Sele Formation

updated to follow: Stratigraphic Guide to the Rogaland Group, Norwegian North Sea. Harald Brunstad, Felix M. Gradstein, Jan Erik Lie, Øyvind Hammer, Dirk Munsterman,  Gabi Ogg, and Michelle Hollerbach. Newsletter on Stratigraphy, vol 46/2 pp137-286, 2013.

Rogaland Group

Members of the Formation

Fiskebank Member | Forties Member | Hermod Member | Sula Member |


Unit definition

The Sele Formation is attributed to the laminated, non tuffaceous shales located stratigraphically between the Lista and Balder formations (Fig. 95).

Fig. 95. Lithostratigraphic summary chart of the Sele Formation (color) with members.


The Sele Formation was given name by Deegan & Scull (1977).

Derivatio nominis

The Formation is named after the Sele High off the coast of southwest Norway.

Type well

UK well 21/10-1. Depth 2131 to 2100 m RKB. Coordinates N 57°43'50.37", E 00°58'29.19". No cores.

Reference wells

Norwegian well  31/2-6 (Fig. 96). Depth 1225-1167 m RKB. Coordinates N 60°54'13.57", E 03°38'49.43". No cores.

Norwegian well 16/5-1 (Fig. 97). Depth 1557-1580 m RKB. Coordinates N 58°38'53.66", E 02°29'39.69". No cores.

Norwegian well 7/11-2 (Fig. 98). Depth 2996-3124 m RKB. Coordinates N 57°04'15.20", E 02°24'26.50". Cores: Core 1.

Fig. 96. Well 31/2-6 Composite log Rogaland Group. Stratigraphic position of the Sele Formation is outlined in stratigraphic column to the right.

Fig. 97. Well 16/5-1 Composite log Rogaland Group. Stratigraphic position of the Sele Formation is outlined in stratigraphic column to the right.

Fig. 98. Well 7/11-2 Composite log Rogaland Group. Stratigraphic position of the Sele Formation is outlined in stratigraphic column to the right.


The formation consists of montmorillinite-rich shales and siltstones which are medium to dark grey or greenish-grey. The sediments are finely laminated and carbonaceous, with minor interbeds of laminated sandstones which are frequently glauconitic. Scattered tuffaceous beds are also observed.

Core photos from Norwegian well 25/7-5 and a core description of Upper Sele Formation Norwegian well 7/11-A5, Central Trough are shown in Figs. 99 and 100.

Fig. 99. Core photo displaying dark grey non-bioturbated shales of the Sele Formation in well 25/7-5. Photo from NPD Fact Pages at

Fig. 100. Core description log from the Sele Formation Rogaland Group well 7/11-A5.

Wire line log characterization

The shales of the Sele Formation are generally characterized by intermediate to high gamma readings. Sonic logs spikes with high acoustic velocity can be related to thin beds or nodules of carbonate.

Upper Boundary

The upper boundary of the formation is taken at an abrupt decrease in gamma-ray response and an increase in velocity when going upwards into the Balder Formation. Lithologically an abrupt increase in the number of tuffaceous beds in the transition to the Balder Formation can be seen.

Lower boundary

The lower boundary of the Sele Formation is usually well defined when the lower parts of this formation or the upper parts of the underlying Lista Formation are not sandy. Typically the boundary can be seen as an abrupt upwards increase in the gamma-ray response from the Lista Formation, often with a well defined peak in the lowest part of the Sele Formation. Lithologically, the boundary can be seen as an abrupt transition from green-grey, bioturbated mudstones of the Lista Formation into dark grey to black laminated shales with only occasional bioturbation. Where the transition is sandy, an overall increase in gamma-readings is seen when going from Lista into the Sele Formation.



The thickness of the Sele Formation is variable. It is 31 m thick in the type well UK 21/10-1, and 58 m thick in the reference well 31/2-6. Including sandstone members the Sele Formation has a thickness of 220 m in well 7/11-3, and 243 m in well 25/1-4.

Seismic characterization

The Top Sele/Base Balder reflector

The top of the Sele Formation (Near Top S2) is often characterized by a marked acoustic impedance drop, when going from the high velocity tuffaceous shales in B1 (lower Balder Formation) and into the lower velocity shales of the Sele Formation. However the Top Sele Formation can sometimes be difficult to pick and may be masked by the effect of top Balder Formation tuff (B1 zone).

Base Sele/Top Lista reflector

The base of the Sele Formation is generally the seismic surface that is easiest to pick. It can be related to the chronostratigraphic surface that marks the boundary between the organic rich shales of the Sele Formation and the bioturbated shales of the Lista Formation. The seismic marker seems is associated with a low velocity spike (corresponding with high gamma spike) in the lowermost part of the Sele Formation, seen as a negative amplitude event. However, the character and amplitude of this event changes laterally.


