Changes

The integrated analysis of basin subsidence shows a relationship between the cycles of depositional space creation in intracratonic areas and orogenic episodes. Several orogenic periods and compressive deformation pulses in the active margin of Gondwana were the major controls of accommodation space variation rates. The orogenic apex matches periods of accelerated development of the interior syneclises, and in the absence of orogenic climax records tectonic uplift on a continental scale in the Paraná Basin. As a result, the temporal amplitude of Paraná Basin supersequences are clearly confined by the temporal limits of the different subsidence cycles controlled by Paleozoic orogenies on the Gondwanan margin. Sea level, climate and sediment supply had supporting roles in transgressive-regressive marine cycles, since their deposits do not match the global eustatic oscillations (Sloss, 1990).

The integrated analysis of basin subsidence shows a relationship between the cycles of depositional space creation in intracratonic areas and orogenic episodes. Several orogenic periods and compressive deformation pulses in the active margin of Gondwana were the major controls of accommodation space variation rates. The orogenic apex matches periods of accelerated development of the interior syneclises, and in the absence of orogenic climax records tectonic uplift on a continental scale in the Paraná Basin. As a result, the temporal amplitude of Paraná Basin supersequences are clearly confined by the temporal limits of the different subsidence cycles controlled by Paleozoic orogenies on the Gondwanan margin. Sea level, climate and sediment supply had supporting roles in transgressive-regressive marine cycles, since their deposits do not match the global eustatic oscillations (Sloss, 1990).

The tectonic-stratigraphic evolution of the Paraná Basin developed in the Gondwanan cratonic interior, which had a convergent relationship with the oceanic lithosphere of Panthalassa (Gondwanides Orogenic Cycle), during the Phanerozoic. This orogenic cycle is marked by two main collisional cycles: Famatinian (Ordovician to Devonian) and Gondwanic (Carboniferous to Triassic) (Ramos, 1988, 1990). The structure of the Paraná Basin developed in NE-SW elongated depressions, according to the plot of the Precambrian substrate.<ref name=Milani_1997>Milani, E. J., 1997, Evolução tectono-estratigráfica da Bacia do Paraná e seu relacionamento com a geodinâmica fanerozóica do Gondwana sul-ocidental. 2 v. Tese (Doutorado) -  Universidade Federal do Rio Grande do Sul, Porto Alegre</ref> The basement weakness zones being reactivated under the compressional field, which originated on the continent's edge by the Ocloyic Orogeny (Famatinian)<ref name=Ramos_1986> Ramos, V. A.; Jordan, T. E.; Allmendinger, R. W.; Mpodozis, C.; Kay, J. M.; Cortés, J. M.; Palma, M., 1986, Paleozoic terranes of the central Argentine- Chilean Andes. Tectonics, Washington, v. 5, n. 6, p.855-880</ref>), which provided accommodation space for the of the first unit: the Rio Ivaí supersequence.

The tectonic-stratigraphic evolution of the Paraná Basin developed in the Gondwanan cratonic interior, which had a convergent relationship with the oceanic lithosphere of Panthalassa (Gondwanides Orogenic Cycle), during the Phanerozoic. This orogenic cycle is marked by two main collisional cycles: Famatinian (Ordovician to Devonian) and Gondwanic (Carboniferous to Triassic) (Ramos, 1988, 1990). The structure of the Paraná Basin developed in NE-SW elongated depressions, according to the plot of the Precambrian substrate.<ref name=Milani_1997>Milani, E. J., 1997, Evolução tectono-estratigráfica da Bacia do Paraná e seu relacionamento com a geodinâmica fanerozóica do Gondwana sul-ocidental. 2 v. Tese (Doutorado) -  Universidade Federal do Rio Grande do Sul, Porto Alegre</ref> The [[basement]] weakness zones being reactivated under the compressional field, which originated on the continent's edge by the Ocloyic Orogeny (Famatinian)<ref name=Ramos_1986> Ramos, V. A.; Jordan, T. E.; Allmendinger, R. W.; Mpodozis, C.; Kay, J. M.; Cortés, J. M.; Palma, M., 1986, Paleozoic terranes of the central Argentine- Chilean Andes. Tectonics, Washington, v. 5, n. 6, p.855-880</ref>), which provided accommodation space for the of the first unit: the Rio Ivaí supersequence.

When regional flexural subsidence resumed, Paraná and Gondwana I Supersequences had accumulated sediments, with the boundary between them marked by a gap of 70 Ma, a gap in the tectonic-sedimentary basin history. The Gondwanic orogenic cycle followed the Famatinian orogenic cycle, creating an extensive mountain belt southwest of the Paraná Basin, which overloaded the continental lithosphere. This was propagated by lithospheric flexure in Gondwana, leading to subsidence in the basin by tectonic adjustment mechanisms and thus initiating the interior synclines phase.<ref name=Ramos_1986 /><ref name=Zalan_1990 />; Sign 1996; <ref name=Milani_1997 /><ref name=Milani_1998> Milani, E. J.; Faccini, U. F.; Scherer, C. M. S.; Araújo, L. M.; Cupertino, J. A., 1998, Sequences and stratigraphic hierarchy of the Paraná Basin (Ordovician to Cretaceous), Southern Brazil. Boletim IG-USP, São Paulo, p. 125-173. (Série Científica, n. 29).</ref>).

