Rocas volcánicas de las series Inferior y Media del Grupo El Cobre en la Sierra Maestra (Cuba Oriental): volcanismo generado en un arco de islas tholeiítico

X. CAZAÑAS, J.A. PROENZA, G. MATTIETTI KYSAR, J. LEWIS, Joan-Carles MELGAREJO

Abstract


A set of 11 samples of igneous rocks from the lower and middle Cobre Group of the Sierra Maestra (SE Cuba) were analyzed. These rocks are volcanic and hypoabyssal bodies with porp hyritic texture and predominantly plagioclase phenocrystals. Their composition ranges from basalt to dacite and shows a tholeiitic trend with low K contents. The REE concentrations are low and, when normalized to chondrite, show a flat pattern with no relative enrichment in either LREE or HREE. In addition, these rocks present a slight enrichment in LILE and a strong Nb negative anomaly, typical of island arc tholeiites. Because of their geochemistry, the rocks of the Sierra Maestra are comparable to those of the Ke rmadec arc in the SW Pacific. Finally, the low REE content, the flat REE pattern, as well as the low uncompatible element contents, are similar to the IAT Series present in the Caribbean Volcanic Arcs. All these new data on the Pa l e ogene volcanism suggest that the tectonic models proposed for the origin of the Sierra Maestra Arc should be revised .

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