Sedimentary organic matter applied to paleoenvironmental reconstruction of the Devonian of the Paraná Basin, SW Gondwana

• Published in: Palaeogeography, palaeoclimatology, palaeoecology Vol. 651; p. 112395
• Main Authors: Gonçalves, Caio Guilherme, Carvalho, Marcelo de Araujo, Trindade, Viviane Segundo Faria, Sedorko, Daniel, Scheffler, Sandro Marcelo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2024
• Subjects: Amorphous organic matter; Kačák event; Marine paleoenvironments; Sedimentary organic matter; Kačák event; Sedimentary organic matter; Amorphous organic matter; Marine paleoenvironments
• ISSN: 0031-0182
• DOI: 10.1016/j.palaeo.2024.112395

The study of sedimentary organic matter (SOM) is essential for understanding paleoenvironmental conditions and depositional settings of geological formations. This paper explores the Devonian strata of the Paraná Basin, utilizing SOM analysis to reconstruct paleoenvironments and identify global events. The Devonian period is notable for significant geological and biological changes, including mass extinctions and extensive organic-rich sediment deposition. By examining the composition, distribution, and diagenesis of SOM in this region, we aim to elucidate the paleoenvironmental dynamics and depositional history. The Devonian outcrops in the state of Mato Grosso do Sul, Brazil rocks reveal distinct depositional characteristics, when compared to those found on the eastern border of the basin. The palynofacies analysis was conducted on 59 samples from four outcrops (MS-26, MS-29, MS-30 and MS-70), which age spans from Pragian to Givetian. The main groups and subgroups of the SOM were identified: amorphous organic matter (AOM) (“amorphous organic matter” and pseudoamorphous), phytoclasts (opaques, non-opaque-non biostructured, cuticles, membranes and Spongiophyton) and palynomorphs (spores, freshwater algae, scolecodonts, chitinozoan and acritarchs). The SOM was grouped into three palynofacies associations: opaques, land-derived and marine+AOM. In the Pragian—Emsian interval (MS-26, MS-29 and MS-30), a prevalent occurrence of phytoclasts and marine microphytoplankton is noted, with their distribution exhibiting distinct alternations in each section suggesting a deposition in the marine environment ranging from onshore to offshore. In the Givetian (MS-70 outcrop), we detected a progressive increase and diversification of marine elements (e.g., acritarchs), indicating a transgressive phase probably related with the Kačák event.
•Comprehension of the Devonian period within the Paraná Basin, situated in the southwestern part of Gondwana.•Paleoenvironmental reconstruction from Pragian to Givetian in SW Gondwana•Palynofacies