Changes

The Devonian package of the basin, the Paraná Group, has a maximum thickness of 800 meters and overlies the Ordovician-Silurian strata of the Rio Ivaí Group, but also can be found directly on [[basement]] rocks.  

The Devonian package of the basin, the Paraná Group, has a maximum thickness of 800 meters and overlies the Ordovician-Silurian strata of the Rio Ivaí Group, but also can be found directly on [[basement]] rocks.  

Two units constitute the Paraná Group: Furnas and Ponta Grossa Formations. The Furnas Formation is represented by a succession of white quartz sandstones, medium to coarse, with high kaolinite content and displaying cross stratification of various kinds. Near the base, are frequent conglomeratic beds up to 1 m thick. In its middle portion, dominated by sandstones of medium [[grain size]], intercalated with thinner siltstone and muscovite rich shale, emphasizing the laminated aspect of that interval. Herringbone cross-stratification also occurs.<ref name=Assine_1996 /> At the top, medium to coarse sandstones come to dominate, but also occur in very thin layers of sandstone with hummocky stratification type. Continuous increase in mudstone interbeds towards the top shows a gradational transition to the Ponta Grossa Formation.

Two units constitute the Paraná Group: Furnas and Ponta Grossa Formations. The Furnas Formation is represented by a succession of white quartz sandstones, medium to coarse, with high kaolinite content and displaying cross stratification of various kinds. Near the base, are frequent conglomeratic beds up to 1 m thick. In its middle portion, dominated by sandstones of medium [[grain size]], intercalated with thinner siltstone and muscovite rich shale, emphasizing the laminated aspect of that interval. Herringbone cross-stratification also occurs.<ref name=Assine_1996 /> At the top, medium to coarse sandstones come to dominate, but also occur in very thin layers of sandstone with hummocky stratification type. Continuous increase in [[mudstone]] interbeds towards the top shows a gradational transition to the Ponta Grossa Formation.

The Ponta Grossa Formation is represented in the lower portion, by shales c.100 meters thick, containing fine sandstone lenses with stratifications reworked by waves, and black laminated carbonaceous shale, which is an important marker for stratigraphic correlation in the subsurface and a potential generator of hydrocarbons throughout its range in the central area of the Paraná Basin. The middle portion, sandstone and siltstone alternations reflect a progradation of deltaic systems. The upper portion, predominantly mudstone, documents renewed flooding on a large scale, which caps this unit.  

The Ponta Grossa Formation is represented in the lower portion, by shales c.100 meters thick, containing fine sandstone lenses with stratifications reworked by waves, and black laminated carbonaceous shale, which is an important marker for stratigraphic correlation in the subsurface and a potential generator of hydrocarbons throughout its range in the central area of the Paraná Basin. The middle portion, sandstone and siltstone alternations reflect a progradation of deltaic systems. The upper portion, predominantly mudstone, documents renewed flooding on a large scale, which caps this unit.  

The Supersequence Paraná is the second transgressive-regressive cycle of the stratigraphic record of the Paraná Basin. Marine drowning in the Paraná Basin persisted until at least the Frasnian, but not with the magnitude and the anoxic development then observed in the Paleozoic basins of northern Brazil.

The supersequence Paraná is the second transgressive-regressive cycle of the stratigraphic record of the Paraná Basin. Marine drowning in the Paraná Basin persisted until at least the Frasnian, but not with the magnitude and the anoxic development then observed in the Paleozoic basins of northern Brazil.

===Gondwana I Supersequence===

===Gondwana I Supersequence===

Six units constitute the Gondwana I Supersequence: Itararé Group, Aquidauana Formation, Guatá Group, Passa Dois Group and Pirambóia and Sanga of the Cabral Formations. The lower portion of Gondwana Supersequence I is represented by deposits related to a phase of deglaciation of the Mississippian glaciers, represented by the Itararé Group and Aquidauana Formation.

Six units constitute the Gondwana I Supersequence: Itararé Group, Aquidauana Formation, Guatá Group, Passa Dois Group and Pirambóia and Sanga of the Cabral Formations. The lower portion of Gondwana Supersequence I is represented by deposits related to a phase of deglaciation of the Mississippian glaciers, represented by the Itararé Group and Aquidauana Formation.

The deglaciation brought as a direct consequence a rise in relative sea level, identified as the "Permian transgression" by Lavina and Lopes (1987). From this transgressive trend, glaciogenic strata are succeeded by the sedimentary strata of Guatá Group, with common reworking of deltaic lobes by tides.  

The deglaciation brought as a direct consequence a rise in relative sea level, identified as the "Permian transgression" by Lavina and Lopes<ref>: Lavina, E. L., and R. C. Lopes, 1987, A transgressao marinha do Permiano Inferior e a evoluçao paleogeografica do Super-Grupo Tubarao no Estado do Rio Grande do Sul: Paula Coutiana, v. 1, p. 51–103</ref>. From this transgressive trend, glaciogenic strata are succeeded by the sedimentary strata of Guatá Group, with common reworking of deltaic lobes by tides.  

Passa Dois Group sedimentation developed following a final regressive trend on a large scale. Continental systems came to dominate the basin, representing the silting of the remaining accommodation space, whilst sedimentary structures linked to the action of tides gave way to a progradational complex of red beds including deltaic lobes lacustrine mudstones, aeolian and fluvial deposits (Lavina, 1988).

Passa Dois Group sedimentation developed following a final regressive trend on a large scale. Continental systems came to dominate the basin, representing the silting of the remaining accommodation space, whilst sedimentary structures linked to the action of tides gave way to a progradational complex of red beds including deltaic lobes lacustrine mudstones, aeolian and fluvial deposits.<ref>Lavina, E. L., 1988, The Passa Dois Group: Sedimentology, stratigraphy and paleontology of the Gondwana sequence of the Paraná Basin: 7th Interational Gondwana Symposium Excursion Guide Book A2, p. 24–29.</ref>

The Sanga of the Cabral Formation in the south and Pirambóia Formation in the north represent the advance of the continental systems on lake remnants of the "Passa Dois Basin". These formations are represented fluvial and aeolian deposits composing a wedge that thins to the southwest of the basin.

The Sanga of the Cabral Formation in the south and Pirambóia Formation in the north represent the advance of the continental systems on lake remnants of the "Passa Dois Basin". These formations are represented fluvial and aeolian deposits composing a wedge that thins to the southwest of the basin.