Geological Survey of Denmark and Greenland Bulletin 7, 2004, p 21-24

Intense drilling activity following the discovery of the Siri
Field in 1995 has resulted in an improved understanding of
the siliciclastic Palaeogene succession in the Danish North
Sea sector (Fig. 1). Many of the new wells were drilled in the
search for oil reservoirs in sand bodies of Paleocene–Eocene
age. The existing lithostratigraphy was based on data from a
generation of wells that were drilled with deeper stratigraphic
targets, with little or no interest in the overlying Palaeogene
sediments, and thus did not adequately consider the signifi-
cance of the Palaeogene sandstone units in the Danish sector.
In order to improve the understanding of the distribution,
morphology and age of the Palaeogene sediments, in parti-
cular the economically important sandstone bodies, a detai-
led study of this succession in the Danish North Sea has
recently been undertaken. An important aim of the project
was to update the lithostratigraphic framework on the basis
of the new data.

The project was carried out at the Geological Survey of
Denmark and Greenland (GEUS) with participants from the
University of Aarhus, DONG E&P and Statoil Norway, and
was supported by the Danish Energy Agency. Most scientific
results cannot be released until September 2006, but a revised
lithostratigraphic scheme may be published prior to that
date. Formal definition of new units and revision of the
lithostratigraphy are in preparation.

All of the widespread Palaeogene mudstone units in the
North Sea have previously been formally established in
Norwegian or British wells, and no reference sections exist in
the Danish sector. As the lithology of a stratigraphic unit may
vary slightly from one area to another, Danish reference wells
have been identified during the present project, and the litho-
logical descriptions of the formations have been expanded to
include the appearance of the units in the Danish sector.

A revised lithostratigraphy for the Palaeogene – lower
Neogene of the Danish North Sea

Poul Schiøler, Jan Andsbjerg, Ole R. Clausen, Gregers Dam, Karen Dybkjær, Lars Hamberg,
Claus Heilmann-Clausen, Lars E. Kristensen, Iain Prince and Jan A. Rasmussen

Geological Survey of Denmark and Greenland Bulletin 7, 21–24 (2005) © GEUS, 2005

5°E

4°E

57°N

56°N

C
o
ffe

e
So

il Fault

50 km

20
40
60
80
100

Thickness
(m)

Siri-3

Siri Canyon

F-1x

Inez-1

Siri-1
Siri-2

C
entral G

raben

North

Sea
Denmark

Fig. 1. Map showing the study well data base

superposed on an isochore map of the Lista

Formation. The Lista Formation thickens to-

wards the northern part of the mapped area;

this thickening is mainly due to the presence

of sandstone bodies within the Siri Canyon.

Many of the sandstone bodies recently discovered in the
Danish sector have a limited spatial distribution and were
sourced from other areas than their contemporaneous coun-
terparts in the Norwegian and British sectors. These sand-
stone bodies are therefore defined as new lithostratigraphic
units in the Danish sector, and are assigned Danish type and
reference sections.

There is a high degree of lithological similarity between
the Palaeogene–Neogene mudstone succession from Danish

offshore boreholes and that from onshore exposures and
boreholes, and some of the mudstone units indeed seem
identical. However, in order to acknowledge the traditional
distinction between offshore and onshore stratigraphic no-
menclature, the two sets of nomenclature are kept separate
herein.

In recent years oil companies operating in the North Sea
have developed various in-house lithostratigraphic charts for
the Paleocene–Eocene sand and mudstone successions in the
Danish and Norwegian sectors. A number of informal litho-
stratigraphic units have been adopted and widely used. In the
present project, these units have been formally defined and
described, maintaining their original names whenever feasi-
ble, with the aim of providing an unequivocal nomenclature
for the Palaeogene – lower Neogene succession in the Danish
sector. It has not been the intention to establish a sequence
stratigraphic model for this succession in the North Sea; the
reader is referred to the comprehensive works of Michelsen
(1993), Neal et al. (1994), Mudge & Bujak (1994, 1996a, b),
Michelsen et al. (1995, 1998), Danielsen et al. (1997) and
Rasmussen (2004).

