Post-glacial Permian debris flow deposits and their paleoclimatic implications (Mariana Pimentel paleovalley, southern Paraná Basin)

• Published in: Journal of South American earth sciences 2021-04, Vol.107, p.103029, Article 103029
• Main Authors: Coitinho, Júlia dos Reis, Kern, Henrique Parisi, Cagliari, Joice, Lavina, Ernesto Luiz Correa, Girelli, Tiago Jonatan, Tedesco, Julia, Lana, Cristiano, da Silveira, Ariane Santos
• Format: Article
• Language: English
• Subjects: Climate change; Coal; Diamictite; Late Paleozoic Ice Age; Post-glacial deposits; Rio Bonito Formation
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2020.103029

The end of the Late Paleozoic Ice Age was followed by a global warming climate. This climate transition is characterized by, beyond other aspects, a decrease in the intensity of physical weathering, characteristic of arid conditions, and an increase in the intensity of chemical weathering. In the southern Paraná Basin, the post-glacial onset and intense record of “Pedra-Areia” diamictite within the Mariana Pimentel paleovalley was likely controlled by warming climate conditions and mark a period of intense rainfall and slope instability. To test this hypothesis, we have performed facies and sequence stratigraphy analysis on cores located within the Mariana Pimentel paleovalley, and U–Pb-Hf investigations to acquire sediment provenance information. Diamictite deposits were produced by debris flow processes, which transported regolith from the valley wall to the bottom, eroding and incorporating mud and peat when reaching the bottom of the valley. The local source of sediment is explained by the sedimentological characteristics of the diamictite and zircon provenance studies. These deposits are preserved within the transgressive system tract and the abundant deposition was controlled by increasing temperature and humidity, and thus the increase in chemical weathering on the walls, forming the regolith. The development of more humid and warmer climatic conditions, contrasting with the cold and dry climate of the glacial period, was an important control over diamictite deposition. •Post-glacial deposits are preserved within the Mariana Pimentel paleovalley.•Onset and intense record of diamictite in the Rio Bonito Formation.•“Pedra-Areia” diamictite genesis is related to warming climate condition.•Debris flow process was sourced by the paleovalley walls regolith.•Mariana Pimentel paleovalley was an important Early Permian landscape feature.