Optical physics applied to mineralogy becomes a complex concept, since it is based on concepts of refractoriness of isotropic and anisotropic materials, dependent on crystallographic parameters. The work aims to materialize these concepts in threedimensional schematic models in wood, such as optical indicatrix and figures of interferences, generated when the plane polarized or polarized light interacts with several transparent minerals. The pieces were applied in the classes of Mineralogy II of the Geology course of the Federal University of Espírito Santo in the years 2017 and 2018, presenting great receptivity by the dissenting body and ease in the profusion of the knowledge of the group of monitors and teachers. The geometric representations were also shown in workshops at the Natural History Museum of Southern Espírito Santo State with the objective of disseminating the geosciences. As a result, the classes obtained satisfactory results of approval and learning

Neoproterozoic-Cambrian rocks from the Oriental Terrane and the Central Superterrane of the Ribeira Belt occur in northwest of Rio de Janeiro state. This paper presents new data on field research, petrology, mineral chemistry and conventional geothermobarometry, fundamental to understanding the geology of the region. The metabasic rocks from the Cambuci Domain are associated with the Central Superterrane retroarc basin and record two metamorphic events: M 0 (before the formation of the main foliation, under conditions of 788 °C) and M 1 (contemporary to the main foliation, with peak at 718-752 ºC and 6.62 kbar). The rocks from the Costeiro Domain, interpreted as the Rio Doce arc (Angelim Suite) and the retroarc basin (São Fidélis Goup) of the Oriental Terrane record a metamorphic peak at granulite facies yielding the highest pressure and temperature among the studied domains (752-784 °C and 8.2-9 kbar). The Italva Domain amphibolites represents the retroarc basin of the Oriental Terrane. Temperature and pressure values obtained for the Italva Domain metamorphic peak record 731 ºC and 6.78 kbar, respectively, in the transition zone between upper amphibolite and granulite facies conditions. This work presents the newest record of metamorphic evolution for the Oriental Terrane of the Ribeira Belt, suggesting an anticlockwise P-T-t path and near-isobaric cooling (IBC) for the rocks of the Cambuci Domain. Therefore, these results contribute to the understanding of the evolution of orogenic belts during the amalgamation of the Gondwana in the Neoproterozoic.

Na região norte do Rio de Janeiro afloram rochas orto e paraderivadas neoproterozoicas de alto grau metamórfico, englobadas no Terreno Oriental da Faixa Ribeira. Dado a carência de estudos de detalhe na região, o presente trabalho contribui com novos aspectos de campo, petrografia, química mineral e geotermobarometria dos granitoides diatexíticos aflorantes na região entre São José de Ubá e São João do Paraíso, no noroeste fluminense. O litotipo é caracterizado por biotita-hornblenda gnaisses migmatíticos e protomiloníticos que são correlacionáveis a ortognaisses e granulitos do Complexo Serra da Bolívia (Domínio Cambuci da Faixa Ribeira). Dois litotipos neoformados são observados: um mesocrático, de caráter residual; e outro leucocrático, que correspondente ao leucossoma. O enriquecimento de K-feldspato no leucossoma em relação ao neossoma residual sugere baixos volumes de fusão por meio de reações de fusão envolvendo água. Aplicando-se diferentes geotermobarômetros, foram obtidas como condições de equilíbrio para o pico metamórfico 6,8 Kbar e 672–680°C (fácies anfibolito superior). Tais valores destoam dos encontrados na literatura para ouras rochas da região, reforçando a ideia de que os domínios do Terreno Oriental da Faixa Ribeira apresentam evoluções metamórficas distintas, em diferentes níveis crustais.

O presente trabalho traz a experiência da confecção de uma maquete geológica na escala de 1:20.000 da Serra do Caparaó, monumento geológico complexo do sudeste brasileiro, com o objetivo de ilustrar aspectos da geologia regional e definir uma rotina para construção de maquetes didáticas. Para tanto, foram utilizados dados de campo e dados espaciais em ambiente SIG para projeção do relevo sobre placas de isopor a partir de curvas de nível. Os resultados da confecção da maquete compreendem um modelo tridimensional da geologia da Serra do Caparaó e a proposta de um roteiro para confecção de maquetes didáticas. As primeiras exposições da maquete ao público proporcionaram boa interação da sociedade com as informações geológicas da região, com a introdução de conceitos de Geomorfologia, Geologia Estrutural, Cartografia e Geodiversidade.

Collisional granites of the Araçuaí Orogen, southeastern Brazil, record petrological and geochronological evidence for multiple crustal melting during the orogeny evolution. U-Pb zircon data indicate that these granites crystallized at 586 ± 2 M.y.High-grade metamorphism (M 1 ) involved partial melting by fl uid-absent reactions that produced the fi rst generation of garnet in temperatures of approx. 750°C. Preservation of the mineral assemblage A 1 (garnet-biotite-plagioclase-K-feldspar-quartz-ilmenite-melt) indicates that most of the generated melt was lost from these rocks at or near peak metamorphic conditions. A second metamorphic event (M 2 ) is characterized by growth of a second generation of garnet in preserved A 2 assemblage (garnet-sillimanite-biotiteplagioclase-K-feldspar-quartz-ilmenite-melt). Mineral equilibria modeling constrains conditions of M 2 metamorphism to 713-729 °C and 6.2-7.3 kbar. Retrograde assemblage (A 3 ) records equilibrium conditions at 610-660 °C. The Hf isotope composition indicates signifi cant crustal contribution to the genesis of the collisional granites. The elevated geotherms in thickened crust provide enough heat for the M 1 event at 562 ± 2 M.y.Subsequent heating probably associated to the transfer of mantle heat to the crust during the extensional thinning and gravitational collapse of the orogen lead to the M 2 event at 526 ± 4 M.y. This event is concomitant to the emplacement of the postcollisional magmas in the orogen.