Investigação geológica na porção central da estrutura de impacto meteorítico Santa Marta, Estado do Piauí, Brasil

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOSanta Marta is a 10 km wide, reasonably well preserved, complex impact structure located in southwestern Piaui state, northeastern Brazil, with a central uplift of 3.2 km diameter. The Santa Marta structure was recently recognized as the sixth confirmed i474673692FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2012/50368-1, 2012/04191-2, 2012/04191-2,166948/2013-6, 305911/2013-

O lineamento Piúma, sul do estado do Espírito Santo: expressão estrutural e significado tectônico

The Piúma lineament, located in the Southern Espírito Santo State, Brazil, is one of the most prominent linear morphostructural features of the northern Mantiqueira Province. The lineament stands out in satellite images and topographic maps, extending for about 70 km in a N50°W direction, between the towns of Iconha and Conceição do Castelo (Espírito Santo). In order to investigate the nature and role played by the Piúma lineament in the tectonic evolution of the Mantiqueira Province and adjacent Campos Basin, we carried out a detailed structural analysis based on fieldwork, as well as geophysical data processing and interpretation. The results we obtained indicate that the Piúma lineament is a brittle shear zone characterized by N50W-trending and SW-dipping shear fractures, faults and joints. These structures record two distinct and incompatible motions, thereby recording the operation of two tectonic regimes: NNE-SSW extension and E-W transtension. Comparing our results with the literature on the Southeastern Brazilian Continental Margin, we conclude that the Piúma lineament more likely developed after the Ediacaran Brasiliano orogenic event in response to an NNE-SSW extension, experiencing later a reactivation as normal dextral to dextral transtensional zone, probably in connection with the South Atlantic rifting in the Lower Cretaceous.The Piúma lineament, located in the Southern Espírito Santo State, Brazil, is one of the most prominent linear morphostructural features of the northern Mantiqueira Province. The lineament stands out in satellite images and topographic maps, extending for about 70 km in a N50°W direction, between the towns of Iconha and Conceição do Castelo (Espírito Santo). In order to investigate the nature and role played by the Piúma lineament in the tectonic evolution of the Mantiqueira Province and adjacent Campos Basin, we carried out a detailed structural analysis based on fieldwork, as well as geophysical data processing and interpretation. The results we obtained indicate that the Piúma lineament is a brittle shear zone characterized by N50W-trending and SW-dipping shear fractures, faults and joints. These structures record two distinct and incompatible motions, thereby recording the operation of two tectonic regimes: NNE-SSW extension and E-W transtension. Comparing our results with the literature on the Southeastern Brazilian Continental Margin, we conclude that the Piúma lineament more likely developed after the Ediacaran Brasiliano orogenic event in response to an NNE-SSW extension, experiencing later a reactivation as normal dextral to dextral transtensional zone, probably in connection with the South Atlantic rifting in the Lower Cretaceous.The Piuma lineament, located in the Southern Espirito Santo State, Brazil, is one of the most prominent linear morphostructural features of the northern Mantiqueira Province. The lineament stands out in satellite images and topographic maps, extending for464531546sem informaçãosem informaçãoO lineamento Piúma, situado na porção sul do estado do Espírito Santo, está entre as feições morfo-estruturais mais proeminentes da província Mantiqueira Setentrional. Constitui uma feição linear regional, bem marcada em imagens de sensoriamento remoto e mapas topográficos, com aproximadamente 70 km de comprimento e direção N50°W, entre as cidades de Iconha e Conceição do Castelo (Espírito Santo). Para investigar sua natureza e o papel que desempenha na evolução tectônica da Província Mantiqueira e da bacia de Campos, adjacente, foi feita uma analise estrutural detalhada, levada a efeito através de trabalhos de campo, processamento e interpretação de dados geofísicos. Os resultados obtidos indicam que o lineamento Piúma se traduz numa zona de cisalhamento rúptil, caracterizada pela presença de falhas e juntas com direção preferencial N50W e mergulho para SW. Essas estruturas registram a ação de dois movimentos distintos e incompatíveis, que marcam a ação de dois regimes tectônicos: distensão NNE-SSW e transtração E-W. Comparando-se os resultados com a literatura disponível para a margem continental sudeste brasileira, conclui-se que o lineamento Piúma, provavelmente, se desenvolveu em algum momento após o evento orogenético ediacarano Brasiliano, em resposta a uma distensão NNE--SSW, posteriormente sendo reativado como uma zona normal dextral a transtracional dextral, possivelmente relacionada à abertura do rifte do Atlântico Sul, no Cretáceo InferiorO lineamento Piúma, situado na porção sul do estado do Espírito Santo, está entre as feições morfo-estruturais mais proeminentes da província Mantiqueira Setentrional. Constitui uma feição linear regional, bem marcada em imagens de sensoriamento remoto

