During Leg 113, a drifting sediment-trap array was deployed to investigate the flux of natural particulate materials from Weddell Sea summer surface waters. This array was launched, tracked, and recovered from the ice-escort vessel Maersk Master, rather than from the JOIDES Resolution drillship, to carry out these upper-ocean studies without interfering with drilling operations. The arrangement proved highly successful, allowing particle traps to be deployed on 16 occasions for 23-59 hr each during the course of the Maersk Master's ice-tending duties. This paper describes the field program and archives data on the geochemical and biochemical constituents of the material that was trapped. Mass fluxes out of the upper 100 m averaged 12 mg/m 2 /hr, with the highest fluxes trapped near Site 695 (90 mg/m 2 /hr). The trapped material was mostly flocculate in appearance, with microplankton assemblages dominated by diatoms of the genera Nitzschia and Thalassiosira and by the foraminifer Neogloboquadrinapachyderma. The material averaged 28% biogenic silica by weight; the organic portion was rich in amino acids, with average organic carbon/organic nitrogen ratio (by moles) of 7 ± 2. Organic carbon isotopic fractionation (5 13 C) ranged from-27 to-31; that of organic nitrogen (6 15 N) ranged from-2 to +7.
Foraminifera, palynomorphs, and stable isotopes in planktonic foraminifera have been studied in piston cores from the northern Labrador Sea, southern Baffin Bay, and the Alpha Ridge region of the central Arctic Ocean. Foraminifera in cores from the Labrador Sea and southern Baffin Bay show glacial‐interglacial δ18O values similar to those reported from the Norwegian and Greenland seas. In contrast to the eastern North Atlantic Ocean, however, peaks of Subarctic foraminifera and dinoflagellates in the western North Atlantic cores show that relatively warm Atlantic surface water continued to flow into the northern Labrador Sea during the early glaciation growth phases of isotopic stages 2, 4, 6, and 8. Boreal and Subarctic pollen suggest that warm Atlantic air flowed into the northern Labrador Sea and Baffin Bay during the ice sheet growth phases. The advection of warm air masses and the presence of open waters during the summer probably provided moisture for the growth of the Laurentide, Innuitian, and Greenland ice sheets. Isotopic and microfossil records in Arctic cores can also be tentatively correlated with major high latitude north Atlantic glacial‐interglacial events. Magnetostratigraphic, palynological and amino acid dating, however, shows that sedimentation on the Alpha Ridge has been very slow during the past 0.73 m.y.; therefore, events of less than 20,000 years duration cannot be clearly discerned. Interpretation of pre‐Pleistocene paleoenvironments is further limited by the sparseness of calcareous and siliceous microfossils.
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