Phanerozoic
Mostrando 1-12 de 25 artigos, teses e dissertações.
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1. Geocronologia da região de Gondola-Nhamatanda (Centro de Moçambique) / não informado
The region of Gondola-Nhamatanda is located at the border between the provinces of Manica and Sofala, central part of Moçambique. It is geologically inserted in the Bárue complex and the Phanerozoic cover. The Bárue complex is composed of the Macossa and Chimoio supracrustal groups intruded by plutonic rocks of various compositions, whereas the Phanerozoi
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 17/01/2012
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2. Geologia do sudoeste do Estado de Goiás : Integração de dados geológicos e aerogeofísicos de alta densidade
The airborne magnetic and gamma ray spectrometry data related to the Airborne Geophysic Survey Project of the State of Goiás (Block 1) executed between 2004 and 2006 and considered of high density by the acquisition and treatment configuration, were integrated in GIS environment with the existing geologic information, in the SW Goiás region located from th
Publicado em: 2007
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3. Análise cladística de Conulariidae Walcott (Neoproterozóico-Triássico): caracterizando e definindo um grupo de cnidários extintos / Cladistic analysis of the Conulariina Miller and gurley 1896 (Cnidaria, Scyphozoa; Vendian/Triassic)
A análise cladística de Conulariidae (Cnidaria) é aqui apresentada, e está fundamentada na hipótese de que os agrupamentos taxonômicos (famílias, subfamílias), propostos no ?Treatise on Invertebrate Paleontology? (TIP), não são filogeneticamente válidos. O estudo apresentado levou em consideração a revisão do material depositado em coleções d
Publicado em: 2006
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4. Caracterização das rochas vulcânicas e plutônicas félsicas e intermediárias do Alvo Estrela (Cu-Au), Serra de Carajás, Pará
The Estrela Cu-Au deposit is situated in the Serra do Rabo, at the easternmost part of Carajás shear zone, at the Serra dos Carajás region. It is hosted by altered andesites and gabbros and rhyolites of the Grão Pará Group, Itacaiunas Supergroup, formed at 2.76 Ga (Sm-Nd isochronic age) cut by Paleoproterozoic porphyritic quartz diorite, orthoclase-albit
Publicado em: 2006
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5. Caracterização metalogenetica do deposito cromotiferos de Pedras Pretas, Santa Luz - BA
The chromitiferous mineralization of Pedras Pretas Intrusive Suite, Bahia, Brazil, is host in serpentinites intrusive into meta-sedimentary and meta-igneous rocks comparable to the 2.2-2.0 Ga old Itapicuru River Greenstone Belt. Field relationships and petrographic data indicate that the study area has undergone four major deformation phases with metamorphic
Publicado em: 1998
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6. Nonprevalence of biochemical fossils in kerogen from pre-Phanerozoic sediments
Evidence of biochemical and geochemical evolution was sought in insoluble carbonaceous matter from 30 selected pre-Phanerozoic sediments ranging in age from about 3.8 to about 0.7 × 109 years. The carbon isotope ratios observed were in the range of -20 to -32 per mil with reference to the Peedee belemnite standard, similar to those previously reported. No s
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7. Effects of sampling standardization on estimates of Phanerozoic marine diversification
Global diversity curves reflect more than just the number of taxa that have existed through time: they also mirror variation in the nature of the fossil record and the way the record is reported. These sampling effects are best quantified by assembling and analyzing large numbers of locality-specific biotic inventories. Here, we introduce a new database
The National Academy of Sciences.
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8. Disparate rates, differing fates: tempo and mode of evolution changed from the Precambrian to the Phanerozoic.
Over the past quarter century, detailed genus- and species-level similarities in cellular morphology between described taxa of Precambrian microfossils and extant cyanobacteria have been noted and regarded as biologically and taxonomically significant by numerous workers world-wide. Such similarities are particularly well documented for members of the Oscill
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9. Geologic constraints on the macroevolutionary history of marine animals
The causes of mass extinctions and the nature of taxonomic radiations are central questions in paleobiology. Several episodes of taxonomic turnover in the fossil record, particularly the major mass extinctions, are generally thought to transcend known biases in the geologic record and are widely interpreted as distinct macroevolutionary phenomena that requir
National Academy of Sciences.
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10. Atmospheric oxygen over Phanerozoic time
It is quite possible that the level of atmospheric oxygen has varied (roughly between 15 and 30% O2) over the past 550 million years. This variation is suggested by modeling of the carbon and sulfur cycles, by the excessive sediment burial of organic matter that accompanied the advent of large vascular land plants, and by recent physiological studies th
The National Academy of Sciences.
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11. Phanerozoic cycles of sedimentary carbon and sulfur
A reservoir model of a Recent steady-state sedimentary system in which the reduced sulfur and oxidized sulfur reservoirs were coupled with the oxidized carbon and reduced carbon reservoirs was constructed. The time curve of the sulfur isotope ratios of the sedimentary sulfate reservoir was used to drive the model back to the beginning of Cambrian time (600 m
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12. 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.