Neogene and Pleistocene glaciations in the northern hemisphere and Late Miocene-Pliocene global ice volume fluctuations: evidence from the Norwegian Sea

Abstract

Studies of ice-rafted detritus in ODP holes from the Norwegian Sea document a series of glacial episodes in the surroundings of the Norwegian - Greenland Sea from the late Miocene (5.45 Ma) through the Pliocene. These glacial events were of smaller magnitude than those of the period postdating the major onset of large scale northern hemisphere glacial cyclicity at 2.57 Ma. A further amplification of the glaciations took place after 1.2 Ma. Oxygen istope records from benthic foraminifers indicate high-frequency global ice volume fluctuations since the late Miocene. The Norwegian Sea was a net exporter of deep-water during most of the last 6 Myr. Periods of carbonate dissolution lasting several 100 kyr indicate intervals of reduced ventilation and a more stable water column in the Norwegian Sea in both the late Miocene - Pliocene and the early Quaternary. While the ventilation and deep-water chemistry of the Norwegian Sea has varied during the late Neogene, the δ18O results indicate that Norwegian Sea deep-waters were denser and colder than those of the Atlantic during major portions of the last 6 Myr. -from Authors