New Seafloor Evidence of Glacial Dynamics of the Barents-Kara Ice Sheet
during LGM Suggests Glacial Advance from the Arctic Ocean
Abstract
Our knowledge of glacial history of the western (Norwegian) part of the
Barents Sea has greatly improved during the last decades, notably due to
the high-resolution multibeam swath bathymetry data. In contrast,
published seafloor data from the eastern part of the Barents Sea and the
Kara Sea are much more sparse. This study presents new
geophysical/geological evidence for reconstructing glacial dynamics of
the eastern part of the Barents-Kara Ice Sheet during the Last Glacial
Maximum and subsequent deglaciation. Archival data used in this study
include more than 300,000 km of sparker and high-resolution Parasound
profiles verified by boreholes drilled with continuous core recovery to
50-100 m below sea bed. This dataset was used to construct continuous
geological cross-sections and a series of maps, including detailed
bathymetry (in 10-m isobaths) and sediment thickness maps of major
seismo-stratigraphic units. Based on the bathymetric and sediment
thickness data we map megascale glacial lineations, drumlin-like ridges
up to 50 m high and subglacial channels up to 100 m deep, as well as
accumulations of glacial deposits (basal, lateral and end moraines) and
ice-proximal acoustically transparent bodies (ATBs). Spatial and
stratigraphic analysis of these bedforms enables us to put forward a new
hypothesis that ice moved on the shelf from the Arctic Ocean along the
Saint Anna Trough (SAT). Further south, near the northern tip of the
Novaya Zemlya islands, the ice flow split into three major lobes moving
to the southwest into the Barents Sea and to the south and southeast
into the Kara Sea. Deglaciation in the study area progressed with
several ice stillstands and subsequent readvances marked by end-moraines
and accumulation of ice-proximal sediments. During deglaciation events,
when the SAT became ice free due to iceberg calving, the ice flow
reversed its direction toward the SAT, forming a fluting and a massive
ATB on the western SAT slope. The exact timing and mechanisms of the ice
transgression(s) from the Arctic Ocean are not well understood.
Additional high-resolution data such as multibeam bathymetry surveys are
needed to verify the spatiotemporal distribution of glaciogenic
bedforms, and glaciological modeling is required to comprehend the ice
dynamics and put it in the pan-Arctic context.