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> Forsiden > Publikationer > Geology of Greenland Survey Bulletin > Vol. 191 Geol. Greenl. Surv. Bull. > Review of Greenland Activities 2001, pp 111-116

GEOLOGY OF GREENLAND SURVEY BULLETIN 191

 
Paleocene sub-basaltic sediments on Savoia Halvø, East Greenland

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Field work by the Geological Survey of Denmark and
Greenland (GEUS) on Savoia Halvø, central East Green-
land in 2001 (see also Larsen et al. 2002, this volume)
included a study of sediments underlying the Palaeogene
basalts on the south coast of Scoresby Sund (Fig. 1). The
importance of this small exposure is based on the fact
that it provides one of the few opportunities for estab-
lishing a marine biostratigraphic date for the sediments
below the basalts. Dinoflagellate cysts from the sedi-
ments provide a maximum Early Paleocene age for the
onset of the volcanism in central East Greenland. Reports
from previous field work have mentioned the sediments
(Hassan 1953; Birkenmajer 1972), but no precise age
assignment was presented due to the absence of diag-
nostic fossils. The sub-volcanic sediments of Savoia Halvø
represent the youngest preserved marine sedimentary
deposits of the Upper Palaeozoic ­ Cenozoic rift-basins
onshore East Greenland. The overlying Palaeogene flood
basalts occasionally contain very thin sedimentary beds
between the lava flows, but these were deposited above
sea level. Neogene uplift of the East Greenland margin
brought a definitive end to accumulation in the old sedi-
mentary basins (Watt et al. 1986; Christiansen et al. 1992).
Geology
South of Scoresby Sund (70°N), the Palaeozoic­Cenozoic
rift basins of East Greenland are concealed by thick
and extensive continental flood basalts of Palaeogene
age. The basalts extend uninterrupted for more than 200
km towards the south (c. 68°N). North of Scoresby Sund
an irregular sub-basaltic peneplain rises above sea level
and basalt outliers cap the mountains on Milne Land
and areas to the west (Watt et al. 1986). A second, less
extensive area of Palaeogene basalts occurs further
north in North-East Greenland in the Hold with Hope ­
Clavering Ø region (Fig. 1).
In the Scoresby Sund region the earliest basalts uncon-
formably overlie Caledonian crystalline gneisses and
Mesozoic­Palaeogene sedimentary rocks. The earliest
flows erupted into palaeovalleys locally developed as
hyaloclastic deposits indicative of extrusion into lakes,
but pene-contemporaneous marine sediments are only
known to crop out at one locality on Savoia Halvø,
adjacent to the Kap Brewster settlement (Fig. 1).
Elsewhere in East Greenland, contemporaneous sub-
basaltic terrestrial sediments are known c. 450 km to
the north on Clavering Ø and Hold with Hope but have
not yet yielded any clear indication of their age. About
250 km towards the south (c. 68°N) in the Kangerlussuaq
region the earliest volcanics are associated with terres-
trial to marginal marine sedimentary deposits.
The Kap Brewster locality
Adjacent to the abandoned Kap Brewster settlement
(Fig. 1), the almost vertical basalt cliffs are 200­1000 m
high. To the west of the settlement, steep scree-slopes
of large basalt blocks at the foot of the cliffs are partly
covered by permanent ice and snow. To the east, the
valley Bopladsdalen provides easy access to the plateau
on southern Savoia Halvø where down-faulted, post-
basaltic sediments crop out (Bopladsdalen, Krabbedalen
and Kap Brewster Formations; Fig. 1; see Larsen et al.
2002, this volume). The Kap Brewster houses are situ-
ated on a narrow beach just west of the entrance to
Bopladsdalen, and the first in situ sediments appear 50
m up the cliff behind the houses. Approximately 40 m
of poorly exposed, dark grey, bioturbated mudstone
occurs between 50 and 90 m above sea level (Larsen
et al. 2002, this volume). Except for imprints of spatangid
echinoderms (Hassan 1953) no macro-fossils have been
reported from the mudstone, but dinoflagellate cysts have
been mentioned (Watt & Watt 1983; Larsen & Marcussen
1992). The contact between sediments and the lowest
basalt flow, at approximately 91 m, is not exposed; the
lowest outcrop of volcanic rocks is a volcanic con-
glomerate about 50 m to the east.
