Estudio morfológico y geoquímico de circones en rocas metamórficas de Ollo de Sapo en Sanabria (NW España). Protolitos plutónicos y volcano-sedimentarios

This work constitutes a combination of morphological and geochemical results of zircon populations of two typical lithologies from the Ollo de Sapo Domain in the Sanabria complex: augengneiss and schist. The combination of these methods allows us discriminating between the discussed plutonic or volcanosedimentary origin of Ollo de Sapo rocks. Results allow the assignment of a peraluminous porphyritic granite derivated from a polygenetic source as protolith of the gneiss. Zircons from the schist are more varied and their characteristics point to a volcanosedimentary protolith constituted by mainly calc-alkaline crystals. Moreover, the morphological and geochemical study of an enclave of gneis in monzodiorite shows there are at least three populations of zircons in this sample. Therefore, these methods result to be useful in order to separate different zircon populations that could be wrongly considered together in geochronological studies