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1. Introduction
This study aims to improve the temporal resolution ofthe established Plio-Pleistocene biostratigraphy of theNordic Atlantic region, through multi-fossil calibra-tions to the standard geologic time scale with its Glob-al boundary Stratotype Section and Point (GSSP) def-initions in the Mediterranean. The definitions of the
relevant Upper Cenozoic chronostratigraphic units,i. e. Gelasian Stage, Pleistocene Series, Neogene andQuaternary Systems follow Ogg et al. (in press); theyare also available from the website of the Internation-al Commission on Stratigraphy (ICS) at www.strati -graphy.org. The orbitally tuned time scale is that ofLourens et al. (2004), which also re-calibrated theBerggren et al. (1995) biochronology.
Newsletters on Stratigraphy © Gebrüder Borntraeger 2008Vol. 43/1: 33–48, June 2008
Late Pliocene and Pleistocene biostratigraphy of the Nordic Atlantic region
Erik D. Anthonissen1
With 3 figures and 1 appendix
Abstract. The lack of primary and secondary GSSP correlative markers in Plio-Pleistocene deposits of theNorth Sea, Nordic seas and northern North Atlantic creates a challenge for the biostratigrapher. This studyhighlights the closest biostratigraphic approximations in this region to the standard chronostratigraphicboundaries of the Gelasian Stage and Lower, Middle and Upper Pleistocene. Via correlations to key OceanDrilling studies and unambiguous magnetostratigraphies in the region, the age of shallower deposits of theNorth Sea has been better constrained. The closest biostratigraphic approximations to these chronostrati-graphic boundaries in the region are presented, together with a framework of calibrated events according tosub-basin. The best approximating boundary events at any given location in this region depends upon boththe paleoceanographic and paleobathymetric settings. In the Nordic Atlantic region only three GSSP correl-ative marker events have been identified in the 15 Ocean Drilling Program sites discussed. At lower neriticto bathyal water depths, the first common occurrence of Neogloboquadrina pachyderma (sinistrally-coiledmorphotype) allows for direct correlation with the base Pleistocene GSSP in Italy. The occurrence of the ben-thic foraminifer Cibicides grossus appears to have been bathymetrically controlled, with a youngest strati-graphic occurrence at upper bathyal depths. At lower neritic depths in the central and northern North Sea thelast occurrence of C. grossus coincides with the base of the Pleistocene. Diachroneity of a number of Nordichigh-latitude bioevents may be primarily due to differences in surface water masses and paleobathymetry.
Key words. North Sea, Norwegian Sea, Foraminifera, calibrations, Quaternary, Pliocene
DOI: 10.1127/0078-0421/2008/0043-0033 0078-0421/08/0043-0001 $ 3.25© 2008 Gebrüder Borntraeger, D-14129 Berlin · D-70176 Stuttgart
Authorʼs address:1 Erik D. Anthonissen (E-Mail: [email protected]), Natural History Museum, University of Oslo, P. O. Box 1172 Blindern,0318 Oslo, Norway
2. Regional setting and biostratigraphy
The “Nordic Atlantic region” is here defined as rough-ly the area stretching from immediately south of theGreenland-Scotland Ridge northwards, encompassingthe North Sea and Nordic Seas (Norwegian Sea,Greenland Sea, Iceland Sea, West Barents Sea) to theArctic Ocean Gateway and the Yermak Plateau(Fig. 1). In this region, the Upper Cenozoic biostrati -graphy is based primarily upon foraminifers, calcare-ous nannoplankton and organic-walled dinoflagellatecysts. Marine diatoms and continental pollen se-quences (van der Vlerk and Florschütz 1953, Zagwijn1974) add paleontological age control across discretetime intervals. At these high latitudes, many of thestandard ‘global’markers present in the mid- to low- latitudes (including the Mediterranean region) are ab-sent; these include most of the primary and secondarycorrelative events defining the relevant GSSPs.
Various abiotic and biotic expressions of late Ceno-zoic climatic change have been used for dating the onsetof the Quaternary and Pleistocene in the Nordic Atlanticregion. Marine isotopic trends and magnetic polarity re-versals show near synchroneity across large geograph-ic regions. However, these dating methods often requireadditional control to interpret an age, being inherentlylimited to two outcomes (e. g. either glacial/interglacial
or normal polarity/reversed polarity). This additionalage control is often in the form of planktonic markerfossils that have been well-documented both spatiallyand temporally (planktonic foraminifera, calcareousnannoplankton, dinoflagellate cysts and siliceous mi-crofossils). Where integration of data sets from a rangeof both abiotic and biotic proxies is possible (e. g. indeep-sea cores), well-constrain ed age models form thebasis for a regional biostratigraphy.
High-resolution biostratigraphies have been con-structed from Upper Cenozoic depositional sequencesin Deep Sea Drilling Project (DSDP) and OceanDrilling Program (ODP) coreholes from the Mediter-ranean to the high Arctic. For the Nordic Atlantic re-gion, the following planktonic foraminiferal zonationstudies have been most utilised: Weaver and Clement(1986) and Weaver (1987) in the northern North At-lantic (DSDP Leg 94) and Spiegler and Jansen (1989) inthe Norwegian Sea (ODP Leg 104). For the North SeaBasin, dominated by shallow neritic benthic fora mini -feral assemblages, the deterministic zonation by King(1983, 1989) and the probabilistic zonation by Grad-stein and Bäckström (1996) are most widely used. Theirzonal boundaries are defined almost entirely upon lastoccurrence events (LOs) due to downhole contami -nation in industrial exploration well samples. Bothschemes are based primarily on poorly constrainedranges of benthic foraminifera, with age interpretationsstrongly dependent upon the biomagnetostratigraphy ofDSDP Leg 94 in the northern North Atlantic.
In response to high-frequency Quaternary climatechange, benthic communities would have been forcedto migrate repeatedly to more preferable environmen-tal conditions. Benthic foraminifera are sensitive towater mass and substrate properties and therefore theyoften exhibit sedimentary facies dependency (Mack-ensen et al. 1985). They are therefore often unreliablemarkers, showing a high degree of diachroneity in theirfirst and last appearances (Denne and Sen Gupta 1990).This is especially evident in the bathymetrically con-trolled last occurrence of Cibicides grossus (C. lobatu-lus var. grossa) in the North Sea (see Appendix 1).
