Advanced search
Start date
Betweenand
Related content
(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The 1590-1520 Ma Cachoeirinha magmatic arc and its tectonic implications for the Mesoproterozoic SW Amazonian craton crustal evolution

Full text
Author(s):
Amarildo S. Ruiz [1] ; Mauro C. Geraldes [2] ; João B. Matos [3] ; Wilson Teixeira [4] ; William R. Van Schumus [5] ; Renata S. Schmitt [6]
Total Authors: 6
Affiliation:
[1] Universidade Federal de Mato Grosso. Departamento de Geologia - Brasil
[2] Universidade do Estado do Rio de Janeiro. Faculdade de Geologia. Tektos - Grupo de Pesquisa em Tectônica - Brasil
[3] Universidade Federal de Mato Grosso. Departamento de Geologia - Brasil
[4] Universidade de São Paulo. Instituto de Geociências - Brasil
[5] University of Kansas. Department of Geology - Estados Unidos
[6] Universidade do Estado do Rio de Janeiro. Faculdade de Geologia. Tektos - Grupo de Pesquisa em Tectônica - Brasil
Total Affiliations: 6
Document type: Journal article
Source: Anais da Academia Brasileira de Ciências; v. 76, n. 4, p. 807-824, 2004-12-00.
Abstract

Isotopic and chemical data of rocks from the Cachoeirinha suite provide new insights on the Proterozoic evolution of the Rio Negro/Juruena Province in SW Amazonian craton. Six U-Pb and Sm-Nd analyses in granitoid rocks of the Cachoeirinha suite yielded ages of 1587-1522 Ma and T DM model ages of 1.88-1.75 Ga (EpsilonNd values of -0.8 to +1.0). In addition, three post-tectonic plutonic rocks yielded U-Pb ages from 1485-1389 Ma (T DM of 1.77-1.74 Ga and EpsilonNd values from -1.3 to +1.7). Variations in major and trace elements of the Cachoeirinha suite rocks indicate fractional crystallization process and magmatic arc geologic setting. These results suggest the following interpretations: (1) The interval of 1590-1520 Ma represents an important magmatic activity in SW Amazonian craton. (2) T DM and arc-related chemical affinity supportthe hypothesis that the rocks are genetically associated with an east-dipping subduction zone under the older (1.79-1.74 Ga) continental margin. (3) The 1590-1520 Ma age of intrusive rocks adjacent to an older crust represents similar geological framework along the southern margin of Baltica, corroborating the hypothesis of tectonic relationship at that time. (AU)