Geologia do depósito de ouro do alvo guarda-mor, na sequência Jaupaci (Israelândia - GO)

The study area of the Guarda-Mor target (Israelândia-GO) contextualizes the terrains of the estaern portion of the Arenópolis Magmatic Arc, more accurately, the Neoproterozoic associations inserted in the field of the Jaupaci volcano-sedimentary sequence. The mapped area is located in the central-western of Goiás state. The presente paper has as main objective to characterize the structural, petrographic and litogeochemistry of the target rocks beyond to compare these factors with the Mina Bacilândia rocks (Fazenda Nova-GO) in order to assess the genetic similarity of volcano-sedimentary units and deposits associated. The Guarda-Mor target is represented by the Jaupaci metavolcanic rocks sequence presenting bimodal volcanism. This sequence consists in metafelsic rocks like sericite/muscovite quartz schist, phyllite and metarriolites and/or metariodacites with calc-alkaline geochemical signature and metamafic rocks with tholeiitic character formed by actinolite - chlorite schist and chlorite - quartz schist. Besides the package of supracrustal rocks also can be observed the occurrence of a local intrusion syn- to late - tectonic named Granito Subvulcânico. In the study area beyond the marked volcanism also seen an event of crustal melting granitogênese evidenced by the presence of 2 granites at the east and the west of the map, Granito Israelândia and Granito Iporá respectively. Structural analysis both at the macro and micro have identified 3 deformation phases. The types of rock on the region record features in the metamorphic facies top and down. These features were subdivided into 3 metamorphic areas: the east and West areas show thermal metamorphism due to intrusion of adjacente granites while the central domain displays features of regional metamorphism. Gold mineralization of the Guarda –Mor deposit target suggests a possible structural control beyond pronounced the hydrothermal alteration. The mineralization may also be...

Mapeamento geológico, caracterização litoquímica e potencial econômico do corpo de cromitito de Cedrolina, Santa Terezinha de Goiás - GO

Studies of mafic-ultramafic bodies have been carried out through the years due to their great use on the interpretation of geochemical and geotectonic processes that took place in Earth's history. Amongst them, chromitites are notably recognized for being excellent indicators of their parental magma chemistry and of different geotectonic environments, as well for frequently containing associated noble metals mineralization. Thus the investigation of one of this ultramafic bodies that occurs inside the Pilar de Goiás Greenstone Belt was proposed, resulting in a detailed map of the chromitites and country rocks, as well as innumerous new data on the chemistry of chromite and associated matrix and accessory minerals. These studies were based upon geological field observations, optic and Scanning Electron Microscope (SEM), besides electron microprobe and cathodoluminescence analysis performed at the “Eugen F. Stumpfl Laboratory” of the Montanuniversität Institute of Resource Mineralogy, University of Leoben - Leoben, Austria. The chromitites are composed of 40-70% in volume of chromite (~50% on average), 14-55% of talc (~30% on average), 3-60% of chromium rich chlorite (~20% on average), traces to 4% of iron hydroxides and traces to 3% of rutile (1,5% on average). The chromite occurs as large spherical aggregates or as fine grained subhedral crystals disseminated in the matrix. This aggregates have diameters of 0.3-1.5 cm (1 cm on average) and are extremely well rounded, massive to intensively fractured, and commonly deformed to ellipsoids. When observed under the microscope, these aggregates show well rounded to slightly irregular borders, but on their interiors, these structures are represented by fine to medium grained euhedral to subhedral chromite crystals that have sharp contacts between themselves. The rock's matrix is basically made of chlorite and talc that define a metamorphic foliation (Sn), being the talc an alteration product ...

Mapeamento geológico e petrologia dos complexos máfico-ultramáficos de Mangabal Sul e Mangabal Norte, região de Sanclerlândia, Goiás

The Mangabal Sul and Mangabal Norte mafic-ultramafic complexes are interpreted as intrusive stratiform bodies in the Goiás Magmatic Arc during the Brazilian cycle, being economically important for harboring significant amounts of nickel and copper sulfides. The main lithotypes of the complexes are gabbronorites, olivine gabbronorites, pyroxenites and peridotites, with variated degrees of deformation, recrystallization and metamorphism superimposed, with metamorphic peak of amphibolite to granulite facies evidenced mainly by the occurrence of coronitic olivine in metamafic rocks and the occurrence of syn-kinematic retrometamorphism associated with the development of the main foliation Sn. The Sn foliation planes show NE-SW preferential direction, consistent with the foliation direction of VIII the enclosing gneisses and schists, also concordant with the general elongation of mafic and ultramafic bodies displayed on map. The sulfide phase presents textures that indicate remobilization, associated with the occurrence of significant amounts of rutile within the ore which reinforces this idea. Along with the sulfides, the occurrence of expressive quantities of titanium oxides such as ilmenite and rutile, make the area more economically attractive. It can be suggested that the Mangabal Norte and Mangabal Sul complexes are contemporary, have the same genetic affinity and suffered the same deformational and metamorphic processes, evidenced by their structural and petrological similarities

