Joint Inversion of Receiver Functions and Surface‐Wave Dispersion in the Pantanal Wetlands: Implications for Basin Formation

Abstract

The origin and evolution of the Pantanal basin have been investigated through velocity‐depth profiles developed from the joint inversion of receiver functions and surface‐wave dispersion velocities at 33 broadband stations. The Pantanal basin is a shallow and wide depression in South‐Central Brazil that developed within the Andean foreland in response to loads and flexural bending of the South American plate. Our results reveal the existence of up to four different crustal types that correlate with surface geology: (i) crust of 35 km with VS < 4.0 km/s, under the basin and along the SW projection of the Transbrasiliano lineament (TBL); (ii) crust of 45 km with VS > 4.0 km/s below 40 km depth, flanking the basin to the east and west; (iii) crust of 50–55 km with VS > 4.0 km/s below 40 km depth, flanking the basin to the north and south and along the TBL; and (iv) crust of 42.5–45.0 km with VS < 4.0 km/s in the neighboring Paraná basin. Existing geodynamic models propose that the Pantanal basin formed either in the back‐bulge of the flexural system or at the top of the forebulge, due to extensional bending stresses that reactivated preexisting faults in the shallow upper crust. We argue that the Pantanal basin was formed in a structurally weaker portion of the foreland crust that was affected by delamination and enhanced bending of the South American plate. Our findings do not allow for discrimination among the competing models but suggest that the TBL was critical in marking the location, origin, and evolution of this basin.

Joint inversion of receiver functions and surface wave dispersion in the Recôncavo–Tucano basin of NE Brazil: implications for basin formation

“…Rondenay et al 2017) and have been successfully applied in a number of tectonic settings including sedimentary basins (e.g. Coelho et al 2018;Cedraz et al 2020;Nemocon et al 2021). Teleseismic waveforms were recorded by a network of 21 seismic stations deployed in and around the Recôncavo, Tucano and Sergipe-Alagoas basins, which included 15 broad-band stations and 6 short-period stations.…”

Source-to-sink controls on modern fluvial sands in the Pantanal back-bulge basin (Brazil)

“…Geologic maps were obtained from Bolivia (Dirección de Ordenamiento Territorial, Gobierno Autónomo Departamental de Santa Cruz), Paraguay (Vice Ministerio de Minas y Energía), and Brazil (Serviço Geológico do Brasil, CPRM). Faults were drawn based on published studies (Rizzotto & Hartmann, 2012;Warren et al, 2015;Faleiros et al, 2016;Barboza et al, 2018;Rivadeneyra-Vera et al, 2019;Cedraz et al, 2020).…”

“…et al, 2016). The crust is thin, ranging from 38-43 km on the west and thinning to <35 km on the eastern margin of the basin (Rivadeneyra-Vera et al, 2019;Cedraz et al, 2020;Shirzad et al, 2020). The Pantanal has been a site of intraplate seismicity, with notably large earthquakes in 1964 and 2009 (Dias et al, 2016).…”

Thermo‐Compositional Structure of the South American Platform Lithosphere: Evidence of Stability, Modification, and Erosion

“…The movement of the plate increased its convergence rate with the subducting Farallon Plate, and initiated a new compressional phase in South America (e.g., Almeida et al., 2000; Folguera et al., 2011; Pilger, 1984; Ramos, 1999, 2009). With uplift and exhumation of the Andean Cordillera, several foreland basins developed parallel to the Andean thrust front, such as the Chaco and Pantanal Basins, and deposits were formed over Paleozoic basins on the platform (e.g., Cedraz et al., 2020; Horton, 2018; Menegazzo et al., 2016; Ussami et al., 1999).…”