Latest Paleocene-Earliest Eocene (Late Thanetian-Earliest Ypresian).


Organic-walled microfossils: The top of the Sele Formation agrees with the top Acme Cenodinium wardenense. The body of the Sele Formation contains the top of Apectodinium augustum (Fig. 101), top of Cenodinium dartmoorium, and top frequent Inaperturopollenites spp. and Taxodiaceae spp. The base of the Sele Formation agrees with the base of Apectodinium augustum. Hence, the Sele Formation is assigned to the A. augustum Zone plus the lower D. oebisfeldensis Zone, using dinoflagellates.

Shelly microfossils: The Sele Formation reflects and corresponds to closure of passages to and from the North Sea, resulting in a freshening of surface water mass and dysaerobia in the deeper water mass. Hence, bottom dwellers are rare and limited to few agglutinated foraminiferal taxa, including isolated Trochamminoides spp. Diatoms are well adapted to freshening surface watermass, and pyritized diatoms of mostly Fenestrella antique are common.

The Sele Formation is assigned to the upper part of Zone NSR2B - Reticulophragmium pauperum and the lower part of the Fenestrella antiqua Zone of Gradstein & Bдckstrцm (1996) using shelly microfossils.

The above biostratigraphy shows that the age of the Sele Formation is late Thanetian through early Ypresian, straddling the Paleocene-Eocene boundary. The disappearance of Apectodinium augustum in the North Sea Basin coincides with the standard Paleocene-Eocene boundary, as defined by the onset of a pronounced negative carbon isotope excursion (CIE), which allows global correlation of a wide variety of marine and terrestrial strata. Note that this formal, international definition of the Paleocene-Eocene boundary places the lower Sele Formation in the uppermost Paleocene and the upper Sele Formation in the lowermost Eocene.

Fig. 101. Example of diagnostic microfossil in the Sele Formation: Apectodinium augustum (Harland 1979c) Lentin and Williams 1981. Dorsal view. Holotype dimensions: pericyst length (excluding horns) = 63.75 µm, pericyst width (excluding horns) = 66.25 µm. From the ODP Drilling Program at

Correlation and subdivision

The Sele Formation is well expressed and easy to recognize from wire line logs in most of the Norwegian North Sea. In northern parts of the Sogn Graben and Måløy Terrace, the Sele Formation is more difficult to distinguish from the Lista Formation, and in the north easternmost parts the two formations appear to interfinger. This interfingering could be a result of less anoxic conditions during deposition of the Sele Formation in this area. Based on the sequence stratigraphic zonation established by Mudge & Bujak (1996) with high gamma shales associated with specific chronostratigraphic bioevents, the Sele Formation can be subdivided into a lower (S1) and an upper (S2) part. The base of the S1 zone is taken at the high gamma peak near the base of the Sele Formation, which is associated with the top of impoverished agglutinated assemblage. The boundary between the two zones is picked at the Apectodinum spp Acme, and is often associated with a marked high gamma peak internally in the Sele Formation. The top of the S2 zone is taken at the common Ceratopsis wardenense.

The Sele Formation contains four sandy members (Fig. 102). The Fiskebank Member found in the Norwegian Danish Basin in the Siri Valley and southeastern flank of the Central Trough fairway, and the Sula Member found along the eastern flank of the Måløy Terrace and Sogn Graben, are believed to have an eastern provenance. The Forties Member in the Central Trough and the Hermod Member in the Viking Graben have a western provenance. These sandy members are coded according to whether they are found in Sele zone S1 or S2: Hermod S1 and Hermod S2; and Forties S1 and Forties S2, etc.

Links to member descriptions

Geographic distribution

The Sele Formation is present in most of the areas where Paleocene sediments are present in the Central and northern North Sea (Fig. 102). Only along the eastern flanks where Paleocene sediments are partly truncated, the Sele Formation is partly or completely eroded. Distribution of the Sele Formation with its respective members is shown below.

Fig. 102. Distribution of the Sele Formation and its sandstone members.

Depositional environment

As earlier mentioned in Subchapters 1, 2 and 3 the Sele Formation was deposited in an anoxic basin restricted by sills established as a response to regional uplift (Wyville Thompson Ridge, Inversion ridge in the London - Brabant area and closing of the earlier seaway passage in the Polish Trough). Accordingly the Sele Formation was deposited during a period of general basin restriction in the North Sea basin, with freshening of surface water (brackish) and dysoxic to anoxic bottom water. This had an extinctive effect on benthonic organisms, and hence sediments remained undisturbed after deposition giving laminated, non bioturbated sediments upon burial.

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