Información oceanógrafica suministrada por los Foraminíferos del Cuaternario terminal de la plataforma del Pacífico Colombiano

Abstract

The study of five Holocene sedimentary cores from the continental shelf of Colombia (Central East Pacific) allowed us to identify 89 species of benthic foraminifers. Two main foraminiferal assemblages have been distinguished. An assemblage, dominated by the cold-water species Brizalina subaenariensis, Uvigerina peregrina, Globocassidulina subgobosa, Bolivina alata and, Bulimina gibba is well developed between Curiche and Cupica Bay, in a water depth less than 60 m. This assemblage is characteristic of low oxygen and high organic carbon waters, possibly caused by upwelling. Southwards, from Baudo till Buenaventura locations, a second benthic foraminiferal assemblage occurs at 20 m depth, with the species Hanzawaia concéntrica and Nonionella atlantica, that appear only on core top samples of this area. The absence of microfauna, as well as the presence of abundant gypsum (desert rose) in the basal portion of these cores, suggest a change from open marine conditions to restricted lagoon paleoenvironment