Datação por U-Pb em rutilos de rochas de metamorfismo de alta pressão do grupo Araxá na região de São Sebastião do Paraíso - MG

Although several studies of Araxá Group in the region of Passos, just a few works deal with the age of metamorphism of this group. The current work aims to determine the cooling age of these rocks by in situ U-Pb dating in rutiles. Interestingly, the region of São Sebastião do Paraíso shows a condensed lithostratigraphic column from the Passos Nappe and exposes the higher metamorphic grade rocks described for this unit. The use of rutile as a geochronometer is based on its ability to incorporate U in its structure, facilitating the calculation of the age of the isotope ratio by U-Pb. Furthermore, the use of in situ dating technique with Laser Ablation has been a reliable and advantageous study because the analysis are punctual, and do not destroy the whole sample to be analyzed. The analyses of this work were made at the University of Gothenburg - Sweden and obtained 238U/206Pb ages between 608-566 ± 10 Ma and 235U/207Pb between 627-572 ± 10 Ma, showing that these ages are concordant with the literature in the area and are interpreted as the cooling age of metamorphism

Geologia do alvo e da mina Sol Nascente, município de Rio Crespo, Rondônia

Eight Mesoproterozoic granite suites are recognized in the Rondônia Tin Province, called Serra da Providência Intrusive Suite (1606-1532 Ma), Rio Crespo Intrusive Suite (1500 Ma), St. Anthony Intrusive Suite (1406 Ma), Teotonio Intrusive Suite (1387 Ma ), Santa Clara Intrusive Suite (1082-1074 Ma) and Younger Granites of Rondônia Intrusive Suite (998-974 Ma), represent successive magmatic type A (anorogenic) and the intra-plate basement rocks intruded in the metamorphic complex named Jamari separated into two distinct lithologic associations, a ortogneiss (U-Pb from 1.76 to 1.73 Ga) and a paragneiss (1675 + / - 12 Ma). Tin mineralization are widely found in the Tin Province and are associated with granitic intrusions known Mesoproterozoic more closely with the last two magmatic events, represented by the Santa Clara and Younger Granites of Rondônia. The tin mineralization are of primary and secondary, with the primary form deposits of different structural styles and is presented in the form of endo-or exogreisens, veins, stockworks and pegmatites. The secondary mineralization are related to natural processes of weathering and erosion of primary rocks, leading to placer deposits classified as colluvial, eluvial and colluvial-alluvial. The Target Alvo Sol Nascente is located in the central-eastern Rondônia Tin Province and has basement rocks of the metamorphic-magmatic region represented by Jamari Complex intrusive suites and Sierra Providence and Rio Crespo. The last tectonic event spa in the area was responsible for the intrusion of Younger Granites of Rondônia (São Carlos and Caripuanã Massifis). The anomalous levels of tin, sufficient to operate (Mina Rising Sun), indicate that there was possibly mineralization event, evidenced by pegmatite veins well defined, easily found relatively close to mine. Plaque deposits associated with Quaternary sedimentary sequences can also be observed

Estudo do metamorfismo de rochas de alto grau do grupo Araxá na região de São Sebastião do Paraíso - MG

