Table 1.

Details of the formations deposited in the Parnaíba Basin during the cratonic phase (Silurian–Triassic) showing lithology, thickness and interpreted depositional environment

AgeGroupFormationThickness (m)LithologyDepositional environment, notes and references
TriassicSambaíba500–600Clean, well-sorted, fine-medium, planar and cross-stratified sandstoneSand desert in an internal basin (Abrantes & Nogueira 2013)
Late Permian–Early TriassicBalsasMotuca280Red mudstone and sandstone, bedded gypsum and/or anhydrite; lenses of limestone; thin salt beds at top of unit; sandier towards the eastShallow lakes, mudflats and saline pans (Góes & Feijó 1994; Vaz et al. 2007; Abrantes et al. 2016)
Late PermianPedra de Fogo100Sandstone, shale, limestone; abundant silicified fossil woodShallow lacustrine system associated with mudflats and ephemeral rivers (Araújo et al. 2016)
Late CarboniferousPiauí100–150Red sandstone and mudstone, white limestone, and conglomerateAeolian, fluvial and shallow marine; forming 8 sequences (Vieira & Scherer 2017)
Early Carboniferous (Tournaisian)Poti130Fine–medium sandstone, with swaley cross-stratification; siltstone; conglomerate and coarse cross-stratified sandstoneUpper-shoreface, tidal-flat and lagoon environments passing up into braided fluvial deposits (Loboziak et al. 1992; Góes 1995)
Late Devonian–Early Carboniferous (Fammenian–Tournaisian)Longá40Laminated mudstone; subordinate sandstone with hummocky cross-stratificationShelf environment with transitional boundary to the overlying Poti Formation (Loboziak et al. 1992; Góes 1995)
Middle–Late Devonian (Givetian–Fammenian)CanindeCabeças100–400Fine to pebbly sandstone; cross-bedded and hummocky cross-stratification; subordinate siltstone interbeds; upper part has glacial depositsFlood-dominated fluvio-deltaic system; delta-front and shelf deposits (Ponciano & Fávera 2009); laterally equivalent in part to the Pimenteiras Formation
Middle–Late Devonian (Givetian–Frasnian)Pimenteiras200–580Dark mudstone, siltstone and fine-grained sandstone with hummocky cross-stratification in the upper partMarine shelf deposit; offshore transition zone to top (Ponciano et al. 2012)
Middle Devonian (Eifelian)Itaim220–400SandstoneMarine shelf; tide- and storm-related deposits (Milani & Zalán 1999)
Silurian (Wenlock)–earliest DevonianJaicós180–420Coarse-grained sandstonesBraided alluvial–fluvial depositional system (Milani & Zalán 1999)
Silurian (Llandovery)Serra GrandeTianguá0–400Dark-grey bioturbated shale, with interbeds of siltstone and micaceous sandstoneShallow marine (Le Hérissé et al. 2001); glacial influence (Grahn & Caputo 1992)
?latest Ordovician–Silurian (Hirnantian–Llandovery)Ipu0–250Conglomerate, (pebbly) sandstone and diamictite; pebbly sandstone is massive or cross-beddedAlluvial and fluvial deposits; glacial outwash and tillite in the upper part (Grahn & Caputo 1992)
  • This is based on Vaz et al. (2007) and a variety of other sources as indicated.