GCG - Comunicações em actas de encontros científicos internacionais
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- Geochemical comparison of circular plutonic complexes with extrusive rocks from Sal Island (Cape Verde)Publication . Garcia-Rodriguez, Maria; Villaseca, Carlos; Ignacio, Cristina; Orejana, David; Mata, João; Caldeira, RitaABSTRACT: Sal island is located in the northeast and is the oldest of the Cape Verde archipelago, with magmatic activity starting ~25 Ma ago. It presents a series of circular plutons that could represent the subvolcanic roots of the exposed extrusive rocks. In this work we compare the geochemical characteristics of melagabbro-gabbro of circular (~16.3 Ma) intrusions in the Old Eruptive Complex, with basaltic and nephelinitic lavas of equivalent age (~15.8 and 14.2 Ma, Torres et al., 2010). This comparison allows observing a geochemical overlap between basalts and gabbros, and the similarity between trends of part of the samples in Harker-type diagrams and REE patterns. However, this compositional overlap is incomplete, with considerable differences and absence of fractionated (intermediate) lava types related to these terms of the circular complexes. This partial but incomplete overlap of the compositional fields of the plutonic and volcanic trends argues against the possibility of a direct genetic relationship between the two.