Abstract
The Varzea Alegre Intrusive Complex is an example of a late to post-tectonic bimodal pluton in the central-southern portion of the Ribeira (Costeiro) Mobile Belt in the State of Espirito Santo, Southeast Brazil. It has an outer charnockitic ring which is enclosed by high amphibolite grade to granulitic rocks. This outer ring was intruded by two different calc-alkalic rock series: a medium-K, represented by hypersthene-gabbros, monzogabbros, quartz-diorites and quartzmonzodiorites, and a high-K, represented by megaporphyritic granitic rocks. Geochemical data from the medium-K calc-alkalic rocks show consistent incompatible element enrichment, mainly of Ba, Sr, La, Ce and Pb, The HFS elements are depleted and Zr, Hf and Ti show similar concentrations to N- type MORB rocks. The parallel REE pattern exhibited by the basic and intermediate rocks, associated to the gradual increase of REE-contents in the late, point towards their cogenetic link. A less evolveu fractional crystallization process is backed by the absence of negative Eu anomalies. The geochemical signature of the granites suggests an origin from the partia! melt of the continental crust. Nevertheless evidence of restricted mantle contribution is indicated by the similarity between REE patterns from basic, intermediate and granitic rocks. Negative Eu anomalies are however restricted to the granitic rocks. The interaction between mantle-derived and crustal magmas yielded calc-alkalic basic and intermediate rocks.
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