Hardråde Formation (Hardrådeformasjonen)
(From NPD Bulletin no. 5)
Shetland Group
Name
Named after Harald "Hardråde" Sigurdsson, a Norwegian King (A.D. 1046-1066).
Well type section
Norwegian well 30/11-3
from 2892 to 2601 m, coordinates N 60°02'38.59", E 02°32'15.47" (Fig. 36).
No cores.
Well reference section
Norwegian well 31/6-2
from 968 to 978 m, coordinates N 60°34'58.24", E 03°54'55.76" (Fig. 37).
Cored through the formation.
Thickness
The formation is 291 m thick in the type well (30/11-3) and 10 m in well
31/6-2. It is absent on tilted fault blocks in the Troll area (e.g. well 31/2-9).
Lithology
The formation consists generally of interbedded limestones and mudstones, except in the Troll
area where it is thin and consists of a single limestone bed. The limestones are white or
pale, moderately hard to very hard. The mudstones are medium to light grey, often silty and
calcareous.
Basal stratotype
The lower boundary is towards the Kyrre Formation or an
unconformity above older rocks. The boundary towards the Kyrre Formation is identified
by the absence of relatively thick limestone beds in this formation and a lower content
of calcareous material in the mudstone. This results in a decrease in gamma-ray intensity
and an increase in velocity from the Kyrre Formation into the Hardråde Formation (Fig. 36).
The formation has an unconformable lower boundary in the Troll area.
Characteristics of the upper boundary
The upper boundary is towards the Rogaland Group. When it is
towards the Lista Formation it is characterised by an upward
increase in gamma-ray intensity and a distinct drop in velocity due to a transition from
limestones to mudstones (Fig. 36). An upper boundary towards the
Våle Formation lacks the distinct drop in velocity. This is due to the presence of
limestones and a more marly facies in the Våle Formation. An upper boundary towards the
Ty Formation is shown by a change to sandstone.
Distribution
The formation is present on the Horda Platform (Fig. 32b).
Occurrences of formation tops in wells
Age
Late Campanian to Maastrichtian.
Depositional environment
Open marine.
Remarks
The Hardråde Formation is time-equivalent with the Jorsalfare
and Tor Formations of the Shetland Group
(Fig. 6).