Contributions to the taxonomy of the Brazilian Leurus Townes, 1946 (Hymenoptera: Ichneumonidae, Metopiinae)

Leurus Townes, 1946 is a small genus of Metopiinae (Hymenoptera: Ichneumonidae), consisting of 13 described species distributed in the Neotropics and the Nearctic region. The present work aims to contribute to the taxonomic knowledge of Leurus in Brazil. A total of 109 specimens were identified and 15 literature records were analyzed. The genus geographical occurrence was evaluated according to data obtained from the literature and labels of analyzed specimens. Five species of Leurus were identified for the Brazilian fauna: L. angustignathus, L. caeruliventris, L. discus, L. gracius and L. nostrus. New municipality records of occurrence were made for L. angustignathus in the state of São Paulo, L. caeruliventris in the states of Bahia, Distrito Federal, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Paraná, Piauí and Rondônia; for, L. discus in the state of Alagoas and São Paulo, and L. gracius in the state of Minas Gerais, Rio de Janeiro, and São Paulo. Females of L. angustignathus and L. gracius were described for the first time in the present study. The genitalia of males of L. caeruliventris, L. discus and L. gracius were described and illustrated for the first time

Techno-Economic Analysis of Ethylene Adsorptive Separation Using Zeolite 13X in Oxidative Coupling of Methane Integrated Process

Performance analysis of the adsorptive separation of ethylene downstream of an oxidative coupling of methane (OCM) process, being an alternative process for converting methane content of natural gas or other methane-rich sources to ethylene, was studied in this research for a production capacity of 1 Mt/yr. This was motivated by observing promising adsorption characteristics and efficiency in the selective adsorption of ethylene using 13X zeolite-based sorbent. The energy and economic performance of alternative scenarios for retrofitting the adsorption unit into an integrated OCM process were analyzed. Simulations of the integrated OCM process scenarios include OCM unit, CO2-hydrogenation, ethane dehydrogenation and methane reforming sections. The use of efficient ethylene adsorption separation enabled the improvement of the economic and energy efficiency of the integrated OCM process under specific operating conditions. For instance, the invested amount of energy and the associated energy cost per ton of ethylene in the cryogenic ethylene-purification section of the integrated process using adsorption unit are, respectively, 75% and 89% lower than the reference integrated OCM process. Under the conditions considered in this analysis, the return on investment for the final proposed integrated OCM process structure using adsorption separation was found to be less than 9 years, and the potential for further improvement was also discussed.</p

Espectrometria de raios gama de granitos pegmatíticos da Província Pegmatítica da Borborema (PPB), nordeste do Brasil

O presente estudo tem como objetivo a caracterização de granitos pegmatíticos localizados na região sul da Província Pegmatítica da Borborema (PPB) usando dados de aerogamaespectrométricos e de gamaespectrometria terrestre. Medidas gamaespectrométricas terrestres, dosagens radiométricas e determinações químicas por ICP-MS indicaram concentrações de urânio variando entre 0,4 ppm e 7,8 ppm, concentrações de tório entre 0,1 ppm e 21 ppm e concentrações de potássio entre 2% e 5,2%. Com base nessas características, e utilizando imagens dos canais individuais, das razões de canais e da composição ternária dos radioelementos foi possível diferenciar das rochas encaixantes regionais um conjunto de granitos pegmatíticos e também diferenciar quartzitos das regiões norte e sul da área investigada com base nas concentrações mais elevadas de tório (Th) nestes últimos. Dados de gamaespectrometria terrestre de detalhe coletados em um desses granitos pegmatíticos conhecido como granito Galo Branco, revelaram irregularidades na distribuição espacial de radioelementos, sugerindo mudanças de conteúdo e concentração de minerais acessórios durante a diferenciação e cristalização magmática da rocha. Pegmatitos encaixados em quartzitos ao sul do granito Galo Branco foram individualizados com base nas razões eU/eTh e eU/K. Os resultados revelam grande potencial dos métodos para a caracterização e mapeamento geológico de granitos e pegmatitos da PPB.The objective of this study is the characterization of pegmatitic granites located in the southern region of the Borborema Pegmatitic Province (BPP) with aerial and ground gamma ray data. Ground gamma ray data, radiometric and ICP-MS laboratory analysis showed that these granites have uranium concentrations varying between 0.4 ppm and 7.8 ppm, thorium concentrations varying between 0.1 ppm and 21 ppm and potassium concentrations varying between 2% and 5.2%. Based on these radiometric characteristics and using individual, ratios and ternary images of radioelements of aerial gamma ray data it was possible to distinguish from others country rocks a group of granitic pegmatitic bodies and also to individualize quartzitic formations from the northern and southern portions of the area, based on their different thorium (Th) contents. Ground gamma ray data, acquired for one of these pegmatitic granites, called Galo Branco granite, reveals an irregular spatial distribution of radioelements, indicating mineralogical changes in contents and concentrations of accessory minerals during magmatic crystalization. Pegmatites intruding quartzites in the south portion of the granite were also distinguished using eU/eTh and eU/K ratios images. The results indicated the potential of these methods for the characterization and mapping of pegmatitic granites and associated pegmatites of the Borborema Pegmatitic Province (BPP)

