Abstract

GREGORI, D.A.; GRECCO, L.E.  and  LLAMBIAS, E. J.. The López Lecube intrusive: evidence of Gondwanic alkaline magmatism in south-western Buenos Aires Province, Argentina. Rev. Asoc. Geol. Argent. [online]. 2003, vol.58, n.2, pp.167-175. ISSN 0004-4822.

The Permian López Lecube intrusive crops out in south-western Buenos Aires province, and is isolated from other igneous or sedimentary rocks. It consists of syenitic and granitic suites, composed mainly of quartz, K-feldspar, hornblende, plagioclase and subordinate titanite, biotite and apatite. The geochemical characteristics of the syenitic suite indicate that it was derived from mantle magmas with peralkaline and metaluminous signatures. The rocks are enriched in LILE and depleted in HFSE. The granitic suite shows slightly metaluminous to peraluminous compositions, indicating the participation of a crustal component in its genesis. The granites are not derived via crystal fractionation from the syenitic suite. The López Lecube intrusive event can be correlated with the magmatic Gondwanic cycle developed in La Pampa and Mendoza Provinces, on the basis of similarities in age and geochemical characteristics.

Keywords : López Lecube; Alkaline magmatism; Gondwana; Argentina.

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