Thirteen samples from the uppermost 40 m of the
mudstone were analysed for dinoflagellates; the highest
111
Paleocene sub-basaltic sediments on Savoia Halvø, East
Greenland
Henrik Nøhr-Hansen and Stefan Piasecki
Geology of Greenland Survey Bulletin 191, 111­116 (2002) © GEUS, 2002
GSB191-Indhold 13/12/02 11:32 Side 111
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112
3 km
Scree and ice
Danmark Stræde
Kap Brewster
Savoia Halvø
Krabbedalen
Muslinge-
hjørnet
Bopladsdalen
Kap Brewster Fm
Krabbedalen Fm
Bopladsdalen Fm
Basalts
Paleocene sediments
Fault
Settlement
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50 km
VBK
25
°
23
°
72
°
Palaeogene basalts
71
°
Jameson
Land
Milne
Land
B
ScoresbySund
C
Gl
Vb
Post-Caledonian basins
Caledonian
Greenland
B
1
3
2
A
Fig. 1. Map of East Greenland with a simplified geological map of Savoia Halvø based on Birkenmajer (1972, fig. 1). The local-
ity with exposed sub-basaltic sediments is situated adjacent to the Kap Brewster settlement. Inset A: Greenland map; 1: West
Greenland, Nuussuaq; 2: North-East Greenland, Wollaston Forland ­ Hold with Hope ­ Clavering Ø region; 3: East Greenland,
Kangerlussuaq region. Inset B: VBK: Volquart Boon Kyst; Vb: Vikingebugt; Gl: Gåseland.
GSB191-Indhold 13/12/02 11:32 Side 112
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sample was taken 1 m below the first basalt flow. The
samples were prepared by standard palynological tech-
niques with HCl and HF. The organic residue was oxi-
dised with HNO
3
, and the microscopic fossils were
separated from the terrestrial debris by swirling or the
tube separation method of Hansen & Gudmundsson
(1979).
Marine flora
Moderately to well-preserved dinoflagellate cysts are
abundant in the mudstone together with an abundance
of terrestrial organic material, spores and pollen. All
analysed samples contain a rich dinoflagellate flora
composed of a mixture of reworked Lower to Upper
Cretaceous dinoflagellate cyst assemblages, together
with Paleocene marker species.
Cretaceous dinoflagellate cysts
Stratigraphically significant dinoflagellate cysts in the com-
posite assemblage suggest reworking from multiple sources
of Cretaceous sediments or perhaps repeated reworking
of Cretaceous dinoflagellate assemblages. Cretaceous
dinoflagellate assemblages in East Greenland have been
described by Nøhr-Hansen (1993), and mid-Cretaceous
to Paleocene dinoflagellate assemblages have been
described from corresponding latitudes in West Greenland
(Nøhr-Hansen 1996; Nøhr-Hansen et al. in press).
The presence of Leptodinium cancelatum and Pseudo-
ceratium expolitum indicates reworking from middle
Albian (Lower Cretaceous) strata according to Nøhr-
Hansen (1993). Epelidosphaeridia spinosa, Hapsocysta
benteae, Ovoidinium sp. 1 Nøhr-Hansen 1993, Rhombo-
dinium paucispina and Subtilisphaera kalaalliti indicate
reworking from Upper Albian to Lower Cenomanian
strata (Nøhr-Hansen 1993). Chatangiella spp. and Isabel-
idinium spp. suggest reworking from Upper Cenomanian
to Upper Maastrichtian (Upper Cretaceous) strata, and
the presence of the pollen genus Aquilapollenites spp.
indicates reworking from Campanian to Upper Maast-
richtian strata (Upper Cretaceous) according to Nøhr-
Hansen (1996). The possibility that even Paleocene strata
could be reworked is indicated by the presence of a few
Spongodinium delitiense which have a range from
Campanian to lower Danian, Paleocene (Hardenbol et al.
1998). These reworked Cretaceous assemblages are very
similar to the assemblages described from North-East
Greenland (Nøhr-Hansen 1993) and West Greenland
(Nøhr-Hansen 1996).
Paleocene dinoflagellate cysts
Paleocene dinoflagellate cysts are rare to very rare and
are generally poorly preserved, but occur in all stud-
ied samples (Fig. 2). Poorly preserved Alisocysta spp.
(probably A. margarita; Fig. 3a­c) occurs together with
Areoligera spp. (Fig. 3d­e), Cerodinium striatum (Fig.
3g­h) and Palaeoperidinium pyrophorum throughout
the studied section whereas Phelodinium kozlowskii
(Fig. 3i), Palaeocystodinium bulliforme (Fig. 3j­k),
Spiniferites septatus (Fig. 3f) and Thalassiphora delicata
(Fig. 3l) are restricted to the upper part.
