| Summary: | The Arctic Ocean and Norwegian-Greenland Seas (NGS) are presently one of the most important areas for deep water formation in the Northern Atlantic Ocean. Therefore, it is particularly essential to better understand Plio-Pleistocene variations of the circulation in these areas. Significant climatic and oceanographic changes occurred during this period of time including the major intensification of the Northern Hemisphere Glaciation (starting at 2.82 Ma) and the Mid-Pleistocene Transition (1.5 – 0.5 Ma). To reconstruct erosional input and water mass exchange between the NGS and the Arctic ocean we use the composition of the radiogenic isotopes neodymium (Nd), lead (Pb) and strontium (Sr). For this purpose, we leached the authigenic metal oxide phase on sediments particles [1] of different ODP Sites in the Norwegian-Greenland Seas (Site 911, 986, and 644) and in the North Atlantic Ocean (Site 982). The first analyses were performed on sediment samples from northernmost ODP site 911 (Leg 151, in 900 m water depth) located on the southeastern slope of the Yermak Plateau in the Fram Strait. Today this location is strongly influenced by the inflow of Atlantic water from the NGS, which is supported by the core top eNd value agreeing well with Atlantic values [2]. Based on these results, downcore samples covering the past 5 million years were analysed. The record of the Yermak Plateau shows no significant general trend with time, but a very high variability with more radiogenic Nd isotope data during glacial periods at 0.72 Ma, 1.36 Ma, 2.4 Ma, and 2.69 Ma. These shifts indicate major inflow of waters influenced by highly radiogenic source areas, either by the Icelandic basalts in the south or by the Siberian Putorana flood basalts in the hinterland of the Kara/Laptev Sea region. The εNd data suggest that mixing of water masses from the Arctic Ocean and the NGS have controlled the Nd isotope signatures of deep waters on the Yermak Plateau since the onset of the Northern Hemisphere Glaciation (NHG). In contrast, the Pb ...
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