Mapping of residual soils by remote sensing for mineral exploration in SW Minas Gerais State, Brazil

Imperial Users onl

Uso de técnicas de sensoriamento remoto e mapeamento geológico para a caracterização da possível estrutura de impacto do Cerro do Jarau, Quaraí - RS

Cerro do Jarau is a prominent, ~13.5 km-wide, circular landform which rises >200m above the plains of the pampas in southern Brazil. Its origin has been debated for decades, and endogenous tectonics processes or large meteorite impact were suggested. However, the search for conclusive evidences continues. Remote sensing images were applied for a preliminary investigation of this anomalous circular landform. In this work we characterized Cerro do Jarau structure by using several satellites images (LANDSAT-7/ETM+, Terra/ASTER multispectral sensor and CBERS 2B/HRC, and by digital elevation model from the Space Shuttle Endeavour/SRTM). This structure was formed in Mesozoic volcanic-sedimentary rocks of the Paraná Basin and consists of the Jurassic-Cretaceous Guará and Botucatu (sandstones) and Serra Geral (basalts) formations. The Botucatu Formation sandstones are intensely silicified and deformed, and were subject to radial and annular faulting. Our investigations in the field identified the occurrence of parautochtonous monomict breccia and polymict breccias resembling suevite, and striated joint surfaces resembling shatter cones in sandstones and basalts. In addition, our first results of mineral deformation analysis show the presence of rare planar features in quartz clasts in polymict breccias, which, for the first time, suggest an impact origin for the structure. If confirmed by further investigation, Cerro do Jarau may become the sixth known impact structure in Brazil, as well as the fifth basalt-hosted impact structure on Earth.Pages: 7494-750

Uso do CBERS-2B/HRC para a interpretação geológica-estrutural da cratera meteorítica da Serra da Cangalha, Tocantins

The Serra da Cangalha structure, located in the northeastern part of Tocantins State, is a meteoritic crater formed in sediments of the Parnaíba Basin. It is approximately 13 km in diameter and its central uplift is about 5.8 km in diameter, according to recent studies. Its well preserved and defined collar in the central portion of the structure, associated with an elevated rim which marks its external limits, allow to accomplish a detailed geological study using available remote sensing data. Previous studies of Serra da Cangalha were supported by remote sensing images, having characterized its general structure. CBERS-2B, the third satellite on the China- Brazil remote sensing program for Earth resources, introduced an innovation with a high spatial resolution panchromatic camera (HRC) with 2.7 meters. Using this panchromatic image Serra da Cangalha was characterized in much more detail regarding its main geologic-structural features, in relation to previous studies. The results show that HRC is a valuable data source for structural studies, allowing to interpret the key structural features of the impact crater, and to define the two inner ring-like lineaments exhibited by Serra da Cangalha. The main trend observed shows that the crater was formed using the regional deformation trend previously existent in the Parnaíba Basin.Pages: 2685-269

Melting and cataclastic features in shatter cones in basalt from the Vista Alegre impact structure, Brazil

Shatter cones are one of the most widely recognized pieces of evidence for meteorite impact events on Earth, but the process responsible for their formation is still debated. Evidence of melting on shatter cone surfaces has been rarely reported in the literature from terrestrial impact craters but has been recently observed in impact experiments. Although several models for shatter cones formation have been proposed, so far, no one can explain all the observed features. Shatter cones' from the Vista Alegre impact structure, Brazil, formed in fine-grained basalt of the Jurassic-Cretaceous Serra Geral Formation (Parana large igneous province). A continuous quenched melt film, consisting of a crystalline phase, mica, and amorphous material, decorates the striated surface. Ultracataclasites, containing subrounded pyroxene clasts in an ultrafine-grained matrix, occur subparallel to the striated surface. Several techniques were applied to characterize the crystalline phase in the melt, including Raman spectroscopy and transmission electron microscopy. Results are not consistent with any known mineral, but they do suggest a possible rare or new type of clinopyroxene. This peculiar evidence of melting and cataclasis in relation with shatter cone surfaces is interpreted as the result of tensile fracturing at the tip of a fast propagating shock-induced rupture, which led to the formation of shatter cones at the tail of the shock front, likely during the early stage of the impact events.5071228124