Viabilidade de aplicação das coberturas argilosas da região de Alfenas na indústra cerâmica

The region of Alfenas, in the state of Minas Gerais, Brazil, is predominantly constituted of Pre-Cambrian rocks with well developed alteration profiles in association with colluvial and alluvial sediments. No study to date has examined in detail its potential use in the ceramic industry. The scarce knowledge of its mineralogical and technological properties limits its value and consequently its industrial use. Until now, these clay materials have been used in a rudimental manner, in small scale in the fabrication of red tiles. The present study aimed at analyzing these clays mineralogically (X-ray diffraction), chemically (major and minor elements by X-ray fluorescence and organic carbon analysis) and technologically (pressing granulometric distribution; mechanical resistence; water absorption, apparent porosity; linear firing shrinkage; color of firing and others) in order to better understand the raw material and develop adequate technological applications. The best results of ceramic properties were the samples with higher organic content (more plastic clays) and higher values of Al2O3 (kaolinite and gibbsite) and Fe2O3 as well lower SiO2 content and finer grain size which contribute to a better sinterization.

Parâmetros físicos pré-eruptivos do magmatismo ácido da província magmática do Paraná: Resultados preliminares

A set of 12 samples of acid rock types Palmas (ATP) and Chapecó (ATC) was used to determine the chemical composition of plagioclase and pyroxene by electron microprobe, with the purpose to get information about the pressure and temperature of crystallization of these rocks. The results show that the pyroxene of ATP rocks (3,2 ± 1,2 kbar, max = 5,1 kbar and 1028 ± 38°C) were formed under pressure conditions higher than those ATC (1,8 ± 0,9 kbar, max = 3,4 kbar and 995 ± 26oC). However, the pressures obtained from plagioclase showed higher pressures for ATC (3.2 ± 1 kbar, max = 6,4 kbar and 1033 ± 12°C) than ATP (1,9 ± 1 kbar, max = 4,8 kbar and 1043 ± 5°C), suggesting that the crystallization of rocktype ATP began with the formation of pyroxene and plagioclase almost simultaneously at a depth of around 17 km while the ATC, began with the crystallization of plagioclase at a depth of about 21 km (assuming a gradient of 3,3 kbar/km). The geothermometry of plagioclase allow us to calculate the concentration of water from about 1 ± 0,3% H2O for both acid rock types. Additional calculations allow us to get the depth of water exsolution of magmatic liquid at 30m below the surface. Although the data are still preliminary and insufficient to model the extrusion of these rocks, they point out to an effusion mechanism of a partially fluidized magma by volatile, which would spread to large areas with small friction with the surface that would increased with the increase of viscosity caused by the loss of volatile and decreasing of temperature, developing coherent structures as lava flows.

Magmatismo do batólito rapakivi Rio Branco, sw do Cráton Amazônico (MT)

Rio Branco Rapakivi Batholith is located on the southwestern portion of the Amazonian Craton in Mato Grosso and belongs to the Cachoeirinha Tectonic Domain, part of the Rio Negro-Juruena Geochronological Province, Central Brasil. The batholith is constituted by microgabbros to quartz microgabbros and microdiorites to quartz microdiorites, middle to fine-grained equigranular to porphyritic varieties form the Rio Branco Intrusive Basic Suite, showing a discontinuous distribution and located near the margins of the intrusion.Majorly constituted by porphyritic, granophyric and isotropic facies of Rio Branco Intrusive Acid Suit which is composed by older dark red rapakivi monzogranites to quartz monzonites and quartz sienites (1403±0.6 Ma) and the younger red rapakivi leuco-monzogranites (1382±49 Ma) and late equigranular to pegmatitic monzogranites. The magmatism is constituted by two distinct magmas related to the end of the collisional event of Cachoeirinha Orogeny, one with alkaline basalts generated in an intraplate environment and the other postorogenic to anorogenic with peraluminous to metaluminous compositions and define a high-K calc-alkaline to shoshonitic magmatism in transition among the I- and A-types. The contacts are marked by extensive mafic sills and dikes of alkaline basalts derived from intraplate environment of the Salto do Céu Intrusive Basic Suite (±808 Ma) associate to the Sunsás-Aguapei Orogenic Belt and metasedimentary rocks of the Aguapeí Grup.

Investigação tecnológica de arenitos silicificados da Formação Botucatu (ne do Paraná) para uso como rocha de revestimento

For many years the silicified sandstone associated of the Botucatu Formation has been the target of interest to researchers and miners, either for understanding the genesis of silicification or for your use as dimension stone and covering on the building industry. If in the first there are several articles available in the geological literature the second there are only technical data marketing available. In the northeast portion of the Paraná State and southwest of the São Paulo State these rocks are mined and traded as covering stones. Not much is known about their intrinsic characteristics and technological properties. To improve the knowledge of the technological behavior of these materials, samples from a quarry from Ribeirao Claro region were petrographically and physically characterized according to the standards established by the Brazilian Association of Technical Standards to dimension stones. Therefore, two bulk samples of silicified sandstone of the Ribeirão Claro/PR region were studied and characterized following the norms established by Brazilian Association of Technical Standards for dimension stones. The results obtained in the petrographical and technological studies are presented and indicated that, in general, the technological performance presented by sandstone studied induces limitations of use as covering materials, mainly horizontally as pavements, door stone and step ladder.

