Description: We determined the isotopic composition of neodymium (Nd) and lead (Pb) of past seawater to reconstruct water mass exchange and erosional input between the Arctic Ocean and the Norwegian-Greenland Seas over the past 5 Ma. For this purpose, sediments of ODP site 911 (leg 151) located at 900 m water depth on the Yermak Plateau in the Fram Strait were used. The paleo-seawater variability of Nd and Pb isotopes was extracted from the sea water-derived metal oxide coatings on the sediment particles following the leaching method of Gutjahr et al. (2007). All radiogenic isotope data were acquired by Multi-Collector (MC) ICP-MS. The site 911 stratigraphy of Knies et al. (2009) was applied. Surface sediment Sr and Nd isotope data, as well as downcore Sr isotope data obtained on the same leaches are close to seawater and confirm the seawater origin of the Nd and Pb isotope signatures. The deep water Nd isotope time series extracted from site 911 was in general more radiogenic ("Nd = -7.5 to -10) than present day deep water ("Nd = -9.8 to -11.8) in the area of the Fram Strait (Andersson et al., 2008) and does not show a systematic trend with time. In contrast, the radiogenic isotope composition of Pb evolved from 206Pb/204Pb ratios around 18.7 to more radiogenic values around 19.2 between 2 Ma and today. The data indicate that mixing of water masses from the Arctic Ocean and the Norwegian-Greenland Seas has controlled the Nd isotope signatures of deep waters on the Yermak Plateau over the past 5 Ma. Prior to 1.7 Ma the Nd isotope signatures on the Yermak Plateau were less radiogenic than waters from the same depth in the central Arctic Ocean (Haley et al., 2008) pointing to a greater influence from the Norwegian-Greenland Seas. After 1.7 Ma the central Arctic and Yermak Plateau data have varied around similar values indicating water mass mixing overall similar to today. In contrast, the Pb isotope composition of deep waters in the Fram Strait appears to have been dominated by weathering inputs from glacially weathering old continental landmasses, such as Greenland or parts of Svalbard since 2 Ma. A similar control over the Pb isotope evolution of seawater since the onset of Northern Hemisphere Glaciation was recorded by ferromanganese crusts that grew from North Atlantic DeepWater in the western North Atlantic. References: Gutjahr, M., Frank, M., Stirling, C.H., Klemm, V., van de Flierdt, T. and Halliday, A.N. (2007): Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments.- Chemical Geology 242, 351-370 Haley B. A., M. Frank, R.F. Spielhagen and A. Eisenhauer (2008): Influence of brine formation on Arctic Ocean circulation over the past 15 million years. Nature Geoscience 1, 68–72 Andersson, P.S., Porcelli, D., Frank, M., Björk, G., Dahlqvist, R. and Gustafsson, Ö. (2008): Neodymium isotopes in seawater from the Barents Sea and Fram Strait Arctic- Atlantic gateways.- Geochim. Cosmochim. Acta 72, 2854-2867 Knies, J., J. Matthiessen, C. Vogt, J.S. Laberg, B.O. Hjelstuen, M.Smelror, E. Larsen, K. Andreassen, T. Eidvin and T.O. Vorren (2009): The Plio-Pleistocene glaciation of the Barents Sea–Svalbard region: a new model based on revised chronostratigraphy - Quaternary Science Reviews 28, 9-10, 812-829

Description: We determined the isotopic composition of neodymium (Nd) and lead (Pb) of past seawater to reconstruct water mass exchange and erosional input between the Arctic Ocean and the Norwegian-Greenland Seas over the past 5 Myr. For this purpose, sediments of ODP site 911 (leg 151) located at 900 m water depth on the Yermak Plateau in the Fram Strait were used. The paleo-seawater variability of Nd and Pb isotopes was extracted from the sea water-derived metal oxide coatings on the sediment particles following the leaching method of Gutjahr et al. (2007). All radiogenic isotope data were acquired by Multi-Collector (MC) ICP-MS. The site 911 stratigraphy of Knies et al. (2009) was applied. Surface sediment Sr and Nd isotope data, as well as downcore Sr isotope data obtained on the same leaches are close to seawater and confirm the seawater origin of the Nd and Pb isotope signatures. The deep water Nd isotope composition extracted from site 911 was in general more radiogenic (εNd = -4.3 to -10) than present day deep water (-10.1 to -11.8) in the area of the Fram Strait (Andersson et al., 2008) and does not show a systematic long-term trend over time. In contrast, the radiogenic isotope composition of Pb evolved from 206Pb/204Pb ratios around 18.55 to more radiogenic values around 19.15 between 2 Ma and today. Over the past 5 million years the data indicate that overall mixing of water masses from the Arctic Ocean and the Norwegian-Greenland Seas have controlled the Nd isotope