Development of Cenozoic deep-sea benthic foraminiferal faunas in Antarctic waters

Abstract

Upper abyssal to lower bathyal benthic foraminifera from Ocean Drilling Program Sites 689 (present water depth 2080 m) and 690 (present water depth 2914m) on Maud Rise (Antarctica) recorded changes in deep-water characteristics at high southern latitudes during the Cenozoic. The benthic foraminiferal faunas show only minor differences as a result of the difference in water depths between the sites, and changes in faunal composition were coeval. These changes occurred at the early/late Paleocene boundary (±61.6 Ma), in the latest Paleocene (±57.5 Ma), in the middle early Eocene (±55.0 Ma), in the middle middle Eocene (±46.0 Ma), in the earliest Oligocene (±36.5 Ma) and in the early middle Miocene (±14.5 Ma). The faunal change at the end of the Paleocene was the most important and has been recognized world-wide. On Maud Rise, the diversity decreased by 50% and many common species became extinct over a period of less than 20 000 years. Diversity increased again during the early Eocene, and reached the same values as in the Paleocene by the middle Eocene. In the middle Eocene the diversity started to decrease, and continued to decrease until the middle Miocene. From the beginning of the middle Miocene until today biosiliceous oozes accumulated and calcareous benthic foraminifera were generally absent, with the exception of part of the late Miocene (±8.5–7.5 Ma) and the Quaternary.