Recent studies have demonstrated that the current tectonics activity plays an important role also in intraplate setting, such as in the Brazilian territory as a whole. The Continental Rift of Southeastern Brazil, which comprises the Neoproterozoic basement and some Paleogene basins (e.g. Taubaté, São Paulo, and Curitiba basins), is one of the most important features affected by Neotectonics, the tectonic regime acting since Neogene. However, information about the effects of the current tectonic regime on the rift surrounding areas is still missing. In this way, the objective of this research is to evaluate the possible effects of Neotectonics on the landform of the Neoproterozoic basement, close to the São Paulo sedimentary basin. In order to achieve this objective, general descriptive characteristics of the drainage system were analyzed, such as: network pattern, drainage and hydrographic densities, junction angles, trophy, and anomalies. These data were compared with the aeromagnetic data and the results of the Stream Length-Gradient (SL), Asymmetry Factor (AF), and Drainage Basin Shape (BS) indexes of the main rivers. In the field, 1330 measurements of tectonic features were surveyed in 122 outcrops. The paleostress orientations were calculated by means of fault and fracture inversions by Daisy3 software. In addition, Geologic-geomorphological Maps (1:25,000) of 3 key areas were prepared. The results suggest that tectonic structures have influenced the general arrangement of hills, ridges, and floodplains, as well as the general characteristics of the drainage system, responsible for the dissection of landforms. Recent deformations indicate Neotectonic activity causing tilting of blocks and channel migration, and formation of escarpments, triangular facets, abandoned meanders, fluvial terraces, knickpoints, and elbows. On the other hand, the field data suggest that the most of faults are related to the Pre Cenozoic tectonics. In this way, Neotectonics is not the principal structural element on the landform evolution of the study area, but it has an important role on the relief formation of some regions.
Neotectonic landforms of the Neoproterozoic basement of Southeastern Brazil: The case of the north border of the São Paulo Basin
Cianfarra, Paola
2024-01-01
Abstract
Recent studies have demonstrated that the current tectonics activity plays an important role also in intraplate setting, such as in the Brazilian territory as a whole. The Continental Rift of Southeastern Brazil, which comprises the Neoproterozoic basement and some Paleogene basins (e.g. Taubaté, São Paulo, and Curitiba basins), is one of the most important features affected by Neotectonics, the tectonic regime acting since Neogene. However, information about the effects of the current tectonic regime on the rift surrounding areas is still missing. In this way, the objective of this research is to evaluate the possible effects of Neotectonics on the landform of the Neoproterozoic basement, close to the São Paulo sedimentary basin. In order to achieve this objective, general descriptive characteristics of the drainage system were analyzed, such as: network pattern, drainage and hydrographic densities, junction angles, trophy, and anomalies. These data were compared with the aeromagnetic data and the results of the Stream Length-Gradient (SL), Asymmetry Factor (AF), and Drainage Basin Shape (BS) indexes of the main rivers. In the field, 1330 measurements of tectonic features were surveyed in 122 outcrops. The paleostress orientations were calculated by means of fault and fracture inversions by Daisy3 software. In addition, Geologic-geomorphological Maps (1:25,000) of 3 key areas were prepared. The results suggest that tectonic structures have influenced the general arrangement of hills, ridges, and floodplains, as well as the general characteristics of the drainage system, responsible for the dissection of landforms. Recent deformations indicate Neotectonic activity causing tilting of blocks and channel migration, and formation of escarpments, triangular facets, abandoned meanders, fluvial terraces, knickpoints, and elbows. On the other hand, the field data suggest that the most of faults are related to the Pre Cenozoic tectonics. In this way, Neotectonics is not the principal structural element on the landform evolution of the study area, but it has an important role on the relief formation of some regions.
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