signatures on the Yermak Plateau. Prior to 1.7 Ma the Nd isotope signatures were somewhat less radiogenic than waters from approximately the same depth in the central Arctic Ocean (Haley et al., 2008) pointing to a greater influence of inflowing waters from the Norwegian-Greenland Seas. After 1.7 Ma intermediate waters in the central Arctic and on Yermak Plateau have varied around similar values indicating general water mass mixing conditions similar to today. In contrast, the Pb isotopic composition increased after 2.2 Ma, which resembles the Pb isotope evolution of the deep Arctic Ocean as recorded by sedimentary ferromanganese micronodules (Winter et al., 1997) and the Pb isotope evolution of North Atlantic Deep water in the North-Atlantic recorded by ferromanganese crusts (Burton et al., 1997; Reynolds et al., 1999). This indicates that the Pb isotope composition of deep waters in the Fram Strait was strongly influenced by Pb inputs resulting from incongruent weathering and preferential release of radiogenic Pb originating from glacially weathering old continental landmasses, such as Northern Canada, Greenland, or parts of Svalbard over the past 2 Ma. References: Andersson, P.S., Porcelli, D., Frank, M., Björk, G., Dahlqvist, R. and Gustafsson, Ö. (2008): Neodymium isotopes in seawater from the Barents Sea and Fram Strait Arctic-Atlantic gateways. Geochim. Cosmochim. Acta 72, 2854-2867 Burton, K., Ling, H.F. and H.L. O‘Nions (1997) Closure of the Central American Isthmus and its effect on deepwater formation in the North Atlantic. Nature, 386, 382-385 Gutjahr, M., Frank, M., Stirling, C.H., Klemm, V., van de Flierdt, T. and Halliday, A.N. (2007): Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments. Chemical Geology 242, 351-370 Haley B. A., M. Frank, R.F. Spielhagen and A. Eisenhauer (2008): Influence of brine formation on Arctic Ocean circulation over the past 15 million years. Nat. Geosci. 1, 68–72 Knies, J., J. Matthiessen, C. Vogt, J.S. Laberg, B.O. Hjelstuen, M.Smelror, E. Larsen, K. Andreassen, T. Eidvin and T.O. Vorren (2009): The Plio-Pleistocene glaciation of the Barents Sea–Svalbard region: a new model based on revised chronostratigraphy. Quaternary Science Reviews 28, 9-10, 812-829 Reynolds, B., M. Frank and R.K., O‘Nions (1999) Nd- and Pb-isotope time series from Atlantic ferromanganese crusts: implications for changes in provenance and paleocirculation over the last 8 Myr. Earth and Planetary Science Letters, 173, 381-396. Winter, B.L., C.M. Johnson and D.L. Clark (1997): Strontium, neodymium, and lead isotope variations of authigenic and silicate sediment components from the Late Cenozoic Arctic Ocean: Implications for sediment provenance and the source of trace metals in seawater. Science 61, 4181-4200

Description: We determined the isotopic composition of neodymium (Nd), lead (Pb) and beryllium (Be) of past seawater to reconstruct water mass exchange and erosional input between the Arctic Ocean and the Norwegian-Greenland Seas (NGS) over the past approximately 5 Myr. For this purpose, sediments of ODP site 911 (leg 151) from 900 m water depth on Yermak Plateau in the Fram Strait were leached to extract the isotopic composition of past bottom water from early diagenetic metal oxide coatings on the sediment particles [1]. Nd isotope signatures extracted from site 911 agree well with the present day deep water &Nd signature of -11.8 ± 0.4 [2]. Overall the Nd isotope composition was more radiogenic in the core section older than 2.7 Ma (&Nd = -9 to -10) and then progressively decreased to less radiogenic values (&Nd = -11 to -12) similar to the present isotopic composition. 206Pb/204Pb ratios evolved from 18.7 to more radiogenic values around 19.2 between 2 Ma and today. The &Nd data indicate that mixing of water masses from the Arctic Ocean and the NGS has controlled the Nd isotope signatures of deep waters on the Yermak Plateau since the onset of the Northern Hemisphere Glaciation (NHG). In contrast, the 206Pb/204Pb of deep waters in the Fram Strait appears to have been dominated by glacial weathering inputs from old continental landmasses, such as Greenland or parts of Svalbard since 2 Ma. The changes in the &Nd and 206Pb/204Pb were similar to those found for the central Arctic Ocean and the North Atlantic (derived from Fe-Mn crusts). A record of cosmogenic 10Be normalized to 9Be in the same leaches shows a strikingly similar short term variability to those of &Nd and 206Pb/204Pb suggesting that all three isotope systems have been influenced by the same process controlled by the extent of continental ice sheets and the associated weathering inputs. [1] Gutjahr et al. (2007) Chemical Geology 242, 351–370. [2] Andersson et al. (2008) GCA 72, 2854–2867.

