THE GRANITE ROCKS S-TYPE OF STOCK PILAR DO SUL, SOUTHEAST OF THE STATE OF SÃO PAULO

S-type granitic rocks of Pilar do Sul Stock, Southeast of the São Paulo State

Abstract

The Neoproterozoic granitic rocks of the Pilar do Sul Stock outcrop in the municipality of Pilar do Sul, in the southeast region of the state of São Paulo and are related to the magmatism evolution of the Agudos Grandes Granitic Batholith, linked to the Cotia Block, of the Apiaí Terrain. It is a body of 35 km² with an elongated shape according to the general NE-SW direction, imposed by the Taxaquara Shear Zone deformation and intrusive in rocks of the metavolcanic-sedimentary sequence of the Votuverava Group of the Açunguí Supergroup. The rocks are represented by varieties of of sieno- to monzogranite, predominantly isotropic to locally anisotropic, with light pink and light gray color, dominating the inequigranular equi- a types of medium to coarse graining and rarely the porphyritic types. The hololeucocratic types predominate with the presence of aluminous minerals such as biotite and muscovite and rare garnet and tourmaline. They are rocks with contents above 71% of SiO₂, high percentages of Al₂O₃ and K₂O and negative anomalies of Rb, Ba, K and Sr, as well as negative anomalies of P, Zr, Ti, high values of Th and U, enriched in light rare earth elements in relation to heavy ones and negative anomalies of europium. They are high-potassium peraluminous leucogranites associated with a post-collisional environment of continental magmatic arc, with a signature of two micas granite type S, generated by the partial crustal fusion deep crustal levels of metasedimentary rocks, associated with the transtensive structures of the shear zones of the end stabilization of the Apiaí Terrain at of the collisional event of the Ribeira Orogenesis