Båt Group (Båtgruppen)
(From NPD Bulletin no. 4)
Name
Norwegian name for boat. The Båt Group comprises the lower and middle
parts of the earlier used informal Halten group (HI).
Type area
The transition from the Halten Terrace to the Trøndelag Platform in
Blocks 6507/11 and 6507/12.
The group's development is illustrated by the type section of its basal
unit in well
6507/12-1
(Saga Petroleum), coordinates 65°07'01.62"N,
07°42'42.61"E from 2920 m to 2213 m (Fig. 7), and in the reference well
6407/1-2
(Statoil), coordinates 64°47'50.61"N, 07°02'23.76"E from 4548 m
to 3907 m (Fig. 8).
Thickness
707 m in well
6507/12-1
and 641 m in well
6407/1-2.
Lithology
The Båt Group consists of alternating sandstone and shale/siltstone units,
with sandstone as the dominant lithology.
Basal Stratotype
The base of the Båt Group is defined by the
base of the Åre Formation as described herein.
Lateral extent and variation
The Båt Group is present in most of the wells drilled to date on
Haltenbanken and Træna-banken, with maximum thicknesses in excess of 700
m. The upper part of the succession is progressively truncated towards the
crestal part of the Nordland Ridge and the whole group is absent on the
highest parts of the ridge. Shallow boreholes off the Trøndelag coast
(Bugge et al. 1984) indicate that the Åre Formation may be absent and
younger strata within the Båt Group onlap directly on Pre-cambrian
basement.
Age
Rhaetian to Toarcian.
Depositional environment
Shallow marine to deltaic environments dominated during deposition of the
group.
Correlation
The group corresponds to the mid-Fruholmen to mid-Stø Formation sequence
in the Realgrunnen Group of the Hammerfest Basin. The group is also
partially equivalent to the Statfjord
Formation and the Dunlin Group of
the North Sea.
Subdivision
The group comprises four formations (Overview-Jurassic) all of which
are defined herein:
Åre Formation
Tilje Formation
Tofte Formation
Ror Formation
