Sauda Formation
(From NPD Bulletin no. 3)
Boknfjord Group
Name
From an industrial town in Rogaland. The formation comprises the upper part
of the Borglum Member and the Fredrikshavn Member as defined by Deegan and
Scull (1977).
Well type section
Norwegian well 9/4-3
(Conoco) from 2250 m to 2400 m, coord N 57°26'54.5", E 04°18'57.7" (Fig. 36).
Well reference section
Norwegian well 8/1-1
(Phillips) from 2425 m to, 2551 m, coord N 57°51'43.53", E 03°12'27.64" (Fig. 37).
Thickness
150 m in the type well and 126 m in the reference well.
Lithology
The lower part is mainly a dark grey claystone with some siltstone and pyrite. The upper part is more silty, commonly developed as a siltstone. Shell fragments and pyrite are common.
Boundaries
The upper boundary is marked by the contrast between the predominantly silty
upper part of the Sauda Formation and the overlying
finer grained shales of the Flekkefjord
Formation. This is usually accompanied by marked breaks both on gamma and
sonic logs. The lower boundary is with the very radioactive
Tau Formation.
Distribution
The formation is present in the Fiskebank and Egersund Sub-Basins. The thickest and most complete sequence is found in the Egersund Sub-Basin. In the western part of the Fiskebank Sub-Basin only the upper silty part is present.
Age
Middle to Late Volgian.
Depositional environment
The Sauda Formation was deposited in a open marine, generally low energy basinal environment. The energy level became slightly higher in the later stages of deposition of the formation.
