The tectonic evolution of the Transbrasiliano Lineament in northern Paraná Basin, Brazil, as inferred from aeromagnetic data

Abstract

Data from six airborne magnetic surveys were compiled and analyzed to develop a structural interpretation for the Transbrasiliano Lineament in northern Paraná Basin, Brazil. Magnetic lineaments, interpreted to reflect geologic contacts and structures at different depths, were illuminated using the matched-filter technique applied to aeromagnetic anomalies. Field-based structural measurements generally support our magnetic analysis. We estimated three primary magnetic zones: (i) a zone of deep magnetic sources at 20 km depth, (ii) an intermediate basement zone at 6 km depth, and (iii) a shallow zone of near-surface geological features at 1.5 km depth. The deepest zone exhibits three major NE trending crustal discontinuities related to the Transbrasiliano Lineament, dividing the region into four geotectonic blocks. Anomalies associated with the intermediate zone indicate directional divergence of subsidiary structures away from the main Transbrasiliano Fault, which strikes N30°E. The shallow magnetic zone includes near-surface post-Brasiliano orogenic granites. Our analysis identified NE trending sigmoidal lineaments around these intrusions, indicating intense zones of deformation associated with probable shear structures. At the shallow depth zone, magnetic anomalies caused by Cretaceous alkaline intrusive bodies and basalts of the Serra Geral Formation are enhanced by the matched-filter method. These igneous bodies are related to extensional NW striking lineaments and seismicity aligned along these lineaments suggests that they currently are reactivated. Prior to flexural subsidence of the Paraná Basin, reactivation processes along transcurrent elements of the Transbrasiliano Lineament promoted extensional processes and formed initial Paraná Basin depocenters. Cretaceous and more recent sedimentation also correlate with reactivations of NE striking structures.

Proveniência de zircões detríticos e implicações para a paleogeografia da Formação Furnas no noroeste da Bacia do Paraná

“…O arcabouço estrutural proposto para o embasamento (Figura 14), obtido por meio da análise de mapas magnéticos e de propostas da literatura Curto et al, 2014), exibe unidades da Faixa Paraguai e do Arco Magmático de Goiás, cujo contato define a principal direção do Lineamento Transbrasiliano na área de estudo. Os lineamentos magnéticos de direção N60-70E seguem a orientação geral da estruturação da Faixa Paraguai e provavelmente são de uma componente secundária do Lineamento Transbrasiliano.…”

“…Após a deformação e granitogênese do Ciclo Brasiliano, a temperatura no Continente Gondwana deveria ser elevada, e o subsequente resfriamento causaria esse efeito sobre um arcabouço do embasamento contendo um núcleo cratônico e faixas móveis, que configuraram zonas de fraquezas, com depósitos molássicos restritos. Curto et al (2014) A unidade molássica descrita por Araújo e Moreton (2008), na região de Piranhas (GO), de idade eo-ordoviciana, apresenta sedimentação associada à reativação de estruturas do embasamento e formação de um graben, relacionada pelos autores a eventos tardi a pós-tectôni-cos, anteriores ao desenvolvimento da Bacia do Paraná. Posteriormente, Gezat (2011), a partir de estudos de proveniência utilizando o método U-Pb em zircões detríticos nas formações Piranhas e Vila Maria, na região da cidade de Piranhas (GO), sugeriu a formação de uma bacia intermontana de natureza molássica em 600 Ma, onde o início da sedimentação da Formação Piranhas foi predominantemente a partir de rochas da sequência metavulcanossedimentar do Arco Magmático de Goiás (600 a 700 Ma).…”

An overview of the Mesozoic-Cenozoic magmatism and tectonics in Eastern Paraguay and central Andes (Western Gondwana): Implications for the composition of mantle sources

“…These peripheral areas have been orogenically active, and crustal reworking has generated large volumes of magmatic rocks during the Precambrian and Phanerozoic, with their distribution controlled by active suture zones (Cordani et al, 2000(Cordani et al, , 2003aKröner and Cordani, 2003). The most important example of a longlived active mega-suture is the Transbrazilian lineament (TBL) that crosses the entire region from South America to west Africa ( Figure 1B; Pedrosa-Soares et al, 1998;Cordani et al, 2013;Curto et al, 2014). In this context, the magmatism was driven by the extensional regime caused by the relative movements (compressive-transpressive) of the ancient blocks.…”

Optimizing depth estimates from magnetic anomalies using spatial analysis tools

“…Various methods are available to automatically and rapidly analyze magnetic anomalies in order to estimate the locations and depths of geologic sources over large, regional areas (Spector and Grant, 1970;Syberg, 1972;Phillips, 2001;Salem et al, 2007;Curto et al, 2014). Regional and residual components of the potential fields can be identified based on the wavenumber in the radial power spectrum, where their respective depths estimates are equivalent to the half of the straight lines slope in the power spectrum (Spector and Grant, 1970).…”