Dunlin Group
Name
Named after Hjalmar Johansen, member of the
Amundsen South Pole expedition.
Well type section
Norwegian well 31/2-1 (Shell), from 2176 m to 2272.5 m, coord N 60°46' 19.16'', EO3°33'15.87", (Fig. 13).
Well reference section
None at present.
Thickness
95.5 m in the type well.
Lithology
In the type well the formation consist of a sequence of sandstones with thin calcite cemented streaks throughout. The lower part is medium to fine-grained, micaceous, well sorted sandstone which grades downwards into light grey silty micaceous claystone. The main section of the formation is composed of medium grained, friable sandstones, with well sorted quartz grains which are angular to subrounded. The uppermost part is composed of medium to fine grained, micaceous sandstones, which are moderately sorted, silty and argillaceous.
Boundaries
In the type well area the Johansen Formation splits the Amundsen Formation. It is distinguished by a low response, crescentic gamma ray profile.
Distribution
The formation is restricted to an area extending from the eastern part of the Horda Platform northwards to the Malay Fault Blocks.
Occurrences of formation tops in wells
Age
Sinemurian to Pliensbachian.
Depositional environment
The formation was probably deposited on a high energy, shallow marine shelf.
