Figure 1) - Chaotic, semi-transparent layer, with low amplitude internal reflections
- Stratified stratigraphy in southwestern area
- underlying bright reflector on great parts of the shelf Figure 2) - Large channels with widths of a few kilometres and
depths of up to 200 ms TWT
- Many small scale channels cover shelf Figure 3) - Wide areas with truncated reflectors
- thin layer of less than 25 ms TWT of seismic transparent material on top of eroded area
Figure 4) - Small scale ridges between 400 m and 600 m water depth
- No internal reflections but a drape of 10 ms TWT
3. Preliminary Results
• recessional moraines evidence for ice stream/shelf retreating upslope in multibeam data
Ice sheet on the Chukchi shelf
• Stratification south of 73°N indication for less intense erosion
• Truncated older layers down to 400 m water depth on Northwind Ridge (NR) and east Chukchi Rise (CR)
evidence for possible thinner ice shelf approaching from east
• Truncation on western Chukchi Rise indicates possible erosion of ice advance from west
• Widespread small scale channels indicate large subglacial drainage system with possible extension to the south
0˚
90˚
180˚
90˚
6000 4000 2000 0 BATHYMETRY
m
19200 19200
24000 24000
20000 20000
20800 20800
21600 21600
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23200 23200
0.50 0.50
0.60 0.60
0.70 0.70
08 recessional moraines
5km
Grounding zone wedge
Recessional moraines
Recessional moraines
19200 20000 20800 20800 22400 23200 24000
TWT{s}
0.70 0.6 0.50
NE SW
Carsten Lehmann (AWI), Wilfried Jokat (AWI), Tabea Altenbernd (AWI)
6. References
Coakley, B (2011), „Summary report MGL11-12..
Dove, D., et al. (2014). "Widespread, multi-source glacial erosion on the Chukchi margin, Arctic Ocean." Quaternary Science Reviews 92: 112-122. , doi:10.1017/S0954102008001557
Jakobsson, M., et al. (2016). "Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation." Nature Communications 7(1): 10365., doi:
10.1038/ncomms10365
Niessen, F., et al. (2013). "Repeated Pleistocene glaciation of the East Siberian continental margin." Nature Geoscience 6(10): 842-846., doi:10.1038/ngeo1904
BREMERHAVEN Am Handelshafen 12 27570 Bremerhaven Telefon 0471 4831-0 www.awi.de
EGU2020-7538
Plio-Pleistocene submarine glaciogenic
morphology of the Chukchi Shelf, Arctic Ocean
1. Introduction
The Chukchi region with its broad and shallow shelf area is of special interest for mapping the ice extension during last glacial periods in the Arctic Ocean. Recent multibeam studies (Dove, 2014) showed the existence of grounded ice sheets/shelves in water depths deeper than 350 m along the Chukchi shelf margin.
Here, we present regional seismic reflection data from the the RV M. G. Lanseth in 2011 (Coakley, 2011) to constrain the thickness and distribution of the glacial sediments along the Chukchi shelf margin up to 150 m water depth.
2. Results
Carsten Lehmann
carsten.lehmann@awi.de
26800 26800
27600 27600
28400 28400
29200 29200
30000 30000
30800 30800
31600 31600
32400 32400
33200 33200
34000 34000
0.25 0.25
0.50 0.50
0.75 0.75
1.00 1.00
TWT[s] TWT[s]
Stratified truncated layer
10 km
Multiple Iceberg scouring
Truncated layers
NE SW
34000 33200
32400 31600
30800
26800 27600
Truncated layer
28400 29200 30000 30800 31600
0.75
1.00 0.50 0.25
Moraine
TWT{s}
We acknowledge the crew of cruise MGL1112 of R/V Marcus G. Langseth. Furthermore, we thank Bernie Coakley for
excellent collaboration. We would like to thank Emerson E&P Software, Emerson Automation Solutions, for providing licenses for the seismic software Paradigm in the scope of the Emerson Academic Program.
4000 4000
11500 11500
4800 4800
5600 5600
6400 6400
7200 7200
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8800 8800
9600 9600
10400 10400
0.20 0.20
0.30 0.30
0.40 0.40
0.50 0.50
TWT[s] TWT[s]
01EA reworked layer
Reworked layer
10 km
stratified chaotic,
semi-transparent
11500
NW Reworked layer SE
5600 6400
4000 4800 7200 8000 8800 9600 10400
0.50 0.30 0.20
0.40
TWT{s}
1)
3)
4)
-150m
-350m -550m
-550m -1000m
-1000m
-1000m
-1000m
-1000m
-1000m
-1000m
-1500m -1500m
-1500m
-1500m
-2500m
170˚
170˚
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160˚
75˚ 75˚
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km
0 75 150 225 300
EROSIONAL THICKNESS
ms
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BATHYMETRY
m
Area of truncated layers Morains at the seafloor Buried morains
Buried channels
Legend
-150m -350m -550m -1000m -1500m -2000m
170˚
170˚
160˚
160˚
75˚ 75˚
0 100
km
0 75 150 225 300
EROSIONAL THICKNESS
ms
4000 2000 0
BATHYMETRY
m
Area of truncated layers Morains at the seafloor Buried morains
Buried channels
1) 3)
2)
4)
NR CR
2000 2000
2400 2400
2800 2800
0.25 0.25
0.50 0.50
0.75 0.75
TWT[s] TWT[s]
Large erosional channel
2 km
Possible buried
moraine?
SE
NW Large erosional channel
2000 2400 2800
0.25
0.50
0.70
TWT{s}
2)
Large channel
-150m -350m -550m -1000m -1500m -2000m
170˚
170˚
160˚ 160˚
75˚ 75˚
0 100
km
0 75 150 225 300
EROSIONAL THICKNESS
ms
4000 2000 0
BATHYMETRY
m
Area of truncated layers Morains at the seafloor Buried morains
Buried channels
-150m -350m -550m -1000m -1500m -2000m
170˚
170˚
160˚
160˚
75˚ 75˚
0 100
km
0 75 150 225 300 EROSIONAL THICKNESS
ms
4000 2000 0
BATHYMETRY
m
Area of truncated layers Morains at the seafloor Buried morains
Buried channels
