Bauru group

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The Bauru group is a lithostratigraphic group from the Upper Cretaceous of southern Brazil . It was deposited in the Bauru Basin , a section of the Paraná Basin , over Lower Cretaceous basalts .

etymology

The name of the group is derived from the city of Bauru in the Brazilian state of São Paulo .

stratigraphy

The formations of the Bauru group in white, Caiuá group in gray, basalts in light blue, quaternary cover in yellow

The sediments of the Bauru Group were deposited in the Bauru Basin, a section of the larger Paraná Basin, with an erosive discordance concordantly on the Lower Cretaceous basalts of the Serra-Geral Formation from the São Bento Group . In the southwest of the sedimentation area they interlock with the sediments of the Santo Anastácio Formation from the Caiuá group or overlay them. The group consists of the following formations :

The basal Adamantina Formation is in turn made up of the Araçatuba Formation and the Vale-do-Rio-do-Peixe Formation and interlocks with the Uberaba Formation in a northeastern direction . The Marília Formation in turn consists of the sub -formations Echaporã, Serra da Galga and Ponte Alta and interlocks towards the south with the São José do Rio Preto Formation , which in turn merges further south into the Presidente Prudente Formation .
On the northern edge of the Vale-do-Rio-do-Peixe Formation, the analcim-bearing volcanic rocks of the Taiúva Formation are switched on.

The total thickness of the Bauru Group is around 300 meters.

Age

For the Bauru group, no absolute age information is yet available, but on the basis of fossils it can be assigned an Upper Cretaceous age from Turonian to Maastrichtian .

Distribution area

The rocks of the Bauru Group are exposed in the Brazilian states of Goiás , Mato Grosso do Sul , Minas Gerais and São Paulo .

Deposit conditions

The Bauru group consists predominantly of terrigenous siliciclastic sedimentary rocks ( sandstones , siltstones , conglomerate layers ); only a few carbonates are found . These sediments were deposited under semi-arid to arid conditions by meandering rivers (wadifacies), whereby the annual climatic course was characterized by a distinctive rainy season-dry season cycle. Other facies conditions are found in the Araçatuba Formation, which represents an occasionally dry paleo swamp, and in the dunes of the Vale-do-Rio-do-Peixe Formation.

Fossil content

The Bauru group has a very rich vertebrate fauna. Remnants of fish (scales and teeth) reveal the presence of flesh fins , pike , tetra , catfish , bones and perch . The terrestrial vertebrates include frogs , lizards and turtles , and some dinosaurs can also be found. Most important, however, are undoubtedly the finds of crocodile relatives . A representative of the enantiornithes was discovered among the birds .

Maxakalisaurus topai
Baurusuchus salgadoensis

Dinosauria - dinosaur

Mesoeucrocodylia - crocodile relatives

Testudinata - tortoises

Characteristic for the Bauru group is the simultaneous occurrence of fauna elements of the Australian Gondwana (association of Abelisauridae with Notosuchidae) and the boreal Gondwana (Carcharodontosauridae). Noteworthy is the absence of Laurasian taxa in the upper part of the group.

The invertebrates include charophytes , conchostraca , mollusca and ostracods .

See also

Individual evidence

  1. ^ Santucci, RA & Bertini, RJ 2006. A new titanosaur from western São Paolo State, Upper Cretaceous Bauru Group, south-east Brazil. Paleontology. 49 (1): 171-185.

swell

  • CANDEIRO, CRA, MARTINELLI, AG, AVILLA, LS & RICH, TH, 2006. Tetrapods from the Upper Cretaceous (Turonian-Maastrichtian) Bauru Group of Brazil: a reappraisal. Cretaceous Research 27 (6): 923-946.
  • DIAS-BRITO, DEA; MUSACCHIO, JC; CASTRO, MSA; MARANHÃO, JM; SUÁREZ, JM & RODRIGUES, R., 2001. Grupo Bauru: uma unidade continental do Cretáceo do Brasil - concepções baseadas em dados micropaleontológicos, isotópicos e estratigráficos. Revue de Paléobiologie, 2: 243-304.
  • FERNANDES, LUIZ A., GIANNINI, PAULO CF & GÓES, ANA MARIA: Araçatuba Formation: palustrine deposits from the initial sedimentation phase of the Bauru Basin. Anais da Academia Brasileira de Ciências (2003) 75 (2): 173-187
  • KELLNER, ALEXANDER WA & CAMPOS, DIOGENES DE ALMEIDA, 1999. Vertebrate paleontology in Brazil - a review. Episodes, Vol. 22, no. 3. Contains a short chapter on the vertebrates of the Bauru group.

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