Cenozoic contourite drifts and palaeoceanographic development of the Faeroe Shetland Basin

This thesis investigated the palaeoceanographic history of the Faeroe Shetland Basin, NE Atlantic, via identification and analysis of contourite drift deposits using petroleum industry seismic and well data. Integration of regional 2D seismic lines, 3D seismic volumes and high resolution seismic profiles w ith industrial well data permitted full spatial and temporal characterisation of the contourites within the basin, including identification of small scale architectural elements and subtle stratigraphic relationships. In turn, it was possible to make interpretations regarding the palaeoceanographic regime within the basin from the onset and evolution of thermohaline current flow through the basin to correlation with the present day oceanographic situation. Overall, the study serves to highlight the efficacy of industrial seismic and well data for contourite and palaeoceanographic research. A variety of contourite drift types were identified during seismic-chronostratigraphic division of the Cenozoic succession. Identification of an early middle Eocene contourite drift within the southern Faeroe Shetland Basin dates the onset of southerly flowing deep waters from the Norwegian Greenland Sea into the North Atlantic as part of a North Atlantic Conveyor Belt-style circulation system at approximately 49 million years, predating previous estimates by more than 15 million years. The presence of Oligocene, Miocene and Pliocene contourite drifts within the basin reveals that following initiation in the middle Eocene, southerly flowing deep water circulation through the basin was continuous throughout the late Palaeocene and Neogene to the present day. A gradual increase in deep water flux through the basin throughout this time is hypothesised based on contourite distribution, and is thought to relate to the global greenhouse to icehouse climatic transition that occurred during the Cenozoic. Pulses of increased deep water current velocity related to a combination of climatic and tectonic factors are thought to be responsible for the formation of major deep w ater erosional unconformities which are associated with the contourite drift successions. A link between contourite deposition and the climatic fluctuations that characterised the late Neogene northern hemisphere is also proposed based on the identification of direct indicators of significant glaciation including iceberg plough marks within the contourite drift units. Contourite drift deposition is interpreted to occur predominantly during climatically warmer episodes, while periods of glaciation are characterised by apparent disruption of ocean current circulation within the basin