Quarry with evidence regarding the origin of enderbites through alteration/metasomatism of the gray metaigneous gneisses. Here a homogeneous tonalite to granodiorite (probably G1) has been partially remolten to generate leucocratic veins. Several irregular domains of enderbite in a metatonalitic to metagranodioritic rock can be observed on a much larger scale. The gneiss carries some poikilitic microcline porphyroblasts, in an oligoclase-quartz-biotite-matrix of tonalitic composition. In the green domains of the metatonalite, where the rock is changed into an enderbite, relicts of metamorphic clinopyroxene are usually found. A later phase of retrometamorphism caused the replacement of clinopyroxene by hornblende and biotite, illustrating the change of H2O/CO2 fluid conditions during metamorphism.
In this Outcrop there is:
the gradational evolution of kinzigite towards augen gneissic layers of granodioritic and granitic composition;
in situ dehydration melting of the metasedimentary pile. A package of sillimanite-cordierite-garnet-biotite gneiss (kinzigite of the Ubu series, Paraíba do Sul Complex similar to outrcrop 2) has undegone partial dehydration melting to form more homogeneous tonalitic to granodioritic layers ascribed to G2. The northern part of the Outcrop contains calc-silicatic layers and lenses (Ubu series) and records amphibolite facies conditions. In the southern part of the Outcrop, the general texture of the rocks changes gradually into an igneous texture and a more homogeneous hypesthene-rich and garnet-poor enderbite suite crops out. Large microcline porphyroblasts are common and account for more K-rich compositions.
Local ductile shear zones with granitic neosome cut the package. The last magmatic event in this area is related to the intrusion of post-kinematic fine- to medium-grained granites and pegmatite veins.
An homogneous granitoid gneiss can be observed along the stairs to the Perocão beach. This Outcrop depicts, in a small scale, the complexity of the geology in the area (fig. 6). The dominant lithology is a G2 suite metagranitoid (augen amphibolitic gneiss from the Costeiro Complex) with G2 enderbitic portions. Two augen-gneiss types were described in the area: 1) a zircon-cordierite-garnet-biotite-quartz-plagioclase (An23-25), and 2) an apatite-zircon-amphibole-plagioclase (An28-43) gneiss. Both grade into hypersthene-bearing enderbitic rocks (Teixeira, 1998). A retrometamorphic event is depicted by the replacement of hypersthene by biotite and amphibole. The gneiss package is locally interlayered with leucogneiss (biotite-poor-garnet-quartz-microcline-plagioclase gneiss or leptinite) and biotite- garnet-quartz-microcline-plagioclase gneiss. Gneisses in this Outcrop are partially molten giving rise to migmatites. Walking along the Outcrop, local K-feldspar augen gneiss grades into quartz-feldspar-garnet gneiss layers, so that augen-gneiss bands alternate with leptinites. The predominant gneissic foliation is E-W / NE-SW (Fig. 6). Ductile N-S shear zones are the usual paths for these intrusions. G2 enderbitic gneisses are interlayered with amphibolitic gneiss, in a similar situation (as in Fig. 5). Along the ductile shear zones, probably due to local H2O-rich fluids, a retrometamorphism process may be observed in the granulitic rocks. Younger tonalitic/granodioritic dykes and sills, containing granitic and/or pegmatic schlieren, intrude the Outcrop and are considered to be related to the bimodal post-collisional magmatism (G5). This region seems to be a magma-collecting zone for the late intrusion of G5 granitoids. This is clearly depicted on the detailed map on Fig. 6. N-S trending younger intrusions in the amphibolet/biotite gneisses are pegmatite richer, while granodiorite/tonalite batches concentrate closer to the green hypersthene-rich patches (enderbitic suite).