3D seismic geomorphology offshore northwest Greenland

Abstract:

Using a combination of industry 2D and 3D seismic reflection data from northwest Greenland this study documents the stratigraphic architecture and seismic geomorphology of the Melville Bugt Trough Mouth Fan. The stratigraphy demonstrates over 100 km of progradation since ~2.7 Ma and the heterogeneous truncation or subsidence of topset strata. Topset character is related to the repeated growth and retreat of the Greenland Ice Sheet across the continental shelf since the onset of glaciation at ~2.7 Ma. Seismic geomorphology and facies analysis of the prograding clinoforms show repeated examples of gullies and debrites that are thought to have been formed by gravity-driven processes and the presence of meltwater-related hyperpycnal flows. Multiple sets of mega-scale glacial lineations provide evidence for the presence and flow pathways of multiple ice streams since the onset of the Middle Pleistocene Transition at ~1.3 Ma. Observations of iceberg scours and grounding-zone wedges provide additional support for marine-based glaciation. Bottomset contourites deposited at the base of the slope provide insights into the evolution of the West Greenland Current in Baffin Bay through the Pleistocene, with deposition estimated to have started at ~1 Ma. The stratigraphic architecture is combined with landform observations to unravel the evolution of the trough mouth fan into four stages. These are controlled by variations through time in the submarine topography and its impact on accommodation availability, coeval ice sheet deposition and erosion trends, ice sheet dynamics, and tectonic subsidence.