Following ODP Leg 104, a number of new oceanicsites have been drilled as part of ODP Legs 151, 152and 162 (Fig 1.). Calibration of the stratigraphy ofthese new sites to astronomical parameters has greatlyincreased Neogene temporal resolution (Lourens et al.,1996; Gradstein et al., 2004). These additional datapoints allow for a broader examination of the relation-ship between the geographic distribution and the de-gree of synchroneity/diachroneity of important north-
34 Erik D. Anthonissen
90° 60° 30° 0° 30° 40°
60°
80°
642
646
907
910
919
981
985
986
987
984
610
982
609611
North Sea
Labrador Sea
Norwegian Sea
Greenland Sea
Yermak Plateau
Svalbard Margin
Iceland Sea
Irminger Basin
644
643
980
918
983
911
607606
Northern North Atlantic
Calibration sites
A. Northern North Atlantic & Labrador SeaDSDP Leg 94 (606-610); ODP Leg 105 (646, 647);ODP Leg 162 (980-984)
B. Irminger Basin (East Greenland Margin)ODP Leg 152 (918, 919)
C. Norwegian Sea & Iceland PlateauODP Leg 151(907); ODP Leg 162 (985)
D. Norwegian Sea (Vøring Plateau)ODP Leg 104 (642-644)
E. Greenland SeaODP Leg 162 (987) Greenland-Scotland Ridge Statfjord C
BGS81/34
898
B10-3,13-3,B-17-5/6
15/9-A-112/4-C-11
34/8-1
Legend
Pleistocene & Gelasian GSSP’s
‘Nordic Atlantic region’Warm ocean current Cool ocean currentIndustrial well/boreholeODP/DSDP Site
647
F. Yermak Plateau & Svalbard MarginODP Leg 151 (910, 911); ODP Leg 162 (986)
G. North SeaStatfjord C borehole; 34/8-1; 15/9-A-11; 2/4-C-11;BGS81/34; B10-3, 13-3, B17-5, B17-6
Barents Sea
Arctic Ocean
Fig. 1. Map showing the location of calibration points usedin this study, including Deep Sea Drilling Project Sites,Ocean Drilling Program Sites, and industrial wells/bore-holes. Locations are grouped according to region/basin andgiven a letter abbreviation.
ern high-latitude bioevents. A better understanding andquantification of the time-transgressive nature of keyplanktonic events from oceanic settings will help toimprove the accuracy of Quaternary biostratigraphyand to better constrain benthic foraminiferal ranges inshallower shelf settings such as the North Sea.
High-resolution integrated stratigraphic data sets arerare in industrial exploration-well studies in the Northand Norwegian seas. Here both quality of material andeconomic constraints limit the availability of paleo-magnetic and isotopic data. Strontium isotope meas-urements may provide a limited degree of independentage control, but contamination has often rendered con-tradictory results (e. g. Eidvin et al. 1993). For latestPleistocene deposits, amino-acid dating and opticallystimulated luminescence (OSL) dating have proveduseful, especially in areas where paleomagnetic data isambiguous or unobtainable and where key planktonicmarkers are absent (e. g. Sejrup and Knudsen 1999).However, due to the strong dependency of amino-acidracemization rates on temperature, water concentrationand alkalinity, uncertainties regarding conditions ofpreservation can obscure the results (Brown 1985).
3. Material and Methods: Mid- to high-latitude correlations
The location of Nordic ocean drilling sites and selectedindustrial petroleum wells with a reliable Plio-Pleis-tocene record is shown in Fig. 1. The sites have been or-ganised from south to north, according to sub-basin.They have been divided into three correlation panels: 1)temperate to subpolar sites located south of the Green-land-Scotland Ridge (GSR) in the northeastern NorthAtlantic; 2) subpolar sites located north of the GSR inthe Nordic Seas; 3) Arctic Sites in the Greenland Seaand on the Yermak Plateau (Figs. 2a–c). Most sites havea reliable magnetostratigraphy, allowing for direct cal-ibration of bioevents via the Geomagnetic PolarityTime Scale (GPTS) to the standard chronostratigraphyof Gradstein et al. (2004). At a few sites, a Pleistoceneoxygen-isotope stratigraphy allows for high-resolutioncalibrations to the marine oxygen isotope stages. In ad-dition, a limited number of astronomically calibratedforaminiferal and calcareous nannoplankton bioevents(with ages according to Lourens et al. 2004) improvethe stratigraphic resolution. In a few cases, new eventshave been identified from the raw fossil occurrence datain the respective publications. Each site record present-ed here is a composite of the results from the individual
site coreholes. Where possible, the standard chronos-tratigraphic boundaries of the Late Pliocene – Pleis-tocene have been correlated between sites. This has fa-cilitated a biostratigraphic comparison of sites at both alocal level between sub-basins and at a more regionalscale from temperate to polar latitudes.
It is only via the high-resolution data sets providedthrough these deep-sea cores that reliable stratigraphicrelationships can be found between the Mediterraneanstages and the Nordic Atlantic biostratigraphy. The re-liability of these relationships or calibrations can beranked according to the number of correlations neces-sary. First-order calibrations are those involving a di-rect and onsite stratigraphic link between the respectivebioevent and the standard Geologic Time Scale. Thishas most often been achieved via an onsite stratigraph-ic tie to the GPTS or to selected astronomically cali-brated events (Lourens et al. 2004). Second-order cali-brations involved a correlation between the observedbioevent and another locality with a correspondingstratigraphic level which had a 1st order – calibratedage. Third-order calibrations involve two correlations.Updated ages have been calculated based on their rela-tive positions between magnetosubchron and/or nan-nofossil zonal boundaries. For the majority of events,the age has been calculated for the depth originallyquoted in the respective DSDP/ODP publications andgiven to one decimal place only. This is intended to ac-count for low sample resolution, lack of continuous cor-ing, and the often numerous occurrence of bracketingbarren intervals.
4. Results: Late Pliocene –Pleistocene chronostrati -graphic boundaries at Nordic high-latitudes
A critical assessment of the biostratigraphy and corre-lation of key deep-sea cores and industrial petroleumwells has resulted in the framework of calibrated bio-events for the Nordic Atlantic region presented in Ap-pendix 1. Selected bioevents can be used for the iden-tification of the standard chronostratigraphic bound-aries of the Late Pliocene – Pleistocene in this region.
