Late pleistocene to recent sediment deposition in the central and western Mediterranean

Examination of the planktonic foraminiferal fauna in cores from the Mediterranean indicates that the present and probably the past populations do not reflect the water temperatures as in the Atlantic Ocean. Variation in the planktonic foraminiferal assemblage and the oxygen isotope values of some species of foraminifera during Late Würm to Recent times indicate changes in the water circulation pattern of the Mediterranean. The proportions of quartz and clay group minerals have an inverse relationship, quartz being more abundant during Würm times and clays during Post-Glacial and interglacial times. Calcite is essentially of biogenic origin, pyrite is found in sapropels and near stratigraphic breaks. Sapropel formation is attributed to high terrigenous and marine organic input sluggish circulation and high freshwater input from the Black Sea and the Nile. Initiation of sapropel conditions may have been triggered by the re-introduction of Atlantic water into the Mediterranean.