Revista Brasileira de Geociencias

Introdução Em uma comunidade vegetal, as plantas encontram-se arranjadas segundo diversas interações intra e interespecíficas, assim como, de acordo com a atuação das variáveis ambientais ao longo de um gradiente natural. O padrão de distribuição espacial de uma espécie ...

This paper comprises a comparison between the vegetation response in ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) multispectral optical imagery and possibly equivalent bedrock/regolith/soil response in airborne gamma-ray spectrometry grids, employing a tropical rainforest area in the Brazilian Amazon as a control. The applied technique comprised band ratios using a fixed near infrared band (numerator) divided by individual visible and shortwave infrared bands (denominator). These band ratios were subsequently submitted to principal component analysis, and the high frequency information is smoothed by low pass filtering. The colour compositions selected for interpretation were sharpened by the first principal component of the original ASTER bands through an IHS transform in order to add albedo/texture information lost through band rationing back to the imagery. The products show a plausible coherence with airborne gamma-ray data and field observations, provi...

Resumo O Prospecto Aurora localiza-se na região nordeste do Brasil (Estado do Ceará), na porção central da Província Borborema, no Domínio da Zona Transversal e possui idade meso a neoproterozoica, ao longo do Lineamento Patos. As ocorrências de cobre de ...

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The inclusion of fibre reinforcement in concrete, mortar and cement paste can enhance many of the engineering properties of the basic materials, such as fracture toughness, flexural strength and resistance to fatigue, impact, thermal shock and spalling. In recent years, a great deal of interest has been created worldwide on the potential applications of natural fibre reinforced, cement based composites. Investigations have been carried out in many countries on various mechanical properties, physical performance and durability of cement based matrices reinforced with naturally occurring fibres including sisal, coconut, jute, bamboo and wood fibres. These fibres have always been considered promising as reinforcement of cement based matrices because of their availability, low cost and low consumption of energy. In this review, the general properties of the composites are described in relation to fibre content, length, strength and stiffness. A chronological development of sisal fibre r...

The aeolian sandstones of Caiuá Group (Bauru Basin - Upper Cretaceous - Paraná, northwest of Brazil) are lying on basalts of Serra Geral Formation (São Bento Group - Mesozoic of Paraná Basin) and both form significant aquifers. Although permo-porosity of sandstone is granular, unlike basalts that is crystalline, upper slice of Serra Geral Aquifer System - SGAS - is classified as free, close as Caiuá Aquifer System - CAS. Magnetic susceptibility contrast between rocks allows applying aeromagnetic data to model most prominent structures that form the basement of sandstones. Analysis of sandstones surface was based in morphological/structural interpretation from drainage net, digital elevation model (DEM) and Landsat 7/ETM+ image. Comparison between two levels of investigation reveal coexistence of some mapped structures and results in a common structural framework. Maps of water discharge, specific capacity, total dissolved solids and cation of water pumped from CAS wells indicate zones with characteristic water from SGAS into CAS, indicate hydraulic connection of refer aquifer systems. Superimpose of hydrogeological maps by common structural framework indicate that presence of larger mapped structures often act on hydrogeological compartments.

With the ending of the eocretaceous volcanic manifestations (133 Ma) the Southeastern portion of the South American Plate was submitted by a process of tectonics reorganization generating basins that had sheltered continental sedimentary sequences. The responsible tectonics events for the accumulation of these sequences can be divided in two main phases. The first phase is related to the eocretaceous thermal subsidence, that was widely in the regions where if they point out the biggest thicknesses of basalts of the Serra Geral Formation, in the middle-west of the Rio Grande do Sul State, the northwest of the Paraná State and west of the São Paulo State, responsible for the formation of the basins Jacuí and Caiuá. During the second phase, in which if it originated the Bauru Basin, had it the neocretaceous uplifting in the southwestern region of Minas Gerais State and South of Goiás State, resultants of the magmatic activities associates to the Trindade Mantle Plume. The analyses had ...

... Celso Dal R?? Carneiro1, Pedro Wagner Gon??alves1, Carlos Alberto Lob??o da Silveira Cunha1 & Oscar Braz ... Sugere-se comparar esta foto com as ilustra????es de Almeida (1948). ... Doc??ncia e trabalhos de campo nas disciplinas Ci??ncia do Sistema Terra I e II da UNICAMP 138 ...

Resumo Unidades litotectônicas com idades arqueanas a eo-paleozóicas ocorrem no Terreno Nico Pérez (Uruguai), Cráton Rio dela Plata retrabalhado, em um arranjo estrutural complexo. A análise estrutural das unidades da porção sul deste terreno permitiu o reconhecimento de dois eventos estruturais (E1-E2) que compreendem quatro fases de deformação (D1-D2-D3-D4). Os eventos E1 e E2 foram gerados em regime transpressivo, como conseqüência da convergência oblíqua entre as placas Rio de la Plata (oeste) e ...