Adamantina formation

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The Adamantina Formation is a lithostratigraphic unit ( formation ) of sedimentary rocks from the Upper Cretaceous of southern Brazil . It belongs to the Bauru Group , whose sediments were deposited in the Bauru Basin , a section of the Paraná Basin . The name of the formation is derived from the city of Adamantina in the Brazilian state of São Paulo .

Stratigraphic structure

Stratigraphy of the Paraná Basin - the Adamantina formation in yellow

The Adamantina Formation is concordantly superimposed on an erosive discordance of the basalts of the Serra-Geral Formation and is covered by the Marília Formation or its southward equivalents ( São José do Rio Preto Formation and Presidente Prudente Formation ) . In the southwest it interlocks with the Santo Anastácio Formation or overlays it, to the northeast it interlocks with the Uberaba Formation . It also contains the analcim-bearing volcanic rocks of the Taiúva Formation .
The formation is divided into the following units:

description

The sedimentary rocks of Adamantina Formation in the Brazilian states of Goiás , Mato Grosso do Sul , Minas Gerais and western São Paulo minded .

There is no absolute age dating for these rocks, they are usually placed in the Turonian to Santonian period , but Campanian to Maastrichtian is also being considered.

The Adamantina Formation is a continental red facies and consists mainly of sandstones and siltstones that were deposited under semi-arid conditions. With Aeolian sandstones and the associated intermediate loess horizons (together they form the Vale-do-Rio-do-Peixe Formation) it overlays the Lower Cretaceous basalts of the Serra-Geral Formation. An endorheic drainage network ( wadis ) had formed on the basalts with a large swamp area in its central part. The generally fine-grained sediments of the Araçatuba Formation were deposited in this swamp - mostly siltstones, but also gray-green sandstones with cement containing carbonate . The marsh was dry periodically - documented by dry cracks and pseudomorphs after gypsum and dolomite . Ultimately, the paleo swamp was filled in by the advancing sand dunes of the Vale-do-Rio-do-Peixe formation.

Fossil content

The Adamantina Formation has moderate vertebrate fauna, including dinosaur taxa . The formation is known for Titanosauridae such. B. Adamantisaurus mezzalirai and Maxakalisaurus topai . There are also osteoderms from dinosaurs .

In general, the dinosaur finds are made up of the remains of typical representatives of the Australian Gondwana ( Aeolosaurus and Abelisauridae ) and taxa of the boreal Gondwana ( Carcharodontosauridae ).

Important are also numerous findings of crocodile relatives ( Mesoeucrocodylia ), including the controversial taxon Brasileosaurus pachecoi and Notosuchidae ( Adamantinasuchus navae , Mariliasuchus amarali ) Goniopholidae ( Goniopholis paulistanus ) baurusuchidae ( baurusuchus pachecoi , baurusuchus salgadoensis , baurusuchus sp. , Stratiotosuchus maxhechti ) and Peirosuchidae ( Montealtosuchus arrudacamposi ).

Also worth mentioning are the turtle taxa Podocnemis elegans and Roxoquelis wanderlii .

In addition to the remains of fish , a representative of the enantiornithes , a group of tooth-bearing birds, was discovered.

In addition to charophytes , photosynthesizing eukaryotes, there are also invertebrates such as mussel-shell crabs , molluscs and mussel crabs .

See also: List of dinosaurs leading rock formations

Individual evidence

  1. ↑ 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.
  2. ↑ GOBBO-RODRIGUES, SR; PETRI, S. & BERTINI, RJ, 1999. Ocorrências de ostrácodes na formação Araçatuba do grupo Bauru, Cretáceo Superior da Bacia do Paraná, e possibilidades de correlação com depósitos isócronos argentinos - Part II: Família Limnocytheridae. Revista da Universidade de Guarulhos (Série Geociências), 4 (6): 5-11.
  3. ↑ TORRES, SANDRA R., AVILLA, LEONARDO S., ABRANTES, ERIKA AL & BERGQVIST, LÍLIAN P., 2002. Dinosaur Osteoderms from the Adamantina Formation, Upper Cretaceous of São Paulo State, Brazil. Anais da Academia Brasileira de Ciências, vol.74 no.2
  4. ↑ Pedro Henrique Nobre, and Carvalho, Ismar de Souza: Adamantinasuchus navae : A new Gondwanan Crocodylomorpha (Mesoeucrocodylia) from the Late Cretaceous of Brazil Archived from the original on July 6, 2011. (pdf) In: Gondwana Research . 10, 2006, pp. 370-378. doi : 10.1016 / j.gr.2006.05.008 .
  5. ^ Suarez, JM 1999. The fossiliferous place of Pirapozinho (São Paulo state, Brazil). In: Schobbenhaus, C .; Campos, DA; Queiroz, ET; Winge, M .; Berbert-Born, M. (Edit.) Sítios Geológicos e Paleontológicos do Brasil.

swell

  • LUIZ A. FERNANDES, PAULO CF GIANNINI and ANA MARIA GÓES: Araçatuba Formation: palustrine deposits from the initial sedimentation phase of the Bauru Basin. Anais da Academia Brasileira de Ciências (2003) 75 (2): 173-187

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