| Summary: | This thesis is focused on studies of glacial and slope morphology in the high Arctic of western Greenland shelf and the Molloy Hole seafloor spreading area, based on high-resolution acoustic methods and other geophysical data. The main purpose is to improve our understanding of glacial dynamics and associated processes in the marginal region of a large marine-terminating ice sheet. Newly acquired data, together with existing datasets have been compiled to create bathymetric models, which were used to study the seafloor landscape and its preserved record of glacial and sedimentary processes. The new bathymetric models were used with novel processing tools combined with seismic profiles, sub-bottom profiles and overlays of geological- and gravimetric maps to describe the observed landforms and interpret causal relationships. The main conclusions are: 1) The underlying geology is an important control on the cross-shelf trough (CST) dimensions in western Greenland. This is likely due to the influence of underlying geology to the frictional resistance of the ice flow over the basement rock. Our observations show that ice streaming in areas with basaltic bed-types cause minimal over-deepening of the main trunk of the trough, which also has weaker lateral boundaries allowing the ice stream to shift flow direction more easily. CSTs on the Cenozoic-Mesozoic sedimentary basins indicate a stronger eroding and more focused paleo-ice streams. 2) Bedrock lithology has an important part in controlling the location of the head-to-trough transition in CSTs of western Greenland. The areas where the head’s network of channels converges to form the main trunk of the trough are mostly located on the boundary from crystalline to sedimentary bedrock. These areas are also marked by distinct over-deepenings. 3) Preglacial conditions such as faults/fractures and lithological properties of the basement rocks in western Greenland served as an important control on the erosional potential of the glacial processes, particularly on a local ...
|
|---|