Riachuelo Formation

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Riachuelo Formation
Stratigraphic range: Late Aptian-Early Cenomanian
~115–97 Ma
Reconstruction of the fauna from the Riachuelo Formation
TypeGeological formation
Sub-unitsAngico Member

Taquari Member

Maruim Member
UnderliesCotinguiba Formation
OverliesMuribeca Formation
Thickness500 m (1,600 ft)
Lithology
PrimaryPackstone, Grainstone
OtherMudstone, siltstone, siliciclastic
Location
RegionSergipe-Alagoas Basin of Northeastern Brazil
Country Brazil
Extent20 kilometres (12 mi)
Type section
Named forRiachuelo, Sergipe
Named byMoraes Rego

The Riachuelo Formation is a geologic formation of the Early to Late Cretaceous (Late Aptian to Cenomanian) age in northeastern Brazil's Sergipe-Alagoas Basin. It is the first Formation of the Basin to contain sediments deposited under fully marine conditions. The formation is subdivided into three members: Angico, Taquari and Maruim.[1]

The formation has provided fossils of ammonites, gastropods, bivalves, brachiopods, serpulids, equinoderms, ostracoids, radiolarians, lobsters and Crabs. Several fish species reported from the Santana Formation also occur in this formation, namely: Cladocyclus gardneri, Neoproscinetes penalvai, Notelops brama, Rhacolepis buccalis, Tharrhias araripis and Vinctifer comptoni.[2][3][4][5] Santanichthys diasii is also reported from the Taquari Member of the Riachuelo Formation.[6] Teeth and vertebrae of elasmobranchii have also been found in the formation.[7]

Description[edit]

The Riachuelo Formation is a 500 metres (1,600 ft)[8] thick mix of Aptian and Albian sediments formed by high-energy shelf carbonate deposits (oncolitic-oolitic-peloidal-bioclastic packstones and grainstones), interbedded with lagoonal mudstones and siltstones, and fan-delta like siliciclastic rocks.[9] It overlies Muribeca Formation and underlies the Cotinguiba Formation.[10] The formation sprouts in a track approximately 20 km wide and it extends itself between the cities of Itaporanga d’Ajuda and Pacatuba.[10] It also has outcrops in the cities of Riachuelo, Santa Rosa de Lima, Divina Pastora, Laranjeiras, Rosário do Catete, Maruim, General Maynard and Carmópolis.[11]

There are three members of this formation: Angico Member, whose environment has been interpreted as costal areas consisting of the basin margins and grabens, deltaic fans formed, and the coarse sediments they carried, the Maruim Member, in the lower sedimentation areas,with carbonate ramps and dolomitized oolite/oncolite banks deposited under fluctuating sea level conditions, and the Taquari Member, corresponding to calcareous mudstone and shale from lagoonal and slope environments.[5][11]

Cross section of riachuelo formation's shelf and sea.

Ammonites are particularly plentiful and have provided a firm biocronostratigraphic control for the basin. The succession of ammonites is divided in five zones: The Epicheloniceras-Diadochoceras-Eodouvilleiceras zone, from the Aptian, the Douvilleiceras zone, from the lower Albian, the Oxytropidoceras zone, from the middle Albian, and the Elobiceras and Mortoniceras-Neokentroceras zones, both from the late Albian.[1]

History[edit]

The name Riachuelo Formation was used for the first time in the geological literature by Moraes Rego in 1929. Then, in 1959, Bender made a new interpretation, separating the upper part of the Riachuelo Formation from the lower one, naming it Maruim. This lower unit described by Bender was considered by Beurlen K. in 1963 as only one facies of the Riachuelo-Maruim Complex. In 1970, Schaller analyzed the unit again and segmenting it into four members: Angico, Taquari, Maruim and Aguilhada. Feijó, in 1994, classified the formation as a siliciclastic-carbonatic platform complex and divided it into the members: Angico, Taquari and Maruim, which is the classification currently used.[4]

Fossil content[edit]