Four chronostratigraphic boundaries divide theQuaternary: Base Upper Pleistocene Subseries, BaseMiddle Pleistocene Subseries, Base Pleistocene Se-ries, and Base Gelasian Stage. To date, the Pleistoceneand Gelasian GSSPs have been ratified by the Interna-
35Late Pliocene and Pleistocene biostratigraphy of the Nordic Atlantic region
36 Erik D. Anthonissen
LowerPleistocene
(Upper Pliocene)Gelasian
MiddlePleistocene
UpperPleist.S
ou
thG
ree
nla
nd
-Sco
tla
nd
Rid
ge
Na
tS
Ehu
x
Pla
c
1n
1r.1
r
1r.1
n
1r.2
r
1r.3
r
2n
2r.1
r
2r.1
n
Sit
e 9
81
(co
mp
osi
te)
Fe
ni D
rift
0
10
20
30
40
50
60
70
80
90
10
0
110
12
0
13
0
14
0
15
0
16
0
17
0
18
0
Gin
f
Gp
un
Gr. inflataN. pachyderma (s) G. bulloides N. atlantica (s)
N O D A T A
NN 21 NN 20 NN 19
2A
n.1
n
2r.2
r
Dsu
r
Cm
ac
0.4
4
0.2
90
.34
0.5
5
2.1
4
2.3
52
.39
2.6
6
1.6
61
.67
2.5
4
NN 16NN 17
Depth (mbsf)
Polarity/ chron
Age (Ma)
CalcareousNannoplankton
Zone
PlanktonicForaminiferal
Zone
Np
aS
(FC
O)
Sit
e 9
82
(co
mp
osi
te)
Ro
cka
ll P
late
au
1n
1r.1
r
1r.1
n
1r.2
r
2n
2r.1
r
2r.2
r
2A
n.1
n
0
20
40
60
80
Np
aS
(FC
O)
Gin
fN
atS
Gp
un
Gcr
a
Pla
c
NN 19
Cm
ac
0.4
4
0.2
9
2.0
92
.30
2.8
12
.65
1.6
61
.23
0.4
1
0.1
8
2.5
4
Pla
c
Ehu
x
2021
Dsu
r
Depth (mbsf)
Polarity/ chron
Age (Ma)
CalcareousNannoplankton
Zone
PlanktonicForaminiferal
Zone
N. pachyderma (s) N. atlantica (s)
0
10
20
30
40
50
60
70
80
90
10
0
110
12
0
13
0
14
0
15
0
16
0
17
0
18
0
19
0
20
0
21
0
22
0
23
0
Ehu
x
Pla
c
1n
1r.1
r
1r.1
n
1r.2
r
2n
Sit
e 9
83
(co
mp
osi
te)
Ga
rda
r D
rift
Np
aS
(FC
O)
Gr. inflataN. pachyderma (s)
24
0
25
0
Gsp
p
NN 21 NN 20 NN 19
2r.1
r
Cm
ac
0.4
4
0.2
9
1.2
4
1.6
61
.65
0.3
0.6
0.6
8
0.8
4
1.2
5
1.5
3
1.8
9
N O D A T ADepth (mbsf)
Polarity/ chron
Age (Ma)
CalcareousNannoplankton
Zone
PlanktonicForaminiferal
Zone
1 5 7 9 11
13
15
17
19
21
23
25
27
29
31
33
35
Nre
i
Pcu
r
Nse
m
N. seminaeP. curvirostrisT. oestrupii
Nfo
s
N. reinholdii
Nse
m
Pd
ol
Pcu
r
Marine IsotopeStage
DiatomZone
0
10
20
30
40
50
60
70
80
90
10
0
110
12
0
13
0
14
0
15
0
16
0
17
0
18
0
19
0
20
0
21
0
22
0
23
0
Ehu
x
Pla
c
24
0
25
0
26
0
1n
1r.1
r
1r.1
n
1r.2
r
1r.3
r
2n
2r.1
r
2r.1
n
2r.2
r
Sit
e 9
84
(co
mp
osi
te)
Bjo
rn D
rift
Np
aS
(FC
O)
N. pachyderma (s)
Na
tl3
00
Gr. inflata / G. bulloides
Gsp
p
NN 21 NN 20 NN 19
0.4
4
0.2
9
(~2
.57
)
1.2
4
N O D A T A
Depth (mbsf)
Polarity/ chron
Age (Ma)
CalcareousNannoplankton
Zone
PlanktonicForaminiferal
Zone
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Sit
e 9
18
(co
mp
osi
te)
Ea
st G
ree
nla
nd
Ma
rgin
1n
2n
1r.1
n
2r.1
r
2r.1
n
1r.1
r
1r.2
r -
1
r.3r
Ehu
x
NN 21
0.2
9
NN 20
Na
tDN
atS
N. pachyderma (s)
UpperN. atlantica (d)
N. atlantica (s)
]
Na
tD
Na
tD
Np
aS
(FC
O)
Nd
ut
(LC
O)
Np
aD
(LC
O)
Max. PF diversity in Pleistocene
Depth (mbsf)
Polarity/ chron
Age (Ma)
CalcareousNannoplankton
Zone
PlanktonicForaminiferal
Zone(+ warm fauna)
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Sit
e 9
19
(co
mp
osi
te)
Ea
st G
ree
nla
nd
Ma
rgin
1n
1r.1
r
Ehu
x
NN 21
0.2
9
NN 20
N. pachyderma (s)
NN 19
Pla
c0
.44
Gin
f(LC
O),
Gsc
i(LC
O)
Tnid
0.3
10
Pcu
r0
.33
5
Nse
m0
.81
7-
0.8
95
N. sem.P. curvirostrisT. oestrupii
25
21
19
17
15
13
119751
Depth (mbsf)
Polarity/ chron
Age (Ma)
CalcareousNannoplankton
Zone
PlanktonicForaminiferal
Zone(+ warm fauna)
Marine IsotopeStage
DiatomZone
Max. PF diversity in Pleistocene
1.8
3
3.1
7
Fig
.2a.
Lat
e Pl
ioce
ne-P
leis
toce
ne c
orre
latio
n pa
nel
show
ing
sele
cted
oce
an d
rilli
ng s
ites
loca
ted
sout
h of
the
Gre
enla
nd-S
cotla
nd R
idge
(G
SR).
For
tax
on a
b-br
evia
tions
see
Fig
.2c.
Age
s in
bol
d ar
e ac
cord
ing
toth
e as
tron
omic
al c
alib
ratio
ns o
f L
oure
ns e
t al
. (20
04),
all
othe
r ag
es a
re b
ased
on
inte
rpol
atio
ns a
ccor
ding
to
the
stud
ies
cite
d. W
here
pos
sibl
e, t
he f
our
chro
nos-
trat
igra
phic
bou
ndar
ies
disc
usse
d ar
e in
dica
ted.
For
Site
s 98
1, 9
82, 9
83&
984
: mag
neto
stra
tigra
phy
is a
c-co
rdin
g to
Cha
nnel
l an
d L
ehm
an (
1999
); c
alca
reou
sna
nnop
lank
ton
bios
trat
igra
phy
is a
ccor
ding
to S
hipb
oard
Sci
entif
ic P
arty
(19
96a)
; pla
nkto
nic
fora
min
ifer
al b
iost
ratig
raph
y is
acc
ordi
ng to
Flo
wer
(19
99);
mar
ine
diat
ombi
ostr
atig
raph
y an
d ox
ygen
isot
ope
stra
tigra
phy
is a
ccor
ding
to K
oc e
t al.
(199
9). F
or S
ites
918
and
919:
mag
neto
stra
tigra
phy
is a
ccor
ding
to F
ukum
a (1
998)
; cal
care
ous
nann
opla
nkto
n st
ratig
raph
y is
acc
ordi
ng to
Wei
(199
8); p
lank
toni
c fo
ram
inif
eral
bio
stra
tigra
phy
is a
ccor
ding
to S
pezz
afer
ri (1
998)
; mar
ine
diat
om b
iost
ratig
raph
y an
d ox
y-ge
n is
otop
e st
ratig
raph
y is
acc
ordi
ng to
Koc
and
Flo
wer
(19
98).
