Eocene-Pliocene planktonic foraminifera biostratigraphy from the continental margin of the southwest Caribbean

Abstract

Biostratigraphy in northern Colombia has traditionally been done using foraminifera. Quantitative biostratigraphic techniques could improve the zonations that have been proposed for the region. We analyze the biostratigraphic information from 190 planktonic foraminifera species, and 1961 ditch-cutting samples from 26 oil wells in northern Colombia to produce a zonation for the region. A quantitative biostratigraphic technique known as Constrained Optimization was used to analyze the data. The proposed zonation relies exclusively on last occurrences, which are readily applied to petroleum exploration. It has thirteen zones and eight subzones for the Eocene to Pliocene interval. Three zones and two subzones are defined for the Eocene, three zones for the Oligocene, six zones and six subzones for the Miocene, and one zone for the Pliocene. The zonation reveals three major unconformities: (1) a late Eocene - early Oligocene hiatus; (2) a late Oligocene - early Miocene hiatus; and (3) a late Miocene hiatus; the hiatuses are related to the collision of the Caribbean with the South American plate.