Quiricó formation

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The Quiricó Formation is a lithostratigraphic unit ( formation ) of sedimentary rocks from the Lower Cretaceous in Brazil . It belongs to the Areado Group , a group of the Sanfranciscana Basin . The formation is known for numerous fossils, such as the remains of the sauropod dinosaur Tapuiasaurus .

The location of the dinosaur Tapuiasaurus in the Sanfranciscana Basin
Stratigraphic position of the Quiricó formation in the Sanfranciscana basin

Stratigraphic structure and classification

The Quiricó Formation is the middle of the three formations in the Areado Group. Below the formation follows the Abaeté formation , above the Três-Barras formation . The Areado Group belongs to the Sanfranciscana Basin, a huge sedimentary basin that stretches about 1100 kilometers in north-south direction in central Brazil. This basin is interpreted as a rift valley that was created by the same tensile forces that led to the opening of the southern Atlantic Ocean .

description

The sediments were probably the formation lacustrine deposited within a shallow lake at a high evaporation rate, whereupon the relationship between quartz and calcium oxide indicates. The rocks are mainly mudstone , silt and limestone , but also layers of sandstone . The thickness of the formation is up to 100 meters. The time of the deposition can be dated to the aptium .

Fossil content

15 non-marine species of ostracods could be detected from the formation . Fishes of the formation include Laeliichthys and Dastilbe . The find of the titanosaur Tapuiasaurus is significant , which, in addition to the bones of the remaining skeleton, includes an almost complete skull - the only titanosaur skull found in South America.

Individual evidence

  1. ↑ a b c d Hussam Zaher, Diego Pol, Alberto B. Carvalho, Paulo M. Nascimento, Claudio Riccomini, Peter Larson, Rubén Juarez-Valieri, Ricardo Pires-Domingues, Nelson Jorge da Silva Jr., Diógenes de Almeida Campos: A Complete Skull of an Early Cretaceous Sauropod and the Evolution of Advanced Titanosaurians . In: PLoS ONE . tape 6 , no. 2 , 2011, p. e16663 , doi : 10.1371 / journal.pone.0016663 . Supporting information, geology
  2. ↑ Geraldo Norberto Chaves Sgarbi, 2000: The cretaceous Sanfranciscan Basin, Eastern Plateau of Brazil . In: Revista Brasileira de Geociências, 30 (3), pages 450-452. ( PDF )