Seismic Geomorphology: Subsurface Analyses, Data Integration and Palaeoenvironment Reconstructions

The spatial extent and quality of seismic and subsurface datasets have substantially improved in recent years due to traditional hydrocarbon activities and the emergence of green technologies like offshore wind. This Special Publication investigates the opportunities for (re)investigating past environments using seismic geomorphology and its integration with other datasets.
Rapid glacial sedimentation and overpressure in oozes causing large craters on the mid-Norwegian margin: integrated interpretation of the Naust, Kai and Brygge formations Available to Purchase
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Published:March 15, 2024
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CiteCitation
Benjamin Bellwald, Ben Manton, Nina Lebedeva-Ivanova, Dmitry Zastrozhnov, Reidun Myklebust, Sverre Planke, Carl Fredrik Forsberg, Maarten Vanneste, Jacques Locat, 2024. "Rapid glacial sedimentation and overpressure in oozes causing large craters on the mid-Norwegian margin: integrated interpretation of the Naust, Kai and Brygge formations", Seismic Geomorphology: Subsurface Analyses, Data Integration and Palaeoenvironment Reconstructions, A. M. W. Newton, K. J. Andresen, K. J. Blacker, R. Harding, E. Lebas
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Abstract
Along continental margins with rapid sedimentation, overpressure may build up in porous and compressible sediments. Large-scale release of such overpressure has major implications for fluid migration and slope stability. Here, we study if the widespread crater-mound-shaped structures in the subsurface along the mid-Norwegian continental margin are caused by overpressure that accumulated within high-compressibility oozes sealed by low-permeability glacial muds. We interpret 56 000 km2 of 3D and 150 000 km2 of 2D-cubed seismic data in the Norwegian Sea, combining horizon picking, well ties and seismic geomorphological analyses of the crater-mound landforms. Along the mid-Norwegian margin, the base of the glacially influenced sediments abruptly deepens to form 28 craters with typical depths of c. 100 m, areal extents of up to 5130 km2 and volumes of up to 820 km3. Mounds are observed in the vicinity of the craters at several stratigraphic levels above the craters. We present a new model for the formation of the craters and mounds where the mounds consist of remobilized oozes evacuated from the craters. In our model, repeated and overpressure-driven sediment failure is interpreted to cause the crater-mound structures, as opposed to erosive megaslides. Seismic geomorphological analyses suggest that ooze remobilization occurred as an abrupt energetic and extrusive process. The results also suggest that rapidly deposited, low-permeability and low-porosity glacial sediments seal overpressure that originated from fluids being expelled from the underlying high-permeability and high-compressibility biosiliceous oozes.
- Arctic Ocean
- bottom features
- buried features
- clastic sediments
- compressibility
- continental margin
- continental margin sedimentation
- craters
- electron microscopy data
- engineering properties
- Europe
- fluid flow
- framework silicates
- geophysical methods
- glacial sedimentation
- mounds
- Norway
- Norwegian Sea
- ocean floors
- ooze
- opal
- opal-A
- opal-CT
- overpressure
- permeability
- pore water
- porosity
- Scandinavia
- sedimentary rocks
- sedimentation
- sediments
- seismic methods
- seismic stratigraphy
- SEM data
- silica minerals
- silicates
- slope stability
- statistical analysis
- Western Europe
- Vema Dome
- Naust Formation
- North Sea Fan
- Brygge Formation
- Kai Formation