Glacial geomorphology of the Central Arctic Ocean: the Chukchi Borderland and the Lomonosov Ridge

Abstract

The last decade of geophysical seafloor mapping in the Arctic Ocean from nuclear submarines and icebreakers reveals a wide variety of glaciogenic geomorphic features at water depths reaching 1000 m. These findings provide new and intriguing insights into the Quaternary glacial history of the Northern Hemisphere. Here we integrate multi-and single beam bathymetric data, chirp sonar profiles and sidescan images from the Chukchi Borderland and Lomonosov Ridge to perform a comparative morphological seafloor study. This investigation aims to elucidate the nature and provenance of ice masses that impacted the Arctic Ocean sea floor during the Quaternary. Mapped glaciogenic bedforms include iceberg keel scours, most abundant at water depths shallower than ~350-400 m, flutes and megascale glacial lineations extending as deep as ~1000 m below the present sea level, small drumlinlike features and morainic ridges and grounding-zone wedges. The combination of these features indicates that very large glacial ice masses extended into the central Arctic Ocean from surrounding North American and Eurasian ice sheets several times during the Quaternary. Ice shelves occupied large parts of the Arctic Ocean during glacial maxima and ice rises were formed over the Chukchi Borderland and portions of the Lomonosov Ridge. More geophysical and sediment core data combined with modeling experiments are needed to reconstruct the timing and patterns of these events. CruiseArctic Ocean 96 SCICEX 98/99 HLY0302 HLY0501/0503 *The bathymetric and sidescan sonar data acquisition was only partly working during the 1998 cruise. VesselSwedish icebreaker Oden US Navy nuclear submarines USS Pargo and Hawkbill USCGC Healy USCGC Healy Geophysical mapping/geological sampling chirp sonar profiling/sediment coring chirp sonar profiling/swath bathymetry and sidescan with interferometric sonar* chirp sonar profiling/multibeam bathymetry chirp sonar profiling/multibeam bathymetry/sediment coring References (e.g.)Backman et al. (1997) Edwards and Coakley (2003) Jakobsson et al. (2005) Darby et al. (2005) 528 M. Jakobsson et al.Figure 2. (a) Bathymetric map of the Chukchi Borderland and Mendeleev Ridge (see the methods section for an explanation of the bathymetric compilation). Major glaciogenic features and mapped limits of erosion are indicated. The directional features refer to drumlins (Northwind Ridge) and ice-dragged sediment blocks or boulders (Chukchi Plateau). Locations of sub-bottom profiles in Figures 4(a) and 8 are indicated with bold yellow lines; also shown are locations of Figures 6 and 7. The 1000 m isobath is shown with a white line and the 600 m with a black line. (b) Bathymetric profile along the Northwind Ridge. Mapped depths of erosion are shown by dashed lines. Also shown is the location of chirp sonar fragments and locations of figures with multibeam and sidescan images.contain widespread, diverse glaciogenic morphology such as sets of parallel lineations (flutes), transverse ridges and drumlins . The combination of these features depict...

An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data

“…1). However, the limited spatial distribution of previously collected seafloor morphological data did not provide conclusive evidence for or against a continuous floating ice shelf covering the entire Arctic Ocean (Jakobsson et al, 2008b).…”

“…The shallowest part (w940 m) at the opposite end of the ridge, off the Siberian margin, contains no signs of glaciogenic seabed disturbance (Jokat, 1999). The central Lomonosov Ridge between about 85 and 87 20 0 N is the area in the central Arctic Ocean where ice grounding was first mapped (Jakobsson, 1999;Jakobsson et al, 2008b;Polyak et al, 2001) (Fig. 1).…”

Spatial and temporal Arctic Ocean depositional regimes: a key to the evolution of ice drift and current patterns

“…Ice-grounding on the Morris Jesup Rise, recorded in GC-09 and GC-10 has been precisely identified in these cores and dated to pre-MIS 5.5 (Jakobsson et al, this issue). This implies that the ice-grounding on the Morris Jesup Rise took place during MIS 6, at the same time as grounding events dated on the central Lomonosov Ridge Jakobsson et al, 2008c).…”

“…These bathymetric highs have steep slopes and relatively flat crests found at generally less than 1000 m water depths (600 m for the Chukchi Plateau) (Hall, 1990;Jakobsson et al, 2003b). Recent geophysical mapping has revealed extensive glacial erosion down to 900 m water depth Darby et al, 2005;Jakobsson et al, 2005;Polyak et al, 2007;Jakobsson et al, 2008c). This information is critical when interpreting the stratigraphy in cores from this area.…”

“…Results from a detailed 14 C study on a core within this basin show a relatively high sedimentation rate of 7e9 cm/ka during the last deglaciation, possibly indicating that the Intra Basin is a local sediment trap (Hanslik et al, this issue). Similar to the Chukchi Borderland, the shallow portions of the Lomonosov Ridge (<1000 m) were subjected to ice-grounding, with the oldest dated event being associated with marine isotope stage (MIS) 6 Polyak et al, 2001;Jakobsson et al, 2008c).…”