The meaning of felsic microgranular enclaves in the evolution of granitic magmas: petrology of enclaves in the Salto Granite, State of São Paulo

Abstract

Felsic microgranular enclaves are abundant in the ~585 Ma Salto Pluton (Itu Granitic Batholith, São Paulo), and bring important information about the evolution of the magma chamber. In order to characterize them and understand their petrologic significance, this work will initially focus on field aspects, mainly the geometry of the granitic facies, their contact relationships, and the structures and distribution of felsic microgranular enclaves within the pluton. This information will make it possible to evaluate their physical meaning (new magma pulses? chilled margins? products of in situ remelting?). The mineralogical and geochemical diversity of the enclaves will be characterized through petrographic analyses, whole-rock major and trace element geochemistry and Sr-Nd isotopy. Together with the mineral chemistry of the main minerals (feldspars, amphibole and biotite), these results will be used to compare enclaves and host rocks in terms of crystallization conditions, source areas and genetic links.