Thin lithosphere between the Amazonian and São Francisco cratons, in central Brazil, revealed by seismic P-wave tomography

Lithospheric Features of the São Francisco Craton

“…c Geological profile across the eastern border of the craton between Jequitaí and Salinas, indicated as dashed line in the map (Uhlein et al 1998) upper-mantle velocities in areas with alkaline intrusions (Artemieva 2009). Both these models are consistent with a weak lithosphere (either due to higher temperature or due to a wet mantle lid) being responsible for higher seismicity near the APIP as well as the Iporá igneous provinces (Assumpção et al 2004;Azevedo et al 2015).…”

“…The high velocities outside the surface limits of the SFC, especially at 150 km depth, indicate possible extension of the craton beneath the low-grade metamorphic margins of the Brasilia and Araçuaí belts. In the profile "C-D" the horizontal bar LAB denotes the Lithosphere/Asthenosphere boundary at 160 km depth (Heit 2007) Here we show an updated P-wave tomography inversion adding more data from the Tocantins Province (Azevedo et al 2015), as well as from recently deployed stations of the Brazilian Seismographic Network in SE Brazil (Fig. 2.4).…”

Crustal framework of the northwest Paraná Basin, Brazil: Insights from joint modeling of magnetic and gravity data

“…We suggest that the thinner crust between the two major faults reflects a zone of crustal weakness, in agreement with studies related to the NE trending intra-plate seismicity along the lithospheric thinning in the Tocantins Province (Rocha et al, 2011;Assumpção and Sacek, 2013;Azevedo et al, 2015). In the Neoproterozoic, the thin crust in the study area would have been part of the continental shelf which received sediment of the former basin of the Paraguay Belt, while the eastward-directed Brasiliano subduction was occurring towards the Paranapanema Block.…”

“…Blum and Pires (1996) estimated an average Curie depth of 30 km in this same region, with shallow regions of the Curie isotherm related to faults, including the TBL. Regionally, the NE-SW trending zone between Amazonian and São Francisco paleoplates (Figure 1), in agreement with the main trend of TBL, is characterized by thinner lithosphere compared to adjacent terranes (Rocha et al, 2011;Azevedo et al, 2015), which may explain high intraplate seismicity along this direction (Assumpção and Sacek, 2013). Pavão et al (2012) and compiled crustal thickness values obtained with receiver-function analysis and seismic-refraction data and showed that the area of the TBL, within the northern portion of Paraná Basin, is characterized by thinned crust ranging from 31 to 36 km thick.…”

Modelo de velocidade sísmica de ondas P da crosta e manto superior ao longo do perfil PABBRISE, estado de São Paulo

“…Nos últimos anos, no Brasil, vêm sendo envidados esforços no sentido de utilizar métodos sísmicos (Bassini, 1986 e referências ali contidas; Soares, 2005;Soares et al, 2006;Tavares, 2014;Evain et al, 2015;Lima et al, 2015) e sismológicos (Assumpção et al, 2002;França & Assumpção, 2004;Julià et al, 2008;Rocha et al, 2011;Trindade, 2014;Azevedo et al, 2015) para mapear a estrutura profunda da crosta e manto superior e, com isso, aprimorar o entendimento da compartimentação tectônica e evolução crustal do território brasileiro.…”