Kyrre Formation (updated) (Kyrreformasjonen)

(From NPD Bulletin no. 5)

updated to follow: Stratigraphic Guide to the Cromer Knoll, Shetland and Chalk Groups of the North Sea and Norwegian Sea. Felix M. Gradstein & Colin C. Waters (editors), Mike Charnock, Dirk Munsterman,  Michelle Hollerbach, Harald Brunstad, Øyvind Hammer & Luis Vergara (contributors). Newsletter on Stratigraphy, vol 49/1 pp71-280, 2016

Shetland Group


The term Kyrre Formation was introduced by Isaksen & Tonstad (1989) for a thick, monotonous unit of marine mudstones with sporadic limestone stringers that lay between the Tryggvason and Jorsalfare formations in the Norwegian Northern North Sea in the Viking Graben. The Kyrre Formation was extended into the UK Northern North Sea by Johnson & Lott (1993). It was informally designated 'Formation' D of the Shetland Group by Deegan & Scull (1977). It has also been informally designated the 'Shetland Clay' in several published accounts describing oilfields in the East Shetland Basin (see Abbotts, 1991).


Named after Olav "Kyrre" Haraldson, a Norwegian king (A.D. 1067-1093).


Norwegian Sector: The formation consists of mudstones with occasional limestone beds. Some sandstone beds are found in the Agat region. The mudstones are medium grey to grey, silty to calcareous, occasionally pyritic, glauconitic or micaceous. The sandstones are clear to white, and very fine- to fine-grained.

UK Sector: The Kyrre Formation typically comprises a thick, monotonous sequence of mudstones with sporadic limestone stringers. The mudstones are grey, silty, slightly calcareous and occasionally pyritic, glauconitic and micaceous. The limestones are off-white to pale brown, argillaceous, chalky and locally dolomitic (Johnson & Lott, 1993).


Norwegian Sector: The formation is 585 m thick in the type well (25/1-1), 1199 m in well 35/3-2, 521 m in well 24/9-1 and 270 m in well 30/11-3.

UK Sector: The formation reaches a thickness of about 1100 m; 1200 m is recorded in the Magnus Trough (Johnson et al., 1993). Seismic data suggest that it thins by onlap over contemporaneous highs, but condensed basal sections may also occur (Johnson et al., 1993).

Geographical Distribution

Norwegian Sector: With the exception of the Gullfaks area, the formation is present in the Viking Graben, on the Tartipen Spur and the western margin of the Horda Platform.
On the Norlex website under this formation is a button to find the occurrence of formation tops in wells, and a relative thickness map.

UK Sector:The Kyrre Formation is widely distributed across the Viking Graben, Beryl Embayment and East Shetland Basin, covering intrabasinal highs (Johnson & Lott, 1993).

Type Well

Well name: N25/1- l (Norwegian Sector)

WGS84 coordinates: 59° 53' 17.4'' N 2° 4' 42.7'' E
UTM coordinates: 6639470.41 N 448427.57 E
UTM zone: 31
Drilling operator name: Elf Petroleum Norge AS
Completion date: 22.07.1971
Status: P & A
Interval of type section & thickness in type well: 2997-3582 m (9832.5- 11752 ft) below KB (Isaksen & Tonstad, 1989, p.29, fig.33). Part of one core (0.5 m), including the upper boundary.

Norwegian Reference Wells

35/3-2 from 2864 to 1665 m, coordinates N 61°51105.98", E 03°46'28.22" (Figure 34 in Isaksen & Tonstad (1989)). No cores.
24/9-1 from 3638 to 3117 m, coordinates N 59°16'09.48", E 01°41'31.18" (Figure 35 in Isaksen & Tonstad (1989)). no cores.
30/11-3 from 3162 to 2892 m, coordinates N 60°02'38.59", E 02°3ri5.47" (Figure 36 in Isaksen & Tonstad (1989)). No cores.

