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The Guará Formation is a Late Jurassic sedimentary unit, outcropping on the southeastern edge of the Paraná Basin; in the western part of Rio Grande do Sul state (Brazil) and western Uruguay. It is described as fine to conglomeratic sandstones, deposited in arid to semiarid climate, composing fluvial channels and flood plains in the northern portion and aeolian dunes alternating with ephemeral fluvial systems in the south. The main fluvial paleocurrents are from NE to SW, marking a unique period in geological history of the Paraná Basin where its [[depocenter]] was shifted to the SW.

The Guará Formation is a Late Jurassic sedimentary unit, outcropping on the southeastern edge of the Paraná Basin; in the western part of Rio Grande do Sul state (Brazil) and western Uruguay. It is described as fine to conglomeratic sandstones, deposited in arid to semiarid climate, composing fluvial channels and flood plains in the northern portion and aeolian dunes alternating with ephemeral fluvial systems in the south. The main fluvial paleocurrents are from northeast to southwest, marking a unique period in geological history of the Paraná Basin where its [[depocenter]] was shifted to the southwest.

==Definition==

==Definition==

 

The Guará Formation was first recognized and identified by Prof. Renato Andreis, however without formalization of technical work. Later it was mapped by Lavina<ref name=Lavina_1991>Lavina, E. L., 1991, Geologia sedimentar e paleogeografia do Neopermiano e Eotriássico (intervalo Kazaniano-Scitiano) da Bacia do Paraná: Curso de Pós-Graduação em Geociências, 336 p. Tese (Doutorado em Geociências) – Instituto de Geociências, Universidade Federal do Rio Grande do Sul.</ref>, detailed in Scherer & Lavina<ref name=Lavina_et_Scherer_1997>Lavina, E. L., and C. M. S. Scherer, 1997, Arquitetura estratigráfica da sedimentação Neopermiana e Mesozóica na região oeste do estado do Rio Grande do Sul: Implicações na construção do arcabouço estratigráfico da Bacia do Paraná. In: SIMP. CRONOESTRAT. BACIA DO PARANÁ, 3, Boletim de Resumos, p. 33-34.</ref>, and formally designated in 2005<ref name=Scherer_et_Lavina_2005>Scherer, C. M. S., and E. L. Lavina, 2005, Sedimentary cycles and facies architecture of eolian-fluvial strata of the Late Jurassic–Early Cretaceous Guará Formation, Southern Brazil: Sedimentology, v. 52, p. 1323-1341.</ref>.

The Guará Formation was first recognized and identified by Prof. Renato Andreis, however without formalization of technical work. Later it was mapped by Lavina<ref name=Lavina_1991>Lavina, E. L. 1991. Geologia sedimentar e paleogeografia do Neopermiano e Eotriássico (intervalo Kazaniano-Scitiano) da Bacia do Paraná. Curso de Pós-Graduação em Geociências. 336p. Tese (Doutorado em Geociências) – Instituto de Geociências, Universidade Federal do Rio Grande do Sul.</ref>, detailed in Scherer & Lavina<ref name=Lavina_et_Scherer_1997>Lavina, E.L. & Scherer, C.M.S. 1997. Arquitetura estratigráfica da sedimentação Neopermiana e Mesozóica na região oeste do estado do Rio Grande do Sul. Implicações na construção do arcabouço estratigráfico da Bacia do Paraná. In: SIMP. CRONOESTRAT. BACIA DO PARANÁ, 3, Boletim de Resumos, p. 33-34.</ref>, and formally designated in 2005<ref name=Scherer_et_Lavina_2005>Scherer, C.M.S. & Lavina, E.L. 2005. Sedimentary cycles and facies architecture of eolian-fluvial strata of the Late Jurassic - Early Cretaceous Guará Formation, Southern Brazil. Sedimentology (Amsterdam), London, v. 52, p. 1323-1341.</ref>.

==Geological Setting==

==Geological Setting==