Penultimate and last glacial oceanographic variations in the Bering Sea on millennial timescales: Links to North Atlantic climate

Intermediate- and Deep-Water Oxygenation History in the Subarctic North Pacific During the Last Deglacial Period

“…Thus, changes in ventilation might contribute to intermediatewater oxygenation in the western Bering Sea. A rough covariation of the NGRIP record, the Bering Sea oxygenation, export productivity, and ventilation data (Figure 4) might confirm the previously discussed hypothesis about a close coupling between the climate in the North Atlantic and the intermediate-depth of the North Pacific (e.g., Mikolajewicz et al, 1997;Mix et al, 1999;Max et al, 2012;Schlung et al, 2013;Ovsepyan et al, 2017;Tetard et al, 2017).…”

“…The TOC variations indicate low export production at the core sites 85KL and 77KL during the LGM-H1 and YD and enhanced organic matter flux to the seafloor during the B/A and EH (Figure 4; Riethdorf et al, 2013a). Previously published BF and PF data concur with the TOC record and further point to high/low sea-surface bioproductivity during the warm/cold intervals in the Bering Sea (Kohfeld and Chase, 2011;Riethdorf et al, 2013a;Ovsepyan et al, 2013, Ovsepyan et al, 2017. During the warmer intervals, high sea surface bioproductivity might be explained by high sea surface temperatures (Max et al, 2012) and the absence of sea ice cover (Max et al, 2012;Méheust et al, 2016).…”

“…Here, we study BF assemblages in comparison with previously obtained results from two sediment cores retrieved in 2009 during the SO201-KALMAR Leg 2 cruise of the R/V "Sonne" (Max et al, 2012;Ovsepyan et al, 2013;Max et al, 2014;Ovsepyan et al, 2017;Riethdorf et al, 2013a, Riethdorf et al, 2013b. Based on our results, available published data, and transfer functions (Tetard et al, 2017;Tetard et al, 2021a), we estimate millennial-scale variations in oxygen concentrations at present-day water depths (w.d.)…”

“…According to these age models, bottom water conditions were mostly oxic during the LGM-the onset of the B/A, suboxic at the mid-B/A, and dysoxic during the end of B/A-EH with a slight increase in [O 2 ] (up to 0.20 ml L −1 ) at the B/A-YD boundary and EH on the top of the Shirshov Ridge (core site 85KL) (Figure 3). High values of the Mn/Ti ratios suggest the precipitation of manganese in a solid phase during the B/A and FIGURE 4 | Oxygen estimates, productivity, ventilation, and preservation proxies from Core SO201-2-85KL (A) and Core SO201-2-77KL (B) relative to the Northern Greenland ice core record (NGRIP δ 18 O, AICC2012 timescale, Veres et al, 2013) and the Antarctic isotopic signatures (EDML δ 18 O, EPICA community members, 2006), TOC records after (Riethdorf et al, 2013a), benthic foraminiferal abundance (BF) and accumulation rates (BFAR) from Core SO201-2-85KL, according to (Ovsepyan et al, 2013(Ovsepyan et al, , 2017, BF-to-PF ratio, δ 13 C C.wuellerstorfi from Core SO201-2-85KL after (Max et al, 2014) and δ 13 C U. akitaensis/auberiana from Core SO201-2-77KL according to (Riethdorf et al, 2013b). Note that the North Atlantic climatostratigraphy has been applied to both groups of proxy records.…”

“…During the rest of deglaciation, the deepest sites experienced a further increase in oxygenation due to continued reduction of oxygen solubility (Jaccard and Galbraith, 2012;Jaccard et al, 2014), whereas the upper ocean underwent oxygen deficiency due to high sea-surface bioproductivity conditions over the EH (Kim et al, 2011;Ovsepyan et al, 2013Ovsepyan et al, , 2017Bubenshchikova et al, 2015) Enhancement of deoxygenation due to highly productive sea surface conditions during the EH became less pronounced with greater depth, demonstrating a very modest maximum between 1.0 and 2.3 kmbsl. The latter might be partly explained by the opening of the Bering Strait at 11 ka BP (Jakobsson et al, 2017).…”