Agglutinated foraminiferal assemblages of the San Cayetano Formation (San Jacinto Fold Belt, Northern Colombia)

The San Jacinto Fold Belt comprises a heterolithic succession, particularly in the Lower Paleogene, which might hamper the presence of diagnostic fossils. This case is notorious in the San Cayetano Formation, which strata have been interpreted as deposited in turbiditic setting and presents a late Paleocene-Early Eocene age using foraminiferal assemblages. However, the presence of foraminifers in the San Cayetano Formation is scattered, mostly constituted by benthic agglutinated assemblages, and the input of new data (sedimentology, macrofossils) have increased the discussion about the age and depositional context of that unit. Considering these issues, a detailed taxonomic study of the foraminiferal assemblages that define the Lower Paleogene in the San Jacinto Fold Belt was elaborated, using material of several sections of the San Cayetano Formation. Despite the agglutinated foraminifers present low diversity values, these have several abundance and preservation degrees, comprising tubular and multiserial agglutinated forms. Though some of the taxa have been referred in the San Cayetano formation, some of the identified species such as Aschemocella subnodosiformis, Bathysiphon eocanicus, Budhashevaella trinitatensis, Nothia lattissima or Reticulophragmoides jarvisi might refine the age proposal of late Paleocene-early Eocene. Furthermore, the foraminifers can be interpreted as flysch-type assemblages, or also associated with highly unstable substrates, aspects previously reported for this unit. In view of the most recent studies on the San Cayetano Formation, our contribution reinforces the importance of integrating paleontological and sedimentological data in incoming projects. This, in order of segregating the possible turbiditic settings of this unit from those proposed like more proximal.