The electrical structure of the lithosphere in the southeastern margin of the Amazonian craton: Contribution to West Gondwana tectonics

Autor(es)

Dutra, Alanna C. ; Bologna, Mauricio S. ; Dragone, Gabriel N.

• Tipo de documento: Artigo Científico
• Fonte: Precambrian Research; v. 410, p. 15-pg., 2024-06-16.

Resumo

A high electrical conductivity belt near the southeastern margin of the Amazonian craton, known as ParaguayAraguaia Conductivity Anomaly (PACA), has been discovered and mapped over a distance of more than 1,000 km by a large array of magnetometer measurements. To precisely determine the location and structure of the conductive anomaly, we conducted a 200 -km -long magnetotelluric (MT) profile with typical site spacing of 8 km over the northern part of PACA and crossing the Goi <acute accent>as magmatic arc and Araguaia belt in Central Brazil. Threedimensional resistivity models derived from this data indicate that the PACA is not a single conductor but comprises at least two contiguous bodies at the upper to middle crust. The enhanced conductivity of the northern part of PACA is likely due to sulfide minerals deposited in an inter -arc or back -arc basin that were deformed and subsequently emplaced tectonically beneath the western Goi <acute accent>as magmatic arc. The PACA is truncated to the west by a prominent sub-vertical resistor, attributed to the Transbrasiliano lineament (TBL), a continental-scale structural feature interpreted here as a mylonitic shear zone developed late in the Neoproterozoic to Cambrian tectonic history involving the collision between Amazonian craton and proto-West Gondwana. We cannot confirm the prevailing view of an east-dip subduction of oceanic lithosphere from the Amazonian plate under the Goi <acute accent>as arc terranes. Instead, our results probably represent the record of an oblique continental collision. Regardless of its origin, the PACA may serve as a proxy for the paleo border of the Amazonian plate. Therefore, additional geophysical mapping, especially in areas covered by thick Phanerozoic sediments, is essential to constrain the tectonic evolution of West Gondwana. (AU)

• Processo FAPESP: 16/06114-6 - O Sistema Terra e a evolução da vida durante o Neoproterozoico
• Beneficiário: Ricardo Ivan Ferreira da Trindade
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 18/08149-7 - Determinação da estrutura de resistividade elétrica da crosta e manto litosférico entre o Maciço de Goiás e o Cráton Amazônico
• Beneficiário: MAURICIO DE SOUZA BOLOGNA
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Brasil
• Processo FAPESP: 09/54006-4 - Um cluster de computadores para o Departamento de Astronomia do IAG-USP e para o Núcleo de Astrofísica da UNICSUL
• Beneficiário: Elisabete Maria de Gouveia Dal Pino
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários