| Full text | |
| Author(s): |
Total Authors: 4
|
| Affiliation: | [1] Universidade de São Paulo. Institute of Geosciences - Brasil
[2] Universidade de São Paulo. Institute of Geosciences - Brasil
[3] Universidade de São Paulo. Institute of Geosciences - Brasil
[4] Universidade de São Paulo. Institute of Geosciences - Brasil
Total Affiliations: 4
|
| Document type: | Journal article |
| Source: | BRAZILIAN JOURNAL OF GEOLOGY; v. 46, p. 5-35, 2016-06-00. |
| Abstract | |
ABSTRACT: Here we report the results of several U-Pb zircon ages, made to generate an integrated history for the Rio Negro-Juruena tectonic province, for the northwestern part of the Amazonian Craton. This region comprises granitoid rocks, described as calc-alkaline syntectonic gneisses, granites and migmatites, affected by medium level amphibolite facies metamorphism. The new measurements, with the available Rb-Sr and K-Ar ages, indicate the formation of these rocks within a series of essentially juvenile magmatic arcs, that are closely related with subduction. Sm-Nd analyses indicate that all samples, regardless of their zircon ages, yielded TDM model ages roughly between 1.9 and 2.2 Ga, suggesting the absence of a much older source material. In the northeastern part (areas of Puerto Inírida and San Carlos), the Atabapo belt comprises rocks formed within a period of about 60 Ma, from 1800 to 1740 Ma. In the southwestern region, including the towns of Mitú and Iauaretê, the granitoids formed in the Vaupés belt between 1580 and 1520 Ma. Finally, the available K-Ar measurements indicate the onset of the Nickerie-K'Mudku intraplate heating event, with temperature above 300oC within the entire region at 1200 - 1300 Ma. (AU) | |
| FAPESP's process: | 13/12754-0 - U-Pb and LA-ICP-MS precision geochronology on zircon: a contribution to the knowledge of the tectonic evolution of South America |
| Grantee: | Umberto Giuseppe Cordani |
| Support Opportunities: | Regular Research Grants |