The presence of probable Alisocysta margarita sug-
gests a late Danian (61.58 Ma) to early Thanetian (57.16
Ma) age (Hardenbol et al. 1998), but according to the
same authors the presence of Palaeocystodinium bul-
liforme and Palaeoperidinium pyrophorum excludes
113
50
60
70
80
90
Metr
es abo
v
e
sea le
v
e
l
late Danian
Paleocene
earl
y Selandian ?
Age
GGU sample n
umbers
Ar
eolig
er
a
spp
.
Cer
odinium str
iatum
P
alaeoper
idinium p
y
r
ophorum
Alisoc
ysta margar
ita
Spinif
er
ites septatus
Ar
eolig
er
a
aff.
gipping
ensis
Cer
odinium
spp
.
P
alaeoc
ystodinium bullif
orme
Phelodinium k
ozlo
wskii
Thalassiphor
a delicata
246950
246949
246948
246947
246946
246945
246944
246943
246942
246941
246940
459739
459738
Kap Brewster
Fig. 2. Stratigraphic occurrence of selected in situ Paleocene
dinoflagellate cysts in pre-basaltic mudstones at Kap Brewster.
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114
j
e
d
b
a
c
f
h
i
k
l
20
µ
m
g
Fig. 3. Stratigraphically important dinoflagellate cysts. The scale bars represent 20 µm. GGU numbers identify the samples, followed
by preparation-slide number and the co-ordinates of the microscope table. MI and LVR numbers identify records in the MicroImage
database. The illustrated specimens are deposited in the type collection of the Geological Museum, University of Copenhagen and
are identified by the MGUH number.
a: Alisocysta margarita, GGU 459738-4, 37.0­102.5, MI 11762, LVR 1.23519, MGUH 26.391.
b: Alisocysta margarita, GGU 246940-13, 33.2­108.2, MI 11728, LVR 1.23439, MGUH 26.392.
c: Alisocysta margarita, GGU 246940-12, 28.5­112.2, MI 11729, LVR 1.23440, MGUH 26.393.
d: Areoligera spp., GGU 246940-12, 31.5­103.0, MI 11730, LVR 1.23441, MGUH 26.394.
e: Areoligera spp., GGU 246945-7, 43.0­108.6, MI 11735, LVR 1.23451, MGUH 26.395.
f: Spiniferites septatus, GGU 246943-4, 33.7­106.4, MI 11733, LVR 1.23447, MGUH 26.396.
g: Cerodinium speciosum, GGU 246946-7, 27.0­109.0, MI 11736, LVR 1.23452, MGUH 26.397.
h: Cerodinium striatum, GGU 246943-4, 20.3­100.5, MI 11740, LVR 1.23456, MGUH 26.398.
i: Phelodinium kozlowskii, GGU 246942-4, 39.6­111.6, MI 11741, LVR 1.23457, MGUH 26.399.
j: Palaeocystodinium bulliforme, GGU 246950-4, 38.7­109.3, MI 11739, LVR 1.23455, MGUH 26.400.
k: Palaeocystodinium bulliforme, GGU 246947-8, 29.5­95.0, MI 11738, LVR 1.23454, MGUH 26.401.
l: Thalassiphora delicata, GGU 246949-7, 36.4­93.9, MI 11737, LVR 1.23453, MGUH 26.402.
GSB191-Indhold 13/12/02 11:32 Side 114
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Thanetian and suggests an age no younger than late
Selandian (58.04 Ma). The first occurrence of Thalassi-
phora delicata in the upper part of the succession sug-
gests an early Selandian or younger age for this part of
the section according to Thomsen & Heilmann-Clausen
(1985) although Köthe (1990) recorded rare T. delicata
from the latest Danian in Germany.
Therefore, it can be concluded that the dinoflagellate
assemblage indicates a late Danian age for the lower
part (50­72 m) and a late Danian ­ early Selandian? age
for the upper part (74­90 m) of the succession, based
on correlations with North-West Europe (Köthe 1990;
Powell 1992) and West Greenland (Nøhr-Hansen et al.
in press).