Methodology

The multidisciplinary project integrates biostratigraphic
results from palynology and micropalaeontology with results
from sedimentological studies, petrophysical log interpreta-
tion and conventional seismic interpretation, in an attempt
to identify, describe and correlate lithological units. The
lithostratigraphy proposed is based on analysis of petrophy-
sical logs from more than 80 wells (Fig. 1) and studies of cut-
tings samples and core sections. Lithostratigraphic well
correlation is supported by results from biostratigraphic
analysis of 29 wells encompassing both palynological and
micropalaeontological data. This analysis has established a
detailed succession of first downhole occurrences of bio-
stratigraphical events which are of crucial importance for well
correlation and age determination in the region. Resulting
well correlations have been matched with results from inter-
pretation of key seismic sections.

A revised lithostratigraphy

An important outcome of the project is a revised lithostrati-
graphic chart for the siliciclastic Palaeogene – lower Neogene
succession of the Danish North Sea (Fig. 2). The chart is
based on the subdivision proposed by Deegan & Scull
(1977), but incorporates subsequent improvements by Hardt
et al. (1989) and Knox & Holloway (1992).

The revised lithostratigraphy presented in Fig. 2 has its
genetic base at the top of the Chalk Group (Ekofisk For-

Fig. 2. Diagram showing the correlation between key lithostratigraphic

schemes for the Central Graben and eastern North Sea. White: mud-

stone units. Yellow: sandstone units. Names in bold indicate units of

formation or group rank.

Nordland
Group

Hordaland
Group

Balder

Sele

Lista

Unnamed
Unit

Ekofisk

CEN5

CEN4

CEN3

CEN2

CEN1

North
Sea
Marl

Ekofisk

Nordland
Group

Hordaland
Group

Balder

Sele

Lista

Våle

Ekofisk

Nordland
Group

Lark

Horda

Balder

Tay

M
o

u
sa

H
e
fr

in
g

D
u
fa

F
re

K
o
lg

a
F

u
r

R
in

d
Id

u
n

T
y
r

B
o
r

Sele

Lista

L
is

F
o
rt

ie
s

C
ro

-
m

ar
ty

M
e
y

V
a
d

F
o

r
ti

e
s

A
n

d
re

F
is

k
e
b

a
n

F
is

k
e
b

a
n

F
r
ig

Maureen

M
a
u

re
e
n

Ekofisk Ekofisk

Nordland
Group

Lark

Horda

Balder

Sele

Bue

Vile

Våle

Deegan & Scull
(1977)

Kristoffersen
& Bang
(1982)

Hardt et al.
(1989)

Knox & Holloway
(1992)

This study

R
o

g
a
la

n
d

G
ro

u
p

mation). The top is at the mid-Miocene unconformity, a bas-
inwide erosion surface that separates the Oligocene to Mid-
dle Miocene Hordaland Group from the overlying Middle
Miocene to Recent Nordland Group.

The succession is subdivided into seven formations con-
taining eleven new members. The Våle, Lista, Sele, Fur, Bal-
der, Horda and Lark Formations of previous lithostra-
tigraphic schemes are adequate for subdividing the Danish
sector at formation level and are retained herein with ex-
panded lithological descriptions. The five first-mentioned
formations constitute the Rogaland Group of early Selandian
(Late Paleocene) to earliest Eocene (pre-classical Ypresian)
age, and the Horda and Lark Formations constitute the
Hordaland Group of Ypresian (Early Eocene) to early Ser-
ravallian (Middle Miocene) age.

Rogaland Group

The Våle Formation (Hardt et al. 1989) consists of light grey
to greenish grey marlstones and is retained largely unchanged
from its original description.

The Lista Formation (Deegan & Scull 1977) is subdivided
into three new mudstone members (Vile, Ve and Bue). The
predominantly light to dark grey mudstones of the Vile and
Bue Members are separated by the greenish, bluish to red
coloured mudstones of the Ve Member.

The Sele Formation (Deegan & Scull 1977) overlies the
Lista Formation; the boundary is placed where laminated
dark grey to black mudstones overlie the light to dark grey,
smectitic, non-laminated mudstones of the Bue Member.
This boundary definition differs from that used by Knox &
Holloway (1992), who placed the Lista–Sele boundary at the
base of the Bue Member as recognised here (Fig. 2).
Incidentally, the Lista–Sele boundary as originally defined
coincides with the Paleocene–Eocene boundary recently
approved by the International Commission of Stratigraphy,
at the conspicuous 13C isotope excursion in Chron C24r.

The Balder Formation is retained largely unchanged from
its original description by Deegan & Scull (1977).

The Fur Formation (Pedersen & Surlyk 1983) is charac-
terised by interbedded diatomite and tuffs and has been
recognised in one Norwegian and three Danish offshore wells
by Thomsen & Danielsen (1995) at a similar stratigraphic
level to that of the Sele and Balder Formations. It is therefore
included in the North Sea lithostratigraphic chart (Fig. 2).

