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The first record of Hirnantian Ostracoda in South America: implications for the biostratigraphy and paleozoogeography of the Paraná basin

Published online by Cambridge University Press:  22 September 2021

Lívio Reily de Oliveira Gonçalves
Affiliation:
Institute of Geosciences, University of Brasília, Brasília, Brazil 70910-900 , , , ,
Dermeval Aparecido Do Carmo*
Affiliation:
Institute of Geosciences, University of Brasília, Brasília, Brazil 70910-900 , , , ,
Maria José Salas
Affiliation:
Center for Research in Earth Sciences, National Scientific and Technical Research Council, Córdoba, Argentina X5016GCA
Rodrigo Rodrigues Adôrno
Affiliation:
Institute of Geosciences, University of Brasília, Brasília, Brazil 70910-900 , , , , Geological Survey of Brazil, Center for Technological Development, Brasília, Brazil, 70040-904
Tõnu Meidla
Affiliation:
Department of Geology, University of Tartu, Tartu, Estonia 50411
Matheus Denezine
Affiliation:
Institute of Geosciences, University of Brasília, Brasília, Brazil 70910-900 , , , ,
Lívia Cardoso da Silva Rodrigues
Affiliation:
Institute of Geosciences, University of Brasília, Brasília, Brazil 70910-900 , , , ,
Mario Luis Assine
Affiliation:
Department of Geology, São Paulo State University, Rio Claro, Brazil 13506-752
Lucas Silveira Antonietto
Affiliation:
Institute of Geosciences, University of Brasília, Brasília, Brazil 70910-900 , , , ,
*
*Corresponding author

Abstract

Herein is reported the first occurrence of ostracodes from the Iapó Formation, an uppermost Ordovician unit of the Rio Ivaí Group in the Paraná basin, Brazil. Two ostracode species were identified in the Três Barras Farm section: Harpabollia harparum (Troedsson, 1918) and Satiellina paranaensis Adôrno and Salas in Adôrno et al., 2016 were recovered from dropstone-bearing shale overlying glaciogenic diamictites, a feature typical of Hirnantian (uppermost Ordovician) strata throughout Gondwana. The taxonomy of the Genus Harpabollia, as well as its type species Harpabollia harparum, was reviewed, and emended and new diagnoses were respectively proposed for each taxon. Occurrences of Harpabollia harparum and Satiellina species were common in areas influenced by cold waters. Additionally, the occurrence of Harpabollia harparum, an index species to the uppermost Ordovician of several stratigraphic units in Baltica and southern Gondwana, allowed us to infer a Hirnantian age for the deposits of the Iapó Formation. Other than being associated with Harpabollia harparum in Iapó Formation of the Paraná basin, Satiellina paranaensis is also found in lower levels of the Vila Maria Formation; therefore, these are also considered Hirnantian in age. Above these lower levels of the Vila Maria Formation, a well-dated Rhuddanian (lowermost Llandovery, Silurian) palynomorph assemblage is observed within the formation. These occurrences are evidence of a continuous process of sedimentary deposition during the Ordovician–Silurian transition in the Paraná basin.

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Articles
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Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of The Paleontological Society
Figure 0

Figure 1.Chronolithostratigraphic chart of the Rio Ivaí Group, Paraná basin, Brazil, according to Assine et al. (1998) and Adorno et al. (2016).

Figure 1

Figure 2.Lithologic log of the Três Barras Farm section, Bom Jardim de Goiás, State of Goiás, Brazil. (1) Contact between the Iapó Formation and the basement. (2) Diamictite facies of Iapó Formation. (3) Shale facies of the Vila Maria Formation. Symbols used herein follow the Federal Geographic Data Committee (2006).

Figure 2

Figure 3.Geographical map showing the location of the Três Barras Farm section and Paleozoic surfaces around the Bom Jardim de Goiás Municipality, State of Goiás, Brazil. Other Paleozoic units in the area include the Furnas and Ponta Grossa (Devonian) and the Aquidauana formations (Carboniferous), while the Ordovician–Silurian is represented by the Vila Maria and Iapó formations (Alvarenga et al., 1998). Symbolization standards follow the Federal Geographic Data Committee (2006).

Figure 3

Figure 4.Ostracode species found in the Iapó Formation, Rio Ivaí Group, Paraná basin, Brazil. (1–5) Harpabollia harparum (Troedsson, 1918). (1, 2, 4, 5) Adult carapace (CP 851): (1) right lateral view; (2) left lateral view; (4) dorsal view; (5) ventral view. (3) Adult carapace (CP 852) displaying a preserved connection between L1 and L4 lobes (the dotted line marks the approximate posterior end of the right valve). (6–9) Satiellina paranaensis Adôrno and Salas in Adôrno et al., 2016: (6), adult carapace (CP-902), right lateral view (the dotted line marks the approximate posterior end and dorsal margins of the carapace); (7) (CP-903) dorsal view of disarticulated valves; (8) juvenile valve (CP 904), right lateral view; (9) juvenile valve (CP 905), right lateral view.

Figure 4

Figure 5.Species diversity and stratigraphic distribution of the ostracod genera Satiellina Vannier, 1986 and Harpabollia Schallreuter, 1990, the brachiopod genus Kosoidea Havlíček and Mergl, 1988, and the ichnospecies Arthrophycus alleghaniensis (Harlan, 1831).

Figure 5

Figure 6.Composite section of the Iapó–Vila Maria interval around the Bom Jardim de Goiás Municipality, State of Goiás, Brazil: (1) Aldeia Creek outcrop; (2) Três Barras Farm outcrop; (3) COHAB outcrop. Co-occurrences of Harpabollia harparum (Troedsson, 1918), Satiellina paranaensis Adôrno and Salas in Adôrno et al., 2016, and Kosoidea australis Zabini et al., 2019 are exclusive of shale with dropstone levels of the Hirnantian Iapó Formation; the latter two also co-occur at the shale levels of the Hirnantian–Ruddanian basal Vila Maria (Adôrno et al., 2016; Zabini et al., 2019), which is also constrained by Rb/Sr dating (Mizusaki et al., 2002). Arthrophycus alleghaniensis (Harlan, 1831) is found in sandstone/siltstone levels typical of the upper Llandovery (Silurian) Vila Maria (Burjack and Popp, 1981).

Figure 6

Figure 7.Late Ordovician (Katian–Hirnantian) paleogeographic map (modified from Scotese, 2014 according to Cocks and Torsvik, 2020) showing the latest Ordovician paleozoogeographic distribution of the ostracode genera Harpabollia Schallreuter, 1990 and Satiellina Vannier, 1986. Notice that species of both genera are confined to regions dominated by cold-water marine currents (Scotese, 2000).