Age and Paleoenvironmental Interpretations of Foraminiferal data from the Hornitos Locality, Northern Chile

Marine sediment samples were collected from the coastal cliff exposed at Hornitos (70°53'50" W, 22°17'00" S), northern Chile, and analyzed for foraminifera. The section is equivalent to the Pliocene La Portada Formation. The 25m section was sampled for biostratigraphic control of a major conglomerate event bed and to interpret the paleoenvironmental significance of the section compared to other Neogene marine sediments deposited on the Mejillones Peninsula. The samples were processed for benthic and planktonic foraminifera using standard techniques. Statistical analyses of the benthic foraminiferal data were used to identify biofacies and species assemblages. Planktonic foraminifera were used for age determination of the section. Four biofacies and five species assemblages were identified. Identification of the planktonic species Globigerinoides conglobatus and Neogloboquadrina acostaensis place the section within planktonic foraminifera zones N18-N20 (early to middle Pliocene). The benthic foraminiferal biofacies identified indicate a fall and rise in sea-level comparable to global sea-level curve estimates of the early to middle Pliocene.