Geological implications
The axis of the Mesozoic Jameson Land basin dips south-
wards below the fjord of Scoresby Sund. Seismic lines
in the fjord reveal sediments intruded by numerous sills
and dykes such that stratigraphical correlation with the
onshore succession on Jameson Land is difficult; how-
ever, sediments younger than the topmost, Lower Creta-
ceous succession of Jameson Land are known to occur
below the basalts (Larsen & Marcussen 1992). Seismic
data along Volquart Boon Kyst show that the base of the
basalt succession reaches 500 m below sea level in the
central part of the basin (Larsen & Marcussen 1992) but
gradually approaches sea level towards the basin mar-
gins (i.e. at Kap Brewster in the east and Vikinge-
bugt­Gåseland in the west; Fig. 1B). Pre-basaltic erosion
planed off basinal areas of sediments between highs of
crystalline rocks of the basin margins (Larsen et al. 1989).
In Gåseland and Milne Land basalts rest on Jurassic sed-
iments and in the central part of the basin on presumed
Upper Cretaceous ­ Paleocene sediments which provide
a maximum age for the overlying volcanic rocks.
On Savoia Halvø near the Kap Brewster settlement
the base of the basalts comprises the basal Milne Land
Formation (Larsen et al. 1989; L.M. Larsen, personal
communication 2002). Observations at the Kap Brewster
locality and seismic data from the central Jameson Land
basin (Larsen & Marcussen 1992) suggest that the basalts
are conformable with the youngest sedimentary unit.
Correlation of the extended Milne Land Formation
(includes the earlier Magga Dan Formation; L.M. Larsen,
personal communication 2002) with the lowermost
Middle Series of the Faeroe Islands basalt succession
indicates equivalence to lower Chron 24R, latest
Paleocene age, 55 Ma (Larsen et al. 1999). However, the
onset of volcanism in East Greenland as recorded from
boreholes offshore South-East Greenland (Sinton &
Duncan 1998) and onshore in the Kangerlussuaq region
occurred at maximum 61­62 Ma, corresponding to
Chron 27N of latest Danian, Early Paleocene (Hansen
et al. in press). The latter is contemporaneous with the
earliest West Greenland volcanic rocks (60­61 Ma; Storey
et al. 1998) whereas the proposed correlation of the East
Greenland flood basalts (e.g. at Kap Brewster) with a
second, younger magmatic phase in West Greenland at
approximately 55­52.5 Ma is more speculative.
The dark mudstones below the basalts at Kap
Brewster have previously been considered Cretaceous
on the basis of screening of dinoflagellate assemblages
(Watt & Watt 1983; Larsen & Marcussen 1992), and indeed
the sediments are rich in well-preserved but reworked
Cretaceous dinoflagellate cysts. However, the new dino-
flagellate flora described above clearly indicates a late
Danian ­ early Selandian? (Paleocene) age for these mud-
stones, i.e. significantly older than the overlying basalts.
It can be surmised that a distinct hiatus corresponding to
most of the Upper Paleocene separates the mudstone
from the overlying basalts. This hiatus may reflect either
pre-basaltic erosion of the basin margin (e.g. at Kap
Brewster) or a basal unconformity, even though there is
an apparent seismic conformity of basalts and the youngest
sediments in the central part of the basin.
Conclusions
No sedimentary successions from which the distinctly
reworked dinoflagellate Cretaceous assemblages were
derived are known in the onshore outcrops of the
Jameson Land basin in the Scoresby Sund region,
although corresponding strata may be represented in
the offshore Lower Cretaceous ­ Paleocene succession
beneath Scoresby Sund.
The in situ Paleocene dinoflagellate cyst assemblage
can be correlated with Paleocene assemblages from the
uppermost pre-volcanic sedimentary successions known
onshore Nuussuaq in West Greenland (Nøhr-Hansen
et al. in press), and corresponds in age to the upper,
marine part of the Ryberg Formation in the Kanger-
lussuaq region (Soper et al. 1976).
The latest Danian ­ early Selandian? (Paleocene) age
of the youngest pre-basaltic sediments both in West Green-
land and in the Kangerlussuaq region (East Greenland)
corresponds to the age of the earliest volcanic rocks in
these regions. The biostratigraphic age is also in agree-
ment with the radiometric age of the earliest eruptives
115
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offshore South-East Greenland, onshore at Kangerlussuaq
(East Greenland) and in West Greenland. In contrast, a
significant hiatus separates the Danian ­ lowermost
Selandian? sediments from the uppermost Paleocene ­
Lower Eocene volcanics at Kap Brewster.
Acknowledgements
The work is part of the Survey's programme of studies in stratig-
raphy, sedimentology and basin evolution in Greenland and the
northern North Atlantic.
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Authors' address
Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark. E-mail: hnh@geus.dk
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Review of Greenland Activities 2001, pp 111-116