Zircon
Mostrando 1-12 de 81 artigos, teses e dissertações.
-
1. Pseudosection modeling and U-Pb geochronology on Piranga schists: role of Brasiliano Orogeny in the Southeastern Quadrilátero Ferrífero, Minas Gerais, Brazil
ABSTRACT In the Southeastern Quadrilátero Ferrífero, a package of metapelitic rocks previously attributed to the Archean Rio das Velhas Supergroup crops out in Piranga locality. This study presents the mineral chemistry and U-Pb-Hf zircon geochronology on foliated staurolite-garnet mica schists. Garnet and staurolite index minerals are syn- to post-kinemat
Braz. J. Geol.. Publicado em: 21/10/2019
-
2. U-Pb SHRIMP dating of basement rocks of the Iriri-Xingu domain, Central Amazonian province, Amazonian craton, Brazil
Abstract The Iriri-Xingu domain, located in the central part of the Amazonian craton, consists of extensive occurrences of Paleoproterozoic volcanic rocks and granites with published ages of ca. 1990 to 1840 Ma, which show a strong crustal contribution for their magmas. Exposures of basement rocks are small and rare. Samples from two areas were dated in this
Braz. J. Geol.. Publicado em: 21/10/2019
-
3. Geochemistry, Sm-Nd isotopes and SHRIMP U-Pb geochronology of the Morro do Coco Granite (RJ, Brazil): another piece of the post-collisional magmatism of the Ribeira Belt
Abstract The Morro do Coco granite (MC) is a post-collisional intrusive body that was emplaced at Ribeira Belt, in the Cambro-Ordovician, succeeding the final stages of the Gondwana supercontinent amalgamation. This unit requires more studies, contrasting with similar best investigated occurrences of the central Ribeira Belt. This work presents a detailed in
Braz. J. Geol.. Publicado em: 12/09/2019
-
4. Interações ambientais e resistência física de um depósito de resíduos finos da indústria de rochas ornamentais
RESUMO Embora vários trabalhos proponham aplicações para os resíduos finos gerados no beneficiamento de rochas ornamentais, ainda não há evidências das vantagens financeiras para tal aproveitamento. Assim, a descrição dos depósitos existentes, muitos deles construídos sem triagem ou qualquer medida de proteção ambiental, torna-se imprescindível
Eng. Sanit. Ambient.. Publicado em: 15/08/2019
-
5. Provenance of the Ediacaran Salinas Formation (Araçuaí Orogen, Brazil): Clues from lithochemical data and zircon U-Pb (SHRIMP) ages of volcanic clasts
Abstract Salinas Formation occurs in a large region of the Northern Araçuaí orogen, Southeastern Brazil. It includes turbiditic wackes (> 10% matrix) to arenites (< 10% matrix), pelites and clast-supported conglomerates, metamorphosed from the biotite zone of the greenschist facies to the sillimanite zone of the amphibolite facies. Salinas Formation lies u
Braz. J. Geol.. Publicado em: 01/07/2019
-
6. 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
-
7. Sedimentary and U-Pb detrital zircons provenance of the Paleoproterozoic Piracicaba and Sabará groups, Quadrilátero Ferrífero, Southern São Francisco craton, Brazil
Abstract The Quadrilátero Ferrífero is an important mineral province located in Southern São Francisco craton, SE Brazil. Its prominent feature is the Gandarela syncline that was formed as part of the regional deformation event in the southernmost part of the craton at ca. 2,000 Ma. The syncline exposes several economically important units of Rio das Velh
Braz. J. Geol.. Publicado em: 03/06/2019
-
8. Petrography and detrital zircon U-Pb geochronology of sedimentary rocks of the Campo Alegre Basin, Southern Brazil: implications for Gondwana assembly
Abstract The Campo Alegre Basin is a volcano-sedimentary sequence covering an area of about 500 km 2 , located at the northeast portion of Santa Catarina state (Brazil), and formed during the late stages of the Neoproterozoic era. Three main stratigraphic units compose this basin, the lowermost of which is the Bateias Formation, corresponding to the pre-volc
Braz. J. Geol.. Publicado em: 15/04/2019
-
9. Reappraisal of the Sumé Complex: geochemistry and geochronology of metaigneous rocks and implications for Paleoproteorozoic subduction-accretion events in the Borborema Province, NE Brazil
Abstract The Alto Moxotó Terrane represents the largest exposure of Paleoproterozoic rocks in the central Borborema Province. Several medium- to high-grade metamorphic units are described in the terrane, however geochronological data are still scarce, and the main periods of crust build-up and recycling are poorly known. In this study, we investigate the na
Braz. J. Geol.. Publicado em: 08/04/2019
-
10. The Vazante and Canastra groups revisited: Sm-Nd and Sr isotopes - evidence for contribution from Tonian intraplate magmatism during passive margin development along the SW São Francisco margin, Brazil
Abstract Combined Sm-Nd isotope studies and U-Pb ages of detrital zircons have shown significant differences between the provenance patterns of Neoproterozoic metasedimentary successions in the Southern Brasília belt. The Vazante and Canastra groups are passive margin deposits with source areas in the Archean/Paleoproterozoic São Francisco Craton basement
Braz. J. Geol.. Publicado em: 08/04/2019
-
11. Determinación de bajas concentraciones de hidrógeno en aleaciones de circonio utilizando radiografía de neutrones como técnica no destructiva
ABSTRACT Zircon base alloys (Zr) are used in the manufacture of fuel sheaths and structural components of power reactors because of their low neutron absorption. These alloys are susceptible to damage by hydrogen (H) because the concentration of the alloys can be increased locally in response to temperature or stress gradients. This causes a general degradat
Matéria (Rio J.). Publicado em: 19/07/2018
-
12. Influence of attrition variables on iron ore flotation
Abstract The presence of slimes is harmful to the flotation process: the performance and consumption of reagents are negatively affected. Traditionally, the desliming stage has been responsible for removing slimes. However, depending on the porosity of the mineral particles, desliming may not be sufficient to maximize the concentration results. An attrition
REM, Int. Eng. J.. Publicado em: 2018-03