Paleoenvironmental evolution of an Early Devonian section from Paraná Basin (South of Brazil) based on a multiproxy approach

• Published in: Journal of Sedimentary Environments 2022-06, Vol.7 (2), p.111-123
• Main Authors: Gama, Renata Marins Alvim, Costa, Kassi Bragança, dos Reis, Darlly Erika Silva, Pereira, Egberto
• Format: Article
• Language: English
• Subjects: cities; Earth and Environmental Science; Earth Sciences; Environment; Evolutionary Biology; Geography; Review Article; Sedimentology; towns; Urban Geography; Urbanism (inc. megacities
• ISSN: 2662-5571; 2447-9462
• DOI: 10.1007/s43217-021-00085-0

Although there are many studies in the Devonian Paraná Basin (Jaguariaíva Member, Ponta Grossa Formation; Brazil) aiming to know paleoenvironmental conditions, there are still many gaps in knowledge on this matter. Therefore, this work, based on a multiproxy approach (sedimentology, ichnology, geochemistry and sequence stratigraphy), characterizes the Early Devonian shales of the Ponta Grossa Formation to detail the paleoenvironmental conditions prevailing in the region. In addition to the recognition of trace fossils ( Chondrites , Phycosiphon , Skolithos , Teichichnus , Zoophycos , Helminthopsis , Helminthopsis , Palaeophycus and Planolites ), the bioturbation intensity index, total organic carbon (TOC) contents and organic matter carbon isotopic (δ 13 C organic ) values were estimated. Four sedimentary facies were identified: (H) heterolithic, (Sl) siltstone, (F) claystone and (Fl) black shale. The results indicate that facies Fl is the richest organic matter unit (TOC > 1%) and is unbioturbated, according to the ichnofabric index (ii = 1). These characteristics agree with the maximum flooding surface (MFS) of third-order from the Emsian, at the Paraná Basin, based on interpretations already carried out in the basin. The well core was divided into five complete fourth-order sequences, of high-resolution, which are limited in your top for fourth-order transgressive surfaces. This subdivision in the fourth-order sequences was based on the third-order division already proposed for the Jaguariaíva member. The MFS sedimentary layers displayed sharp negative δ 13 C organic values, probably caused by changes in the input of organic matter from the oceanic productivity. Anoxic/dysoxic depositional events are recorded during events of sea-level rise and they were identified in the studied well core. The multiproxy approach pointed to a possible recording of Zlíchov-Daleje events in the studied interval. This event was registered in several places around the Globe, being important for the reconstruction of the paleogeography of Gondwana, of the Lower Devonian.