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 (Milani, 1997)<ref name=Milani_1997>MILANI, E. J. Evolução tectono-estratigráfica da Bacia do Paraná e seu relacionamento com a geodinâmica fanerozóica do Gondwana sul-ocidental. 1997. 2 v. Tese (Doutorado) -  Universidade Federal do Rio Grande do Sul, Porto Alegre, 1997.</ref>. The basement weakness zones being reactivated under the compressional field, which originated on the continent's edge by the Ocloyic Orogeny (Famatinian - Ramos et al., 1986<ref name=Ramos_1986>RAMOS, V. A.; JORDAN, T. E.; ALLMENDINGER, R. W.; MPODOZIS, C.; KAY, J. M.; CORTÉS, J. M.; PALMA, M. Paleozoic terranes of the central Argentine- Chilean Andes. Tectonics, Washington, v. 5, n. 6, p.855-880, 1986.</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 syneclises phase (Ramos et al 1986<ref name=Ramos_1986 />; Zalán et al 1990<ref name=Zalan_1990 />; Sign 1996; Milani 1997<ref name=Milani_1997 />; 1998<ref name=Milani_1998>MILANI, E. J.; FACCINI, U. F.; SCHERER, C. M. S.; ARAÚJO, L. M.; CUPERTINO, J. A. Sequences and stratigraphic hierarchy of the Paraná Basin (Ordovician to Cretaceous), Southern Brazil. Boletim IG-USP, São Paulo, p. 125-173. nov. 1998. (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>).

The start of Carboniferous sedimentation occurred at a time of major changes, both tectonic and climatic. The package that happens to be the neo-Devonian discordance, the Gondwana I supersequence (Milani, 1997)<ref name=Milani_1997 />, demonstrates a complete transgressive-regressive cycle; the result of the invasion and subsequent exit of the Panthalassa Sea into Gondwana. The accumulation of the Gondwana I supersequence was accompanied by a gradual closing of the Paraná Basin, restricting marine incursions from the west. The character of an intracratonic basin was then gradually assumed, and the basin became trapped in the arid interior of the continental Mesozoic Gondwana.

The start of Carboniferous sedimentation occurred at a time of major changes, both tectonic and climatic. The package that happens to be the neo-Devonian discordance, the Gondwana I super sequence,<ref name=Milani_1997 /> demonstrates a complete transgressive-regressive cycle; the result of the invasion and subsequent exit of the Panthalassa Sea into Gondwana. The accumulation of the Gondwana I supersequence was accompanied by a gradual closing of the Paraná Basin, restricting marine incursions from the west. The character of an intracratonic basin was then gradually assumed, and the basin became trapped in the arid interior of the continental Mesozoic Gondwana.

The arrival of the Triassic saw a widespread strain in the southern portion of paleocontinent Gondwana (Uliana and Biddle, 1988)<ref name=Uliana_et_Biddle_1988>ULIANA, M. A.; BIDDLE, K. Mesozoic-Cenozoic paleogeographic and geodynamic evolution of southern South America. Revista Brasileira de Geociências, São Paulo, v. 18, p. 172-190, 1988.</ref>. The Gondwana II supersequence of the Paraná Basin, restricted to occurrences in Rio Grande do Sul and the Uruguayan portions of the basin, is part of this regional context and seems to represent a sedimentation accumulation in graben type basins.

The arrival of the Triassic saw a widespread strain in the southern portion of paleocontinent Gondwana.<ref name=Uliana_et_Biddle_1988>Uliana, M. A. and K. Biddle, 1988, Mesozoic-Cenozoic paleogeographic and geodynamic evolution of southern South America. Revista Brasileira de Geociências, São Paulo, v. 18, p. 172-190</ref> The Gondwana II supersequence of the Paraná Basin, restricted to occurrences in Rio Grande do Sul and the Uruguayan portions of the basin, is part of this regional context and seems to represent a sedimentation accumulation in graben type basins.

In the Early Cretaceous, the Earth's crust underwent to a colossal splitting, associated with basaltic magmatism ratios without compare in the planets history. This event caused the breakup of the Gondwanan supercontinent and began the evolution of the South Atlantic Ocean. The Serra Geral magmatism marked the end of extensive sedimentation events in the supercontinent´s interior. After the opening of the Atlantic Ocean, the South American Platform maintained its widespread ascensional character - started at the time of Botucatu sedimentation - until the buildup of almost 2,000 m thickness of basaltic lavas. When the volcanic activities ceased, there were some isostatic adjustments and established of a depression on the basaltic package where, in the Late Cretaceous, would later build the last supersequence (Bauru Supersequence) in the area occupied by the Paraná Basin.

In the Early Cretaceous, the Earth's crust underwent to a colossal splitting, associated with basaltic magmatism ratios without compare in the planets history. This event caused the breakup of the Gondwanan supercontinent and began the evolution of the South Atlantic Ocean. The Serra Geral magmatism marked the end of extensive sedimentation events in the supercontinent´s interior. After the opening of the Atlantic Ocean, the South American Platform maintained its widespread ascensional character - started at the time of Botucatu sedimentation - until the buildup of almost 2,000 m thickness of basaltic lavas. When the volcanic activities ceased, there were some isostatic adjustments and established of a depression on the basaltic package where, in the Late Cretaceous, would later build the last supersequence (Bauru Supersequence) in the area occupied by the Paraná Basin.