Amundsen Formation (elevated)
(From NPD Bulletin no. 3)
Dunlin Group
Name
Named by Deegan & Scull (1977) who gave it "sub-unit" status.
Well type section
UK well 211/29-3 (Shell), from 2993 m to 3051 m, coord N 61°08'06", E 01°43'36.5 (Fig. 10).
Well reference sections
Norwegian wells 33/9-1 (Mobil) from 2838 m to 2923 m, coord N61°15'07.5",E01°50'25.8",
Thickness
58 m in the type well, 85 m in well 33/9-1 128.5 m in well 30/6-7 and 62 m in well 31/2-1, where the formation is split by the Johansen Formation, forming an upper (42 m) and a lower (20 m) unit.
Lithology
In the well type section the formation consists of light to dark grey, firm, non-calcareous siltstones and shales, in part carbonaceous and pyritic. Thin, fine to coarse grained, grey calcareous and glauconitic sandstone beds are present in the marginal areas of the basin. In the Norwegian sector the formation is more calcareous, especially in the lower part.
Boundaries
The base of the formation is the base of the Dunlin Group (defined above). The top is marked by the change to the more regular gamma ray and sonic log response of the overlying Burton Formation. Where the Burton Formation is missing (on the Horda Platform), the upper boundary is the base of the Cook Formation.
Distribution
The formation is widely distributed in the East Shetland Basin and Viking Graben north of 59°N. Towards the northwest the formation appears to overstep the Statfjord Formation and rests on the Hegre Group.
Age
Probably Hettangian to Sinemurian or Early Pliensbachian.
Depositional environment
The formation contains exclusively marine sediments, representing deposition on a shallow marine shelf.
