Abstract
The area in discussion, in a geologic context, constitutes one of the most interesting and complex, within the South American Platform, in Brazilian territory, over which granitoid-greenstone belts are outstanding. The Goiano Complex is the oldest unit in the geologic column herein adopted and composed largely of granitoids, gneiss and migmatites, in the amphibolite facies. Dated samples of the complex have shown two isochrones of Rb/Sr reference, the oldest one is 2.926 +- 65 m.y. and the {sup 87} Sr/{sup 86} Sr initial ratio of 0.7001 and the youngest on of 2.471 + 20 m.y. and {sup 87} Sr/{sup 86} Sr initial ratio of 0.701. Although the initial ratios data of the Rb/Sr isochron, as well as the parameters in the Pb/Pb analyses may indicate material of mantle source, it may be interpreted, with the help of field data, that the youngest values may indicate the reworking of crustal sialic rocks formed 2.925 +- 65 m.y. ago (oldest isochron), with primitive material contribution. Before such reworking volcanic-sedimentary sequence was deposited over the already formed sialic crust, and it is denominated Pilar de Goias Supergroup which characterizes the Greenstone Belts in the region. The Archean age for the supergroup was evident
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Citation Formats
Montalvao, R M.G. de.
Geotectonic evolution of granitoid-greenstone belts from Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias), Brazil; Evolucao geotectonica dos terrenos granitoide-greenstone belts de Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias).
Brazil: N. p.,
1985.
Web.
Montalvao, R M.G. de.
Geotectonic evolution of granitoid-greenstone belts from Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias), Brazil; Evolucao geotectonica dos terrenos granitoide-greenstone belts de Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias).
Brazil.
Montalvao, R M.G. de.
1985.
"Geotectonic evolution of granitoid-greenstone belts from Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias), Brazil; Evolucao geotectonica dos terrenos granitoide-greenstone belts de Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias)."
Brazil.
@misc{etde_10157488,
title = {Geotectonic evolution of granitoid-greenstone belts from Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias), Brazil; Evolucao geotectonica dos terrenos granitoide-greenstone belts de Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias)}
author = {Montalvao, R M.G. de}
abstractNote = {The area in discussion, in a geologic context, constitutes one of the most interesting and complex, within the South American Platform, in Brazilian territory, over which granitoid-greenstone belts are outstanding. The Goiano Complex is the oldest unit in the geologic column herein adopted and composed largely of granitoids, gneiss and migmatites, in the amphibolite facies. Dated samples of the complex have shown two isochrones of Rb/Sr reference, the oldest one is 2.926 +- 65 m.y. and the {sup 87} Sr/{sup 86} Sr initial ratio of 0.7001 and the youngest on of 2.471 + 20 m.y. and {sup 87} Sr/{sup 86} Sr initial ratio of 0.701. Although the initial ratios data of the Rb/Sr isochron, as well as the parameters in the Pb/Pb analyses may indicate material of mantle source, it may be interpreted, with the help of field data, that the youngest values may indicate the reworking of crustal sialic rocks formed 2.925 +- 65 m.y. ago (oldest isochron), with primitive material contribution. Before such reworking volcanic-sedimentary sequence was deposited over the already formed sialic crust, and it is denominated Pilar de Goias Supergroup which characterizes the Greenstone Belts in the region. The Archean age for the supergroup was evident through the age results of its ultramafic rocks, showing 2.600 m.y. isochron age, with Sm/Nd methods. Besides the geochronology and field studies, basic information for the construction of the geologic column herein presented, there has been done petrographic and litho geochemical studies, both in the Goiano Complex and Pilar de Goias Supergroup, as for the Pilar de Goias Supergroup, the studies were concentrated on its mafic-ultramafic rocks. (author).}
place = {Brazil}
year = {1985}
month = {Dec}
}
title = {Geotectonic evolution of granitoid-greenstone belts from Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias), Brazil; Evolucao geotectonica dos terrenos granitoide-greenstone belts de Crixas, Guarinos, Pilar de Goias - Hidrolina (Goias)}
author = {Montalvao, R M.G. de}
abstractNote = {The area in discussion, in a geologic context, constitutes one of the most interesting and complex, within the South American Platform, in Brazilian territory, over which granitoid-greenstone belts are outstanding. The Goiano Complex is the oldest unit in the geologic column herein adopted and composed largely of granitoids, gneiss and migmatites, in the amphibolite facies. Dated samples of the complex have shown two isochrones of Rb/Sr reference, the oldest one is 2.926 +- 65 m.y. and the {sup 87} Sr/{sup 86} Sr initial ratio of 0.7001 and the youngest on of 2.471 + 20 m.y. and {sup 87} Sr/{sup 86} Sr initial ratio of 0.701. Although the initial ratios data of the Rb/Sr isochron, as well as the parameters in the Pb/Pb analyses may indicate material of mantle source, it may be interpreted, with the help of field data, that the youngest values may indicate the reworking of crustal sialic rocks formed 2.925 +- 65 m.y. ago (oldest isochron), with primitive material contribution. Before such reworking volcanic-sedimentary sequence was deposited over the already formed sialic crust, and it is denominated Pilar de Goias Supergroup which characterizes the Greenstone Belts in the region. The Archean age for the supergroup was evident through the age results of its ultramafic rocks, showing 2.600 m.y. isochron age, with Sm/Nd methods. Besides the geochronology and field studies, basic information for the construction of the geologic column herein presented, there has been done petrographic and litho geochemical studies, both in the Goiano Complex and Pilar de Goias Supergroup, as for the Pilar de Goias Supergroup, the studies were concentrated on its mafic-ultramafic rocks. (author).}
place = {Brazil}
year = {1985}
month = {Dec}
}