Molluscs[edit]

Molluscs of the Riachuelo Formation
Genus Species Presence Family Images
Douvilleiceras[12] D. sergipensis

D. euzebioi

Douvilleiceratidae
Puzosia[12] P. rosarica

P. brasiliana
P. garajuana

Desmoceratidae
Neokentroceras[12] N. tectorium Brancoceratidae
Elobiceras[4]

E. lobitoense
E. raymondi

Brancoceratidae
Oxytropidoceras[4]

O. buarquianum
O. sergipensis
O. involutum
O. mauryae

Brancoceratidae
Mortoniceras[4] M. sergipensis

M. rostratum

Brancoceratidae
Vectisites[13] V. simplex
Eodouvilleiceras[13] Douvilleiceratidae
Cheloniceras[14] Douvilleiceratidae
Diadochoceras[14] Parahoplitidae
Deshayesites[14] Deshayesitidae
Anisoceras[14] Anisoceratidae
Protanisoceras[14] Anisoceratidae
Inoceramus[12] Indeterminate Inoceramidae
Neocomiceramus[4] N. anglicus Inoceramidae
Neithea[2] N. alpina

N. coquandi
N. hispanica

 Pectinidae
Linotrigonia[13] Trigoniidae
Pleuromya[13] Pleuromyidae
Pinna[13] Pinnidae
Lopha[13] Ostreidae
Turritella[13] Turritellidae
Tylostoma[13] Tylostomatidae
Natica[13] Naticidae

Echinoderms[edit]

Echinoderms of the Riachuelo Formation
Genus Species Presence Family Images
Stereocidaris[15] S. branneri Cidaridae
Rhabdocidaris[15] R. brasiliensis Rhabdocidaridae
Salenia[15] S. sergipensis Saleniidae
Phymosoma[15] P. binexilis

P. braziliensis

Phymosomatidae
Orthopsis[15] O. australis Orthopsidae
Coenholectypus[15] C. pennanus Holectypidae
Conolypus[15] C. nertoanus
Parapygus[15] P. aequalis Echinolampadidae
6 to 9 is Parapygus antillarum.
6 to 9 is Parapygus antillarum.
Hemiaster[15] H. cranium Hemiasteridae
Temnocidaris[13] Cidaridae
Douvillaster[13] Toxasteridae
Leptosalenia[13] Saleniidae
Phyllobrissus[16] P. humilis Nucleolitidae

Annelids[edit]

Annelids of the Riachuelo Formation
Genus Species Presence Family Images
Diploconcha[17] D. riachueloi

D. scalata

Serpulidae
Serpula[17] S. sergipensis Serpulidae

Crustaceans[edit]

Crustaceans of the Riachuelo Formation
Genus Species Presence Family Notes Images
Palinura[3] Indeterminate Angico Member Lobster Only posterior part of the body preserved
Brazilomunida[18] B. brasiliensis Galatheidae (squat lobster)
Archaeopus[17] A. rathbunae Ocypodidae
Cyclothyreus[17] C. sergipensis Dromioidea
Maurimia[18] M. sergipensis Dynomenidae
Galalheites[17] G. brasiliensis Maruim Member Decapoda
Reticulocosta[5] R. edrianae Cytherettidae (ostracod)
Aracajuia[5] A. benderi

A. antiqua

An ostracod
Harbinia[5] H. sinuata An ostracod
Sergipella[5][19] S. viviersae

S. transatlantica
S. grosdidieri

Taquari Member An ostracod
Praebythoceratina[5] P. amsittenensi An ostracod

Fishes[edit]

Fishess of the Riachuelo Formation
Genus Species Presence Description Notes Images
Cladocyclus[2] C. gardneri Ichthyodectidae
Neoproscinetes[2] N. penalvai Pycnodontid
Mercediella[20] M. riachuelensis Pycnodontid fish Originally described as Camposichthys riachuelensis[7]
Notelops[2] N. brama Elopiform fish
Rhacolepis[2] R. buccalis Crossognathiform fish
Tharrhias[2] T. araripis Gonorynchiform fish
Vinctifer[2] V. comptoni Aspidorhynchiform fish
Santanichthys[6] S. diasii Taquari Member Characiform fish
Beurlenichthys[7] B. ouricuriensis Clupeomorph fish
Nolfia[21] N. riachuelensis Taquari Member Clupeoid fish

