Thermochronology and exhumation history of the basement and sediments of the NNE border of the Parana basin, Brazil

Autor(es)

Resende, Rosana Silveira ^[1] ; Tello Saenz, Carlos Alberto ^[1] ; Dantas, Elton Luiz ^[2] ; Hackspacher, Peter Christian ^[3] ; Chavez Machaca, Cesar Anthony ^[2] ; Glasmacher, Ulrich A. ^[4]

Afiliação do(s) autor(es)

^[1] Univ Estadual Paulista, Dept Phys, UNESP, BR-19060900 Presidente Prudente, SP - Brazil

^[2] Univ Brasilia, Inst Geosci, Lab Geochronol Studies Geodynam & Environm, BR-70910900 Brasilia, DF - Brazil

^[3] Univ Estadual Paulista, Inst Geosci & Exact Sci, UNESP, BR-13506900 Rio Claro, SP - Brazil

^[4] Heidelberg Univ, Inst Earth Sci, Thermochronol & Archaeometry Res Grp, Postfach 103980, D-69029 Heidelberg - Germany

• Tipo de documento: Artigo Científico
• Fonte: Journal of South American Earth Sciences; v. 99, APR 2020.
• Citações Web of Science: 0

Resumo

Combined zircon fission-track (FT) and U-Pb dating were used to obtain correlated cooling ages and tectonic processes in the eastern border of the Phanerozoic Parana Basin, a large cratonic sedimentary basin in South America deposited over Precambrian basement, which is represented mainly by the Neoproterozoic Brasilia Orogenic Belt. Zircon ages obtained for clastic sediments suggest that the provenance history of the Parana Basin was derived chiefly from the proximal basement sources. Twelve zircon samples were collected, from which 194 grains were analyzed and simultaneously dated by the FT and U-Pb methods, and 146 zircon grains were additionally dated only through the fission-track method (FT). The standard sample of Fish Canyon Tuff (FCT) was also analyzed through FT and U-Pb, and the age results of 26.6 +/- 1.1 Ma, and 28.33 +/- 0.68 Ma, respectively, are consistent with the literature data. The fission-track ages, obtained for the Araxa (similar to 330 Ma) and Canastra (similar to 500 Ma) Groups, and Piumhi Massif (similar to 700 Ma) pertaining to the Brasilia Belt, in average increase towards the Sao Francisco Craton. This fission-track age pattern can be linked to the temperature and exhumation of each one of these units. The U-Pb detrital zircon ages obtained for the basement units range from 1.6 to 3.2 Ga and indicate different provenance sources in the evolution of the Brasilia Belt. However, it is clear that the main sources of metasedimentary rocks are derived from the Sao Francisco-Congo Craton. For samples collected in the NNE border of the Parana Basin, FT ages were obtained for 127 zircon grains with ages ranging between 100 and 600 Ma. Forty of these grains dated simultaneously with FT and U-Pb bear mean age populations of 0.6 and 1.0 Ga, and subordinately between 1.5 and 2.5 Ga. These results suggest that the units that represent the Sao Francisco Craton's Neoproterozoic passive margin were being formed with depositional sediments 1.0 Ga ago and their recycling was the main source for the zircon derivation recorded in the Parana Basin sediments. An important methodological result of this work is that U-Pb radiometric dating was done in the same areas of single zircon crystals employed to determine the FT ages, which improved the concordance in the U-Pb ages. As such, U-Pb dating on zircon micro areas that have undergone leaching, metamictization or another type of lattice damage was avoided. (AU)

• Processo FAPESP: 11/14943-9 - Efeitos do ataque químico nos minerais apatita e zircão e suas implicações no Método de Traços de Fissão: Geocronologia da Serra da Canastra.
• Beneficiário: Rosana Silveira Resende
• Modalidade de apoio: Bolsas no Brasil - Doutorado