Geochronological evidence for pervasive miocene weathering, Minas Gerais, Brazil

Ar-40/Ar-39 laser incremental-heating analyses of 22 individual grains of supergene cryptomelane from three weathering profiles, up to 400 km apart, in the Rio Doce valley and Barbacena regions at Minas Gerais, Brazil, show that the formation of weathering profiles in these regions is contemporaneous, suggesting a strong weathering event in the Middle to Late Miocene (10-8 Ma). The preservation of these Miocene samples at or near the present surface suggests that either erosion rates have been very low in the region since the Miocene or that a much thicker weathering mantle was present in the region originally. Assuming a constant thickness of weathering profiles in the region throughout the Tertiary, we may calculate weathering front propagation rates of 4-8 m Myr(-1) during the past 10 Ma. Copyright (C) 2004 John Wiley Sons, Ltd.

40Ar/39Ar geochronological constraints on the evolution of lateritic iron deposits in the Quadrilatero Ferrifero, Minas Gerais, Brazil

Weathering profiles overlying the Sapecado, Pico and Andaime iron ore deposits, Quadrilátero Ferrífero (QF), Minas Gerais, Brazil, reach depths of 150–400 m and host world-class supergene iron orebodies. In addition to hosting supergene ore bodies of global economic significance, weathered banded iron-formations at the Quadrilátero Ferrífero and elsewhere (e.g., Carajás, Hamersley) are postulated to underlie some of the most ancient continuously exposed weathering profiles on earth. Laser incremental-heating 40Ar/39Ar results for 69 grains of hollandite-group manganese oxides extracted from 23 samples collected at depths ranging from 5 to 150 m at the Sapecado, Pico and Andaime deposits reveal ages ranging from ca. 62 to 14 Ma. Older Mn-oxides occur near the surface, while younger Mn-oxides occur at depth. However, many samples collected at the weathering–bedrock interface yield ages in the 51–41 Ma range, suggesting that the weathering profiles in the Quadrilátero Ferrífero had already reached their present depth in the Paleogene. The antiquity of the weathering profiles in the Quadrilátero Ferrífero is comparable to the antiquity of dated weathering profiles on banded iron-formations in the Carajás Region (Brazil) and the Hamersley Province, Western Australia. The age versus depth distributions obtained in this study, but not available for other regions containing similar supergene iron deposits, suggest that little further advance of the weathering front has occurred in the Quadrilátero Ferrífero lateritic profiles during the Neogene. The results suggest that weathering in some of these ancient landscapes is not controlled by the steady-state advance of weathering fronts through time, but may reflect climatic and geomorphological conditions prevailing in a remote past. The geochronological results also confirm that the ancient landsurfaces in the Quadrilátero Ferrífero probably remained immune to erosion for tens of millions of years. Deep weathering, mostly in the Paleogene, combined with low erosion rates, account for the abundance and widespread distribution of supergene iron, manganese, and aluminum orebodies in this region.

40Ar/39Ar geochronology constraints on late miocene weathering rates in Minas Gerais, Brazil

Ar-40/Ar-39 incremental heating ages for twenty one grains of cryptomelane, collected at 0, 42, 45, and 60 in depths in the Cachoeira Mine weathering profile, Minas Gerais, permit calculating long-term (10 Ma time scale) weathering rate (saprolitization rate) in SE Brazil. Pure well-crystallized cryptomelane grains with high K contents (3-5 wt.%) yield reliable geochronological results. The Ar-40/Ar-39 plateau ages obtained decrease from the top to the bottom of the profile (12.7 +/- 0.1 to 7.6 +/- 0.1 Ma at surface; 7.6 +/- 0.2 to 6.1 +/- 0.2 Ma at 42 m; and 7.1 +/- 0.2 to 5.9 +/- 0.1 Ma at 45 in; 6.6 +/- 0.1 to 5.2 +/- 0.1 Ma at 60 in), yielding a weathering front propagation rate of 8.9 +/- 1.1 m/m.y. From the geochronological results and the mineral transformations implicit by the current mineralogy in the weathering profiles, it is possible to calculate the saprolitization rate for the Cachoeira Mine lithologies and for adjacent weathering profiles developed on granodiorites and scbists. The measured weathering front propagation rate yields a saprolitization rate of 24.9 +/- 3.1 t/km(2)/yr. This average long-term (> 10 Ma) saprolitization rate is consistent with mass balance calculations results for present saprolitization rates in weathering watersheds. These results are also consistent with longterm saprolitization rates estimated by combining cosmogenic isotope denudation rates with mass balance calculations. (c) 2005 Elsevier B.V All rights reserved.

