool to constrain the characteristics of the mantle sources of basaltic series. However, as the composition of the volcanic rocks may be the result of several combined magmatic processes, it is necessary to identify them before any attempt to their quantitative modelling. On the other hand, the information provided by partial melting modelling is limited to the final composition of the mantle source whereas some characteristics, like the presence of minor phases, can be cloaked if those minerals have not remained in the residue. A good example to illustrate the problems of this method is found in the Quaternary primitive basaltic rocks of La Garrotxa (ME Volcanic Region of Spain) which, according to a combined study o f trace element modelling and Sr-Nd-Pb isotopic ratios, can be interpreted as the result of the melting of a previously enriched lithospheric source which has been subsequently pervaded by basaltic melts derived from a common European sublithospheric reservoir.