Autor/a:
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Campeny, Marc; Menéndez, Inmaculada; Quevedo-González, Luis; Mangas, José; Yepes, J.; Tauler, Esperança; Melgarejo, Joan Carles; Casillas, R.; Méndez-Ramos, J.; Acosta-Mora, P.
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Abstract:
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A representative sampling of carbonatites, alkaline felsic
igneous rocks and corresponding paleosols was carried out on
Gran Canaria and Fuerteventura (Canary Islands, Spain) in
order to assess the geochemical composition, focussing on
Rare-Earth Elements (REE). Thus, we analysed 70 samples of
plutonic, subvolcanic and volcanic rocks from the Miocene
declining and Pliocene rejuvenation volcanic stages, and
associated soils (B-C horizons) on Gran Canaria. In addition,
40 samples from the Oligocene-early Miocene submarine
magmatic stage composed by syenites, nepheline-syenites and
carbonatites (veins, dykes and stocks), as well as from the
Miocene alkaline declining stage with trachytes and quartztrachytes (domes) have been studied on Fuerteventura. The
maximum REE contents (mg/kg) for Gran Canaria are in the
Miocene syenites (474-590), trachytes (588-601), phonolites
(828-1036) and rhyolites (446-577), whereas lower values are
found in Pliocene trachytic lavas (446) and phonolitic domes
(333-577). REE enriched C-B horizons range from 429 to
1,584 mg/kg. In Fuerteventura, REE contents in Oligoceneearly Miocene syenites range between 51 and 1,761 mg/kg;
from 697 and 7,372 in carbonatites and from 90 to 394 in
Miocene trachytes. According to our results, LREE are one
order of magnitude higher than HREE, and REE resources
from Gran Canaria are significant in Miocene felsic igneous
rocks and their paleosols, while early-Miocene carbonatites
are the best REE exploration target in Fuerteventura. |