Geotermobarometria de Granulitos Associados à Supracrustais na Porção Norte do Complexo Guaxupé - Região de Arceburgo - Santa Cruz do Prata, MG

This paper is a contribution for the understanding of the geological evolution of Guaxupé Complex. New data on petrography and mineral chemistry as well as estimates of metamorphic (P-T) conditions in the region of Arceburgo - Santa Cruz do Prata (MG) Brazil, at the southern portion of the Brasília Belt, more specifically at the Guaxupé Complex (Domain) are now presented. The lithotypes are high-grade metamorphic rocks subdivided into two groups: metasediments and granulites (orthoderivates). Chemical analysis of minerals was performed in three steps including core and rim of amphibole, pyroxene, feldspar, biotite, and garnet from samples of the following rock types: enderbites, mafic granulites, charnockites, and alkali feldspar charnockites. Results obtained with geothermobarometric calculations show metamorphic peak around 900°C of T and 10 kbar of P. Enderbites and tonalite granulites (mafic) show the highest values of temperature and pressure, while alkali feldspar charnockites show the lowest probably due to their late generation in relation to mafic rock types (enderbites and mafic tonalite granulite). Chemical mineral analysis in metamorphic parageneses and geothermobarometric calculations indicate that the possible metamorphic peak may be higher than 900°C of temperature and around 10 kbar of pressure, within a isothermal decompression (ITD) regime.

Polarização induzida aplicada no estudo de ocorrencia de cobre localizada a nordeste de Caçapava do Sul (RS)

Mineral research works are fundamentals for recognition and incorporation of new reserves. This paper present an integrated analysis of geologic and metallogenetics data, with results gotten from the application of the Induced Polarization geophysical method, in an copper ore occurrence, inserted in Camaquã sedimentary basin, situated in northeast of Caçapava do Sul city (RS). In area ocurr arkosean arenites average coarse, the intensely silicified and recrystallized, pertaining to Passo da Promessa Formation. The presence of azurita and malachite in breakings and high porosity zones of the host rock characterizes the mineral occurrence in surface, located in the crossing two fault families. The inversion models indicate the predominance of high chargeability in vulcanics tuff, rock of high porosity in relation to the andesites and metaconglomerates gifts in the area. The strong structural control of the mineral occurrence associated the high chargeability in volcanic tuff is indications of the hydrothermal fluid access by means of faults, until rocks with great porosity, where it occurred disseminations of copper sulfides in depth and carbonates in surface.

Suíte plutônica Alumiador, grupo Amonguijá, maciço rio apa - MS

The Rio Apa Massif corresponds the southern portion of the Amazon Craton and is located in the southwest of Mato Grosso do Sul State. It consists on Paleoproterozoic rocks of Rio Apa Complex, Alto Tererê Group and Amonguijá Group, is subdivided into Alumiador Plutonic Suite and Serra da Bocaina Volcanic Suite. The volcanic suite is comprises sub volcanic, volcanic and varied volcanoclastics rocks with composition ranging from alkali-rhyolitic to rhyolite types. The plutonic suite corresponds to an N-S elongated batholith and is characterized by four main segments delimited by NW-SE faults. The southern and central main segments, discussed in this paper, are characterized by the following petrographic facies: medium to fine grained hornblende-biotite monzogranites, coarse grained biotite monzogranites, graphic biotite sienogranites and muscovite sienogranites and the northern segment is contemporaneous and is composed of two different sequences of rocks, one acid and another of basic to ultrabasic composition. The southern and central segment consists of to chemically compatible rocks with the types I and A Granites. These are calc-alkaline rocks of high potassium to the shoshonitic and subalkaline. Constitute sin-collisional granites of metaluminous the peraluminous characters of the Amonguijá Magmatic Arc, but they exhibit late litotypes with chemical characteristics of post tectonic granites from intraplate environment.

Relação do meio físico com o manejo sustentável de plantio de eucalipto em áreas de terrenos acidentados - A Fazenda Santa Edwirges, Vale do Paraíba, Sudeste do Brasil

This study intends to evaluate the effects of landscape physical elements (rocks and relief) associated with silviculture activities. The study was carried out on a small farm (Fazenda Santa Edwirges) covered by Eucalyptus forested situated in the Paraiba do Sul Basin, Southeast Brazil. The methodology consisted of detailed geological and geomorphological studies at 1:10,000 scale, and laboratory analysis of soil physical properties. The results showed three geologic-geomorphologic associations (ridge escarpment with granitic rocks, steep and gentle hills cut by shear zones and gentle hill with alluvial sediments) present high vulnerability for the development of the physical processes such as accelerated erosion landslides and flooding. In contrast, mountains associated with gneissic rocks present smaller vulnerability and high resilience for the development of the physical processes. The results have showed the importance of considering the interactions among landscape physical for the eucalyptus forest management contributing to a better selection area for eucalyptus cultivation and minimize adverse environment impact in road design.

Fontes e doses de potássio na cultura do café (Coffea arabica L.)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Dinâmica da qualidade da água em tanques de peixes de sistema pesque-pague: aspectos físico-químicos e plâncton

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Síntese e caracterização de partículas de poli(álcool vinílico) utilizadas em aplicações biomédicas: contribuição da análise fractal e entropia de Shannon

Pós-graduação em Biofísica Molecular - IBILCE

A diversidade morfológica da ictiofauna reflete a estrutura do hábitat em riachos?

Pós-graduação em Biologia Animal - IBILCE

Efeitos da textura e heterogeneidade de substratos artificiais em função da velocidade da correnteza e da escala temporal sobre as comunidades de macroalgas de ambientes lóticos

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

'Ti''O IND.2'/'Sn''O IND. 2 modificado com 'Ag IND. 2''O', para obtenção de fotocatalisadores

Pós-graduação em Química - IQ

Efeito da moagem em moinho de bolas e do tratamento térmico com baixa umidade sobre as características estruturais e físico-químicas dos amidos de mandioca e mandioquinha-salsa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)