Late Pleistocene-Holocene paleoceanographic changes on the eastern Canadian margin: stable isotopic evidence

Abstract

Earlier studies of this area show profound Holocene-Pleistocene paleoceanographic changes along the eastern continental margin of Canada, based on benthic foraminiferal assemblages. Here we demonstrate that stable isotopic measurements from benthonic foraminifera substantiate and place numerical limits on physical parameters from some of the glacial/postglacial environments. In Holocene intervals, where modern analogues of present-day benthonic foraminiferal faunas can be used to delimit the physical environment, the isotopic results closely parallel the faunal results. In the glacial-marine intervals, where we have no modern analogues, the isotopic results provide us with the first independent evidence that the salinities were not lower than 30% in the bottom waters along this former ice margin. At the time of peak glaciation, salinities may actually have been above normal. We see no indication of a large meltwater event in the 10–11 k.y. B.P. time period that has been suggested to occur with the younger Dryas events. These results demonstrate that stable isotopes can be useful outside the context of relatively stable, deep-sea environments.