Late Quaternary Glaciations on the Chukchi Margin, Arctic Ocean:
Insights from Echo Sounding and Sediment Records
Abstract
Glacigenic bedforms such as multiple glacial lineations and moraines on
the Chukchi and East Siberian margins reveal recurrent waxing and waning
by voluminous ice masses. Despite their paleoclimatic significance, the
timing, geographic distribution, and mechanisms of these glaciations
remain inadequately understood. To enhance our understanding of the
Quaternary Arctic glacial history, we study high-resolution swath
bathymetry and subbottom profiling data with lithostratigraphy and
provenance of four sediment cores. These data characterize deposits of
the last two glaciations at the Chukchi margin and adjacent basins. In
all cores, multiple peaks of plagioclase are prominent in both glacial
intervals, probably reflecting predominant glacigenic input from the
East Siberian Ice Sheet (ESIS). Peaks of dolomite and quartz for tracing
the Laurentide Ice Sheet sources occur around the last glacial/deglacial
interval and in sediment preceding the penultimate glaciation. By
integrating seismostratigraphy with sediment cores, we constrain the
formation of mid-slope moraines on the western side of the Chukchi Rise
to the penultimate glaciation (estimated age range MIS 4 to 6).
Considering the coeval glacial erosion off the East Siberian margin, our
results confirm that the ESIS at that time extended to water depths of
~650/950 m on the Chukchi Rise/East Siberian margin. In
comparison, the last ESIS (MIS 2 to possibly 4) was smaller, with the
identified seafloor imprint limited to water depths of
~450 m on the Chukchi Borderland, while its extent on
the East Siberian margin remains to be determined.