The deglacial development of the Oxygen Minimum Zone in the Bering Sea : a study based on high-resolution laminated sediment records

Abstract

A suite of partly laminated, mid-depth sediment cores from the Bering Sea shows that during the Bolling-Allerod (B/A) and early Holocene the oxygen minimum zone in this region strengthened to anoxic values of <0.1 ml/l and expanded vertically to water depths of >2100 m. Throughout the Bering-Sea and the Gulf of Alaska the onset of deglacial anoxia and thus the formation of laminations was a synchronous event. The disappearance of laminations was a diachronous process. A decadal-scale correlation of laminated sediment cores to the NGRIP d18O record revealed that lamina formation was tightly coupled to warm phases of the B/A and early Holocene, and the presence of varves. Anoxia were driven on millennial scales by basin-wide remineralization of organic matter, in combination with decadal scale export productivity increases during warmer times. Spectral analyses revealed that high primary productivity was related to the 18.6 yr nodal tidal cycle and Pacific Decadal Oscillation.