37Late Pliocene and Pleistocene biostratigraphy of the Nordic Atlantic region
LowerPleistocene
(Upper Pliocene)Gelasian
MiddlePleistocene
Sit
e 9
85
(co
mp
osi
te)
Ice
lan
d S
ea
Depth (mbsf)
Polarity/ chron
Age (Ma)
PlanktonicForaminiferal
Zone
1n
2n
2r.2
r
1r.2
r -
1
r.3r
1r.1
n
0 10
20
30
40
50
60
70
2A
n.1
n
Np
aS
(FC
O)
N. pachyderma (s)
Na
tS1
.7
Sit
e 9
07
(co
mp
osi
te)
Ice
lan
d P
late
au
Depth (mbsf)
Polarity/ chron
Age (Ma)
PlanktonicForaminiferal
Zone
1n
0 10
20
30
40
50
60
Np
aS
(FC
O)
N. pachyderma (s)
Na
tS1
.8
1r.1
n1
r.1r
1r.2
r
2r.1
r
1r.3
r
2r.2
r
2A
r
2A
n.1
n
2A
n.2
n2
An
.3n
2n
1n
2A
n.1
n
1r.1
nSit
e 6
43
(co
mp
osi
te)
Vø
rin
g P
late
au
Depth (mbsf)
Polarity/ chron
0 10
20
30
40
50
60
1r.1
r
Age (Ma)
PlanktonicForaminiferal
Zone
Np
aS
(FC
O)
‘en
cru
ste
d’
N. pachyderma (s) Na
tS
?1.8
N. atl. (s)
CalcareousNannoplankton
Zone
Dinoflagellatecyst Zone
3.1
1
Pla
c
Ehu
x
21 20 NN 19
Mm
in,
Bsi
m
Ffil
Ffil
top
Aa
nd
acm
e
M. minuta - B. simplex
F. filifera
0.2
9
0.4
4
1n
2n
1r.1
nSit
e 6
42
(co
mp
osi
te)
Vø
rin
g P
late
au
Depth (mbsf)
Polarity/ chron
0 10
20
30
40
50
60
Age (Ma)
PlanktonicForaminiferal
Zone
Np
aS
(FC
O)
‘en
cru
ste
d’
N. pachyderma (s) Na
tS,
Gb
ul
(LC
O)
1.8
N. atl. (s)
CalcareousNannoplankton
Zone
Dinoflagellatecyst Zone
3.1
1
Pla
c
Ehu
x
NN 21 20 NN 19
Mm
in,
Bsi
m
Ffil,
Nle
m
Ffil,
Tp
elA
um
b(L
CO
)
M. minuta - B. simplex
0.2
9
0.4
4
70
Np
aS
Ffil
acm
e(u
pp
er)
Ffil
acm
e(l
ow
er)
Tpel
, Se
lo
0 10
20
30
40
50
60
70
80
90
10
0
110
12
0
13
0
14
0
15
0
16
0
17
0
18
0
19
0
20
0
21
0
22
0
23
0
Gin
f
Na
tD,
Gp
un
Gp
un
Gin
f
Na
tDN
atS
*co
ilin
g
cha
ng
e*
Np
aD
2.3
0.4
4
0.2
9
M. minuta - B. simplex F. filifera
1n
1r.1
n
2n
2r.1
n
2A
n.1
nSit
e 6
44
(co
mp
osi
te)
Vø
rin
g P
late
au
Depth (mbsf)
Polarity/ chron
Age (Ma)
PlanktonicForaminiferal
Zone
CalcareousNannoplankton
Zone
Dinoflagellatecyst Zone
Pla
c
Ehu
x
NN 21 NN 20 NN 19
Mm
in,
Bsi
m
Nle
m
Np
aS
(FC
O)
‘en
cru
ste
d’
N. pachyderma (s)
Upper N. atlantica (d) N. atl. (s)
0 50
10
0
15
0
20
0
25
0
30
0
35
0
1n
1r.1
r1
r.1n
2n
1r.2
r-
1r.3
r
2r.1
r
2r.2
r
2A
n.1
n
Ffil
Np
aS
(FC
O)
N. pac. (s)
Sit
e 9
87
(co
mp
osi
te)
Gre
en
lan
d S
ea
Depth (mbsf)
Polarity/ chron
Age (Ma)
PlanktonicForaminiferal
Zone
DinoflagellateCystZone
F. filifera
1.8
So
uth
Gre
en
lan
d-S
cotl
an
d R
idg
e
Fig
.2b
.L
ate
Plio
cene
-Ple
isto
cene
cor
rela
tion
pane
l sho
win
g se
lect
ed o
cean
dri
lling
site
s lo
cate
d no
rth
of th
e G
reen
land
-Sco
tland
Rid
ge(G
SR).
For
taxo
n ab
brev
iatio
ns s
ee F
ig.2
c. D
inof
lage
llate
cys
t acm
e ev
ents
are
new
inte
rpre
tatio
ns a
ccor
ding
to a
naly
sis
of th
e ra
w f
os-
sil o
ccur
renc
e da
ta in
the
resp
ectiv
e st
udie
s. A
ges
in b
old
are
acco
rdin
g to
the
astr
onom
ical
cal
ibra
tions
of
Lou
rens
et a
l. (2
004)
. All
oth-
er a
ges
are
base
d on
inte
rpol
atio
ns a
ccor
ding
to th
e st
udie
s ci
ted.
Whe
re p
ossi
ble,
the
four
chr
onos
trat
igra
phic
bou
ndar
ies
disc
usse
d ar
ein
dica
ted.
For
Site
s 98
5&
907
: m
agne
tost
ratig
raph
y is
acc
ordi
ng t
o C
hann
ell
et a
l. (1
999a
); p
lank
toni
c fo
ram
inif
eral
bio
stra
tigra
phy
isac
cord
ing
to F
low
er (
1999
). F
or S
ites
643,
642
& 6
44: m
agne
tost
ratig
raph
y is
acc
ordi
ng to
Ble
il (1
989)
; pla
nkto
nic
fora
min
ifer
al b
ios-
trat
igra
phy
is a
ccor
ding
to
Spie
gler
and
Jan
sen
(198
9);
calc
areo
us n
anno
plan
kton
bio
stra
tigra
phy
is a
ccor
ding
to
Don
nally
(19
89);
di-
nofl
agel
late
cys
t bi
ostr
atig
raph
y is
acc
ordi
ng t
o M
udie
(19
89).
For
Site
s 98
7&
986
: m
agne
tost
ratig
raph
y ac
cord
ing
to C
hann
ell
et a
l.(1
999b
); p
lank
toni
c fo
ram
inif
eral
bio
stra
tigra
phy
is a
ccor
ding
to F
low
er (
1999
); c
alca
reou
s na
nnop
lank
ton
bios
trat
igra
phy
is a
ccor
ding
to S
hipb
oard
Sci
entif
ic P
arty
(19
96b)
; di
nofl
agel
late
cys
t bi
ostr
atig
raph
y (i
nclu
ding
sei
smic
ref
lect
ors)
is
acco
rdin
g to
Sm
elro
r (1
999)
.Fo
r Si
tes
910
& 9
11: m
agne
tost
ratig
raph
y is
acc
ordi
ng to
Shi
pboa
rd S
cien
tific
Par
ty (
1995
); p
lank
toni
c fo
ram
inif
eral
bio
stra
tigra
phy
ac-
cord
ing
to S
pieg
ler
(199
6);
calc
areo
us n
anno
plan
kton
bio
stra
tigra
phy
acco
rdin
g to
Sat
o an
d K
ameo
(19
96);
din
ofla
gella
te c
yst
bios
-tr
atig
raph
y ac
cord
ing
to M
atth
iess
en a
nd B
renn
er (
1996
).
38 Erik D. Anthonissen
0 50
10
0
15
0
20
0
25
0
30
0
35
0
40
0
45
0
50
0
55
0
60
0
65
0
70
0
75
0
80
0
85
0
90
0
95
0
1n
1r.1
n1r
.1r
? 2n ? ?
2r.1
r
N O D A T A
1r.x
x
Na
tS,
Gb
ull
(LC
O)
Sbre
Ra
ct, I
lac
Spli
Au
mb
Ois
r
Oce
nac
me
Ffil
~2
.3Sd
io
Tpel
~1
.0R5
sei
smic
re
flect
or
Selo
Aa
nd
acm
e
1r.2
n?
