Geochemical Study of the Itabirite Iron Ores of the Alegria Mine - Quadrilátero Ferrífero, Minas Gerais, Brazil

The iron ores of Alegria mine are composed of itabirites enclosing minor bodies of high-grade ores. The itabirites are classified according to mineralogical composition in five types: martite-rich, goethite-rich, specularite-rich, magnetite-rich and anphibolite-rich ores. The hematites are martite-rich, magnetite-rich, specularite-rich and more rarely, amphibolite-rich. Other classification criteria of the ores are based on the physical properties and the degree of compaction. As such, the itabirites and hematites can be classified as hard, friable and soft types. The mineralogical/textural evolution of the ores is linked to the pressure and temperature conditions that accompanied the tectonic processes in anphibolite facies and the different degrees of subsequent surficial weathering processes. Petrographic and microstructural studies indicate that the magnetite and amphibole bearing itabirites represent the parent rocks that created the other itabirites and that the specularite itabirites and the hard martite types are related to silica dissolution and redeposition in zones of high and low strain. Most of itabirites ores correspond to chert oxide facies banded iron formation, except the goethite and amphibole bearing itabirite that resemble a silicate or oxide-silicate facies with minor carbonate impurities. The great mass and pods of soft martite itabirites are probably shaley oxide facies BIFs with little volcanic contribution. Trace element contents of the Alegria's itabirites show strong dissimilarities with BIFs associated with volcanism (Algoma type), but closely ressemble to the Lake Superior type, with high content in Cr, Co and low V, Ni, Cu and Zn. Although the absolute contents of REE present in the Alegria's itabirites are, in general very low, the pattern when normalised by NASC is similar to the great majority of the Archean and Paleoproterozoic BIFs elsewhere in the world, and characterised by positive Eu anomaly.

Interações entre aves frugívoras e plantas em um fragmento de mata atlântica de Minas Gerais

We studied the frugivorous birds and their fruiting plants during two years in a forest fragment in Viçosa, Minas Gerais State, Brazil. Our aim was to identify the importance of birds and plants based on an importance index that comprise both the number of interactions and interaction exclusiveness. Twentynine bird species and 25 plant species were recorded. Small birds (< 100 g) comprised 85% of the interactions, and Chiroxiphia caudata reached the largest importance index (0.296), with 12 interactions, being six exclusive. Among plants, the melastome Miconia cinnamomifolia reached the largest importance index (0.277), interacting with 72.4% (21) of the bird species. This study showed that seed dispersal by small birds couldn't be underestimated because they disperse seeds of many plant species, even in pristine forests. Studies like this are also important to list the main food resources to frugivorous birds that could be used in management plans.

Diversidade florística de plantas vasculares no município de Januária, Minas Gerais, Brasil

The vegetation in north Minas Gerais State is poorly known, and for some authors it is the southern limit of natural occurrence for 'carrasco' and 'caatinga' species. Floristic sampling was made in different areas of Januária municipality, Minas Gerais, including physiognomies of 'carrasco' (tree-shrub 'caatinga'), deciduous forest, 'cerrado', floodable field and riparian vegetation ('vereda'), besides calcicolous vegetation. Six-hundred-eight species in 114 families were found, the five most diverse families were Fabaceae (87 species), Asteraceae (35 species), Euphorbiaceae (28 species), Bignoniaceae (25 species), and Malpighiaceae (21 species). The sampled vegetation included a diversity of vegetation forms. The most diverse areas were the 'carrasco' and the deciduous forest (274 species), secondary vegetation along roads and trails, and pastures (160 species), 'cerrado' (105 species), 'vereda' (98 species), and calcicolous vegetation and riparian vegetation (78 species each). Compared to other floristic surveys performed in northeastern Brazil, even considering only the woody component (tree and shrubs with 323 species), these results highlight the floristic and physiognomic diversity of the studied area. © 2005 Instituto de Ciências Biológicas - UFMG.

Erosão hídrica de Latossolo Vermelho muito argiloso relevo ondulado em área de pós-plantio de eucalipto no Vale do Rio Doce, região Centro Leste do Estado de Minas Gerais

The erosion caused by running water constitutes important cause of environmental degradation and productivity reduction, which justifies its evaluation in areas of eucalypt commercial plantations, mainly in ondulated slope conditions. The present study was intended to evaluate the influence of different management systems, in an undulated eucalypt pos-planting area, upon soil and water losses by erosion. The experiment was installed in a very clayey Red Latosol (Oxisol) under three eucalypt management systems (downhill planting with burning of crop residues - EDq; downhill planting with maintenance of crop residues on soil surface - ED; level planting with maintenance of crop residues on soil surface - EN), native forest (FN), bare soil (SD), and native pasture (PN). The soil and water losses evaluations were performed in standard plots installed in the field. All eucalypt systems presented very low values of soil losses in relation to the established tolerance limit, indicating the adequacy of these management systems concerning water erosion. The sustainability of these environments regarding erosion is indicated by the fact that soil losses in eucalipt were very close to those observed in native forest (reference).

