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| HARTMANN,LÉO A.; SANTOS,JOÃO O. S.; McNAUGHTON,NEAL J.; VASCONCELLOS,MARCOS A. Z.; DASILVA,LUIZ C.. |
| Complex polymetamorphic granulites have been dated in the Santa Catarina granulite complex of southern Brazil through SHRIMP study of zircon. This complex is dominated by intermediate-acid plutonic rocks and contains small volumes of mafic and ultramafic rocks, and minor quartzite and banded iron formation. Porphyroblasts of orthopyroxene, clinopyroxene and plagioclase in mafic and acid rocks are interpreted as magmatic remnants in a volumetrically dominant granoblastic aggregate (M1) of the same minerals and hornblende. Hornblende formed during a later M2 metamorphic event constitutes rims around pyroxene, but the hornblende is also rimmed by granoblastic simplectites of orthopyroxene, clinopyroxene, hornblende and plagioclase in a second granulite facies... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Granulites; SHRIMP; U/Pb geochronology; Santa Catarina granulite complex; Brazil; Symplectites; Zircon. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652000000400007 |
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| HARTMANN,LÉO A.; ANTUNES,LUCAS M.; ROSENSTENGEL,LEONARDO M.. |
| The Entre Rios mining district produces a large volume of amethyst geodes in underground mines and is part of the world class deposits in the Paraná volcanic province of South America. Two producing basalt flows are numbered 4 and 5 in the lava stratigraphy. A total of seven basalt flows and one rhyodacite flow are present in the district. At the base of the stratigraphy, beginning at the Chapecó river bed, two basalt flows are Esmeralda, low-Ti type. The third flow in the sequence is a rhyodacite, Chapecó type, Guarapuava subtype. Above the rhyodacite flow, four basalt flows are Pitanga, high-Ti type including the two mineralized flows; only the topmost basalt in the stratigraphy is a Paranapanema, intermediate-Ti type. Each individual flow is uniquely... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amethyst geode; Entre Rios mining district; Paraná volcanic province; Geochemistry; Gamma-spectrometry. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652014000100187 |
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| RIZZOTTO,GILMAR J.; HARTMANN,LÉO A.; SANTOS,JOÃO O.S.; MCNAUGHTON,NEAL J.. |
| New U-Pb zircon geochronological data integrated with field relationships and an airborne geophysical survey suggest that the Nova Brasilândia and Aguapeí belts are part of the same monocyclic, metaigneous and metasedimentary belt formed in the late Mesoproterozoic (1150 Ma-1110 Ma). This geological history is very similar to the within-plate origin of the Sunsás belt, in eastern Bolivia. Thus, we propose that the Nova Brasilândia, Aguapeí and Sunsás belts represent a unique geotectonic unit (here termed the Western Amazon belt) that became amalgamated at the end of the Mesoproterozoic and originated through the reactivation of a paleo-suture (Guaporé suture zone) in an intracontinental rift environment. Therefore, its geological history involves a short,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amazonian craton; Intracontinental rift; Mesoproterozoic; Western Amazon belt; U-Pb geochronology. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652014000100057 |
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| BAGGIO,SÉRGIO B.; HARTMANN,LÉO A.; BELLO,ROSA M.S.. |
| ABSTRACT The occurrences of glassy rocks containing long and curved phenocrysts in the Paraná volcanic province, South America, are here interpreted as paralavas. The large number of thin (0.1-0.5 m) dikes and sills of glassy volcanic rocks with hopper, hollow or curved, large crystals of clinopyroxene (up to 10 cm), plagioclase (up to 1 cm), magnetite and apatite are contained in the core of thick (>70 m) pahoehoe flows. They are strongly concentrated in the state of Paraná, coincident with the presence of the large number of dikes in the Ponta Grossa arch. These rocks were previously defined as pegmatites, although other names have also been used. A paralava is here interpreted as the product of melting of basaltic rocks following varied, successive... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Paralava; Paraná volcanic province; Pyrometamorphism; Remelting; Metal remobilization. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652016000602167 |
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