Hordaland Group

The Horda and Lark Formations of Knox & Holloway
(1992) are introduced in the Danish sector for the basinal
mudstones that overlie the Balder Formation. The Horda

Formation consists of greenish-grey to greyish-green fissile
mudstone, whereas the Lark Formation comprises greenish-
grey to dark brown non-fissile mudstones. The transition
from the Horda to the Lark Formation is characterised by a
significant increase in gamma ray response.

Sandstone members

Eight discrete sandstone members have been recognised in
the Palaeogene – lower Neogene mudstone succession (Fig.
2). The lower five of these occur exclusively in the Siri
Canyon, a 20 km wide and up to 200 m deep erosional
depression that truncates reflectors in the Chalk Group (Fig.
1; Hamberg et al. 2005). The Bor Member is a sandstone
unit in the Våle Formation. Three sandstone members occur
in the Lista Formation and are named Tyr, Idun and Rind.
The Sele and Horda Formations each contain sandstone
units for which the names Kolga and Hefring Members are
proposed, respectively. The Hefring Member occurs in an
area south of the Siri Canyon. Two sandstone members (Dufa
and Freja) are present in the Lark Formation. The Dufa
Member occurs in the north-eastern part of the Danish sec-
tor, around the wells F-1X and Inez-1 (Fig. 1); the Freja
Member occurs above the Siri Canyon, south of the Siri-1
well (Fig. 1).

Rogaland Group sandstones:
reservoir facies

The economically important Paleocene–Eocene oil reservoir
sandstones of the Rogaland Group are situated at the mouth
of, and within, the Siri Canyon (Fig. 1). The sandstones oc-
cur as in situ sediment bodies deposited by gravity flows and
as remobilised, injected sandstones (Hamberg et al. 2005).
Although the sandstone bodies occur at different strati-
graphic levels within the Rogaland Group, they are strikingly
uniform. The sandstones are quartzose and very fine- to fine-
grained, well sorted and rich in glaucony with a greenish grey
colour. The sandstone bodies appear massive and structure-
less with primary sedimentary structures preserved only in
their basal part. Individual sandstones may be up to 100 m
thick but are usually much thinner. Identification and corre-
lation of individual sandstone members are feasible by means
of 3D seismic data, with support from borehole logs and
high-resolution biostratigraphy. An example of results from
such an integrated correlation in the lower part of the Siri
Canyon is shown in Fig. 3.

Acknowledgements

This work was made possible through grants from the Danish Energy

Authority, under the Energy Research Programme 2000. DONG E&P is

thanked for access to lithostratigraphic data from Siri Canyon wells.

References

Danielsen, M., Michelsen, O. & Clausen, O.R. 1997: Oligocene sequence

stratigraphy and basin development in the Danish North Sea sector

based on log interpretations. Marine and Petroleum Geology 14,

931–950.

Deegan, C.E. & Scull, B.J. (compilers) 1977: A standard lithostratigraphic

nomenclature for the Central and Northern North Sea. Institute of Geo-

logical Sciences Report 77/25; Norwegian Petroleum Directorate

Bulletin 1, 36 pp.

Hamberg, L., Dam, G., Wilhelmson, C. & Ottesen, T.G. 2005: Paleocene

deep-marine sandstone plays in the Siri Canyon, offshore Denmark –

southern Norway. In: Doré, A.G. & Vining, B.A. (eds): Petroleum geo-

logy: North West Europe and global perspectives. Proceedings of the

6th Petroleum Geology Conference, 1185–1198. London: Geological

Society.

Hardt, T., Holtar, E., Isaksen, D., Kyllingstad, G., Lervik, K.S., Lycke, A.S.

& Tonstad, K. 1989: Revised Tertiary lithostratigraphic nomenclature

for the Norwegian North Sea. In: Isaksen, D. & Tonstad, K. (eds): A

revised Cretaceous and Tertiary lithostratigraphic nomenclature for

the Norwegian North Sea. Norwegian Petroleum Directorate Bulletin

5, 35–55.

Knox, R.W.O’B. & Holloway, S. 1992: Paleogene of the Central and Nor-

thern North Sea. In: Knox, R.W.O’B. & Cordey, W.G. (eds): Lithostrati-

graphic nomenclature of the UK North Sea, 133 pp. Nottingham:

British Geological Survey.

