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The palynological study of a composite section of 14 cores drilled from the Sinu-San Jacinto Basin in the Colombian Caribbean (NW South America) provides for the first time a Cenozoic palynostratigraphic zonation scheme for this region. In addition, the study of calcareous nannofossils and planktonic foraminifera allowed an independent calibration of the palynomorph assemblages to the international chronostratigraphic chart. The palynological results were compared with other studies for the northern part of South America and Colombia. Twelve Late Paleocene-Pliocene palynological zones are proposed for the Caribbean, some of which differ from those proposed for the Llanos and Llanos Foothills basins. A Paleocene palynological assemblage is reported for this part of the basin. Variations in the biostratigraphic ranges of some palynomorphs and new species with stratigraphic value are described. High diversity and abundance of dinoflagellate cysts in some stratigraphic intervals require more detailed study. Evidence of reworking in some stratigraphic intervals (e.g., Cretaceous and Oligocene in Miocene sediments), makes it necessary to be careful about the last appearance record of microfossils in exploration and geologic mapping. • Palynological zonation scheme for the Colombian Caribbean (NW South America). • Twelve palynozones proposed for the Cenozoic (Late Paleocene to Pliocene) in the Colombian Caribbean. • Palynomorph age ranges calibrated using calcareous nannofossils and planktonic foraminifera. • First record of late Paleocene palynomorph assemblage to the Caribbean (Sinú-San Jacinto basin). • An improvement of the applicability of zonation schemes proposed for the north of South America. [ABSTRACT FROM AUTHOR]

The Caribbean area is currently considered a frontier basin for hydrocarbon exploration; however, the knowledge of the Cenozoic geological evolution is controversial and requires to be reviewed as new information becomes available. This study integrates for the first-time calcareous microfossils and palynomorphs and proposes a biostratigraphic framework for the early Eocene (Ypresian), in two marine sequences obtained from the ANH Piedras Blancas 1-X and ANH San Cayetano 1-X wells drilled in the Sinu-San Jacinto basin. This information was compared with palynological publications in the Llanos, Llanos Foothills, Middle Magdalena Valley, Catatumbo, and Maracaibo basins. The new information from the Caribbean suggests that the marine palynomorph events reported in the Llanos are diachronic, but they concur with global records in low-middle latitude. Similarly, we extend the biostratigraphic range of some terrestrial palynomorphs considered traditionally of Oligocene-Miocene until Ypresian. In the studied wells lateral changes of facies (turbiditic fan to outer fan-abyssal plain) seem to control the preservation and abundance of calcareous microfossils (calcareous nannofossils and planktonic foraminifera), however, the terrestrial palynology did not show stronger variation. • Integrated biostratigraphy of calcareous microfossils and palynomorphs for the Ypresian in the Caribbean Colombian. • The palynology from the early Eocene in basins from north of South America was compared. • New reports of the Adnatospharidium Acme for the Ypresian in the Colombian Caribbean. • Contributions about to age range of some palynomorphs for the north of South America. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous deposits of northwestern Colombia accumulated in two regions with distinct tectonic settings. The eastern deposits, consisting of Turonian–Maastrichtian rocks from the Upper Magdalena Valley (UMV) and the Cesar-Rancheria basins, were deposited by an epicontinental sea that partially covered the South American Plate. In contrast, the western deposits, which comprise a series of highly faulted and folded Coniacian–Maastrichtian deposits in the Sinú-San Jacinto Folded Belt (SSJFB), Gorgonilla Island, and Western Cordillera, were influenced by a seaway connecting the eastern Pacific Ocean with the proto-Caribbean Sea and were deposited near the collision zone between the Caribbean and South American Plates. We conducted a biostratigraphic analysis of 119 rock samples from these deposits. Although some well-preserved microfossils were found in the Cesar-Ranchería Basin, most samples exhibited poor to moderate preservation of nannofossils. Biostratigraphic markers identified in the Upper Magdalena Valley Basin were Quadrum gartneri , Micula concava , Micula staurophora , Lithastrinus septenarius , Lithastrinus grillii , Arkhangelskiella cymbiformis , Uniplanarius trifidus , Uniplanarius sissinghii , and Reinhardtites anthophorus. In the Cesar-Rancheria Basin, the markers identified were Arkhangelskiella cymbiformis , Lithraphidites cf. L. praequadratus , and an acme of Kamptnerius magnificus. Based on these taxa, the eastern stratigraphic sections accumulated sometime between UC7 (CC11) and UC20 (CC26) biozones, which is equivalent to an age range of early Turonian to upper Maastrichtian. Key biostratigraphic taxa from the western outcrops were more limited, yielding only Uniplanarius trifidus and Uniplanarius sissinghii , which are indicative of biozones UC15d–UC17 (CC22–CC23). This signifies a sedimentation age sometime from late Campanian to early Maastrichtian. Our results correlate well with previous age models and reveal that undistinguished upper Campanian–lower Maastrichtian deposits of the collision zone can be correlated with the last marine deposits of the epicontinental sea in the UMV. Although calcareous nannofossils from the Cesar-Rancheria Basin displayed the best preservation, low-latitude biostratigraphic markers were absent in this locality, making regional correlations challenging. We hypothesize that these deposits formed during the Maastrichtian, but changes in oceanic water conditions of the proto-Caribbean Sea affected productivity and preservation of biostratigraphic markers. • Turonian – Maastrichtian calcareous nannofossils from the La Luna Sea. • Late Campanian – early Maastrichtian calcareous nannofossils from the Caribbean Plate. • Late Cretaceous calcareous nannofossils from the proto-Caribbean Sea and eastern equatorial Pacific Ocean. [ABSTRACT FROM AUTHOR]