Ffil
0.2
-0
.44
R1 s
eism
ic
refle
ctor
Np
aS
(FC
O)
N. pachyderma (s) N. atl. (s)
Pla
c
NN 20 NN 19
?0.4
4
R7 s
eism
ic
refle
ctor
Ffil
acm
e(u
pp
er)
Ffil
acm
e(l
ow
er)
Sit
e 9
86
(co
mp
osi
te)
Sv
alb
ard
Ma
rgin
Depth (mbsf)
Polarity/ chron
Age (Ma)
PlanktonicForaminiferal
Zone
CalcareousNannoplankton
Zone
Dinoflagellatecyst Zone
0
10
20
30
40
50
60
70
80
90
10
0
110
12
0
13
0
14
0
15
0
16
0
17
0
18
0
19
0
20
0
21
0
22
0
23
0
0.4
4
Go
ce,
Gca
r(G
spp
me
d.)
Dat
ump
lane
“A”
? 2
.78
N O D A T A
1.6
7 -
1.7
3
Np
aS
(co
nsi
sen
t)
N. pachyderma (s) Ssem
, N
pa
D
N 21
Da
lt,
Mlim
(su
btr
op
ical
)
N 21
Ga
eq
Na
tS
N. atlantica (s)
Cg
ro(L
CO
)
Cg
ro
Sit
e 9
10
(co
mp
osi
te)
Ye
rma
k P
late
au
Depth (mbsf)
Polarity/ chron
Age (Ma)
PlanktonicForaminiferal
Zone
CalcareousNannoplankton
Zone
Pla
c
NN 20 NN 19 NN 19
Pl4 Pl3/Pl4 dro
pst
on
es
3.1
4
Ga
eq(t
em
pe
rate
)
3.1
0 50
10
0
15
0
20
0
25
0
30
0
35
0
Plac
NN 19
0.4
4
Gsp
p(m
ed.)
NN 19
1.7
3
Dat
um p
lane
“A”
?2.7
8
Ehux
0.2
9
20
Rasa
0.8
5
Gsp
p(la
rge)
1.2
4
Gsp
p(la
rge)
1.6
2
1n
1r.1
n1r
.1r
1r.2
r
2n
2A
n.1
n
? 2r
Gin
f, G
sci
(tem
per
ate)
Nat
D, G
rub
(tem
per
ate)
N. atl. (s)
UpperN. atl. (d)
]
Npa
S(c
onsi
sent
)
Npac. (s)
Oce
n ac
me
Ffil
Nat
S
Sit
e 9
11
(co
mp
osi
te)
Ye
rma
k P
late
au
Depth (mbsf)
Polarity/ chron
Age (Ma)
PlanktonicForaminiferal
Zone
CalcareousNannoplankton
Zone
Dinoflagellatecyst Zone
19
Ffil
acm
e(u
pp
er)
Ffil
acm
e(l
ow
er)
LowerPleistocene
(Upper Pliocene) Gelasian
MiddlePleistocene
No
rth
?ba
se P
leis
toce
ne in
Cha
nnel
et a
l. (19
99b)
base
Ple
isto
cene
in F
low
er (1
999)
So
uth
Zone
Even
t
Even
tla
st o
ccu
rre
nce
or
last
co
mm
on
occ
urr
en
ce (
LCO
)
firs
t o
ccu
rre
nce
or
firs
t co
mm
on
occ
urr
en
ce (
FC
O)
Even
tp
oin
t o
ccu
rre
nce
or
acm
e
‘war
m’ a
sse
mb
lag
e
0.4
4
age
fro
m L
ou
ren
s e
t al
. (2
00
4)
age
fro
m in
terp
ola
tio
n b
ase
d o
n
Be
rgg
ren
et
al. (
19
95
)0
.44
PL
AN
KT
ON
ICF
OR
AM
INIF
ER
AB
EN
TH
ICF
OR
AM
INIF
ER
A
TAXO
NCO
DE
TAXO
NCO
DE
Den
togl
obig
erin
a al
tispi
raD
alt
Cibi
cide
s lob
atul
us v
ar. g
ross
a (=
C. g
ross
us)
Cgro
Glo
bige
rinel
la a
equi
late
ralis
Gae
q
Glo
bige
rina
bullo
ides
Gbu
lD
IAT
OM
S
Glo
bige
rinoi
des c
ongl
obat
usG
con
TAXO
NCO
DE
Glo
boro
talia
cra
ssaf
orm
isG
cra
Nitz
schi
a fo
ssili
sN
fos
Glo
boco
nella
(Glo
boro
talia
) inf
lata
Gin
fN
itzsc
hia
rein
hold
iiN
rei
Glo
bige
rinoi
des o
bliq
uus e
xtre
mus
Goe
xN
itzsc
hia
sem
inae
Nse
m
Glo
boco
nella
(Glo
boro
talia
) pun
ctic
ulat
aG
pun
Prob
osci
a cu
rviro
stris
Pcur
Glo
bige
rinoi
des r
uber
Gru
bPs
eudo
euno
tia d
olio
lus
Pdol
Glo
boro
talia
scitu
laG
sci
Thal
assi
osira
jous
eae
Tjou
Glo
bige
rinoi
des t
rilob
usG
tri
Thal
assi
osira
nid
ulus
Tnid
Glo
boro
talia
(Men
arde
lla) l
imba
taM
limTh
alas
sios
ira o
estr
upii
Toes
Glo
boro
talia
(Men
arde
lla) m
enar
dii
Mm
en
Neo
glob
oqua
drin
a at
lant
ica
(dex
.)N
atD
DIN
OF
LA
GE
LL
AT
EC
YS
TS
Neo
glob
oqua
drin
a at
lant
ica
(sin
)N
atS
TAXO
NCO
DE
Neo
glob
oqua
drin
a du
tert
rei
Ndu
tAc
hom
osph
aera
and
alou
sien
sis
Aan
d
Neo
glob
oqua
drin
a pa
chyd
erm
a (d
ex.)
Npa
DA
mic
ulos
phae
ra u
mbr
acul
aA
umb
Neo
glob
oqua
drin
a pa
chyd
erm
a (s
in.)