This study focuses on metasedimentary rocks from the Passos Nappe in São Sebastião do Paraíso, southern Minas Gerais, Brazil. These rocks belong to the Internal Domain (Araxa Group) of the Southern Brasilia Belt, a Neproterozoic orogenic belt associated to the formation of the Gondwana Supercontinent. Rocks from the studied area are characterized by an inverted metamorphic gradient. Previously calculated metamorphic conditions show an increasing from geenschist facies at the base (450°C, 6 kbar), to upper amphibolite facies (750°C, 11 Kbar) at the top of the sequence. However, most of these estimates are based on Fe-Mg exchange thermometers and peak temperatures may be underestimated due to Fe-Mg exchange from cooling after peak metamorphism. In this study, we present new PT results for these rocks, based on metamorphic mineral assemblage LA-ICP-MS analyses. In the studied area, rocks from the top of the sequence have a typical granulite facies mineral assemblage: Grt+Ky+Kfs+/-Pl+liq. These rocks lack muscovite and have only minor amounts of Ti-rich, dark brown biotite. In a simplified NaKFMASH system the stability field for this mineral assemblage is bounded by the reactions Sil = Ky on the low pressure side, Ms+Ab = Ky+Kfs+liq on the low temperature side and for high-Mg bulk compositions Bt + Grt = Opx + Ky + liq on the high-temperature side. Minimum temperatures (considering post-peak reequilibration) of ca. 750°C are obtained by Fe/(Fe+Mg) values of 0.7 in garnets from a Grt+Ky+Kfs bearing sample. LA-ICP-MS results obtained for three samples show that rutiles included in garnets have up to 1847 ppm of Zr, which would translate into temperatures up to 830°C for a pressure between 12 to 15 kbar. Also for retroeclogite sample, the results indicate the contents of Zr in the garnet 537 ppm at a temperature of 708 ° C. It is noteworthy that several occurrences of retroeclogites occur in the upper part of the sequence and pressures...

Análise estrutural e microtectônica da inflexão do jordino e depósitos de ouro associados no greenstone belt de Pilar de Goiás

The study area is included in the geological context of the Goias Median Massif, a region where there are associations of Archean granite-gneiss complex (Block Moquém) and a Paleoproterozoic metavolcano-sedimentary sequence ( Pilar greenstone belt ). At the south of area, the greenstone sequence is partially overlain by Neopreoterozoic metasediments of the Araxá Group. The lithostratigraphic units of the Pilar greenstone belt define a shift from about N30W direction (north of the deposit) to N60 and 70W in the region south of the Jordino deposit, where are truncated by the Araxá Group rocks. Mineralogical associations described in this paper allow to indicate that the regional metamorphism that affected the rocks of the greenstone belt and Araxá Group, in the mapped area, reached the upper greenschist facies (garnet zone). Data obtained during mapping and by microtectonics analysis allow to indicate the existence of at least four deformational events that acted on the rocks of the Guarinos greenstone belt and Araxá Group, represented by the phases called Dn-1, Dn, Dn + 1 and Dn+2. It was observed that the pattern of sulphide porfitoblasts in mineralized levels is similar to garnet, biotite and muscovite porfiroblasts (tardi to post Dn) that marks the metamorphic peak of the area

Palavras em desdobramento na poesia de Herberto Helder

No poema Em silêncio descobri essa cidade no mapa, inserido em A máquina lírica (1964), Herberto Helder desenha um contra mapa desnorteante com as palavras, que pulalam na travessia da escrita, deslocando-se incessantemente e ocupando diferentes posições nos versos. A proliferação dos vocábulos que se cruzam em novas combinações dão origem aos fios cambiantes que se dobram, redobram e desdobram-se no tecido da linguagem que objetivamos desfiar neste trabalho.

Atividade de fosfomonohidrolases presentes em fígado de girino de rã-touro (Lithobates catesbeianus) durante a metamorfose

Pós-graduação em Biotecnologia - IQ

Prospecção geológica e geofísica com ênfase em formações ferríferas na faixa meridional do Quadrilátero Ferrífero do Supergrupo Minas Indiviso

Pós-graduação em Geociências e Meio Ambiente - IGCE

Erosion rates and landscape evolution of the lowlands of the Upper Paraguay river basin (Brazil) from cosmogenic Be-10

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Prospecção geofísica entre as ocorrências cupríferas Capão Grande e Victor Teixeira, Caçapava do Sul - RS

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Tiouréia no desenvolvimento de girinos de rã-touro e no desempenho de animais pós-metamórficos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Gravimetria no estudo da extremidade sudeste da faixa de dobramentos Brasília

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo geofísico em aterro controlado disposto sobre rochas fraturadas

Geophysical survey is an important method for investigation of contaminated areas used in the characterization of contrasting physical properties in the presence of pollutants. This work applied the geophysical methods of Electrical Resistivity and Self Potential in waste landfill, located in Caçapava do Sul city, RS. The landfill is located over fractured metamorphic rocks. Eight lines of electrical profiling with 288 measures of self potential were done. In addition, 83 measurements of direction and dip of fractures were taken. The application of spontaneous potential method permitted to detect the direction of groundwater flow. The electrical resistivity measurements allowed the identification of low-intensity anomalies associated with the presence of leachate. There is a relationship between anomalous zones and the directions of fractures.