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Simultaneous application of the fission track and U-Pb methods in zircon: geothermochronology of the Canastra, Araxá and Bambuí groups in the Southern portion of the Brasília Belt

Grant number: 20/13514-6
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): June 01, 2021
Effective date (End): May 31, 2023
Field of knowledge:Physical Sciences and Mathematics - Geosciences - Geology
Principal researcher:Carlos Alberto Tello Sáenz
Grantee:Marcio Fernando dos Santos Albuquerque
Home Institution: Faculdade de Ciências e Tecnologia (FCT). Universidade Estadual Paulista (UNESP). Campus de Presidente Prudente. Presidente Prudente , SP, Brazil

Abstract

In southernmost segment of Brasilia thrust-fold belt, geothermochronological analyzes will be performed on the metasedimentary rocks of the Araxá, Canastra and Bambuí groups. Previous studies carried out in this region which combined simultaneously zircon fission-track and U-Pb dating have been performed by Geochronology group of UNESP, Presidente Prundente campus. The fission-track (FT) ages obtained on zircon grains of Araxá (~ 330 Ma), Canastra (~ 500 Ma) and Piumhi Massif (~ 700 Ma) increase toward of the São Francisco craton. FT ages are related to the exhumation temperature of each one these geological unites, whereas the U-Pb ages ranging from 3.2 to 1.6 Ga indicate several sources contributions (especially from those metasedimentary rocks of the Sao-Francisco-Congo craton) on the evolution of Brasilia belt. By the other hand, this current project proposal will determinate the FT and U-Pb ages from 30 samples (~40 zircon grains by sample) to complementary the geothermochronological knowledge of the southernmost segment of Brasilia thrust-fold belt. The U-Pb zircon ages (closure temperature of ~900 ºC) will be obtained by laser ablation coupled to a mass spectrometer (ICP-MS). The FT ages will provide the cooling ages (time elapsed during the passage of the sample through the 240oC isotherm). Therefore, the obtained results will allow detail the thermal and tectonic evolution in the study area, and also relating the acquired ages and the cooling profiles of the samples with the previous geological and thermo-tectonic studies carried out by the geological community in the same region. Moreover, this project proposal will allow improve the methodological routine of the FT and U-Pb dating on zircon grains with high to low grade of metamorphism. This will be done by SEM, Electron microprobe and Micro-Raman, and proceed with the FT dating routine on the laboratory of the DETRAN Group of DF/FCT-UNESP, Presidente Prudente campus. Finally, the Research Internship Scholarship Abroad, which will be carried out on the Dalhousie University (Halifax, Canada) for dating zircon detrital grains by U-Th/He (5 samples, 10 aliquots per sample) is attached to item "other documents". Keywords: Araxá, Canastra and Bambuí groups, Geothermochronological, Brasilia thrust-fold belt, U-Pb, Fission-track dating (AU)