Precambrian
Mostrando 1-12 de 63 artigos, teses e dissertações.
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1. Reconstruction of Precambrian terranes of Northeastern Brazil along Cambrian strike-slip faults: a new model of geodynamic evolution and gold metallogeny in the State of Bahia
Abstract The Precambrian basement of Northeastern Brazil is the product of Rhyacian block convergence. The main deformation and intrusion of crustal granitoids occurred between 2.15 and 1.8 Ga ago. This large area has been subjected to long-lasting and rather uniform stresses during the Cambrian period. Gold provinces in Bahia represent metallogenetic produc
Braz. J. Geol.. Publicado em: 21/10/2019
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2. The performance of the (U+Th)/He thermochronology laboratory at UNESP Rio Claro, Brazil
We have developed the first laboratory for (U-Th-Sm)/He thermochronology measurements in South America. Helium is measured using a high-sensitivity magnetic sector mass spectrometer (GVI-Helix-SFT) and a double focusing single collector inductively coupled plasma mass spectrometer (Thermo Scientific ELEMENT2) is used for U, Th and Sm determinations. Repeated
An. Acad. Bras. Ciênc.. Publicado em: 21/03/2019
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3. Scientific Integrity, Precambrian Acritarchs from Brazil and Mangroves and Climate Change
An. Acad. Bras. Ciênc.. Publicado em: 2015-06
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4. Acritarchs of the Ediacaran Frecheirinha Formation, Ubajara Group, Northeastern Brazil
We report for the first time the occurrence of organic-walled microfossils in Ediacaran limestones and marls of the Frecheirinha Formation, Ubajara Group, and the first Precambrian acritarchs so far reported for northeastern Brazil. The assemblage of the Frecheirinha Formation represents a low-diversity microflora comprising Leiosphaeridia, Lophosphaeridium
An. Acad. Bras. Ciênc.. Publicado em: 2015-06
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5. Petrologia e geocronologia do complexo máfico-ultramáfico trincheira, sudoeste do cráton amazônico: implicações tectônicas do mesoproterozóico
The tectonic framework of the ultramafic-mafic rocks of the southwestern Amazon Craton is generally little known. Most of work this cratonic portion is focused on the geochronological studies of granitoids, so that little is known about the origin and tectonic significance of these rocks. In this context, this study contributes to the knowledge of the tecton
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2012
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6. Concentrações de randônio nas águas subterrâneas, rochas e solos de Porto Alegre, RS
Many water-supply systems in Brazil utilize groundwaters at least as part of their networks. This is the case of Porto Alegre, capital of Rio Grande do Sul State, whose population is about 1.4 million inhabitants. However, there is little present knowledge in Brazil of the factors affecting Rn presence in the water supplied for end-users, despite the economi
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2011
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7. Áreas fontes dos minerais pesados e sua distribuição sobre a plataforma continental sul-brasileira, uruguaia e norte-argentina
The heavy mineral fraction of sedimentary rocks and sediments can provide important information about provenance in sedimentary basins studies because some minerals or group of minerals can be traced to a source rock or terrain of specific composition. This work is a provenance study based on heavy mineral analyses of samples collected on the Rio Grande do S
Publicado em: 2010
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8. Argilominerais em solos de manguezais da costa brasileira / Clay minerals in mangrove soils of Brazilian coast
Mangroves are transitional ecosytems between continental and marine environments. Its widely distributed along Brazilian coast under great variability of climatic, oceanographic, geological and geomorphological conditions. Its soil mineralogy has a relevant role in the pedogenic processes and biogeochemical behavior of nutrients and potential inorganic and o
Publicado em: 2010
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9. Geocronologia e evolução tectônica paleo-mesoproterozoica do oriente boliviano - região sudoeste do craton amazônico / Paleo-mesoproterozoic Tectonic Evolution and Geocronology of Eastern Bolivia, SW Amazonian Craton
This work characterizes the tectonic and magmatic evolution of the Precambrian shield of Bolivia. The complex geological evolution of the eastern Bolivia extends from the Paleo- to Mesoproterozoic, and can be related with the magmatic and metamorphic events that are ascribed to the Rio Negro - Juruena (1.78-1.60 Ga), Rondonian - San Ignacio (1.56-1.30 Ga) an
Publicado em: 2010
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10. Micropaleontolgy applied to the stratigraphic and paleoclimatic interpretation of the transition between the Paranoá Group and São Francisco Supergroup (Neoproterozoic, Cabeceiras, Goiás) / Micropaleontologia aplicada na interpretação estratigráfica e paleoclimática da transição entre o Grupo Paranoá e o Supergrupo São Francisco (Neoproterozóico, Cabeceiras, GO)
The Proterozoic record of the Fazenda Funil, near Cabeceiras, GO, includes three sedimentary units: carbonate at the top of Paranoá Group, diamictite of the Jequitaí Formation, and a succession of shale, marl-shale rhythmites, and carbonate of the Sete Lagoas Formation. Microfossiliferous chert occurs in these three units in the form of lenses in the Paran
Publicado em: 2010
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11. Análise da deformação pós-Rifte na Bacia do Araripe, Nordeste do Brasil
The Araripe Basin is located over Precambrian terrains of the Borborema Province, being part of Northeast Brazil inner basins. Its origin is related to the fragmentation of the Gondwana supercontinent and consequently opening of South Atlantic during early Cretaceous. The basin has a sedimentary infill encompassing four distinct evolution stages, comprising
Publicado em: 2010
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12. Molecular Systematics and Biogeography of Monogenoidea (Platyhelminthes: Cercomeromorpha), Gill Parasites of Potamotrygonidae (Chondrichthyes: Rajiformes: Myliobatoidei) / Sistemática molecular e biogeografia dos Monogenoidea (Platyhelminthes: Cercomeromorpha), parasitas das brânquias de Potamotrygonidae (Condrichthyes: Rajiformes: Myliobatoidei)
South America is the only biogeographical region in the world where is possible to find an exclusive stenohalin group of elasmobranchs: the Potamotrygonidae stingrays. Between 19 and 21 species of potamotrygonid stingrays are taxonomically organized in three genera, distributed in the Atrato, Magdalena, Maracaibo, Orinoco, Essequibo, Amazonas e la Plata rive
Publicado em: 2009