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Cotinguiba Formation
Cotinguiba Formation
Stratigraphic range: Late Cretaceous, ~Cenomanian–Coniacian PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Sub-units	Aracaju and Sapucari Members
Underlies	Calumbi Formation
Overlies	Riachuelo Formation
Thickness	from 200 metres (656 ft) up
Location
Region	Sergipe-Alagoas Basin of Northeastern Brazil
Country	Brazil
Extent	200 kilometres (120 mi)

The Cotinguiba Formation is a geologic formation of Late Cretaceous (Cenomanian to Coniacian)^[1] age in the northeastern Brazil's Sergipe-Alagoas Basin. The Formation is composed of carbonates with clastic intercalations, moreover, the two members dividing it, the Sapucari and Aracaju members, are defined by the proportion of said carbonates.^[2] It also possesses a rich macroinvertebrate fauna, of which stands out its bivalve mollucs, gastropods, ammonites, as well as equinoderms and crustaceans.^[3]

Description

On average, the Cotinguiba Formation had a thickness of around 200 meters, although in some sections over 1000 meters have been measured. It is formed by carbonates with clastic intercalations, and it is also divided into two members, the Aracaju and Sapucaru Members. Said members are defined by the proportions of these carbonates within them.^[2] It is 200 km long and 5–10 km wide parallel to the coast. It is mainly composed by limestone–marlstone couplets, with sandstones, coquinas and limestone breccias being included in some places. These sediments were largely produced by algae and bioeroders on a shallow-water ramp. The origin of such rocks has been related with the seasonal oscillations of phytoplankton productivity, mud content and calcium production. The Turonian laminated carbonates of the Sergipe Basin have been associated with orbital-climatic-driven cycles.^[4]

The Cotinguiba Formation formed as result of a transgressive event which ended in the drowning of the shallow platform of the Riachuelo Formation.^[3]

History

Various works have discussed the paleontology of the Sergipe-Alagoas Basin, where the Cotinguiba Formation is found. Among the first works on the formation, are highlighted those by Dr. C. A. White in 1887 and Maury in 1936, which described the various species of ammonites, bivalves, gastropods and equinoderms.^[3]

The first biochronostratigraphic study based on ammonites was done by G. Beurlen in 1970, followed by others like Reyment and Bengtson.^[1]

Fossil contents

Although not as abundant as the Riachuelo Formation fauna that precedes it, the Cotinguiba Formation contains a very diversified macrofauna, including ammonites and inoceramid bivalves.^[1]

Molluscs

Molluscs of the Cotinguiba Formation
Genus	Species	Description	Image
Solgerites^[5]	S. armatus	An Collignoniceratidae ammonite
Barroisiceras^[5]	B. onilahyense	An Collignoniceratidae ammonite
Prionocyclus^[5]	P. germari	An Collignoniceratidae ammonite
Subprionocyclus^[5]		An Collignoniceratidae ammonite
Mammites^[5]	M. nodosoides	An Acanthoceratidae ammonite
Watinoceras^[5]	W. amudariense	An Acanthoceratidae ammonite
Pseudotissotia^[5]	P. nigerienses	An Pseudotissotiidae ammonite
Vascoceras	V. harttii	An Vascoceratidae ammonite
Aporrhais^[6]	A. dutrugei A. subgibbosus	A Aporrhaidae gastropod
Avellana^[6]		A Ringiculidae gastropod
Drepanocheilus^[6]		A Aporrhaidae gastropod
Epitonium^[6]		A Epitoniidae gastropod
Fasciolaria^[6]		A Fasciolariidae gastropod

References

^ ^a ^b ^c Souza-Lima, W; Andrade, E. J (2002). "A bacia de Sergipe-Alagoas: evolução geológica, estratigrafia a e conteúdo fóssil". Phoenix, Edição Especial. 1 (1): 22–23.
^ ^a ^b Bengtson, Peter (1983). "The Cenomanian–Coniacian of the Sergipe Basin, Brazil". Fossil and Strata. 12: 1–78 – via ResearchGate.
^ ^a ^b ^c Franco Neto, Emmanuel (2018). "Paleontologia e Paleoecologia dos moluscos biválvios da localidade Pedro Gonçalves, Formação Cotinguiba, Bacia de Sergipe" (PDF). Universidade Federal de Sergipe Centro de Ciências Exatas e Tecnologia Departamento de Geologia: 17.
^ Scarparo Cunha, Armando A.; M. Koutsoukos, Eduardo A. (2001). "Orbital cyclicity in a Turonian sequence of the Cotinguiba Formation, Sergipe Basin, NE Brazil". Cretaceous Research. 22 (5): 529–548. doi:10.1006/cres.2001.0280 – via ResearchGate.
^ ^a ^b ^c ^d ^e ^f ^g SANTOS LIMA, HANDREI FELIPE (2018). "Paleontologia e Bioestratigrafia da seção Pedro Gonçalves, Formação Cotinguiba, Bacia de Sergipe" (PDF). Universidade Federal de Sergipe Centro de Ciências Exatas e Tecnologia Departamento de Geologia – via Repositório Instiucional da UFS.
^ ^a ^b ^c ^d ^e ANDRADE, Edilma de Jesus; FELIX, Ivan Lúcio Cruz (2012). "GASTRÓPODOS MARINHOS DO TURONIANO (CRETÁCEO SUPERIOR) DA BACIA DE SERGIPE". Cadernos de Geociências. 9 (2): 103–111.