U-Pb Zircon Geochronology of Detrital and Ash Fall Deposits of the Southern Paraná Basin: A Contribution for Provenance, Tectonic Evolution, and the Paleogeography of the SW Gondwana

Abstract

Zircon U-Pb geochronology was applied to investigate the provenance, depositional ages, and paleogeography of the southwestern Gondwana in detrital and ash fall sediments from Carboniferous to Jurassic succession of the southern Paraná Basin. Four detrital age populations suggest provenance from local and distal sources located to the south, southeast, and southwest: (i) Archean to Paleoproterozoic zircons from the Rio de La Plata Craton, Nico Peres and Taquarembó terranes; (ii) Grenvillian zircons from the basement of the Gondwanides and Namaqua–Natal belts; (iii) Neoproterozoic grains from the Don Feliciano Belt; and (iv) Phanerozoic populations from Paleozoic orogenic belts and related foreland systems in Argentina, as well as eroded units of the Paraná Basin. The paleogeographic reconstruction indicates an evolution in three distinct stages: (1) a gulf open to the Panthalassa Ocean during the Carboniferous; (2) an epicontinental sea with the rise of the Gondwanides Orogeny during the Permian; and (3) continental deposits controlled by an intra-plate graben system during the Triassic. Permian–Triassic volcanogenic zircons provide constrained maximum depositional ages and attested persistent volcanism, related to the Choiyoi magmatism and effects of the climate change episodes. During the Triassic, the extensional graben system recorded the uplift of the basement through regional northwest and northeast fault systems, and the recycling of Permian zircons, modifying source-to-sink relationships.

Skull anatomy and paleoneurology of a new traversodontid from the Middle‐Late Triassic of Brazil

“…This sequence is well-documented within the Triassic Santa Maria Supersequence (lithostratigraphy: Santa Maria Formation) (Zerfass et al, 2003;Horn et al, 2014;Philipp et al, 2023), and has been correlated with other Gondwanan formations, such as the Chañares Formation in Argentina, the Lifua Member from the Manda Beds of Tanzania, the Omingonde Formation of Namibia, and the Ntawere Formation of Zambia (Langer et al, 2007;Marsicano et al, 2016;Martinelli et al, 2017;Ordoñez et al, 2020;Schultz et al, 2020). The Pinheiros-Chiniqu a Sequence is considered late Ladinian-early Carnian in age (Schultz et al, 2020).…”

“…The Pinheiros-Chiniqu a Sequence is considered late Ladinian-early Carnian in age (Schultz et al, 2020). Moreover, recent U-Pb Zircon geochronology revealed maximum ages of deposition of 244-241 million years (Anisian/Ladinian) for this stratigraphic unit (Philipp et al, 2023). Recent advances in the biostratigraphy of the Chañares Formation, with the recognition of at least two distinct biozones at that unit, suggest that, likewise, different faunal assemblages may exist within the Dinodontosaurus Assemblage Zone (AZ) (see Ezcurra et al, 2017;Martinelli et al, 2017;Ordoñez et al, 2020;Schultz et al, 2020).…”