Abstract
Fast-flowing ice streams and outlet glaciers play a key role in glacial discharge and the associated stability of contemporary and palaeo-ice sheets. However, our understanding of the extent, evolution and dynamic behaviour of major glacial outlets is still limited despite their significance for predicting the implications of present and future climate change. To constrain the drainage history of the western Greenland Ice Sheet, this PhD thesis documents the temporal and spatial evolution of the Disko Bay Trough Mouth Fan (TMF) and associated glacigenic and sedimentary processes on the central West Greenland margin. Three studies have been carried out applying 2Dand 3D-seismic reflection data, seabed bathymetry and stratigraphic information from exploration wells and published records. The early development stage of the Disko Bay TMF, probably representing the late Pliocene – early/middle Pleistocene, is associated with fast-flowing, shelfgrounded ice streams that effectively transported sediments to major slope-front depocentres (Paper I). In contrast, during most of the late TMF stage (~middle/late Pleistocene – Holocene), ice streams reaching the shelf edge were primarily floating over former troughs and bathymetric lows resulting in widespread sedimentation of stratified deposits, presumably of glacimarine origin, over the shelf margin. The development of floating ice shelves extending from Disko Bay was maintained by structurally controlled shallow banks and ridges providing anchoring points, or grounding zones, around which the ice could stabilize. It is suggested that the evolutionary change from fast-flowing ice streams to floating ice shelves is related to topographic changes driven by late Cenozoic vertical adjustments along old tectonic elements.
Another focus of this PhD study is on the more recent depositional and glaciation history of the shelf regions adjoining the Disko Bay TMF (Paper II and Paper III). Changes in spatial sedimentary geometries associated with last two depositional units, probably of middle-late Pleistocene age, emphasize the role of regional climatic-oceanographic factors and interactions between ice dynamics, margin topography and neo-tectonic adjustments. For a better understanding of the Disko Bay TMF, sediment coring is required. The stratified sediment packages on the outer shelf have the potential to serve as glacimarine archives that can provide detailed information on the interplay between glacial-interglacial climate variations and Greenland Ice Sheet dynamics.
Another focus of this PhD study is on the more recent depositional and glaciation history of the shelf regions adjoining the Disko Bay TMF (Paper II and Paper III). Changes in spatial sedimentary geometries associated with last two depositional units, probably of middle-late Pleistocene age, emphasize the role of regional climatic-oceanographic factors and interactions between ice dynamics, margin topography and neo-tectonic adjustments. For a better understanding of the Disko Bay TMF, sediment coring is required. The stratified sediment packages on the outer shelf have the potential to serve as glacimarine archives that can provide detailed information on the interplay between glacial-interglacial climate variations and Greenland Ice Sheet dynamics.
| Original language | English |
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| Publisher | Natural History Museum of Denmark, Faculty of Science, University of Copenhagen |
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| Publication status | Published - 2018 |
