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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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| 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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