A família Myrtaceae na reserva particular do patrimônio natural da Serra do Caraça, Catas Altas, Minas Gerais, Brasil

This is a floristic survey of Myrtaceae in the Serra do Caraça, Minas Gerais. Fifty two species were found belonging to 12 genera - Myrcia with 17 species, Eugenia with nine, Campomanesia and Myrciaria with five species each, Psidium with four, Siphoneugena with three, Blepharocalyx, Calyptranthes, Marlierea and Myrceugenia with two species each, and Accara and Plinia with one species each. Descriptions of the genera and species, identification keys, geographical distributions, illustrations and comments are provided. © 2005 Instituto de Ciências Biológicas - UFMG.

Proveniência e idade do metamorfismo das rochas da faixa Brasilia, na região de tapira (SW de Minas Gerais)

The Brasilia Fold Thrust Belt at Tapira area (SW of Minas Gerais State, Brazil) has four different litho-tectonic domains imbricated by thrust faults with vergency to the São Francisco Craton. Sm/Nd isotopic studies were undertaken and the results show different model and metamorphic ages for the thrust sheets. Rocks from the lower thrust sheet yield a metamorphic age of 543 Ma while the upper thrust sheet has a metamorphic age of 581 Ma. The TDM model ages are similar for both thrust sheets, between 1.7 and 2.2 Ga. Because of their lithologic characteristics, the thrust sheets are interpreted as having been deposited in a distal continental platform environment, their main source being Paleoproterozoic rocks of the São Francisco Craton. The upper thrust sheet rocks presents a metamorphism age of 612 Ma and a bimodal distribution of TDM model ages between 1.3 and 1.9 - 2.0 Ga, respectively. The lithologic and isotopic characteristics of this thrust sheet the rocks are interpreted as a result of deposition on a continental slope or oceanic floor environment, with mixed contributions from Paleo - and Mesoproterozoic rocks of the São Francisco Craton. In spite of the small number of analyzed samples and the uncertainties inherent to the Sm/Nd method the metamorphisms are not considered to be synchronous in the different thrust sheets. This is to be expected in a thrust belt system, in which the more metamorphosed thrust sheets are juxtaposed to less metamorphosed ones.

Chionanthus greenii (Oleaceae), a new species from Minas Gerais, Brazil

Chionanthus greenii Lombardi, a new species of Oleaceae, is described and illustrated. It is distinguished by the unique combination of strigose indument, short congested inflorescences, small corolla lobes and reniform anthers, which do not match any described South American species. © The Board of Trustees of the Royal Botanic Gardens, 2006.

Escape of the fiddler crab Uca rapax (Smith, 1870) (Crustacea: Ocypodidae) in the state of Minas Gerais, Brazil

A escape of the fiddler crab Uca rapax (Smith, 1870), in the state of Minas Gerais is reported for the first time. This record was made more than 200 km away from its original habitat, a mangrove area in the state of Rio de Janeiro. The species has been introduced in ponds in the study area, located in the largest ornamental pisciculture/aquaculture center of Brazil. Male individuals of U. rapax were observed engaged in territorial and courtship displays around their burrows. Despite this, there is no well-established population of the species in the area, due to the physiological dependence of the larvae on brackish water. © 2007 Instituto de Ciências Biológicas - UFMG.

Cytogenetical analyses in three Astyanax scabripinnis populations (Pisces, Characidae) from Minas Gerais State, Brazil

Cytogenetical data in 3 populations of characid fish assigned to the complex of Astyanax scabripinnis from São Francisco river basin and Grande river basin, Minas Gerais State, Brazil, are presented for the first time. The same diploid number, 2n=50, was detected in the 3 populations, which has conspicuous differences involving karyotype morphology: 8M, 20SM, 6ST and 16A (Cambeba stream), 6M, 28SM, 6ST and 10A (Machado headwater), 6M, 24SM, 8ST and 12A (Pedra Branca stream). Differences involving amount and/or locations of heterochromatin blocks, number and position of nucleolar organizer regions (NORs) and CMA3 positive signals were also observed. Some aspects related to the chromosome diversification of Astyanax scabripinnis are discussed. © 2007 The Japan Mendel Society.

Incorporación de la telesalud en el sistema público de salud de Minas Gerais, Brasil

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Análise dos parâmetros morfométricos da bacia do Rio Preto, Serra do Espinhaço (Minas Gerais, Brasil)

The Rio Preto Hydrographic Basin (RPHB) is located in the North-central portion of the state of Minas Gerais, Brazil, 30 km ENE of the city of Diamantina. The sources of the stream of that name are found in the Rio Preto State Park, which has an area of 10,755 hectares. The total area, perimeter, extension, and axial length of the RPHB, as well as other morphometric characteristics, with emphasis on shape indexes, were obtained with the help of the ArcGis 9.2 program. The cartographic data were taken from digitalized topographic charts in a scale of 1:100,000 of the Brazilian Geographical Institute (IBGE). The measured drainage area is of 389.3 km2 and the perimeter is 136.9 km. Due to structural influence, the shape of the RPHB is irrgular and elongated, with drainage developed in a dendritic and parallel pattern. Those characteristics were checked by means of the compaxity coefficient and the shape factor. The first one was estimated in 1.94, what implies that the basin is not subject to fast flooding in years with normal precipitation. The high degree of fluvial downcutting of the basin is confirmed by the fact that it is a 5th order basin, it presents a significant branching rate and a medium drainage density.

