North American origin of “pink-white” layers at the Mendeleev Ridge (Arctic Ocean): New insights from lead and neodymium isotope composition of detrital sediment component

Dolomite-rich layers of distinct pinkish colour are used as lithostratigraphic markers in the Amerasian Basin of the Arctic Ocean. However, origin of dolomite in these sediment units has not been studied in detail. In this study, lead (Pb) and neodymium (Nd) isotope composition of detrital clay-size fraction from different lithofacies were investigated in core PS72/340-5 recovered at the eastern flank of the Mendeleev Ridge. Prior to the geochemical analyses, grain-size distribution was analyzed in order to minimize the grain-size effect on the provenance signature. For provenance discrimination, results of isotope measurements were compared with marine surface sediment data and values for the circum-Arctic subaerial provinces. Late Quaternary sediment supply variability was analyzed using the mixing model constrained by two tracers: 207Pb/206Pb and εNd. Variations of sediment isotopic composition are inferred to result from mixing of volcanic and plutonic components. Usage of Pb isotopic ratios alone does not allow distinction between these two types of sources. Results confirm that over the last estimated ca. 200 ka dolomite-rich pink layers at the Mendeleev Ridge were deposited during events probably associated with intensified iceberg transport from North America. In general, however, sedimentation was mostly controlled by terrigenous input from the Chukchi and East Siberian Seas, whereas sediment supply from the Laptev Sea area remained less important and relatively constant at the studied location.