Description: The late Neogene evolution of the Arctic to Subarctic region is poorly understood due to few available records and poor age control. At the margin of the Arctic Ocean, Yermak Plateau Ocean Drilling Program (ODP) Hole 911A is strategically located for establishing a stratigraphic framework for the Arctic. Here we present dinoflagellate cyst and acritarch data from 24 stratigraphic levels in the lower part (474.26-505.64 metres below the seafloor (mbsf)) of ODP Hole 911A. The marine palynomorphs indicate a latest Miocene to earliest Pliocene age (between 5.8 and 5.0 Ma) for the base of the hole based on the co-occurrence of the dinoflagellate cyst Barssidinium evangelineae and acritarch Lavradosphaera crista. Our age estimate for the sediments can possibly be further refined to 5.0-5.33 Ma based on the presence of Achomosphaera andalousiensis suttonensis, which apparently has a range restricted to the Pliocene. An age close to the Miocene/Pliocene boundary agrees with the planktonic foraminifer data. Together with recently available magnetostratigraphic data, the base of the hole is likely to be placed at ~5.2 Ma. This new chronostratigraphy is a first step towards a better understanding of the late Neogene palaeoenvironment for the Yermak Plateau and also for the wider Arctic to Subarctic region. The terrestrial and fresh water palynomorphs were most likely redistributed and/or displaced from the shelf towards deeper parts of the basin during contourite deposition under the influence of the West Spitsbergen Current. The in situ marine dinoflagellate cyst assemblage contains a mixture of cool water and thermophilic taxa, indicating sea-ice free, cool-temperate, warmer than present conditions at the Yermak Plateau. Rivers were likely the source for the freshwater influence.

Description: The modern polar cryosphere reflects an extreme climate state with profound temperature gradients towards high-latitudes. It developed in association with stepwise Cenozoic cooling, beginning with ephemeral glaciations and the appearance of sea ice in the late middle Eocene. The polar ocean gateways played a pivotal role in changing the polar and global climate, along with declining greenhouse gas levels. The opening of the Drake Passage finalized the oceanographic isolation of Antarctica, some 40 Ma ago. The Arctic Ocean was an isolated basin until the early Miocene when rifting and subsequent sea-floor spreading started between Greenland and Svalbard, initiating the opening of the Fram Strait / Arctic-Atlantic Gateway (AAG). Although this gateway is known to be important in Earth’s past and modern climate, little is known about its Cenozoic development. However, the opening history and AAG’s consecutive widening and deepening must have had a strong impact on circulation and water mass exchange between the Arctic Ocean and the North Atlantic. To study the AAG’s complete history, ocean drilling at two primary sites and one alternate site located between 73°N and 78°N are proposed. These sites will provide unprecedented sedimentary records that will unveil (1) the history of shallow-water exchange between the Arctic Ocean and the North Atlantic, and (2) the development of the AAG to a deep-water connection and its influence on the global climate system. The specific overarching goals of our proposal are to study: • the influence of distinct tectonic events in the development of the AAG and the formation of deep water passage on the North Atlantic and Arctic paleoceanography, and • the role of the AAG in the climate transition from the Paleogene greenhouse to the Neogene icehouse for the long-term (~50 Ma) climate history of the northern North Atlantic.