The Amazonian Craton and the Rio Apa Terrane in paleocontinents based on paleomagnetic studies of Proterozoic geological units.

Abstract

The main purpose of this project is to elucidate the geodynamic evolution of the Amazonian Craton and Rio Apa Block in the formation of paleocontinents during the Proterozoic, using key paleomagnetic poles, and monomineral U-Pb geochronology. Geodynamic models proposed for the craton in global paleogeographic reconstructions (supercontinents) will be tested by the paleomagnetic data. The chosen targets for this study are unmetamorphosed intrusive and extrusive bodies of different ages, located at key areas: (i) the 1110 Ma Rio Perdido dyke swarm (Rio Apa Terrane) located to the south of Bonito city (MS); (ii) the 1110 Ma Huanchaca dyke swarm (Amazonian Craton) located close to Serra Ricardo Franco (MT), near the frontier between Brazil and Bolivia; (iii) rocks from the anorthosite/mangerite/rapakive granite (AMCG) Mucajaí Complex (~1540 Ma); and (iv) Serra Grande charnockitic rocks dated at 1430 Ma, both located near Boa Vista, Roraima State. Paleomagnetic analyses of other geological units that are already in progress will also be a part of this project: felsic rocks from the Iriri Group (1880 Ma) close to São Felix do Xingu, and mafic and felsic dykes (1880 Ma) from the Tucumã and Rio Maria areas, both situated in the Pará State, mafic intrusive bodies and dykes from the Guadalupe Intrusive Suite (1530 Ma), the mafic dykes from the Nova Lacerda Suite (1360-1390 Ma) and rocks from the Planalto da Serra alkaline Complex (630 Ma), located in the Mato Grosso State. Eventually, other units may be studied according to results. At least six field trips are planned for sampling the different geological units, with the participation of expert geologists in the respective areas. (AU)