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

Autor(es)

Cedraz, V ^[1] ; Julia, J. ^{[2, 1]} ; Assumpcao, M. ^[3]

Afiliação do(s) autor(es)

^[1] Univ Fed Rio Grande do Norte, Programa Posgrad Geodinam & Geofis, Natal, RN - Brazil

^[2] Univ Fed Rio Grande do Norte, Dept Geofis, Natal, RN - Brazil

^[3] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH; v. 125, n. 2 FEB 2020.
• Citações Web of Science: 1

Resumo

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 V-S < 4.0 km/s, under the basin and along the SW projection of the Transbrasiliano lineament (TBL); (ii) crust of 45 km with V-S > 4.0 km/s below 40 km depth, flanking the basin to the cast and west; (iii) crust of 50-55 km with V-S > 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 V-S < 4.0 km/s in the neighboring Parana basin. Existing geodynamic models propose that the Pantanal basin formed either in the hack-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. Plain Language Summary We report on a number of velocity models for the crust and uppermost mantle in the Pantanal basin and neighboring regions of South-Central Brazil that were developed from recordings of distant earthquakes. The Pantanal basin developed in the Andean region of South America, and it represents a unique geological feature along the entire Andean foreland. The velocity models provide constraints on subsurface structure with unprecedented detail, revealing the presence of up to four different crustal types in the study region. We discuss how existing models of formation and evolution should be altered to incorporate our new findings and conclude that the influence of the Transbrasiliano lineament played a critical role in the formation and evolution of this enigmatic basin. (AU)

• Processo FAPESP: 13/24215-6 - As bacias do Pantanal, Chaco e Paraná (PCPB): evolução e estrutura sísmica da crosta e manto superior
• Beneficiário: Marcelo Sousa de Assumpção
• Modalidade de apoio: Auxílio à Pesquisa - Temático