When regional flexural subsidence resumed, Paraná and Gondwana I Supersequences had accumulated sediments, with the boundary between them marked by a gap of 70 Ma, a gap in the tectonic-sedimentary basin history. The Gondwanic orogenic cycle followed the Famatinian orogenic cycle, creating an extensive mountain belt southwest of the Paraná Basin, which overloaded the continental lithosphere. This was propagated by lithospheric flexure in Gondwana, leading to subsidence in the basin by tectonic adjustment mechanisms and thus initiating the interior synclines phase.<ref name=Ramos_1986 /><ref name=Zalan_1990 />; Sign 1996; <ref name=Milani_1997 /><ref name=Milani_1998> Milani, E. J.; Faccini, U. F.; Scherer, C. M. S.; Araújo, L. M.; Cupertino, J. A., 1998, Sequences and stratigraphic hierarchy of the Paraná Basin (Ordovician to Cretaceous), Southern Brazil. Boletim IG-USP, São Paulo, p. 125-173. (Série Científica, n. 29).</ref>).

===Rio Ivaí Supersequence===

===Rio Ivaí Supersequence===

This unit, the oldest identified in the Paraná Basin, rests directly on the various areas of the basement. Its top is marked by a regional unconformity surface that juxtaposes the Early Silurian strata of the upper Rio Group Ivaí when it displays its complete record into the Lower Devonian, at the base of the Furnas Formation.

This unit, the oldest identified in the Paraná Basin, rests directly on the various areas of the [[basement]]. Its top is marked by a regional unconformity surface that juxtaposes the Early Silurian strata of the upper Rio Group Ivaí when it displays its complete record into the Lower Devonian, at the base of the Furnas Formation.

Three units constitute the Rio Ivaí Group: Alto das Garças, Iapó and Vila Maria Formations.<ref name=Assine_1996>Assine, M. L., 1996, Aspectos da estratigrafia das sequências pré-carboníferas da Bacia do Paraná no Brasil. 1996. 207 p. Tese (Doutorado) - Universidade de São Paulo, São Paulo.</ref>. The Alto das Garças Formation, with a maximum thickness of 300 meters, is essentially sand dominated and may include a basal quartzose conglomerate, passing to conglomeratic sandstones with cross stratification. The upper portion of the unit is represented by an increase in the amount of silt and clay and reddish coloration.

Three units constitute the Rio Ivaí Group: Alto das Garças, Iapó and Vila Maria Formations.<ref name=Assine_1996>Assine, M. L., 1996, Aspectos da estratigrafia das sequências pré-carboníferas da Bacia do Paraná no Brasil. 1996. 207 p. Tese (Doutorado) - Universidade de São Paulo, São Paulo.</ref>. The Alto das Garças Formation, with a maximum thickness of 300 meters, is essentially sand dominated and may include a basal quartzose conglomerate, passing to conglomeratic sandstones with cross stratification. The upper portion of the unit is represented by an increase in the amount of silt and clay and reddish coloration.

===Paraná Supersequence===

===Paraná Supersequence===

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.

===Bauru Supersequence===

===Bauru Supersequence===

Bauru Supersequence corresponds lithostratigraphically to the Caiuá and Bauru Groups. It represents a continental post-lava cover strata and it is constituted by a siliciclastic unit, (sandy-conglomeratic deposits, including clasts of various lithologies, such as volcanics, sandstones, shales and basement crystalline rocks), accumulated in semi arid to desert conditions. This sequence was accommodated in the flexural depression originated by the load of the basalt pile. This was the last significant episode of subsidence in the Paraná Basin. The accumulation of Bauru Supersequence took place during Aptian to Maastrichtian time and it has c.300 m of thickness over 370.000 km².

Bauru Supersequence corresponds lithostratigraphically to the Caiuá and Bauru Groups. It represents a continental post-lava cover strata and it is constituted by a siliciclastic unit, (sandy-conglomeratic deposits, including clasts of various lithologies, such as volcanics, sandstones, shales and [[basement]] crystalline rocks), accumulated in semi arid to desert conditions. This sequence was accommodated in the flexural depression originated by the load of the basalt pile. This was the last significant episode of subsidence in the Paraná Basin. The accumulation of Bauru Supersequence took place during Aptian to Maastrichtian time and it has c.300 m of thickness over 370.000 km².

The Caiaú Group corresponds to the aeolian system of the Caiuá Desert and it is compound by the Uberaba, Vale do Rio do Peixe, Araçatuba, São José do Rio Preto, Presidente Prudente and Marília formations.

The Caiaú Group corresponds to the aeolian system of the Caiuá Desert and it is compound by the Uberaba, Vale do Rio do Peixe, Araçatuba, São José do Rio Preto, Presidente Prudente and Marília formations.