Açu Formation Explained

Açu Formation should not be confused with Itajaí-Açu Formation.

Açu Formation
Type:	Geological formation
Age:	Albian ~
Period:	Albian
Prilithology:	Sandstone
Region:	Ceará
Coordinates:	-5.8°N -38.1°W
Paleocoordinates:	-11.9°N -10.9°W
Unitof:	Apodi Group
Underlies:	Jandaíra Formation
Overlies:	Alagamar Formation
Extent:	Potiguar Basin

The Açu Formation is an Early Cretaceous (Albian) geologic formation of the Potiguar Basin in Ceará, northeastern Brazil. The formation comprises coarse-grained sandstones deposited in a fluvio-deltaic environment. The Açu Formation, belonging to the Apodi Group, has provided fossils of an indeterminate rebbachisaurid.

Description

The Açu Formation was deposited in a passive margin setting, overlying the Alagamar Formation and is overlain by the Jandaíra Formation. In the petroleum producing Potiguar Basin, the formation is a reservoir rock.^[1]

Fossil content

The following fossils were reported from the formation:^[2]

• Reptiles
  • Dinosaurs
    • Carcharodontosauria indet.
    • Maniraptora indet.
    • Megaraptora indet.
    • Rebbachisauridae indet.^[3]
    • Spinosauridae indet.
    • Tiamat valdecii^[4]
    • Titanosauria Indet.^[5]
• Fish
  • Cartilaginous fish
    • Tribodus limae
  • Ray-finned fis
    • Amiidae Indet.
    • Bawitius bartheli
    • Lepisosteiformes Indet.
    • Tharrhas araripis
    • Pycnodontiformes indet.
  • Lobe-finned fish
    • Arganodus cf. tinguidiensis
    • Ceratodus latissimus
    • Mawsonia cf. gigas

See also

• Crato Formation
• Romualdo Formation
• Malhada Vermelha Formation
• Missão Velha Formation

References

Bibliography

Notes and References

1. Maraschin et al., 2010, p.87
2. http://www.fossilworks.org/cgi-bin/bridge.pl?action=displayStrata&geological_group=Apodi&group_formation_member=Apodi Açu Formation
3. Gomes da Costa Pereira et al., 2020
4. Pereira . P. V. L. G. C. . Bandeira . K. L. N. . Vidal . L. S. . Ribeiro . T. B. . Candeiro . C. R. A. . Bergqvist . L. P. . A new sauropod species from north-western Brazil: biomechanics and the radiation of Titanosauria (Sauropoda: Somphospondyli) . 2024 . Zoological Journal of the Linnean Society . 10.1093/zoolinnean/zlae054 .
5. Pereira . P.V.L.G.C. . Marinho . T.S. . Candeiro . C.R.A. . Bergqvist . L.P. . 2018 . A new titanosaurian (Sauropoda, Dinosauria) osteoderm from the Cretaceous of Brazil and its significance . Ameghiniana . 55 . 6 . 644–650 . 10.5710/AMGH.26.08.2018.3168.