Laminated sediment cores in the Bering Sea

• Main Authors: Kühn, Hartmut, Lembke-Jene, Lester, Lohmann, Gerrit, Gersonde, Rainer, Esper, Oliver, Arz, Helge Wolfgang, Kuhn, Gerhard, Tiedemann, Ralf
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2016
• Subjects: AWI_Paleo; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Bering Sea; Greenland; Greenland ice core; ice core; NGRIP; North Atlantic; North Greenland; Sea ice; Alaska
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.857851; https://doi.org/10.1594/PANGAEA.857851

During the last glacial termination, the upper North Pacific Ocean underwent dramatic and rapid changes in oxygenation that lead to the transient intensification of oxygen minimum zones (OMZs), recorded by the widespread occurrence of laminated sediments on circum-Pacific continental margins. We present a new laminated sediment record from the mid-depth (1100 m) northern Bering Sea margin that provides insight into these deglacial OMZ maxima with exceptional, decadal-scale detail. Combined ultrahigh-resolution micro-X-ray-fluorescence (micro-XRF) data and sediment facies analysis of laminae reveal an alternation between predominantly terrigenous and diatom-dominated opal sedimentation. The diatomaceous laminae are interpreted to represent spring/summer productivity events related to the retreating sea ice margin.We identified five laminated sections in the deglacial part of our site. Lamina counts were carried out on these sections and correlated with the Bølling–Allerød and Preboreal phases in the North Greenland Ice Core (NGRIP) oxygen isotope record, indicating an annual deposition of individual lamina couplets (varves). The observed rapid decadal intensifications of anoxia, in particular within the Bølling–Allerød, are tightly coupled to short-term warm events through increases in regional export production. This dependence of laminae formation on warmer temperatures is underlined by a correlation with published Bering Sea sea surface temperature records and d18O data of planktic foraminifera from the Gulf of Alaska. The rapidity of the observed changes strongly implies a close atmospheric teleconnection between North Pacific and North Atlantic regions.We suggest that concomitant increases in export production and subsequent remineralization of organic matter in the Bering Sea, in combination with oxygen-poor waters entering the Being Sea, drove down oxygen concentrations to values below 0.1ml/l and caused laminae preservation. Calculated benthic–planktic ventilation ages show no significant variations ...