The eastern extent of the Barents–Kara ice sheet during the Last Glacial Maximum based on seismic-reflection data from the eastern Kara Sea

Abstract

We present sub‐bottom profiling (sparker and Parasound) results from the eastern Kara Sea, on the Eurasian Arctic margin, which enable the identification of the Last Glacial Maximum (LGM) ice extent. The analysed profiles show that glacigenic diamicton is ubiquitous at the seafloor, east of about 95°E and 78°N. The eastern margin of this diamicton is expressed in a conspicuous morainic ridge at the entrance to the Vilkitsky Strait, and to the south the diamicton projection aligns with the LGM limit mapped at the north‐western Taymyr. The bottom of the Voronin Trough further north is also covered with diamicton and has numerous erosional bedforms, indicating a streamlined flow of grounded ice along the trough. Accurate dating of the diamicton is not attainable, but the correlation of pre‐diamict sediments to well‐dated sections in the Laptev Sea, and available 14C ages from sediments on top of the diamicton, indicate its LGM age. These results support the palaeogeographic reconstruction that assumes the extension of the LGM Barents–Kara ice sheet as far east as Taymyr. This configuration implies that LGM ice blocked the drainage of the Ob and Yenisey rivers on the Kara shelf. This inference is consistent with the presence of large (>100 km wide) lenses of basin infill adjacent to the southern margin of the diamicton. However, the limited distribution of the eastern Kara ice lobe, not extending on Severnaya Zemlya, suggests that the ice was fairly thin and short‐lived: insufficient for the accumulation of the gigantic proglacial lakes that occurred during earlier glaciations.

Modeling the evolution of climate‐sensitive Arctic subsea permafrost in regions of extensive gas expulsion at the West Yamal shelf

“…[], existing estimates vary from 0.04 cm/yr subsidence to 0.4 cm/yr uplift. Although the southern Kara Sea was not glaciated during the Late Weichselian (LGM ~21 ka) [ Polyak et al ., ], the study area may have been affected by small glacio‐isostatic vertical movements, reaching tens of meters in adjacent areas of the northwestern Barents Sea [ Forman et al ., ; Peltier , ]. However, according to these authors the impact from such motions on the West Yamal shelf was insignificant.…”

“…Reconstructions of the ice sheet extent suggest that the West Yamal shelf was last glaciated in the Early Weichselian (~90 ka), but it remains unclear whether the Middle Weichselian ice sheet (~60 ka) reached the study area [Svendsen et al, 2004]. However, during the Last Glacial Maximum (LGM) (~21 ka), West Yamal shelf was not reached by an ice sheet [Polyak et al, 2008].…”

“…Dashed white line shows the extent of the Last Glacial Maximum from the West, modified from Polyak et al . []. White triangles show the heat flux values (W m −2 ) onshore and offshore the Yamal Peninsula [ Khutorskoy and Podgornyh , ].…”

MIS 3 to MIS 1 temporal and LGM spatial variability in Arctic Ocean sea ice cover: Reconstruction from biomarkers

“…Red arrow refers to the Atlantic water advection, and dark blue arrow from the continental shelves shows the freshwater input. The exposed continental shelves occupied by tundra-steppe due to lower sea level are indicated in brown [Sher, 1995;Mangerud et al, 2002;Polyak et al, 2008]. (b) Mean LGM summer sea ice concentration obtained from modeling results [Stärz et al, 2012].…”

Offshore permafrost decay and massive seabed methane escape in water depths >20 m at the South Kara Sea shelf

“…According to ice sheet reconstructions, the West Yamal shelf was not glaciated during the Late Weichselian [ Polyak et al ., ]. As a result, the continental shelf was exposed to continuous subaerial conditions, leading to the development of a several hundred meter thick permafrost layer.…”