Millennial-scale variability of marine productivity and terrigenous matter supply in the western Bering Sea over the past 180 kyr

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

Centennial to millennial climate variability in the far northwestern Pacific (off Kamchatka) and its linkage to the East Asian monsoon and North Atlantic from the Last Glacial Maximum to the early Holocene

“…Contents of TOC, CaCO 3 , and biogenic opal in deep-sea sediments are usually used as key parameters to assess paleoproductivity (Berger et al, 1989;Narita et al, 2002;Prahl et al, 1989;Seki et al, 2004). The color b * values correlate well with the changes in biogenic opal content in sediment cores (Nürnberg and Tiedemann, 2004) and are widely used as a paleoproductivity proxy in the NW Pacific and its marginal seas Max et al, 2012;Riethdorf et al, 2013). Total carbon and inorganic carbon contents in core 41-2 were measured at every 2 cm throughout the core by coulometry using an AN-7529 analyzer in the same way, which has been reported by Gorbarenko et al (1998).…”

“…Previous studies also found the occurrence of increased export of productivity during the period of millennial-scale climate and environmental ameliorations, correlated with DO interstadials, in the Okhotsk and Bering seas Kim et al, 2011;Riethdorf et al, 2013;Seki et al, 2004).…”

“…Variations in the Earth's magnetic field, recorded by RPI, present an independent chronological instrument of marine and continental sediments (Channell et al, 2009) and are widely used for sediment correlation and chronology determination (Kiefer et al, 2001;Riethdorf et al, 2013). The sediment paramagnetic magnetization (PM) was formed in marine sediments in the open NW Pacific by silicate, paramagnetic iron sulfide (FeS), and fine clay minerals, the main part of which was transported from land as an eolian dust through atmospheric circulation by westerly jets (Serno et al, 2015).…”

“…The sequence of abrupt warming and environmental ameliorations similar to DO interstadials in Greenland were also interpreted by using alkenone-derived SST (Harada et al, 2008) and geochemical, diatom and pollen data (Gorbarenko et al, 2004) in sediment cores investigated from the Okhotsk Sea. The Bering Sea was also characterized by climate and environmental oscillations corresponding to DO cycles based on productivity proxies, sediment density, opal content and micropaleontological records Kim et al, 2011;Riethdorf et al, 2013;Schlung et al, 2013).…”

Pulses of enhanced North Pacific Intermediate Water ventilation from the Okhotsk Sea and Bering Sea during the last deglaciation

“…1) is presented in detail in Max et al (2012). These records are part of a stratigraphic framework for the subarctic northwest Pacific and its marginal seas (Riethdorf et al, 2013). In general, it is based on detailed core-to-core correlations using high-resolution XRF measurements and core-logger data, further constrained by 40 planktic foraminiferal AMS 14 C datings spanning the time interval of the last deglaciation.…”