Isotopic Variation in Arctic Pleistocene and Pliocene Marine Sediments

摘要

Sedimentation rates in many Arctic Ocean cores need to be determined using paleomagnetic variations, carbonate concentration and radiocarbon age determinations because there is often an insufficient supply of biogenic material for biostratigraphic determination. Using these methods in the eastern basins, the sedimentation rates obtained are generally a few centimeters per thousand years, which is significantly higher than sedimentation rates within the western, Canadian Basin. In the western basin, where enough biogenic material is available for both radiocarbon age determination and stable isotopic analysis, sedimentation rates are about one order of magnitude lower. The oxygen isotopic records are highly variable, indicating that the records are affected significantly by melt water and riverine input. Missing stratigraphic sections and higher variability in oxygen isotopic composition preclude identifying the typical open ocean marine isotope stratigraphy. Sediments from the last glacial maximum (20ka) contain few fossils or are completely missing, implying that the Arctic may have been frozen year round during this extreme period of glaciation.