Kvitnos Formation
Shetland Group
Introduction
The Kvitnos Formation was originally introduced by Dalland et al.(1988) for a widespread unit of
calcareous mudstones developed below the Nise Formation. Two new sandstone members
are defined within this
formation: the Tumler Member, an interval of Santonian sandstones in the Vøring
Basin, and the Kvitskjæving
Member, a unit with a similar stratigraphic age developed in the Vestfjorden Basin.
Name
English/ Norwegian and any previous names: No previous formal or published informal names.
Derivatio nominis:
Kvitnos is the Norwegian name for the white-beaked dolphin or Lagenorynchus albirostris. This small
(up to 3m long) 'springar-type' species is found in flocks up to 30 individuals over large parts of the north
Atlantic, around the British Isles and the Norwegian and Barents Seas, primarily in shallow coastal areas,
in contrast to the closely related Kvitskjæving, which is found in deeper waters.
Lithology
The Kvitnos Formation consists predominantly of calcareous mudstones with subordinate carbonate and
sandstone stringers (Dalland et al., 1988). The mudstones light-medium grey, green-grey, occasional medium-dark
grey, soft, plastic, amorphous, occasional firm to blocky, subfissile, slightly to moderately
calcareous and slightly silty. The limestones stringers are grey-white, occasionally light brown, soft to
moderately hard, occasionally argillaceous and micritic. The dolomite stringers are light brown to light
orange brown, moderately hard to hard. The minor thin sand beds are predominantly loose to cemented, light
grey-white, very fine to fine, occasionally coarse, clear translucent quartz, sub-rounded to subangular,
sub-spherical, well sorted, and occasionally weakly calcite cemented.
Sample depository
Palynological preparations (organic matter depository)
Type well
6506/12-4: 44 slides (dc and 6 swc) covering
the interval 2614 m dc - 3124 m dc (Stratlab, RRI and
Saga preparations) deposited at the Norwegian Petroleum Directorate. Note that the four core samples
analysed between 3129.1 m-3132.5 m fall within the depth range of the formation
but due to a core shift of +5.9 m are part of the Blålange Formation and
Lysing Member and have been
excluded from this formation (see below).
Reference well
6506/12-1: 75 slides (dc and 2 swc samples)
covering the interval 2660 m dc - 3170 m dc
(Stratlab, RRI and OD preparations) deposited at the Norwegian Petroleum Directorate.
Core photographs
No cores were taken in the designated type
6506/12-4 and reference
6506/12-1 wells.
Note that in the type well 6506/12-4, core#1 (3129 m- 3150.9 m MDRKB) falls within the depth range of the
formation but due to a +5.9 m depth shift lies entirely within the Blålange Formation and Lysing Member
rather than the Kvitnos Formation.
Thickness
The Kvitnos Formation has a thickness range of 3.5 m to 1108 m.
Regional isochore of the Kvitnos Formation thickness in the Norwegian Sea based on released well data.
The isochore map is generated from Norlex data using thin plate splines (thickness constrained to original
range).
Thicknesses in metres.
Circled wells contain both top and base horizons.
The red wells have Norlex biostratigraphy. Click for large version.
Interactive Function:
Note that this map is only a regional interpretation and the user can generate more specific, local area
isochore maps
interactively within Norlex using the link below.
Interactive Norlex isochore map for the Kvitnos Formation
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Geographical distribution
The formation is laterally continuous in the Vøring Basin and on the Halten-Dønna Terrace areas. The main
depositional centres of the Kvitnos Formation are recorded in wells on the structural highs in the Vøring
Basin e.g.
6707/10-1 (1108 m at well TD),
6706/11-1
(1037 m), Helland Hansen Dome well
6505/10-1 (933 m) and
the Ormen Lange Dome well
6305/1-1 (862m) in the Møre Basin. An
anomalously thick interval is developed in
the
6507/1-1 well located on the Dønna Terrace where
the Kvitnos Formation reaches almost 1000 m. Generally
thicknesses decrease on the Halten-Dønna Terrace areas to between 600-150 m. The Kvitnos Formation is,
together with other Cretaceous formations, either thin or absent on the Nordland Ridge e.g.
6507/6-1 or on
the crest of fault structures on the Halten Terrace such as the Heidrun Field e.g.
6507/7-6 (3.5 m).
Occurrences of formation tops in wells
Type well
Well name: 6506/12-4
WGS84 coordinates: N 65°12'46.97, E 06°43'30.37
UTM coordinates: 7234298.14 N 393591.29 E
UTM zone: 32
Drilling operator name: Den norske stats oljeselskap a.s. (Statoil a.s.)
Completion date: 13.08.1985
Status: P & A
Interval of type section & thickness in type well:
3132.5 m - 2600 m, 532.5 m thickness.
Type well 6506/12-4 (click to enlarge)
Reference well
Well name: 6506/12-1
WGS84 coordinates: N 65°10'07.58, E 06°43'44.07
UTM coordinates: 7229359.52 N 393591.68 E
UTM zone: 32
Drilling operator name: Den norske stats oljeselskap a.s. (Statoil a.s.)
Completion date: 06.02.1985
Status: P & A
Interval of type section & thickness in reference well:
3175 m - 2658 m, 517 m thickness.
