Oxygen and carbon isotopic composition of benthic foraminifers at Deep Sea Drilling Project Sites 548 and 549 (Hole 549A): Pleistocene climatic changes and circulation in the northeastern Atlantic.

Abstract

Oxygen and carbon isotopic compositions of benthic foraminifers Planulina wuellerstorfi, Uvigerina peregrina, and Cibicides kullenbergi from DSDP Holes 549 and 549A in the northeastern Atlantic reveal two modes of isotopic variation in the Pleistocene, linked with glacial conditions and oceanographic evolution in the region of deep-water sources. The lower Pleistocene is characterized by more highly oxygenated deep waters, less pronounced glacial extremes, and glacial-interglacial delta 18O variations of lower amplitude than for the last 425 000 yrs., as documented here. A 1per mille difference between delta 18O glacial maximal values of the lower and upper Pleistocene cannot have resulted from a change in ice volume alone. Less-oxygenated and colder North Atlantic Deep Water of the upper Pleistocene may indicate a major northward penetration and increased inflow rate of Antarctic Bottom Water. -Authors