Neogene bottom water-masses and benthic foraminifera in the NE Atlantic Ocean

Abstract

Modern benthic foraminiferal assemblages show a correlation with oceanic bottom water-masses. A study of the Neogene benthic foraminifera from seven sites to the south and two sites to the north of the Azores Ridge shows patterns of change which can be interpreted in terms of past water-masses. An Antarctic bottom water (AABW) influence has been present to the south since the mid-Miocene but to the north of the Azores Ridge, AABW was present only up to the late Pliocene, since when it has been absent. Overlying AABW is North Atlantic deep water (NADW) and North East Atlantic deep water (NEADW). The latter shows a spectacular increase in importance from the late Pliocene to Recent. The faunal changes can be correlated with changes in circulation in the late Pliocene which heralded the incoming of major glacial events from c. 2.4 Ma.