Reference well 6506/12-1 (click to enlarge)
Upper and lower boundaries
Upper Boundary
The top of the Kvitnos Formation and the boundary with the overlying
Nise Formation reflects a downward
change to more calcareous mudstones. This change is marked on logs by a downward decrease in gamma-ray
values and an increase in average sonic velocity and density values. Dalland et al. (1988) also
noted a corresponding downward increase in resistivity values.
Lower Boundary
The base of the Kvitnos Formation is normally taken at a downward change from calcareous mudstones to
non-calcareous mudstones of the Blålange Formation or sandstones of the
Lysing Member. It is marked on
logs by a downward decrease in average gamma-ray values and increase in average sonic velocity. Dalland
et al. (1988) also noted a corresponding downward increase in resistivity values (typically when
associated with the underlying Lysing member).
Well log characteristics
The Kvitnos Formation has a relatively uniform profile on gamma-ray logs reflecting the monotonous
background deposition of marine mudstones. However, the formation can be sub-divided into a series of
regionally correlatable units based on the sonic log. A downward increase in average sonic velocity within
the lower part of the formation appears to coincide with the Santonian/Coniacian boundary as defined on
biostratigraphy and provides an important regional log feature informally denoted k66 e.g.
6506/12-1
3033 m. This provides log control prior to the penetration of
Lysing sandstones. Similarly, higher in the
formation at approximately the mid-point, there is another downward increase in average sonic velocity that
appears to be close to the early/middle Santonian boundary and is defined as k68 e.g. 6506/12-1, 2950 m.
Above this event sonic velocities appear to be more irregular than those in the lower part of the formation
and may reflect the increased frequency of sandstones at this level.
Type seismic section
Biostratigraphy
The lower boundary of the Kvitnos Formation is above the Turonian dinocyst markers LO Stephodinium
coronatum and Cyclonephelium membraniphorum (Zone 27). The lower part of the Kvitnos Formation
is characterised by a marked increase in Heterosphaeridium difficile and Palaeoperidinium
pyrophorum.
As indicate above in the well log character, within the Kvitnos Formation are some discrete, regionally
identifiable units defined on the sonic log. The Coniacian/Santonian boundary, as defined by the LO
Florentina deanei and more reliably, a marked down-section increase in Chatangiella
'spinosa', that is close to the informal surface k66 defined on sonic logs.
The upper boundary of the Kvitnos Formation is close to the (down-section) influx of the planktonic bivalve
Inoceramus (Zone 26) and probably reflects a general increase in availability or preservation
potential of
calcium carbonate within the formation. This is the key event for the definition of the top Kvitnos
Formation. The LO Spongodinium cristatum and LO Whiteinella baltica are developed within the
basal part of the overlying Nise Formation.
Age
Late Cretaceous, Coniacian to late Santonian. (revised this study).
Dalland et al. (1988) had a slightly broader Turonian - Santonian age range in their definition of
the formation. The lower boundary is generally close but above the Turonian/Coniacian stage boundary, i.e.
earliest Coniacian, and the upper boundary is broadly coincident with that of the Santonian/Campanian stage
boundary within the limits of the available biostratigraphy.
Correlation
The Kvitnos Formation is laterally equivalent to the middle part of the
Kyrre Formation developed in the
Shetland Group of the northern North Sea and the
Thud and upper Narve Formations
(formerly part of the Hod Formation) in the Chalk province of the North Sea.
Depositional environment
Open marine, outer shelf - upper bathyal with more open marine circulation than developed during the
underlying Blålange and overlying Nise Formations. This
is indicated by the increase in calcareous
lithologies and floods of planktonic Inoceramus (Gradstein et al., 1999).
Remarks
A thin sandstone unit of early Santonian age is developed in the lower part of the Kvitnos Formation in the
Vema Dome well
6706/11-1 (3737 m - 3750 m) and below the
Tumler Member. This is retained as an informal unit
due to insufficient data but it may represent a significant event in the deeper parts of the Vøring Basin
that represent a precursor to the main rifting phase that developed during the Campanian-Paleocene.
The Kvitnos Formation represents deposition within the lower part of the K4 sequence of Swiecicki et
al. (1998), K80 of Vergara et al. (2001) and the majority of the K60 sequence of Færseth and
Lien (2001).
References
Dalland, A., Worsley, D. and Ofstad, K. 1988. A lithostratigraphic scheme for the Mesozoic and Cenozoic
succession offshore Mid and Northern Norway. Bulletin of the Norwegian Petroleum Directorate,
Bulletin No.
4, 1-65.
Færseth, R. and Lien, T. 2002 Cretaceous evolution in the Norwegian Sea - a period characterized by
tectonic quiescence. Marine and Petroleum Geology, 19, 1005 -1027.
Gradstein, F., Kaminski, M.A. and Agterberg, F.P. 1999. Biostratigraphy and paleoceanography of the
Cretaceous seaway between Norway and Greenland. Earth-Science Reviews, 46, 27-98.
Swiecicki, T., Gibbs, P.B., Farrow, G.E. and Coward, M.P. 1998. A tectonostratigraphic framework for the
Mid-Norway region. Marine and Petroleum Geology, 15, 245-276.
Vergara, L., Wreglesworth, I., Trayfoot, M., Richardsen, G. 2001. The distribution of Cretaceous and
Paleocene deep-water reservoirs in the Norwegian Sea basins. Petroleum Geoscience, 7, 395-408.