Npa
SBr
igan
tedi
nium
sim
plex
Bsim
Spha
eroi
dine
llops
is se
min
ulin
a s.
l.Ss
emFi
lisph
aera
filif
era
Ffil
Turb
orot
alita
qui
nque
loba
Tqui
Inve
rtoc
ysta
lacr
ymos
aIla
c
Mul
tispi
nula
min
uta
(=Ba
tiaca
spha
era
min
uta)
Mm
in
CA
LC
AR
EO
US
NA
NN
OP
LA
NK
TO
NN
emat
osph
aero
psis
lem
nisc
ata
Nle
m
TAXO
NCO
DE
Ope
rcul
odin
ium
cen
troc
arpu
mO
cen
Calc
idis
cus m
acin
tyre
iCm
acO
perc
ulod
iniu
m is
rael
ianu
mO
isr
Dis
coas
ter s
urcu
lus
Dsu
rRe
ticul
atos
phae
ra a
ctin
ocor
onat
aRa
ct
Emili
ania
hux
leyi
Ehux
Sele
nope
mph
ix b
revi
spin
osa
Sbre
Gep
hyro
caps
a ca
ribbe
anic
a (M
ediu
m)
Gca
rSe
leno
pem
phix
dio
naec
ysta
Sdio
Gep
hyro
caps
a oc
eani
ca (M
ediu
m)
Goc
eSp
inife
rites
elo
ngat
usSe
lo
Gep
hyro
caps
a sp
p. (L
arge
)G
spp
Sum
atra
dini
um p
lioce
nicu
mSp
li
Pseu
doem
ilian
ia la
cuno
saPl
acTe
ctat
odin
ium
pel
litum
Tpel
Retic
ulof
enes
tra
asan
oiRa
sa
Dat
um p
lane
"A" o
f Sat
o &
Kam
eo (1
996)
-
MIS
CE
LL
AN
EO
US
TAXO
N/E
VEN
TCO
DE
Seis
mic
refle
ctor
R1
R1
Seis
mic
refle
ctor
R5
R5
Seis
mic
refle
ctor
R7
R7
Leg
end
Fig
.2c.
Lat
e Pl
ioce
ne-P
leis
toce
ne c
orre
latio
n pa
nel
show
ing
sele
cted
oce
an d
rilli
ng s
ites
loca
ted
in t
heA
rctic
reg
ion.
Din
ofla
gella
te c
yst a
cme
even
ts a
re n
ew in
terp
reta
tions
acc
ordi
ng to
ana
lysi
s of
the
raw
fos
-si
l occ
urre
nce
data
in th
e re
spec
tive
stud
ies.
Age
s in
bol
d ar
e ac
cord
ing
to th
e as
tron
omic
al c
alib
ratio
ns o
fL
oure
ns e
t al.
(200
4). A
ll ot
her
ages
are
bas
ed o
n in
terp
olat
ions
acc
ordi
ng to
the
stud
ies
cite
d. W
here
pos
-si
ble,
the
four
chr
onos
trat
igra
phic
bou
ndar
ies
disc
usse
d ar
e in
dica
ted.
For
Site
986
: mag
neto
stra
tigra
phy
ac-
cord
ing
to C
hann
ell e
t al.
(199
9b);
pla
nkto
nic
fora
min
ifer
al b
iost
ratig
raph
y is
acc
ordi
ng to
Flo
wer
(19
99);
calc
areo
us n
anno
plan
nkto
n bi
ostr
atig
raph
y is
acc
ordi
ng to
Shi
pboa
rd S
cien
tific
Par
ty (
1996
b); d
inof
lage
l-la
te c
yst b
iost
ratig
raph
y (i
nclu
ding
sei
smic
ref
lect
ors)
is a
ccor
ding
to S
mel
ror
(199
9). F
or S
ites
910
& 9
11:
mag
neto
stra
tigra
phy
is a
ccor
ding
to S
hipb
oard
Sci
entif
ic P
arty
(19
95);
pla
nkto
nic
fora
min
ifer
al b
iost
ratig
-ra
phy
acco
rdin
g to
Spi
egle
r (19
96);
cal
care
ous
nann
opla
nkto
n bi
ostr
atig
raph
y ac
cord
ing
to S
ato
and
Kam
eo(1
996)
; din
ofla
gella
te c
yst b
io -s
trat
i gra
phy
acco
rdin
g to
Mat
thie
ssen
and
Bre
nner
(19
96).
tional Commission on Stratigraphy as formal globalboundaries (Ogg et al. in press). The Base Upper Pleis-tocene Subseries is provisionally placed at the base ofthe Eemian Interglacial in Marine Isotope Stage (MIS)5. The Base Middle Pleistocene Subseries is provi-sionally placed at the Brunhes-Matuyama magnetic re-versal (Gibbard 2003). The identification of thesechronostratigraphic boundaries outside of the Mediter-ranean type area is possible via first-order principaland secondary correlative events associated with theGSSPs (Aguirre and Pasini 1985, Rio et al. 1998). Inthe Nordic Atlantic region, only two secondary correl-ative marker events for the base Pleistocene GSSP atVrica have been identified. These are the calcareousnannofossil last occurrence of Calcidiscus macintyrei(northern North Atlantic) and the first occurrence ofmedium Gephyrocapsa spp. (Yermak Plateau). For di-rect correlation to the base Gelasian GSSP, the last oc-currence of Discoaster surculus was the only primarycorrelative event observed in the northern North Atlantic (Fig. 3). In addition to these relatively rare observations, the following microfossil markers bestapproximate the four main chronostratigraphic bound-aries dividing the Late Pliocene – Pleistocene intervalin this region (see Appendix 1 for details):
4.1 Base Upper Pleistocene (0.126 Ma)
Planktonic foraminiferaAt all ODP sites in the Nordic Atlantic region whereMIS 5e was identified, this level occurred within theNeogloboquadrina pachyderma (sinistral) Zone. Inaddition, it marks the base of a warm temperate plank-tonic foraminiferal assemblage at ODP Sites 918 and919 (Spezzaferri 1998), consistent with the Eemian In-terglacial.
Benthic foraminiferaThis level coincides with a high-productivity benthicforaminiferal assemblage rich in Bulimina marginata,Cassidulina laevigata and Bolivina spp. in the NorthSea (Knudsen and Sejrup 1988). It may coincide withthe last common occurrence of Elphidium ustulatum inneritic deposits (see Appendix 1).
Calcareous nannoplanktonAt ODP Site 983, on the Gardar Drift in the northernNorth Atlantic, the base of MIS 5 occurs approximate-ly 15 metres below the seafloor (Koç et al. 1999), andca. 10 metres above the first occurrence of Emilianiahuxleyi (0.29 Ma in Lourens et al. 2004). The base of
the Upper Pleistocene occurs at a level approximatingto the middle of Calcareous Nannoplankton ZoneNN21. The same is true for ODP Site 919 on the EastGreenland margin (Koç and Flower 1998) and ODPSite 643 on the Vøring Plateau (Jansen et al. 1989).
DiatomsBased on the oxygen isotope studies at ODP Sites 983and 919, the boundary should be placed within theThalassiosira oestrupii Zone of Koc et al. (1999). Itcan be identified more precisely as the base of the sec-ond and largest acme of T. oestrupii, as counted eitheruphole or downhole.
4.2 Base Middle Pleistocene (0.781 Ma)
Planktonic foraminiferaAt ODP Site 919, on the East Greenland margin in thenorthern North Atlantic, the top of MIS 19 (warm stage)corresponds to the last common occurrence (LCO) ofthe ‘warm-temperate’ species Globorotalia scitula andGloborotalia inflata (new event identified in Flower1998 and Spezzaferri 1998). Similarly, at neighbouringODP Site 918 the last common occurrence of the ‘cool-temperate’ (‘warm-subpolar’) Neo globoquadri-na pachy derma (dextral) and the slightly later LCON. dutertrei occur close to the Brunhes-Matuyamaboundary. This level is also marked by a maximum inPleistocene planktonic foraminiferal species diversityat both East Greenland Margin ODP Sites 918 and 919(Spezzaferri 1998), consistent with the top of the MIS19 warm stage (Fig. 2a). North of the Greenland-Scot-land Ridge, this ‘cool-temperate’ assemblage appearsto be absent at this level with the LCO (consistent)N. pachyderma (dextral) occurring older, close to thePliocene-Pleistocene boundary (Spiegler and Jansen1989; Spiegler 1996). On the Yermak Plateau, the LCO(consistent) N. pachyderma (dextral) does, however,occur together with the last occurrence of a cool-tem-perate assemblage close to the Pliocene-Pleistoceneboundary (Spiegler 1996). The lack of a clearly identi-fiable younger LCO N. pachyderma (dextral) and other“warmer species” at most sites north of the GSR may beattributed to a reduced impact of warmer interglacialsurface currents at these higher latitudes.
