Variations of an oxygen minimum zone in the Okhotsk Sea over the last glacial-interglacial cycle as recorded by benthic foraminiferal and sedimentological data

• Main Authors: Bubenshchikova, Natalia, Nürnberg, Dirk, Tiedemann, Ralf, Lembke-Jene, Lester
• Format: Conference Object
• Language: unknown
• Published: 2011
• Subjects: Okhotsk; Pacific; okhotsk sea
• Online Access: https://oceanrep.geomar.de/id/eprint/13582/

ABSTRACT FINAL ID: PP41C-1793 At present, the Okhotsk Sea contributes to ventilation of intermediate NW-Pacific via production of the oxygenated Okhotsk Sea Intermediate Water (OSIW: ~200-800 m). In the Okhotsk Sea, oxygen minimum zone appears as water layer between ~800 and 1500 m water depths with oxygen contents 0.3-1.5 ml/l. The paleoreconstructions of the OSIW production and the OMZ intensity in the Okhotsk Sea are important to understand the glacial-interglacial variations of oxygenation / ventilation of intermediate NW-Pacific. This study presents high-resolution benthic foraminiferal and sedimentological data for the last 115 ka of the IMAGES core MD01-2415 (Figure 1). The resulting reconstructions of the OMZ intensity for core MD01-2415 are compared with those for the KOMEX cores: LV28-2-4, LV28-40-5 and LV28-43-5 covering the last 52, 80 and 46 ka, respectively. To reconstruct intensity of the OMZ, we applied downcore distributions of the relative abundance (%) and accumulation rate (AR, sp. cm/kyr) of the dominant benthic foraminifera and assemblages indicative of the different bottom water oxygenation (Figure 1). The Dysoxic (0.1-0.3 ml/l), Suboxic (0.3-1.5 ml/l) and Oxic (1.5-6 ml/l) assemblages were obtained by grouping of all species of cores. Additional proxies included the sediment color* b, magnetic susceptibility, the percentage and AR of total organic carbon, calcium carbonate and biogenic opal for cores under study. We discuss probable causes of the reconstructed intensification of the Okhotsk Sea OMZ during the Termination I – Holocene (with maximum in the Preboreal) and the OMZ weakening during the Marine Isotope Stages 2-5d.