The Palaeogene volcanic rocks that are exposed on Disko, Nuussuaq and Svartenhuk Halvø are known to extend offshore. Their southern limit is just south of the Hellefisk-1 well, where they were drilled (Rolle 1985) (Fig. 3.1).
Southeast of the volcanics is the deep Sisimiut Basin (Fig. 3.1 and 3.2). The northern parts of the Sisimiut Basin have been uplifted and eroded in relatively recent geological times (Chalmers 2000), possibly as late as Miocene or even Pliocene, and the eastern border of the Sisimiut Basin is a major fault, so close to the coast that many of the seismic lines do not cross it because of skerries composed of basement.
The Sisimiut Basin is bounded to the west, northwest and north by the tectonically disturbed Ikermiut Fault Zone (Fig. 3.1 and 3.2). This structure is interpreted as a major strike-slip fault zone that is locally in transpression, forming flower structures (Chalmers et al. 1995). The Sisimiut-West licence area is over part of the Ikermiut Faul Zone.
West of the Ikermiut Fault Zone is a shallow basin exhibiting synclinal folding (Fig. 3.1 and 3.2), and west of that is the shallow to outcropping basement of the Davis Strait High (Srivastava 1983), which consists probably of continental basement at or near the seabed.
To the southeast of the Sisimiut Basin is the Nukik Platform, an area of shallow basement and volcanics drilled by the Nukik-1 and Nukik-2 wells (Figs 3.1, 3.3 and 3.4).
The Sisimiut Basin is separated from the Nuuk Basin (Figs 3.1, 3.4, 3.5, 3.6 and 3.7) by three en-echelon basement ridges between 65º 30‘N and 66º 20‘N. The middle of the three, the Kangâmiut Ridge (Figs 3.1 and 3.3), was drilled by the Kangâmiut-1 well (Rolle 1985). Fault-blocks visible on the western part of Fig. 3.2 are on the eastern margin of the Davis Strait High which is entirely in Canadian waters at the latitude of this line.
The northern Nuuk Basin is flanked to the east by the Nukik Platform and to the west by the shallow basement/volcanic complex here termed the Maniitsoq Rise (Figs 3.1 and 3.4). The western margin of the Maniitsoq Rise consists of westward-facing fault blocks (Fig. 3.4).
The southern limit of the Nukik Platform is at approximately 65°N, south of which is an area of fault-blocks here termed the Atammik Structural Complex (Figs 3.1, 3.5 and 3.6). Southwest of the Atammik Structural Complex, and partly separated from it by an area of shallow basement, is the Fylla Structural Complex (Fig. 3.1 and 4.4.2) over part of which is the Fylla licence area. South-east of the Fylla Structural Complex is another faulted area with a different structural style. Much of this area is under water depths greater than 1000 metres.
A major SSW–NNE-trending fault separates the Atammik and Fylla Structural Complexes from the Nuuk Basin to the west (Figs 3.1 and 3.5). The southern part of the Nuuk Basin is bordered to its west by the shallow basement and volcanic Hecla Rise (Tucholke & Fry 1985) (Fig. 3.1 and 3.7). The western part of the Hecla Rise consists of large fault-blocks that step down to the Lady Franklin Basin (Fig. 3.1 and 3.7), most of which is in Canadian waters.
An area of faulting, partly of block-faults and partly of more complex character, stretches all the way along the Canadian margin west of the Hecla Rise and Maniitsoq Rise (Figs 3.1, 3.4 and 3.5).
The stratigraphically deepest well offshore West Greenland (Qulleq-1) has only penetrated mid-Cretaceous sediments (Ghexis Newsletter 19) referred to the Kangeq sequence (Fig. 2.1; Chalmers et al. 1993, Chalmers et al. 1995). On the seismic data, several deeper seismic sequences (Appat, Kitsissut and ‘Deep‘ sequences) can be seen that may contain possible reservoirs and seals. Recent biostratigraphy (Nøhr-Hansen 1998) has shown that the regional mid-Cenozoic unconformity depicted in Chalmers et al. (1995) and Chalmers et al. (1993) to be at the end of the Eocene is, in fact, between the Lower and Middle Eocene.
Various basalt units of both Paleocene and early Eocene age that are the stratigraphic equivalents of the Palaeogene sedimentary interval can be mapped in the region between 63°20'N and 66°15'N and north of 67°40'N (Fig. 3.8).