So close and yet so far: U-Pb geochronological constraints of the Jaibaras Rift Basin and the intracratonic Parnaiba Basin in SW Gondwana

Author(s)

Cerri, Rodrigo, I ; Warren, Lucas, V ; Varejao, Filipe G. ; Silva, Alex J. Choupina A. ; Lana, Cristiano ; Assine, Mario L.

• Document type: Journal article
• Source: GEOLOGICAL MAGAZINE; v. N/A, p. 21-pg., 2021-04-06.

Abstract

Several sag-type basins apparently developed from rift systems, but there is no consensus about how and if these grabens influenced the sedimentation of the post-rift thermal subsidence phase. The Ediacaran Jaibaras Rift Basin is one of the best-exposed sedimentary records among the NE Brazil late Precambrian - early Cambrian rift system, cropping out at the eastern margin of the intracratonic Parnaiba Basin and extending below it towards the west. Here we present detrital zircon U-Pb ages of rocks from the Jaibaras (Aprazivel Formation) and Parnaiba (Ipu Formation) basins, in order to understand the provenance patterns, maximum depositional ages (MDA) and age relationship between these units. The MDA for the Aprazivel Formation (c. 499 +/- 5 Ma) indicates a Cambrian age for the upper part of the Jaibaras Basin. The bulk U-Pb data indicate that the Ipu Formation started to deposit during late Cambrian and/or Early Ordovician time, despite its MDA (c. 528 +/- 11 Ma) being older than that of the Aprazivel Formation. Detrital zircon provenance suggests that the primary source areas for the early deposits of the Parnaiba Basin were mountains related to the Brasiliano Orogeny to the south and SE (e.g. Rio Preto and Riacho do Pontal metamorphic belts). Finally, our data emphasize the key change in source areas from the rift to the initial deposition of the intracratonic phase, indicating major depositional style changes between both basins after the Gondwana assembly. (AU)

• 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
• 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