Benthic foraminiferaAt shallow neritic paleo-water depths in the North Sea,the base of the Middle Pleistocene corresponds to thetop of a warm assemblage of abundant Bulimina mar-
39Late Pliocene and Pleistocene biostratigraphy of the Nordic Atlantic region
ginata, Trifarina fluens and Cassidulina teretis (Sejrupet al. 1987). This may coincide with the first commonoccurrence of the cold-indicator Elphidium asklundi(Knudsen and Asbjørnsdottir 1991). At Lower Neriticto Upper Bathyal depths the last occurrence of Cibi-cides grossus approximates the boundary (King 1989;Osterman 1996). At Lower Bathyal depths the Mid-Pleistocene saw the extinction of deep-sea benthicforaminifera with elongate, cylindrical tests and high-ly specialised apertures. The ‘Stilostomella Extinction’has been documented globally as occurring around theBrunhes-Matuyama boundary. This includes ODPSites 980 and 982 in the northern North Atlantic,where the event was seen to culminate at ~ 0.694 Maat Lower Bathyal water depths (Kawagata et al. 2005).
Calcareous nannoplanktonAt ODP Site 911, on the Yermak Plateau, Sato andKameo (1996) found the last occurrence of Retic-ulofenestra asanoi at 0.85 Ma. This species had its lastcommon occurrence calibrated astronomically in the
South Atlantic and Eastern Mediterranean to 0.9 Ma inLourens et al. (2004). This is the only nannofossilmarker for the base Middle Pleistocene in the NordicAtlantic region and was only identified at this high-Arctic location. It is believed to have entered the Arc-tic through the Bering Strait.
DiatomsSouth of the Greenland-Scotland Ridge, the best bio-stratigraphic approximation to the base of the MiddlePleistocene is the last occurrence of the diatomNitzschia seminae. This event was dated to 0.84 Ma(MIS 21) at the northern North Atlantic ODP Site 983(Koç et al. 1999) and 0.817–0.895 Ma (MIS 22–24) atODP Site 919 on the East Greenland Margin (Koç andFlower 1998).
Dinoflagellate cystsIn the Norwegian Sea, Smelror (pers. comm.) placedthe last occurrence of Filisphaera filifera at 1.4 Ma.This age is according to correlations with the nanno-
40 Erik D. AnthonissenA
ge (
Ma)
StandardChrono-
stratigraphy
Epoc
h
Stag
e
Geom
agne
ticPo
larity
Tim
e Sc
aleCalcareous Nannoplankton
Selected (Sub-)Tropical Bioevents according to Lourens et al. (2004)(Bold = GSSP correlative events)
0
1
2
3
Plio
cene
Ple
isto
cene
Hol
.
Pia
cenz
ian
Gel
asia
n
2.59
1.81
E. P
leis
t.
0.78
M. P
leis
t.
L.Pl.0.13
0.78
0.991.171.19
1.78
1.95
2.132.15
2.59
3.033.123.21
3.33
4.19
C2A
C2
C1
NN16
NN172.49
NN18
2.39
NN19
1.93
NN21
0.29
0.61Gephyrocapsa sp.3
1.02small Gephyrocapsa spp. dominance
1.24
N20
/N21
N22
2.0
PL3
PL43.14
PL5
3.13
PL6
2.39
Pt1
1.77
2.0 Gr. truncatulinoides
0.61Globorotalia tosaensis
1.77Gs. fistulosus
2.39Gr. miocenica [Atl.]
3.13Dentoglobigerina altispira
3.14Sphaeroidinellopsis seminulina
3.24 Gr. inflata
1.3Globigerinoides obliquus
1.58
Neogloboquadrina acostaensis
1.64Globoturborotalita apertura
1.98Globigerinoides extremus
2.24Globorotalia limbata
2.3Globoturborotalita woodi
3.23Globoquadrina baroemoenensis
0.29Emiliania huxleyi
0.44
Pseudoemiliania lacunosa
0.91Reticulofenestra asanoi
1.6
Calcidiscus macintyrei
1.93Discoaster brouweri1.95Discoaster triradiatus
2.39Discoaster pentaradiatus
2.49Discoaster surculus
2.8Discoaster tamalis
large Gephyrocapsa spp.
Planktonic Foraminifera
Selected (Sub-)Tropical Bioevents according to Lourens et al. (2004)(Bold = GSSP correlative events)
2.41Gr. puncticulata +
Neogloboquadrina atlantica (s) [Med.]
1.79Neogloboquadrina spp.(s) common [Med.]
Selected Age Calibrated Nordic Markers
0.13base 2nd acme (up/downhole) of(DT) Thallassiosira oestrupii (A,B)
0.29 (CN) Emiliania huxleyi (A-D,F)
0.84(DT) Nitzschia seminae (A)
1.0
(DC) Filisphaera filifera and/or(DC) Nematosphaeropsis lemniscata (B,F,G)
0.9(BF) Cibicides grossus L. Neritic-U. Bathyal (F, G)
0.44(CN) Pseudoemiliania lacunosa (A,B,D,F)
1.7-1.8 (PF) N. pachyderma (s)common (A,C,D,F)
1.7-1.9(PF) Neogloboquadrina
atlantica (d) (B,D,F)
1.6(CN) Calcidiscus macintyrei (A)
1.73
medium Gephyrocapsa spp.1.73
(CN) medium
Gephyrocapsa spp. (F)
(DC) top of Upper F. filiferaacme (D,F)
1.8
(PF) N. atlantica (s) consistently common (A,G) 2.6
2.4-2.6(DC) base of Lower Filisphaera filiferaacme (D,F)
0.44NN20
(PF) Foraminifera(CN) Nannoplankton(DC) Dinoflagellates(DT) Diatoms
(A) Northern Atlantic(B) Irminger Basin(C) Iceland Plateau(D) Vøring Plateau
0.3(DT) Proboscia curvirostris (A,B)
0.78(BF) top acme B. marginata-C. teretis-T. fluens (G)
(CN) large Gephyrocapsa spp. (A,F) 1.24
1.8(BF) Cibicides grossus M. Neritic (G)
2.5-2.6(BF) Monspeliensina pseudotepida U-M. Neritic (G)
2.49(CN) Discoaster surculus (A)
2.1 (PF) Globorotalia inflata (A,G)
See Appendix 1 for calibrations(Bold = GSSP correlative events)
(E) Greenland Sea(F) Yermak Plateau(G) North Sea
Legend
Fig. 3. Comparison of the low-latitude standard biozonations and important calibrated Nordic region bioevents. The geo-graphic distribution of calibration points for each Nordic bioevent is indicated by the letters following its name (see Legend).
plankton stratigraphies of ODP Leg 151 (Poulsen et al.1996). Mudie et al. (1990) placed the last occurrenceof F. filifera in the Norwegian Sea and North Atlanticat slightly older than the base of the Middle Pleis-tocene (ca. 1 Ma). The dinoflagellate cyst stratigra-phies for Norwegian Sea ODP Sites 643 and 642 placethis event slightly older than the base of the MiddlePleistocene. At Arctic ODP Site 911 this event occursat a level similar to the Norwegian Sea occurrence. Atthe Svalbard Margin ODP Site 986, it is significantlyyounger, occurring in the Upper Pleistocene (between0.2 and 0.44 Ma). Whether this is due to reworking ortrue extinction events is not known. The last occur-rence of F. filifera, according to these data, appears tobe a rough approximation to the base of the MiddlePleistocene in the Norwegian Sea and possibly furthersouth.
