U-Pb CA-IDTIMS geochronology of the Late Paleozoic glacial and post-glacial deposits in southern Paran&#225; Basin
Authors: Cagliari Joice , Schmitz Mark D. , C. Lavina Ernesto L. , G. Netto Renata 
Published: March 2020

&lt;p&gt;The Late Paleozoic Ice Age (LPIA), one of the best known and prolonged glaciation events in Earth's history, resulted in the deposition of glacial sediments over Gondwana. The terminal deglaciation, a diachronic event starting earlier at the western and later in the eastern part of the continent, caused sea level rise and the widespread deposition of transgressive sedimentary successions. The Paran&amp;#225; Basin is one of these basins recording both glacial influenced (Itarar&amp;#233; Group) and post-glacial (Guat&amp;#225; Group) deposits. However, the absence of Carboniferous and Permian guide fossils has motivated a chronostratigraphic approach based on plants and palynomorphs, which associated with sparse radioisotopic ages have suggested that transition between the glacial-influenced and the post-glacial succession would have occurred in the Sakmarian, early Permian (Holz et al., 2010). &amp;#160;These results are in conflict with recent studies that indicate LPIA glacial deposits are constrained to the Carboniferous (Cagliari et al., 2016; Griffis et al., 2019). Therefore, in this study we present new high-precision single-crystal CA-ID-TIMS U-Pb radioisotopic ages for the glacial influenced (one samples) and post-glacial (six samples) deposits in the southern Paran&amp;#225; Basin. Along with these new radioisotopic ages, a Bayesian age-depth model was applied to constrain the age of the LPIA demise in the southern Paran&amp;#225; Basin, which also represents the icehouse-greenhouse transition. The resulting age for the Rio do Sul Formation, topmost unit of the Itarar&amp;#233; Group, is Ghzelian (Carboniferous). For the Rio Bonito Formation, basal Guat&amp;#225; Group, all samples are Asselian (Permian). The results reinforce that glacial-influenced deposits in the southern Paran&amp;#225; Basin are constrained to the Carboniferous. Based upon the depth-age model, the icehouse to greenhouse transition likely occurred in the Late Carbon&amp;#237;ferous. The integration between our results and recent published high-resolution U-Pb ages allowed us to detail the Carboniferous-Permian chronostratigraphic framework of the southern Paran&amp;#225; Basin.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Holz, M., Fran&amp;#231;a, A.B., Souza, P.A., Iannuzzi, R., Rohn, R. (2010). A stratigraphic chart of the Late Carboniferous/Permian succession of the eastern border of the Paran&amp;#225; Basin, Brazil, South America. Journal of South American Earth Sciences 29, 381&amp;#8211;399.&lt;/p&gt;&lt;p&gt;Cagliari, J., Philipp, R.P., Buso, V.V., Netto, R.G., Hillebrand, P.K., Lopes, R.C.L., Basei, M.A.S., Faccini, U.F. (2016). Age constraints of the glaciation in the Paran&amp;#225; basin: Evidence from new U&amp;#8211;Pb dates. Journal of the Geological Society 173, 871&amp;#8211;874.&lt;/p&gt;&lt;p&gt;Griffis, N.P., Monta&amp;#241;ez, I.P., Mundil, R., Richey, J., Isbell, J., Fedorchuk, N., Linol, B., Iannuzzi, R., Vesely, F., Mottin, T., Rosa, E., Keller, B., Yin, Q. (2019). Coupled stratigraphic and U-Pb zircon age constraints on the late Paleozoic icehouse-to-greenhouse turnover in south-central Gondwana. Geology 47, 1146&amp;#8211;1150.&lt;/p&gt;