References[edit]

  1. ^ a b Souza-Lima, W; Andrade, E.J (2002). "A bacia de Sergipe-Alagoas: evolução geológica, estratigrafia a e conteúdo fóssil". Phoenix, Edição Especial. 1 (1): 24–25.
  2. ^ a b c d e f g h Arai, M (2014). "Aptian/albian (early Cretaceous) paleogeography of the South Atlantic: a paleontological perspective". Braz. J. Genet. 44 (2): 339–350. doi:10.5327/Z2317-4889201400020012.
  3. ^ a b dos Reis, Márcia Aparecida Fernandes; Turbay, Caio Vinícius Gabrig; Cesero, Pedro De (2005-06-01). "A new Decapoda (Natantia, Malacostraca, Crustacea) from the Riachuelo formation (Albian), Sergipe basin". Anuário do Instituto de Geociências (in Portuguese). 28 (1): 80–91. doi:10.11137/2005_1_80-91. ISSN 1982-3908.
  4. ^ a b c d e f Sobral, A.C.S. (2015). "Amonoides e inoceramideos da Formação Riachuelo, Albiano medioefinal, Bacia de Sergipe, Brasil" (PDF). Universidade Federal de Pernambuco, Recife, PE: 104 pp.
  5. ^ a b c d e f g Antonietto, Lucas S.; do Carmo, Dermeval A. (2015). "Biostratigraphic and paleozoogeographic review of the upper Aptian-Albian ostracods of Riachuelo Formation, Sergipe-Alagoas Basin, Northeastern Brazil". Sociedade Brasileira de Paleontologia. 18 (3): 355–368. doi:10.4072/rbp.2015.3.02.
  6. ^ a b Filleul, Arnaud; Maisey, John G. (2004). "Redescription of Santanichthys diasii (Otophysi, Characiformes) from the Albian of the Santana Formation and Comments on Its Implications for Otophysan Relationships". American Museum Novitates (3455): 1–12. doi:10.1206/0003-0082(2004)455<0001:ROSDOC>2.0.CO;2. hdl:2246/2765. S2CID 85575649.
  7. ^ a b c Gallo, Valéria; de Figueiredo, Francisco J. (2012). Síntese da paleoictiofauna marinha das bacias costeiras do Brasil e comentários sobre a paleoictiofauna cronocorrelata da margem oeste da África. Interciencias. pp. 177–208. ISBN 978-85-7193-236-4.
  8. ^ Bengtson, P.; Zucon, M. H.; Sobral, A. da C. S. (2018). "Cretaceous ammonite zonation of the Sergipe Basin, northeastern Brazil". Cretaceous Research. 88: 111–122. Bibcode:2018CrRes..88..111B. doi:10.1016/j.cretres.2017.07.021. S2CID 134100757.
  9. ^ Turbay, Caio V.G.; Cesero, Pedro; Koutsoukos, Eduardo A. (2002). "On a fossil lobster (Decapoda, Malacostraca, Crustacea) from the Riachuelo Formation, Albian of the Sergipe Basin, Brazil". An. Acad. Bras. Ciênc. 74 (2): 363. doi:10.1590/S0001-37652002000200013.
  10. ^ a b MANSO, C. L. de C.; SOUZA-LIMA, Wagner (2012). "NOVOS EQUINÓIDES PARA O INTERVALO APTIANO-ALBIANO (CRETÁCEO INFERIOR) DA SUB-BACIA DE SERGIPE, NORDESTE DO BRASIL". Geociências. 31 (4): 584–605.
