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NORLEX


Teist Formation

(See also NPD Bulletin no. 3 for previous definition)

Hegre Group

Name

Named after the bird Black Guillemot (Norwegian: teist).

Well type section

Norwegian well 31/6-1 from 3455 m to 3739 m, coordinates N60°38'44.89", E03°40'52.28".

Well reference section

Norwegian well 33/5-1 from 3298 m to TD 3800 m, coordinates N 61°44'46.10", E 01°34'47.40".

Thickness

284 m in the type well and 502 m in the reference well.

Lithology

The Teist Formation consists of interbedded sandstone, claystone, mudstone and marl. The sandstones are dominantly very fine to fine grained, dark red brown and calcareous.The sandstones of core cut of this formation in well GB 211/13-1 is well sorted, medium to coarse grained, sub angular to sub rounded sand grains. The claystone and mudstone are red-brown while the marl is red-brown to white.

Boundaries

The lower boundary represents a transition from the fine grained lithology of the Smith Bank Formation to the sandstone prone lithology of the Teist Formation. This transition is characterized by a sudden decrease in the GR readings - from generally high readings of the Smith Bank Formation to the irregular but generally average lower readings of the Teist Formation.

Distribution


Distribution of the Teist Formation (click image for full size).

Occurrences of formation tops in wells

Age

Scythian - Carnian (Lervik et al. 1989)

Depositional environment

No diagnostic flora has been observed so far within the succession of the Teist Formation to indicate in which depositional environment the sediments have been laid down. The sedimentary succession of core 5 in well GB 211/13-1 is interpreted to reflect the migrating character of ephemeral channels of a fluvial system.

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