Abstract The Capelinha Formation (Macaúbas Group) consists of a lower quartzitic unit with metamafic intercalations and an upper metapelitic sequence. It occurs in a complex tectono-metamorphic sector of the Araçuaí orogen, where post-collisional collapse-related structures superimposed collisional structures. The garnet-bearing assemblages started crystallization in the collisional deformation stage that formed the main regional foliation around 570 Ma. Garnet porphyroblasts display a well-developed growth zonation of Fe-Mg-Ca-Mn and show, from core to rim, increasing almandine and pyrope contents in contrast with decreasing grossular and spessartine contents. Mineral relations and microstructures provide criteria for local equilibria and a structurally controlled application of geothermobarometers based on cation exchange and net transfer reactions. The P-T values calculated from cores to rims of garnets, aligned along clockwise trends, resulted in increasing temperatures (from 500 ºC up to 620 ºC) under decompression conditions (from 8.0 kbar to 4.5 kbar). The Th-U-Pb dating of homogeneous monazites by electron microprobe revealed a recrystallization period at around 490 - 480 Ma. These ages can be related to the tectono-thermal event associated with the gravitational collapse, constraining the youngest time limit for metamorphic processes in the Araçuaí orogen.

Sugarcane (Saccharum spp.) is an efficient and sustainable alternative for energy generation compared to non-renewable sources. Currently, during the mechanized harvest process, the straw left in the field can be used in part for the second generation ethanol and increasing the electric energy production. Thus, this study aimed to provide information on the potential for residual biomass cultivars of sugarcane cropping system. This study provides the following information: yield of straw, depending on the calculated leaf area index and the number of tillers per linear meter; primary energy production of several sugarcane genotypes; contribution of dry tops and leaves; biomass yield; and evaluation of fiber, cellulose, hemicellulose and lignin. Preliminary results obtained by researchers of the State of São Paulo, Brazil, and reCviews related studies are presented. The results suggest that the production of sugarcane straw content varies according to the cultivars; the greater mass of sugarcane straw is in the top leaves and that the potential for the crude energy production of sugarcane per area unit can be increased using fiber-rich species or species that produce more straw. The straw indexes was shown to be a good indicator and allow the estimation of straw volumes generated in a sugarcane crop. The cellulose, hemicellulose and lignin composition in sugarcane is distinct among varieties. Therefore, it is possible to develop distinct biomass materials for energy production and for the development of sugarcane mills using biochemical processes and thermal routes.

Ofiolitos são fragmentos de antigas litosferas oceânicas formados em margens de placa construtivas ou divergentes transformantes. Por meio de extensos falhamentos de empurrão, esses corpos ou parte deles são colocados na crosta continental, dentro de pacotes de rochas dos cinturões orogênicos, em estado sólido, mas podendo estar, ainda, relativamente quentes. Os possíveis ambientes produtores de litosfera oceânica incluem cadeias meso-oceânicas, bacias relacionadas a arcos-de-ilhas juvenis e bacias de retroarco. Ofiolitos de idade fanerozoica são abundantes em cinturões orogênicos ao redor do mundo, enquanto que os remanescentes oceânicos do Pré-Cambriano são pouco comuns e encontram-se distribuídos, principalmente, na Finlândia, Canadá, Marrocos, Arábia Saudita, Egito, Rússia, Brasil e China. Diversos registros de remanescentes oceânicos pré-cambrianos de diferentes idades foram reconhecidos no Brasil. A maioria desses corpos situa-se nas faixas orogênicas brasilianas e registra o consumo dos oceanos neoproterozóicos. A partir do que foi exposto, esse trabalho procura sintetizar as principais informações acerca de sequências ofiolíticas, trazendo uma breve revisão de conceitos e classificações ao longo dos quase 200 anos de utilização desse termo.

Ophiolites are fragments of the ancient oceanic lithosphere formed at constructive plate margins or transforming divergent plates. Through extensive thrust faults, these bodies or part of them are emplaced into the continental crust, inside rock piles of orogenic belts, in solid state, but these bodies can be relatively warm. The possible environments which produce oceanic lithosphere include meso-oceanic ranges, basins related to juvenile island arcs and retro-arc basins. Ophiolites of the Phanerozoic age are abundant in orogenic belts around the world whilst Precambrian oceanic remnants are less common and are distributed mainly in Finland, Canada, Morocco, Saudi Arabia, Egypt, Russia, Brazil and China. Several registers of Precambrian oceanic remnants of different ages were recognized in Brazil. Most of these bodies are situated in Brazilian orogenic belts and they register the consumption of the Neoproterozoic oceans. This paper aims to synthetize the main information about ophiolitic sequences, bringing a brief review of concepts and classifications along the 200-year use of this term.