  11. ^ a b da Silva, C. R. M.; Barros, S. D. S. (2017). "AVALIAÇÃO DO POTENCIAL DE FOSFATO NO BRASIL – PARTE III: BACIA SERGIPE-ALAGOAS, ÁREA SUB-BACIA SERGIPE ESTADO DE SERGIPE". Serviço Geológico do Brasil (20).
  12. ^ a b c d Beurlen, G. (1967). "Ammonoidea do complexo Riachuelo-Maruim, Sergipe". Boletim da Sociedade Brasileira de Geologia. 16 (2): 79–106.
  13. ^ a b c d e f g h i j k l Vieira, Fabiana S.; Dantas, M. A. T. (2014). "SERPULIDS (ANNELIDA, POLYCHAETA) AT EARLY CRETACEOUS OF SERGIPE BASIN, BRAZIL SERPULIDE (ANNELIDA, POLYCHAETA) DO CRETÁCEO INFERIOR DA BACIA SERGIPE, BRASIL". Estudos Geológicos. 24 (2): 83–88. doi:10.18190/1980-8208/estudosgeologicos.v24n2p83-88.
  14. ^ a b c d e Beurlen, Karl (1968). "A POSIÇÃO ESTRATIGRAFICA DA FORMAÇÃO RIACHUELO – (Cretáceo, Sergipe)". Sociedade Brasileira de Geologia. 17 (1): 85–88.
  15. ^ a b c d e f g h i Brito, Ignacio M. (1991). "OS EQUINÓIOES AlBIANOS (CRETÁCEO INFERIOR) DO BRASil E SEU POSSíVEL VALOR ESTRATIGRÁFICO". Anuário do Instituto de Geociências. 14: 37–40. doi:10.11137/1991_0_37-40.
  16. ^ Manso, C.L.C. (2020). "A new Cassiduloid (Echinodermata, Echinoidea) in the Albian of the Sergipe-Alagoas basin, Brazil". Brazil.- Carnets Geol. 20 (3): 29–35. doi:10.4267/2042/70719. S2CID 211732076.
  17. ^ a b c d e Barreto, A. M. F.; Oliveira, E. V. (2014). "CATÁLOGO DO MATERIAL-TIPO DA COLEÇÃO PALEONTOLÓGICA DO DEPARTAMENTO DE GEOLOGIA, CENTRO DE TECNOLOGIA E GEOCIÊNCIAS DA UNIVERSIDADE FEDERAL DE PERNAMBUCO". Estudos Geológicos. 24 (3): 3–53. doi:10.18190/1980-8208/estudosgeologicos.v24n3p3-53.
  18. ^ a b Neto, R.G.Martins (2005). "ESTÁGIO ATUAL DA PALEOARTROPODOLOGIA BRASILEIRA: HEXÁPODES, MIRIÁPODES, CRUSTÁCEOS (ISOPODA, DECAPODA, EUCRUSTACEA E COPEPODA) E QUELICERADOS". Arquivos do Museu Nacional. 63 (3): 471–494.
  19. ^ Do Carmo, Dermeval A.; Colin, Jean-Paul (2012). "Reassessment of the genus Sergipella Krömmelbein, 1967 (Ostracoda,Trachyleberididae), uppermost Aptian-Albian of Brazil and West Africa:Taxonomy and paleogeographic distribution". Revue de micropaléontologie. 55 (1): 3–15. Bibcode:2012RvMic..55....3D. doi:10.1016/j.revmic.2011.12.002.
  20. ^ Koerber, Stefan (2012). "Mercediella nom. nov., a replacement name forCamposichthys Figueiredo & Silva Santos, 1991(Pisces: Pycnodontiformes)". Bonn Zoological Bulletin. 61 (1): 29–30.
  21. ^ de Figueiredo, Francisco J. (2009). "A new marine clupeoid fish from the Lower Cretaceous of the Sergipe-Alagoas Basin, northeastern Brazil". Zootaxa. 2164: 21–32. doi:10.11646/zootaxa.2164.1.2.
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