Sedimentary Record of Glacial Impacts and Melt Water Discharge off the East Siberian Continental Margin, Arctic Ocean

Abstract

The East Siberian Continental Margin is a major constituent of the western Arctic Ocean, ideal for studying the evolutionary history of the Siberian Ice Sheet (SIS) based on its unique geographical location and medium‐depth bathymetry. For this study, the sedimentary core CHINARE‐ARC07‐E25 (E25) was analyzed, revealing nearly continuous stable oxygen isotope and mineralogy records that preserved scenarios of the SIS development. Lithostratigraphic evidence suggests that the stratigraphic range of E25 extends to marine isotope stage (MIS) 7. Stable oxygen isotope analysis reveals multiple strong, light‐oxygen isotopic excursions since the penultimate glacial, accompanied by multiple patterns of ice rafted debris content and mineralogy. Based on these isotopic events, the potential factors causing the excursions and the provenance of drainage were evaluated. It was found that the excursion events recorded in pink‐white carbonate detritus layers could be related to the retreat of the Laurentide Ice Sheet. The most typical events, occurring during the deglaciation periods of MIS6/5e and MIS4/3 to early MIS3, were characterized by involving a mixture of two or more sources, and could be used to trace the activity of the SIS, which has been ignored in previous studies. Findings of this study are expected to advance the understanding of SIS contribution to the western Arctic Ocean basin development, which is important for interpreting global climate change behavior of similar ice sheets in the Arctic region.

Arctic deep-water anoxia and its potential role for ocean carbon sink during glacial periods

“…Following this observation, light δ 18 O signatures of planktic foraminifers in multiple sediment cores from the Arctic Ocean since the penultimate glacial including MIS 4-3 and 2 (e.g., refs. 15,39 ) could be primarily attributed to δ 18 O-depleted freshwater discharge, and the associated lower δ 18 O values of the LMC in this study could reflect its sinking into the PDW. For example, general lower calcite δ 18 O values associated with higher authigenic ε Nd during MIS 4-3 can be interpreted as the intrusion of δ 18 O-depleted freshwater 37,38 , likely originating from the Eurasian Ice Sheet 20,40 and perhaps also the East Siberian Ice Sheet 39 (Fig.…”

“…As the process progressed, a very thin sulfate-reducing zone seemed to disappear near the sediment-seawater interface due to the strong anoxic condition of overlying seawater, and then the sediment near the seafloor directly transitioned into the methanogenic zone. In combination with massive meltwater discharge 39 , the inferred existence of thick perennial sea ice or an ice shelf covering the Arctic Ocean during cold stadials including MIS 4 and 2 (refs. 5,70,71,74 ) may have notably inhibited Atlantic water inflow carrying salt and oxygen (Fig.…”

A resilient ice cover over the southernmost Mendeleev Ridge during the late Quaternary

“…2022; Zhao et al . 2022), arguments against the presence of a grounded ice sheet over the East Siberian shelves have been posed in several studies (e.g. Sher 1995; Brigham‐Grette 2013) and have been supported by field investigations (Gualtieri et al .…”

“…This core was analysed by Zhao et al . (2022) who used the Mn‐cyclostratigraphy with ages constrained based on a palaeomagnetic inclination reversal/excursion at ~285 cm interpreted as the Biwa II event, thus leading to the assignment of the base of the core to MIS 7 (Jakobsson et al . 2000).…”

“…2022) and the chronological assignments of Zhao et al . (2022) are subject to debate. Herein, we revised the chronostratigraphy of core E25 mainly based on uranium (U)‐series measurements and, for the lower part of the core, on the tentative assignment of the inclination reversal at the core bottom to the Brunhes/Matuyama boundary.…”