Figure 3. Summary of main controls on Neogene sedimentation on the Atlantic margin of NW Europe

It is becoming increasingly apparent that Neogene sedimentation was strongly influenced by tectonics, which may have driven changes in oceanographic circulation and climate. The potential link between tectonics and changes in deep-water circulation pattern is particularly significant, as the effects of the latter are commonly expressed in the geological record as erosional unconformities. These linkages are summarised below and the resulting regional pattern of sedimentation is illustrated in Fig. 3.

The base of the Neogene succession on the Atlantic margin of NW Europe is marked, for the most part, by a regional unconformity (see Fig. 6 and Fig. 7) that was formed by deep-water erosion. It may be no coincidence that a major change in oceanographic circulation occurred in the North Atlantic region during late Palaeogene–early Neogene time as deep-water pathways were established linking the Arctic and North Atlantic oceans, via the Greenland and Norwegian basins (Tucholke & Mountain 1986). It is the plate-tectonic evolution of the region that strongly influenced the development of deep-ocean connections, which led to the present-day intermediate and deep-water circulation pattern (Fig. 3). Specifically, the opening of the Fram Strait (the Northern Gateway), and the subsidence of the Greenland-Scotland Ridge (the Southern Gateway), which includes the Iceland-Faroe Rise and Wyville-Thomson Ridge (Jansen & Raymo 1996; Thiede & Myhre 1996). 

It has been suggested that deep-water circulation in the Norwegian–Greenland region may have been initiated during late Eocene–early Oligocene time (Berggren & Schnitker 1983; Ziegler 1988; Davies et al. 2001). However, a fully established pattern of deep-water exchange may be a Neogene phenomenon, initiated in the Miocene as the Fram Strait developed a true deep connection, and the Greenland-Scotland Ridge became fully submerged (Eldholm 1990; Jansen & Raymo 1996). This is supported by this study. The widespread influence of deep-water circulation is evident on Fig. 3, which shows that the entire area of the continental margin has accumulated sediment-drift deposits. The base of the Neogene succession is at its most irregular and erosive at the highly constricted, southwest end of the Faroe-Shetland Channel, which represents the deepest passageway across the southern gateway. This is an area where Oligocene inversion domes may have triggered turbulent eddies in the flow path within the channel, causing extreme erosion and sculpting of the sea bed (Smallwood In press).

The most significant intra-Neogene event, marked by the early 'mid' Pliocene unconformity (Fig. 6 and Fig. 7), may have been triggered by late Neogene uplift along the margin. Whilst the Plio-Pleistocene prograding wedges are the most distinct expression of this event (Fig. 3), sea-bed erosion in the adjacent basins, commonly accompanied by a shift in the focus of sediment-drift accumulation, indicates a plate-wide response to change that also affected the deep-water circulation pattern. Although this phenomenon has affected continental margins bordering a large part of the North Atlantic region, its cause remains unknown (Japsen & Chalmers 2000; Lundin & Doré 2002; Doré et al. 2002). Regardless of uplift mechanism, the areas of uplift became focal points for the nucleation and growth of extensive snowfields and ultimately ice sheets as Northern Hemisphere climatic deterioration intensified in the late Neogene (Eyles 1996). Mass-wasting processes have accomplished further modification of the margin, possibly in response to glacio-isostatic rebound and potentially invoking reactivation of long-lived fracture zones.

The combined effects of tectonics, deep-ocean currents and glaciation resulted in a physically-dynamic sedimentary environment on the Atlantic margin of NW Europe throughout the Neogene interval. The preserved record of sedimentation (Fig. 3) documents the interaction of various depositional processes, notably downslope, alongslope and hemipelagic (vertical flux) processes. The main characteristics of each of these groups of processes are detailed in Fig. 4.

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