Antiviral activity of plants occurring in the state of minas gerais (Brazil): Part III

A total of 24 extracts from 14 plant species collected at the state of Minas Gerais, Brazil, and belonging to five botanical families (Annonaceae, Apocynaceae, Ochnaceae, Polygonaceae and Vitaceae) was screened for cytotoxicity in cultured Vero cells and for antiviral activity against human herpes virus type 1 (HSV-1), vaccinia virus (VACV) and murine encephalomyocarditis virus (EMCV). The highest cytotoxicity (CC 50 < 10 μg/mL) was observed for the ethanol extracts from Annona coriacea fruits and seeds. Extracts from Hancornia speciosa, Ouratea castaneafolia and O. semisrrata were the only ones that have shown activity against all the three viruses assayed. Extracts from Polygonum spectabile, Hancornia speciosa, Himatanthus phagedaenica, Ouratea spectabilis and O. semiserrata were the most active against HSV-1 (EC 50 < 50 mg/mL), with favorable SI values (8.0 to 10.0). Hancornia speciosa and Anaxagorea dolichocarpa were the most active against EMCV (EC 50 50 - 100 μg/mL), with reasonable SI values (5.2 to 6.1), while moderate to low activity (EC 50 > 100 μg/mL) was observed for Ouratea spectabilis and O. semiserrata. A total of 7 plant species, Ouratea semiserrata, O. spectabilis, O. castanaeafolia, Rollinia laurifolia, Cissus erosa, Polygonum spectabile, and Hancornia speciosa, were active against VACV, disclosing EC50 < 50 μg/mL and SI values ranging from 6.6 to 67.3. In total, 10 out of the 14 species were selected from a literature survey on plants used to treat viral diseases in Brazil; these species were responsible for 70% of the positive results.

Paleosuperfícies e perfis bauxíticos no Planalto de Poços de Caldas, São Paulo/Minas Gerais, Brasil

This work has the objective of correlating altitude with the bauxite profiles in the Poços de Caldas Plateau in order to identify paleosurfaces. Then, bauxite profiles found in the Plateau have been classified and mapped through DEM. Three different types of bauxite profiles are highlighted in the area: (1) Rim Profiles which are well-developed and thick and are located in the areas of highest altitude in the Plateau; (2) Plateau Profiles which are not very thick and very clayey, normally appear in the lower portion of the landscape; (3) Reworked Profiles, characterized by bauxite reworked fragments composed by similar materials found in the tops of Rim and Plateau Profiles. After relating altitude to the constituting materials of the bauxite profiles, it is noticed that there are occurrences of Rim Bauxite Profiles located in altitudes of Plateau Profiles and Reworked Profiles located over Rim Profiles, above 1,400 meters of altitude. In the opposite direction, tops of the same elevation are found, where there should be Rim Profiles, there are rocky outcrops observed in field, without any evidence of laterite profiles. It is concluded, therefore, that the elevation rates by themselves, at least in this area, are not good enough references to determine the existence and distribution of paleosurfaces.

O Grupo Canastra em sua área-tipo, região de Tapira, sudoeste do estado de Minas Gerais

This work aimed at describing the Neoproterozoic evolution of a Southern Brasília Fold Belt segment, in Tapira area (southwest of Minas Gerais state, Brazil), using detailed geologic mapping. This area, the Canastra Group type-area, has showed great tectonic and stratigraphic complexities unlike the simplicity suggested in previous works. From recognizing the main tectonic discontinuities, it was possible to subdivide the area into some domains. In the west domain, they were individualized in tectonic sheet I, marked by pelitic rocks and pelitic-graphite rocks with psammitic intercalations, and II, pelitic rocks with psammitic and mafic-ultramafic intercalations overlapped by gneisses. In the east domain, a group of three tectonic sheets was defined, in which, in the two lower tectonic sheets, pelitic and pelitic-graphite rocks with psammitic rock intercalations prevailed, which is different in metamorphic conditions. The lower tectonic sheet is marked by mineralogical associations with muscovite + chlorite + quartz ± graphite ± albite, without biotite; however, the superior one is with muscovite + quartz + garnet ± chlorite ± biotite ± chloritoid ± graphite ± albite. In the upper tectonic sheet, pelitic rocks with local contributions of psammitic and ultramafics rocks occur. In the south domain, psammitic rocks basically occur with contributions of pelitics and rudaceous rocks, where the preservation of textures and sedimentary structures is common. Rocks of the several domains are interpreted as part of a passive continental margin basin, located in the western margin of the São Francisco paleocontinent. Thus, the south domain rocks would represent the facies of proximal platform; rocks of the lower and middle tectonic sheets (east domain) and of the tectonic sheet I (west domain) are of facies distal platform; and the ones from the upper tectonic sheet (east domain) and tectonic sheet II (west domain) were acknowledged as deposited in an environment of continental shelf and/or oceanic seafoor.

Planificación estadual en el Brasil: la experiencia de Minas Gerais

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