UK Reference Wells

3/29-1: 2925-3603 m (9596-11821 ft)           Lat. 60º 06’ 46.5”N     Long. 01º 44’ 21.9”E
3/10b-1: 2528-3586 m (8294- 11765 ft)        Lat. 57º 40’ 51.5”N    Long. 00º 08’ 50.4”W

Upper and lower boundaries

Upper Boundary

Norwegian Sector: The upper boundary shows a decrease in gamma-ray intensity and an increase in velocity from the Kyrre Formation upwards into the Jorsalfare Formation (Figures 33 and 34 in Isaksen & Tonstad (1989)). This log change is also a result of the higher carbonate content and the presence of basal limestone beds in the Jorsalfare Formation. In the Horda Platform the Kyrre Formation passes up into the Hardråde Formation (see Table).

UK Sector: The top of the Kyrre Formation is usually marked by a downward change from pale grey and commonly red-brown calcareous mudstones and argillaceous chalky limestones of the Jorsalfare Formation (unit J1) to darker grey mudstones.

Lower Boundary

Norwegian Sector: The lower boundary is defined by an increase in gamma-ray intensity and a decrease in velocity from the Tryggvason Formation into the Kyrre Formation (Figure 33 in Isaksen & Tonstad (1989)) due to changes in carbonate content. The boundary is unconformable on structural highs, usually above the Cromer Knoll Group.

UK Sector: The base of the Kyrre Formation is normally marked by a downward change from mudstones to argillaceous chalky limestones and interbedded mudstones of the Macbeth Formation. On intrabasinal highs, the Kyrre Formation locally rests unconformably on pre-Cretaceous rocks. In the South Viking Graben, the Kyrre Formation locally rests on the Herring Formation of the Chalk Group (e.g. 16/3-1).

Well log characteristics

The top of the Kyrre Formation is marked on wireline logs by a downward increase in gamma values and a decrease in velocity. The base of the formation is marked on wireline logs by a downward decrease in gamma values and an increase in velocity. Locally, the basal sediments of the Kyrre Formation display a progressive downward decrease in gamma values and an increase in velocity (e.g. 3/10b-1, Panel 1, Johnson & Lott, 1993), which is similar to the log signatures displayed by the basal Flounder and Mackerel formations.


In the UK Sector microfaunas in the upper part of the Kyrre Formation are dominated by non­calcareous agglutinated foraminifera, with only sparse calcareous microfaunas. The upper part of the formation includes the Cenosphaera sp. radiolarian biomarker. In the middle part of the formation, calcareous benthonic foraminifera become more common. Planktonic species are consistently present (e.g. Globotruncana and Whiteinella) and the Stensioeina granulata polonica and S. granulata granulata biomarkers may be recognized. Two calcareous nannofossil biomarkers occur: the Broinsonia enormis biomarker and the Watznaueria barnesae acme biomarker.

Dinoflagellate cyst associations in the Kyrre Formation are dominated by peridiniacean taxa (e.g.  Chatangiella spp., Isabelidinium magnum, Laciniadinium spp., Palaeoperidinium pyrophorum and Trithyrodinium suspectum. The following dinoflagellate cyst biomarkers are recognized: Callaiosphaeridium assymetricum, Cassiculosphaeridia reticulata, Heterosphaeridiumdifficile, Endoscrinium campanula, Florentinia deanei and Stephodinium coronatum.


Late Turonian to mid Campanian.


In the South Viking Graben, the Kyrre Formation passes laterally into the lower part of the Flounder Formation. In the East Shetland Basin, the Kyrre Formation passes northwards into undifferentiated mudstones of the Shetland Group (Johnson & Lott 1993). It is also equivalent with the informal "formation D" of Deegan & Scull (1977) (Figure 6 in Isaksen & Tonstad (1989)).

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Depositional environment

The foraminiferal assemblages in the upper part of the Kyrre Formation are dominated by non-calcareous agglutinated foraminifera and indicate relatively restricted bathyal, marine environments. However, planktonic foraminifera are dominant in the lower part of the formation, indicating phases of more 'open' marine conditions (King et al., 1989).