Tofte Formation (Tofteformasjonen)

(From NPD Bulletin no. 4)

Båt Group


Norwegian word for thwart. The unit has informally been called the Leka sandstone (within Hl-3).

Well type section

6506/12-1 (Statoil), coordinates 65°10'07.58"N, 06°43'44.07"E, from 4229 m to 4164 m (Fig. 11). Three cores (41 m recovery), including the base and middle part of the unit.

Well reference section

6407/4-1 (Statoil), coordinates 64°35'45.36"N, 07°08'42.17 "E, from 4208,5 m to 4150 m (Fig. 12). Approximately 40 m of the section belongs to the Tofte Formation, the rest comprises fine-grained deposits of the interfingering Ror Formation.


65 m in the type well, approximately 40 m in the reference well. The formation thins rapidly eastwards across the Halten Terrace.


The Tofte Formation consists of moderately to poorly sorted coarse-grained sandstones which often show large-scale cross bedding. In the type section the quartz content is generally higher than 90%, although the sediment is texturally immature. Bioturbation occurs throughout the cored intervals, especially in zones of very poor sorting and high clay content.

Basal Stratotype

In the type well the lower boundary of the Tofte Formation occurs at the base of an upwards coarsening sequence. Fine-grained heavily bioturbated sandstones rest on medium-grained sandstones of the Tilje Formation and the gamma ray log shows a marked increase. In wells further to the south and east the Tofte Formation overlies mudstones and shales of the Ror Formation. The transition is there associated with a marked decrease in gamma ray response.

Lateral extent and variation

The Tofte Formation is only recognized on the western part of Halten Terrace, where it consists of a continuous succession of coarsegrained sandstones. The sandstones wedge out eastwards and interfinger with the Ror Formation. Reference well 6407/4-1 (Fig. 12) shows a relatively distal development of the formation where lateral interfingering occurs.


Pliensbachian to Toarcian.

Depositional environment

The sandstones were deposited by eastwards prograding fan deltas which reflect tectonic uplift to the west.


No known time-equivalent lithostratigraphic units in surrounding areas are similar to the Tofte Formation.

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