INFLUÊNCIA DA APRENDIZAGEM ORGANIZACIONAL NA INOVAÇÃO DE PRODUTOS: ESTUDO EM EMPRESAS DE BASE TECNOLÓGICA DO VALE DA ELETRÔNICA, EM MINAS GERAIS

Esse estudo investiga como a aprendizagem organizacional pode influenciar a inovação em produtos nas empresas de base tecnológica. As empresas estudadas estão localizadas no Arranjo Produtivo Local Eletroeletrônico, conhecido informalmente como Vale da Eletrônica, na cidade de Santa Rita do Sapucaí, Minas Gerais. O arcabouço teórico envolve a exploração dos temas principais: aprendizagem organizacional e inovação. A decisão em estudar algumas empresas localizadas nessa cidade se deu por este ambiente ser composto de uma estrutura voltada à produção de conhecimentos tecnológicos dotados de inovações. Como objetivos específicos, esta pesquisa busca identificar as formas, fontes e o processo de aprendizagem organizacional que influenciaram as inovações apresentadas pelas empresas. Trata-se de uma pesquisa qualitativa, de caráter exploratório e descritivo. Os dados empíricos foram coletados por meio de entrevistas semiestruturadas a proprietários e gestores das empresas. O resultado evidenciou que formas e fontes internas e externas de aprendizagem e a proximidade da academia como coadjuvante no desenvolvimento das inovações contribuíram e influenciaram a inovação de produtos responsáveis pelo aumento de vantagem competitiva nas empresas. Esse estudo também permitiu apontar a relevância e a contribuição da aprendizagem organizacional na inovação de produtos e abre caminhos para estudos em outras empresas de base tecnológica.

As políticas educacionais em Minas Gerais e seu impacto no plano de carreira dos trabalhadores em educação (2003-2014)

Based on the theoretical approach on the structure and functioning of the capitalist mode of production in the light of the Marxian perspective of Althusser, Poulanzas and Saes, the objective of this study is to describe and analyze the career path of the deployment process of education workers public state of Minas Gerais, in the context of neoliberal educational policies implemented in the period 2003-2014. This study will make use of the techniques of bibliographical and documentary research; to do so, we will try, at first, to establish the correspondence of this peculiar mode of production (capitalism) and the bourgeois state, trying to understand their legal and political structure, characterized by the right and the bourgeois bureaucracy, highlighting the importance of the state apparatus to conditioning ideologies and their structures for prescription of social practices. In the second phase, we will present to the prevailing ideologies School appear in the form of speech and legal and governmental practices in today's society. Finally, we will seek to understand the applicability of the theory studied in the concrete reality of educational public policies implemented in Minas Gerais, in the perspective of democratic government, modernized and efficient state, as opposed to the interests of the Single Union of Education Workers (Sind-UTE / MG). Thus, we can conclude that our work object is to analyze the educational policies of the bourgeois state, focusing on career path in the context of Minas Gerais, from 2003 to 2014, and its social, political and economic education for workers Minas Gerais state and the society today.

Estrutura produtiva da agropecuária, ocupação e pobreza no estado de Minas Gerais no ano de 2010

This thesis aimed to contribute to the discussion about the relationship between agricultural production structure, occupation and poverty in Brazil, specifically in the state of Minas Gerais, in 2010. The issue of employment is becoming increasingly challenging in the face of ongoing modernization process in agriculture, capital intensive and labor saver looking levels ever higher production and productivity. The productive inclusion can be an effective way to exit from poverty (the work is often the only asset of the poor). In this sense, we sought to investigate what activities or groups of activities occupied a larger number of people and generated higher yields and can potentially have contributed to a lower incidence of poverty. The basis for primary data was the 2010 Population Census (microdata). To achieve the objectives we used descriptive analysis, Pearson correlation coefficients and quantile regressions. Among the main findings highlight that agriculture occupied more and generated higher overall income than ranching presented more precarious, despite having lower average incomes and income percentile values, greater heterogeneity and instability, as well as higher proportions of poor. Overall, commodities showed greater formalization and lower poor proportions. In the case of agriculture, commodities activities occupied less, generated lower mass income and middle-income (although income percentiles slightly larger and more informality) and had lower poverty indicators than non-commodity (more heterogeneous rents). In livestock, commodities had higher percentages of occupation, income (although middle-income values and percentiles slightly smaller), and smaller proportions of poor than non-commodity (more heterogenous). In terms of occupation and income stood out the farming activities unspecified (non-commodity), the coffee growing and cattle (commodities). The cultivation of coffee and cattle had the lowest poverty indicators. agricultural production diversification indicators showed positive correlations with the occupation in activities not commodities (only), but also with the proportion of poor, indigent and concentration of income. In addition, the occupation in not commodities showed positive correlations with poverty indicators. It is noteworthy that the occupations in soybeans, coffee and fruit showed negative correlation coefficients with the indicators of poverty, indigence and gini. Finally, among the agricultural activities, there was to go to occupied in agricultural activities not commodities for commodity would be 'more equalizer' (decreasing coefficients over the distribution of income) than for cattle. The occupation in livestock (mostly non-commodity) would generate greater impact on the lower income deciles, but their coefficients grow back in the last deciles, which shows its most perverse character. Among the activities that would affect more strongly the lower deciles and less the higher deciles stand out pig farming, poultry, citrus cultivation, coffee and sugar cane. The cattle and the cultivation of soy, had the highest rates, but they grow back in the last deciles, which shows a more wicked character.

Inovação Institucional e Opinião Pública um Estudo Sobre a Imagem Pública da Assembleia Legislativa de Minas Gerais

Apresenta os resultados de uma pesquisa acerca dos efeitos das inovações institucionais promovidas na década de 1990 pela Assembleia Legislativa de Minas Gerais sobre a opinião pública mineira.