Abstract
Abstract. We used piston cores recovered in the western Bering Sea to reconstruct millennial-scale changes in marine productivity and terrigenous matter supply over the past ~180 kyr. Based on a geochemical multi-proxy approach, our results indicate closely interacting processes controlling marine productivity and terrigenous matter supply comparable to the situation in the Okhotsk Sea. Overall, terrigenous inputs were high, whereas export production was low. Minor increases in marine productivity occurred during intervals of Marine Isotope Stage 5 and interstadials, but pronounced maxima were recorded during interglacials and Termination I. The terrigenous material is suggested to be derived from continental sources on the eastern Bering Sea shelf and to be subsequently transported via sea ice, which is likely to drive changes in surface productivity, terrigenous inputs, and upper-ocean stratification. From our results we propose glacial, deglacial, and interglacial scenarios for environmental change in the Bering Sea. These changes seem to be primarily controlled by insolation and sea-level forcing which affect the strength of atmospheric pressure systems and sea-ice growth. The opening history of the Bering Strait is considered to have had an additional impact. High-resolution core logging data (color b*, XRF scans) strongly correspond to the Dansgaard–Oeschger climate variability registered in the NGRIP ice core and support an atmospheric coupling mechanism of Northern Hemisphere climates.
Highlights
Ocean ScienceThe subarctic North Pacific (N Pacific) is a high-nitrate, low-chlorophyll (HNLC) region (e.g. Kienast et al, 2004; Tyrrell et al, 2005), characterized by salinity driven stratification, which is suggested to control glacial/interglacial variations in atmospheric carbon dioxide (CO2) concentrations (HaSugoelitdal.E, 1a9r9t9h, 2005; Sigman and Boyle, 2000; Sigman et al, 2004, 2010; Jaccard et al, 2005)
Concentrations and their approximating X-ray fluorescence (XRF) data remained low during cold intervals (MIS 6, 5.4, 5.2, 4 to 2), but high during warm intervals (MIS 5.5, 5.3, 5.1, and 1), with maximum values recorded during interglacials in core 77KL
Maxima recorded during Termination I reflect the warm phases of the Bølling–Allerød (B/A; 14.7–12.9 ka BP, Blockley et al, 2012) and Preboreal (PB; ∼ 11.7–11.0 ka BP), whereas deglacial minima are considered to correspond to the Heinrich Stadial 1 (HS1; 18.0– 14.7 ka BP, Sarnthein et al, 2001) and Younger Dryas cold phases (YD; 12.9–11.7 ka BP, Blockley et al, 2012)
Summary
Ocean ScienceThe subarctic North Pacific (N Pacific) is a high-nitrate, low-chlorophyll (HNLC) region (e.g. Kienast et al, 2004; Tyrrell et al, 2005), characterized by salinity driven stratification (permanent halocline), which is suggested to control glacial/interglacial variations in atmospheric carbon dioxide (CO2) concentrations (HaSugoelitdal.E, 1a9r9t9h, 2005; Sigman and Boyle, 2000; Sigman et al, 2004, 2010; Jaccard et al, 2005). Several studies have reported low export production in the N Pacific during glacial times (Narita et al, 2002; Kienast et al, 2004; Jaccard et al, 2005, 2009, 2010; Brunelle et al, 2007; Shigemitsu et al, 2007; Galbraith et al, 2008; Gebhardt et al, 2008). It remains unclear whether this was caused by stronger stratification or by enhanced seaice cover. Both processes would result in a less efficient export of organic carbon to the deep ocean and its subsequent degradation to CO2 (“biological pump”), and hamper
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
