Unraveling the origin of the Parnaiba Basin: Testing the rift to sag hypothesis using a multi-proxy provenance analysis

Author(s)

Cerri, Rodrigo I. ^[1] ; Warren, Lucas V. ^{[1, 2]} ; Varejao, Filipe G. ^[3] ; Marconato, Andre ^[4] ; Luvizotto, George L. ^{[1, 2]} ; Assine, Mario L. ^{[1, 2]}

Affiliation

^[1] Univ Estadual Paulista Unesp, Inst Geociencias & Ciencias Exatas, Ave 24-A, Vista 178, BR-13506900 Rio Claro, SP - Brazil

^[2] Marconato, Andre, Univ Fed Ouro Preto, Dept Geol, Escola Minas, Campus Morro Cruzeiro, BR-35400000 Ouro Preto, MG, Brazil.Cerri, Rodrigo I., Univ Estadual Paulista Unesp, Inst Geociencias & Ciencias Exatas, Ave 24-A, Vista 178, BR-13506900 Rio Claro, SP - Brazil

^[3] Univ Fed Parana, Inst LAMIR, Ctr Politecn, BR-81531980 Curitiba, PR - Brazil

^[4] Univ Fed Ouro Preto, Dept Geol, Escola Minas, Campus Morro Cruzeiro, BR-35400000 Ouro Preto, MG - Brazil

• Document type: Journal article
• Source: Journal of South American Earth Sciences; v. 101, AUG 2020.
• Web of Science Citations: 0

Abstract

Syneclises are long-lived sedimentary basins characterized by complex subsidence and erosion histories. The premise that these geotectonic units evolve from initial rifting processes following thermal (or flexural) subsidence is widespread in the geologic sciences and, to this day, remains a controversial issue. Seeking to test this hypothesis, we proceeded a novel mull-proxy provenance study aiming to identify differences (and/or similarities) in the sedimentary signal and source areas of the Jaibaras (rift) and Parnaiba (sag) basins. We conducted a detailed analysis of trace elements geochemistry of detrital rutile grains, macroscopic gravel composition and paleocurrents from the sedimentary deposits of the Aprazivel Formation (Ediacaran - Cambrian, top of Jaibaras Basin) and the Ipu Formation (Ordovician, basal unit of Parnaiba Basin). Our data reveal that important changes in source areas occurred between the end of the rifting and the beginning of the sag phase, reinforcing the hypothesis that the evolution of the Jaibaras and Parnaiba basins were not genetically related. Our results demonstrate that conglomerates of the rift sequence are predominantly composed of volcanic, sedimentary, and metamorphic angular to sub-angular clasts, pointing to diverse, nearby source areas. Contrastingly, conglomerates of the initial sag sequence have greater sedimentary maturity, with dominant rounded vein quartz clasts and other minor source contributions, which suggest distant source areas, showing a consistent paleocurrent direction towards NW. Indeed, the detrital rutile trace elements geochemistry demonstrates that the source areas of these two units were distinct, revealing an important decrease in the input of granulite facies and metamafic grains in the sag basin comparing with the rift succession. In conclusion, as well as paleomagnetic and geochronological studies, the provenance methods using a mull-proxy approach proved to be an effective and powerful technique for distinguishing modifications in the sedimentary signal between rift-to-sag sequences. (AU)

• FAPESP's process: 14/00519-9 - Centralities of night-time leisure in the city of São Carlos-SP and the interface relations
• Grantee: Tiago Ferreira Lopes Machado
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 17/19550-1 - Jaibaras tectonossequence genesis (Ediacarano - Ordoviciano) and its inheritance in the sedimentation of Serra Grande sequence (Ordoviciano - Siluriano), Northeast edge of Parnaíba Basin
• Grantee: Rodrigo Irineu Cerri
• Support Opportunities: Scholarships in Brazil - Doctorate