AN EXTRUSIVE-PLUTONIC EVENT AT HARDY POINT AND ITS VICINITY GREENWICH ISLAND ANTARCTIC

DELIA DEL PILAR M. DE ALMEIDA, ADRIANE MACHADO, MARCOS A. F. HANSEN, HENRIQUE FENSTERSEIFER, LARISSA DE LIMA, CRISTIANE H. GOMES

Resumo


The volcanic and intrusive rocks at Hardy Point and its vicinity were formed mainly during a Mesozoic magmatism. Andesiticbasalt flows and andesites constitute the volcanic rocks. The intrusive ones were expressed as an epizonal body, with dioritic to granitic composition, and are cogenetic to the volcanic ones. The geochemical patterns indicate that volcanism preceded plutonism. In rare earth elements diagram the intrusive rocks present a further developed pattern, in which all rocks show calc-alkaline affinity, an enrichment in light rare earth elements relative to the heavy ones, probably due to partial melting of the mantle. In the spidergram (LILE, HFSE) the same pattern is observed for all rock groups, with strong negative anomalies of Ti, P and Nb, typical of island arcs, besides a positive anomaly of Ce, which could be related to the assimilation of Ce-enriched marine sediments.

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