Noticias
29.07.2019Publicado el artículo "Distribution of REE-bearing minerals in felsic magmatic rocks and paleosols from Gran Canaria, Spain: Intraplate oceanic islands as a new example of potential, non-conventional sources of rare-earth elements""
El Dr. Xavier Llovet, responsable de la Tecnologia de Microsonda Electrónica de los CCiTUB ha participado en la publicación del artículo "Distribution of REE-bearing minerals in felsic magmatic rocks and paleosols from Gran Canaria, Spain: Intraplate oceanic islands as a new example of potential, non-conventional sources of rare-earth elements” en la revista Journal of Geochemical Exploration.
Este articulo es fruto de la colaboración entre investigadores de las universidades de Barcelona, Las Palmas de Gran Canaria, La Laguna y Córdoba y en él, el Dr. Marc Campeny y la Dra. Esperança Tauler del Departamento de Mineralogia, Petrologia y Geologia Aplicada, detallan una estimación de las concentraciones de "tierras raras", REE (de "Rare-Earth Elements"), que se pueden encontrar en la isla de Gran Canaria.
Tierras raras
‘Tierras raras’ es el nombre con que se conocen un total de 17 elementos com el escandio, itrio, lantano, cerio, praseodimio, neodimio.... difíciles de encontrar en altas concentraciones en su forma pura. Éstos elementos, muy importantes para la fabricación de componentes electrónicos, se encuentran repartidos por toda la corteza terrestre pero, en Europa, se encuentran en bajas concentracoines. Es por eso que se consideran, por parte de la Comissión Europea, como ‘Materias primeras críticas’ desde el año 2017.
La parte analítica necesaria para identificar los diferentes elementos se realizó en los microscopios SEM, en los difractòmetres de rayos X y en la microsonda de los Centros Científicos y Tecnológicos de la Universitat de Barcelona.
El resumen del artículo es el siguiente:
"Gran Canaria is a hotspot-derived, intraplate, oceanic island, comprising a variety of alkaline felsic magmatic rocks (i.e. phonolites, trachytes, rhyolites and syenites). These rocks are enriched in rare-earth elements (REE) in relation to the mean concentration in the Earth's crust and they are subsequently mobilised and redistributed in the soil profile. From a set of 57 samples of felsic rocks and 12 samples from three paleosol profiles, we assess the concentration and mobility of REE. In the saprolite that developed over the rhyolites, we identified REE-bearing minerals such as primary monazite-(Ce), as well as secondary phases associated with the edaphic weathering, such as rhabdophane-(Ce) and LREE oxides. The averaged concentration of REE in the alkaline bedrock varies from trachytes (449 mg kg−1), to rhyolites (588 mg kg−1) and to phonolites (1036 mg kg−1). REE are slightly enriched in saprolites developed on trachyte (498 mg kg−1), rhyolite (601 mg kg−1) and phonolite (1171 mg kg−1) bedrocks. However, B-horizons of paleosols from trachytes and phonolites showed REE depletion (436 and 994 mg kg−1, respectively), whereas a marked enrichment was found in soils developed on rhyolites (1584 mg kg−1). According to our results, REE resources on Gran Canaria are significant, especially in Miocene alkaline felsic magmatic rocks (declining stage) and their associated paleosols. We estimate a total material volume of approximately 1000 km3 with REE concentrations of 672 ± 296 mg kg−1, yttrium contents of 57 ± 30 mg kg−1, and light and heavy REE ratios (LREE/HREE) of 17 ± 6. This mineralisation can be considered as bulk tonnage and low-grade ore REE deposits but it remains necessary to develop detailed mineral exploration on selected insular zones in the future, without undermining environmental and socioeconomic interests. "
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