Ror Formation (Rorformasjonen)

(From NPD Bulletin no. 4)

Båt Group


Norwegian word for rudder or helm. The previous informal unit was the Leka formation (Hl-3).

Well type section

6407/2-1 (Saga Petroleum), coordinates 64°58'04.97"N, 07°28'28.11"E, from 3176 m to 3072 m (Fig. 13). One core (14.5 m recovery), from the upper parts of the formation.

Well reference sections

6507/10-1 (BP), coordinates 65°13'10.75"N, 07°14'00.47"E from 3080.5 m to 2994 m (Fig. 14). One core covers the base and 3.5 m of the lower part of the unit.
6407/4-1 (Statoil), coordinates 64°35'45.36"N, 07°08'42.17"E, from 4272 m to 4106 m (Fig. 12). The section includes approximately 40 m of interbedded Tofte Formation.
6610/7-1 (Statoil), coordinates 66°17'32.82"N, 10°16'52.92"E, from 2745.5 m to 2679 m, (Fig. 15). Two cores, 28 m recovery, cover both the middle and upper parts of the unit.


104 m in the type well, from 66.5 m to 160.5 m in the reference wells.


Dominant grey to dark grey mudstones contain interbedded silty and sandy coarsening upwards sequences, commonly a few metres thick. Such sequences become more frequent towards the top of the formation, giving the unit an overall coarsening upwards trend over most of Haltenbanken.

Basal Stratotype

The base is defined by the abrupt transition from sandstones of the Tilje Formation into mudstone. The break is well defined in most Haltenbanken wells and is easily picked on the gamma log. Well correlation indicates an ero-sional contact, at least in parts of the area. In the northwesternmost Haltenbanken wells (e.g. 6506/12-1, Fig. 11) the Tofte Formation rests directly on the Tilje Formation, with no fine-grained succession in between. The mudstones overlying the Tofte Formation there are equivalent to the upper part of the Ror Formation in its type area.

Lateral extent and variation

The formation is present in all wells on Haltenbanken, where it varies from 70 m to 170 m thick - generally thinning to the northeast. To the west it interfingers with sandstones of the Tofte Formation (Fig. 12), and the oldest part of the Ror Formation is often absent. The Ror Formation is also present in some Trænabanken wells (e.g. Fig. 15), but has been removed by erosion over large areas of the Nordland Ridge.


Pliensbachian to Toarcian.

Depositional environment

The formation was deposited in open shelf environments, mainly below wave base. The coarsening upwards trend reflects ongoing shallowing and storm-generated sands are common in the unit's upper part. Sand input from the west indicates synsedimentary tectonic uplift along the western margins of the basin.

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