Early Paleozoic
Mostrando 1-12 de 14 artigos, teses e dissertações.
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1. Geochronological systematics of the Huayna Potosí, Zongo and Taquesi plutons, Cordillera Real of Bolivia, by the K/Ar, Rb/Sr and U/Pb methods
Abstract The Huayna Potosi, Zongo and Taquesi are Triassic plutons located at the core of the Real Cordillera of Bolivia. In this paper, several Rb-Sr and K-Ar ages obtained in the past at the São Paulo Geochronology Laboratory, yet unpublished, will be presented, along with newer U-Pb Sensitive High-Resolution Ion Microprobe (SHRIMP) determinations made in
Braz. J. Geol.. Publicado em: 01/07/2019
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2. Sedimentology and stratigraphy of Neoproterozoic-lower Paleozoic carbonate-siliciclastic succession of the southwesternmost Amazon Craton, state of Rondônia, Brazil
ABSTRACT: Facies and stratigraphic analysis were carried out in Neoproterozoic-Lower Paleozoic carbonate-siliciclastic deposits of Cacoal and Pimenta Bueno formations exposed on basement rocks and into the Pimenta Bueno Graben, northwestern portion of Parecis Basin, southwesternmost Amazon Craton. The redescription and redefinion of this succession confirmed
Braz. J. Geol.. Publicado em: 22/02/2018
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3. Significado tectônico dos depósitos de leques aluviais da Formação Santa Bárbara (Eo-Paleozóico) na região de Caçapava do Sul (RS, Brasil)
The alluvial fan deposits of Early Paleozoic Santa Bárbara Formation, located in Sul-rio-grandense Shield area of southernmost Brazil, have been analyzed here in terms of facies associations and tectonic significance. The investigated unit comprises conglomerates, sandstones, and siltstones, deposited probably under continental semi-arid climate conditions,
Publicado em: 2010
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4. Razões isotópicas 87Rb/86Sr, 87Sr/86Sr e 143Nd/144Nd como traçadores de proveniência de rochas sedimentares siliclásticas: exemplos no Grupo Camaquã(Paleozóico interior; RS, Brasil)
The Rb-Sr and Sm-Nd isotopic systems are ideal in constraining the provenance of fine-grained clastic rocks. This is particularly true for continental, fluvio-lacustrine, sedimentary units deposited under semi-arid climate conditions, where mechanical desintegration of source rocks dominates the weathering processes. Three sets of red-colored, continental si
Publicado em: 2010
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5. 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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6. Processos metalogenéticos em ambientes de arco magmático tipo andino, caso de estudo: mineralizações da região dos Andes Patagônicos setentrionais do Chile / Metallogenic processes in andean volcanic arc setting, study case: mineralizations in the Chilean North-Patagonion Andes
In the Patagonian Andes region between 41 and 44° S extensive and continuous plutonic rocks of the North-Patagonian Batholith north segment are exposed. During their evolution most of the granitic rocks were emplaced in metamorphic rocks and other parts were emplaced in Late Jurassic-Berriasan volcanic rocks, Early Cretaceous sedimentary and volcanic rocks,
Publicado em: 2008
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7. EVOLUÇÃO TECTONOSSEDIMENTAR DA BACIA DOS PARECIS AMAZÔNIA
The Parecis basin is located in central-western Brazil, on the southwestern part of the Amazon craton, between the Rondônia and Guaporé fold belts. From west to east, the Parecis basin can be divided into three tectono-sedimentary domains: a tectonic low to the west, a central compartment characterized by a negative gravimetric anomaly, and a interior sag
Publicado em: 2007
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8. Paleozoic record of morphologica diversity in blastozoan echinoderms.
There has been extensive debate about the magnitude and implications of morphological diversity in early Paleozoic animals, with some workers using apparently rapid initial diversification to infer unusual evolutionary processes. Analysis of discrete morphological characters shows that initial morphological diversification in the echinoderm subphylum Blastoz
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9. Oxygen-Collagen Priority and the Early Metazoan Fossil Record
The thesis is developed that a low oxygen level Precambrian atmosphere presented early-evolving metazoan organisms with physiological connective tissue priorities resulting from the important molecular oxygen requirements in the biosynthesis of collagen hydroxyproline. Shells, cuticles, and carapaces which are not mandatory metazoan prerequisites but which d
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10. Anatomical and ecological constraints on Phanerozoic animal diversity in the marine realm
We grouped the fossil records of marine animal genera into suites defined by function and physiology. The stratigraphic coherence of the resulting diversity history indicates the importance of ecological structure in constraining taxonomic richness through time. The proportional representation of major functional groups was stably maintained for intervals as
The National Academy of Sciences.
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11. Oxygen and evolutionary patterns in the sea: Onshore/offshore trends and recent recruitment of deep-sea faunas
Over the last 15 years a striking pattern of diversification has been documented in the fossil record of benthic marine invertebrates. Higher taxa (orders) tend to originate onshore, diversify offshore, and retreat into deep-water environments. Previous studies attribute this macroevolutionary pattern to a variety of causes, foremost among them the role of n
The National Academy of Sciences.
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12. Olenid trilobites: The oldest known chemoautotrophic symbionts?
Late Cambrian to early Ordovician trilobites, the family Olenidae, were tolerant of oxygen-poor, sulfur-rich sea floor conditions, and a case is made that they were chemoautotrophic symbionts. Olenids were uniquely adapted to this habitat in the Lower Paleozoic, which was widespread in the Late Cambrian over Scandinavia. This life habit explains distinctive
National Academy of Sciences.