Kristoffersen, F.N. & Bang, I. 1982: Cenozoic excl. Danian limestone. In:

Michelsen, O. (ed.): Geology of the Danish Central Graben. Danmarks

Geologiske Undersøgelse Serie B 8, 62–71.

Michelsen, O. 1993: Stratigraphic correlation of the Danish onshore and

offshore Tertiary successions based on sequence stratigraphy. Bulletin

of the Geological Society of Denmark 41, 145–161.

Michelsen, O., Danielsen, M., Heilmann-Clausen, C., Jordt, H., Laursen,

G. & Thomsen, E. 1995: Occurrence of major sequence stratigraphic

boundaries in relation to basin development in Cenozoic deposits of

the southeastern North Sea. In: Steel, R.J. et al. (eds): Sequence stratig-

raphy on the Northwest European margin. Norsk Petroleum Forening

Special Publication 5, 415–427.

Michelsen, O., Thomsen, E., Danielsen, M., Heilmann-Clausen, C., Jordt,

H. & Laursen, G. 1998: Cenozoic sequence stratigraphy in the eastern

North Sea. In: de Graciansky, P.-C. et al. (eds): Mesozoic and Cenozoic

sequence stratigraphy of European basins. Society of Economic Paleon-

tologists and Mineralogists Special Publication 60, 91–118.

Mudge, D.C. & Bujak, J.P. 1994: Eocene stratigraphy of the North Sea

basin. Marine and Petroleum Geology 11, 166–181.

Mudge, D.C. & Bujak, J.P. 1996a: Paleocene biostratigraphy and se-

quence stratigraphy of the UK central North Sea. Marine and Petro-

leum Geology 13, 295–312.

Mudge, D.C. & Bujak, J.P. 1996b: An integrated stratigraphy for the

Paleocene and Eocene of the North Sea. In: Knox, R.W.O’B., Corfield,

R.M. & Dunay, R.E. (eds): Correlation of the Early Paleogene in North-

west Europe. Geological Society Special Publication (London) 101,

91–113.

Neal, J.E., Stein, J.A. & Gamber, J.H. 1994: Graphic correlation and

sequence stratigraphy in the Palaeogene of NW Europe. Journal of

Micropalaeontology 13, 55–80.

Pedersen, G.K. & Surlyk, F. 1983: The Fur Formation, a Late Paleocene

ash-bearing diatomite from northern Denmark. Bulletin of the Geo-

logical Society of Denmark 32, 43–65.

Rasmussen, E.S. 2004: The interplay between true eustatic sea-level

changes, tectonics, and climate changes: what is the dominating fac-

tor in sequence formation of the Upper Oligocene – Miocene succes-

sion in the eastern North Sea Basin, Denmark? Global and Planetary

Change 41, 15–30.

Thomsen, E. & Danielsen, M. 1995: Transitional Paleocene/Eocene ash-

bearing diatomite in the eastern North Sea. Tertiary Research 15,

111–120.

Siri-2
Siri-1

Siri-3

Rind Mb

Idun Mb

Kolga Mb

Tyr Mb

Horda Fm

Sli
Dbf
Fan

Aau

Ama

Ppy

Balder Fm

Sele Fm

Lista Fm

Våle Fm

50 m
Ipf

Gda

Fig. 3. Correlation diagram of the Rogaland Group in the

lower part of the Siri Canyon (well locations shown in Fig.

1). Horizontal distance not to scale. In this section the Tyr

Member consists of three sandstone beds separated by

mudstone layers. The Idun Member cuts deeply into the

underlying Lista Formation. Key biostratigraphic downhole

events are shown to the left. Sli, Subbotina linaperta; Dbf,

decrease in benthic foraminifera; Fan, influx of Fenestrella

antiqua; Aau, Apectodinium augustum; Ama, Alisocysta

margarita; Ppy, common Palaeoperidinium pyrophorum;

Ipf, increase in planktonic foraminifera; Gda, Globoco-

nusa daubjergensis.

Authors’ addresses

P.S., J.A., K.D., L.E.K. & J.A.R., Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.

E-mail: pos@geus.dk

O.R.C. & C.H.-C., Department of Earth Sciences, University of Aarhus, DK-8000 Århus C, Denmark.

G.D. & L.H., DONG, Agern Allé 24–26, DK-2970 Hørsholm, Denmark.

I.P., Statoil Norway, Forusbeen 50, N-4035 Stavanger, Norway.