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Diana Espitia Vanegas, Gems Ltda (Colombia)
Oswaldo Mantilla Muñoz, Gems Ltda (Colombia)
Claudia Caicedo Nivia, Consorcio Gestión Exploratoria (CGE) (Colombia)
Mauricio Alejandro Pulido Taborda, Instituto Colombiano del Petróleo-ICP-ECOPETROL (Colombia)
Vladimir Torres Torres, Instituto Colombiano del Petróleo-ICP-ECOPETROL (Colombia)
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An Upper Cretaceous sequence based on well data from the Catatumbo Basin, Colombia, yielded a series of planktonic foraminiferal assemblages, most of them lacking key marker species of the Standard Zonation (Robaszinski & Caron, 1995). Furthermore, highly-diverse benthonic foraminiferal assemblages, including both calcareous and agglutinated forms were recognised. These assemblages range from Cenomanian to Maastrichtian (?) in age.
The assemblage of hedbergellids and Heterohelix moremani characterises the lower part of the sequence (Cenomanian in age). The assemblage composed by Whiteinella archaeocretacea, W. baltica, W. paradubia and Heterohelix globulosa belongs to the Turonian. The Coniacian (?) - Santonian assemblage with Contusotruncana fornicata, Globotruncana bulloides, Hedbergella flandrini, Praebulimina petroleana, and Gyroidina spp., characterises the middle part of the sequence. The Campanian interval shows a dominance of rugoglobigerinids, heterohelicids, Globotruncana aegyptiaca and Siphogenerinoides bramlettei. In the uppermost part (probably Maastrichtian in age) where the sequence became progressively shallower, the agglutinated foraminifera (i.e Ammobaculites and Haplophragmoides) are the most abundant taxa. Together with this association there is a scarce number of calcareous forms such as Globotruncanita cf. Globotruncanita stuartiformis and Guembelitria cretacea. The consistency of these events has been proved by diverse biostratigraphic studies through the basin.
Throughout the sequence, the globular and/or non-keeled planktonic forms represented by the genera Rugoglobigerina, Archaeoglobigerina, Hedbergella, Heterohelix and Guembelitria are predominant over the keeled forms such as Globotruncana, Contusotruncana and Globotruncanita. These planktonic assemblages resemble those reported in boreal and austral provinces rather than those of the Tethyan province. They could also indicate a microfaunal distribution controlled by water depth.
The potential of producing a refined upper Cretaceous foraminiferal scheme for Northern South America might increase, since a stratigraphic core spanning the Albian to Paleocene has been recently retrieved from the Cesar Rancheria Basin, northward of the Catatumbo Basin.
Key words: Biostratigraphy, Catatumbo Basin, Colombia, Epicontinental Sea, Foraminifera, Upper Cretaceous.
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