From migmatite to magma - crustal melting and generation of granite in the Camboriú Complex, south Brazil

Abstract

Partial melting of continental crust and granite genesis were investigated in the Camboriú region, south Brazil. Structural geology and geochemistry were used in order to characterize the link between the high Ba-Sr Itapema Granite (IG) and the syntectonic melting of orthogneisses and amphibolites of the Camboriú Complex (CC). The IG is a sheet-like intrusive body of biotite monzogranite to granodiorite with large amount of migmatitic amphibolite and gneiss xenoliths, and a well-developed magmatic foliation concordant with the main gneissic banding. Discordant, m-thick granitic dykes which crosscut the migmatitic sequence and transport magma and xenoliths to feed the IG main body mark the transition from the migmatitic to the magmatic system within the complex. Whole-rock geochemical data reveal important contamination and assimilation processes of xenoliths during IG magmatic flow which give rise to different facies and geochemical signatures. The generation of the IG is an example of a continuous exposure from source to sink formed through a continuous and efficient deformation-driven melting/extraction/transport system generated during coeval folding and anatexis of the CC metamorphic sequence.