Combined high-resolution seismostratigraphic and morphobathymetric
analysis reveals glacial history of the northwestern Chukchi margin,
High-resolution seafloor mapping provides insights into the dynamics of
past ice-sheets/ice-shelves on high-latitude continental margins.
Geological/geophysical studies in the Arctic Ocean suggest widespread
Pleistocene ice grounding on the Chukchi–East Siberian continental
margin. However, flow directions, timing, and behavior of these ice
masses are not yet clear due to insufficient data. We present a combined
seismostratigraphic and morphobathymetric analysis of the Chukchi Rise
off the northwestern Chukchi margin using the densely acquired
sub-bottom profiler (SBP) and multibeam echosounder (MBES) data.
Comparison with deeper airgun seismic records shows that the SBP data
cover most of the glaciogenic stratigraphy possibly spanning ca. 0.5–1
Ma. Based on the stratigraphic distribution and geometry of acoustically
transparent glaciogenic diamictons, the lateral and vertical extent of
southern-sourced grounded ice became smaller over time. The older
deposits are abundant as debris lobes on the slope contributing to a
large trough mouth fan, whereas younger till wedges are found at
shallower depths. MBES data show two sets of mega-scale lineations
indicating at least two fast ice-streaming events of different ages.
Contour-parallel recessional morainic ridges mark a stepwise retreat of
the grounded ice margin, likely controlled by rising sea levels during
deglaciation(s). The different inferred directions of ice advances and
retreats reflect complex geomorphic settings on the borderland. The
overall picture shows that the Chukchi Rise was an area of intense
interaction(s) of different ice-sheets/ice-shelves. In addition to
glaciogenic deposits, we identify a number of related or preceding
seabed features including mounds, gullies/channels, and sediment waves.