4.3 Base Pleistocene (1.806 Ma)
Planktonic foraminiferaNone of the base Pleistocene primary or secondaryGSSP markers are present in the Nordic deep-sea cores(with the exception of a rare occurrence of Globigeri-noides obliquus extremus in discontinuous Upper Plio -cene sediments of ODP Site 910), which usually offermost precise dating via direct correlation to the Geo-magnetic Polarity Time Scale. However, examinationof the microfossil data in the original definition of theVrica GSSP (Aguirre and Pasini 1985) shows, in addi-tion to the secondary markers mentioned, the first oc-currence of Neogloboquadrina pachyderma (sinistral)occurring just above the boundary. In a later study ofthe Vrica Section, Lourens et al. (1996) astronomical-ly calibrated the first common occurrence of N. pachy-derma (s) to 1.799 Ma. The first common occurrence(FCO) of this species has also been recorded in oceandrilling cores throughout the Nordic Atlantic region ascorresponding approximately to the top of the OlduvaiSubchron: North Atlantic DSDP Sites 609, 610, 611(Weaver and Clement 1986 recorded as a first occur-rence of the “encrusted” morphotype); Northern NorthAtlantic ODP Site 985 (Flower 1999), Norwegian SeaODP Sites 642, 643, 644 (Spiegler and Jansen 1989);Iceland Plateau Site 907 and Svalbard Margin ODPSite 986 (Flower 1999).
An additional planktonic foraminiferal event mark-ing the boundary is the last occurrence of Neoglobo-quadrina atlantica (dextral), or the top of the UpperN. atlantica (dextral) Zone of Spiegler and Jansen(1989). It has been noted at ODP Sites 644 on the
Vøring Basin, and 918 in the Irminger Basin. Thisevent can also be described as the last occurrence ofN. atlantica as a species including both coiling mor-photypes. This was the case in the original range chartpublished by Aguirre and Pasini (1985) where they ob-served the last occurrence of N. atlantica just abovethe boundary at Vrica. It may sometimes occur togeth-er with the LCO N. pachyderma (dextral).
Benthic foraminiferaAt upper neritic depths in the southern North Sea, thelast common occurrence of the benthic foraminiferElphidiella hannai occurs close to the Pliocene-Pleis-tocene boundary within the Olduvai Subchron (Kuhl -mann 2004). At deeper lower neritic depths in the central and northern North Sea, the last occurrence ofCibicides grossus is a better approximation to theboundary (see Appendix 1).
Dinoflagellate cystsThe dinoflagellate cyst stratigraphy of Kuhlmann(2004) for the southern North Sea describes a firstand second ‘Filisphera/Habicysta/Bitectatodiniumacme’ during the Olduvai normal event. A second or“upper F. filifera acme” is also evident in the raw fos-sil occurrence data of ODP Site 642 (see Mudie1989) on the Vøring Plateau, and at ODP Site911(see Mat thiessen and Brenner, 1996) on the Yer-mak Plateau. At both sites this upper acme corre-sponds closely to the top of the Olduvai Subchron.On the Svalbard Margin, at ODP Site 986, this sameacme event can be identified (see Smelror 1999),how ever, the ambiguous magnetostratigraphy inthese samples obscures a reliable age estimate. Ittherefore appears that the upper F. filifera acme is themost reliable palynological marker for a level that isslightly younger than the base Pleistocene through-out much of the Nordic Atlantic region.
Calcareous nannoplanktonThe calcareous nannoplankton stratigraphy of north-ern North Atlantic ODP Sites 981, 982 and 983 ap-pears to be the most reliable biostratigraphy for thistime interval, at least south of the GSR. At all threesites the last occurrence of Calcidiscus macintyreioccurs at the same level, above the Olduvai Sub-chron in C1r.3r. This datum was astronomically cal-ibrated to 1.66 Ma according to Lourens et al. (2004)and occurs approximately 10 metres above the firstcommon occurrence of N. pachyderma (s) at all threesites.
41Late Pliocene and Pleistocene biostratigraphy of the Nordic Atlantic region
4.4 Base Gelasian (2.588 Ma)
Planktonic foraminiferaIn the northern North Atlantic (DSDP Sites 609, 610,611), Weaver and Clement (1986) and Weaver (1987)found the last occurrence (LO) Neogloboquadrina at-lantica (sinistral) between the Gauss/Matuyama mag-netic polarity boundary and the Olduvai Subchron. Inthe southern North Sea core study by Kuhlmann(2004), the last common occurrence (LCO) of N. at-lantica was found just above the Gauss/Matuyamaboundary. There may be exceptions to this age inter-pretation (see Discussion).
Benthic foraminiferaThe benthic foraminiferal extinction of Monspeliensi-na pseudotepida in the Lower Neritic North Sea andoffshore Mid-Norway corresponds approximately tothe base of the Gelasian Stage (Kuhlmann 2004). Thisevent was used by King (1989) to define his NSB14/15 zonal boundary in the North Sea, which heplaced close to the LO of N. atlantica (s) at 2.3 Ma(age according to Weaver and Clement 1986). The LOMonspeliensina pseudotepida also occurrs at a levelwith a strontium isotope date of 2.5–4.5 Ma in thecentral North Sea well 2/4-C-11 (Eidvin and Riis1995).
Dinoflagellate cystsIn the southern North Sea, Kuhlmann (2004) found afirst and a second acme of Filisphera/Habicysta/Bi-tectatodinium. The base of the first (or lower) acmecorresponds closely to the Gauss-Matuyama magneticreversal and therefore to the base of the GelasianStage. An analysis of the raw fossil occurrence data forODP Sites 642 (Vøring Plateau), 986 (Svalbard Mar-gin) and 911 (Yermak Plateau) reveals both an upperand a lower F. filifera acme. On the Vøring Plateau, thebase of this acme approximately coincides with theGauss/Matuyama boundary (see Mudie 1989). On theSvalbard Margin, it occurs slightly below the “R7 seis-mic reflector” (Smelror 1999), with a correlated age ofca. 2.3 Ma according to Faleide et al. (1996). Whilethis suggests agreement with the Norwegian Sea age,this is not the case for the Yermak Plateau ODP Site911, where the acme occurs much higher in the se-quence. Further study is needed to ascertain the relia-bility of these acme events as regional markers.
A comparison between the key Nordic region bio-events and the standard (sub)tropical zonations is giv-en in Fig 3.
5. Discussion: Synchroneity/diachroneity of selectedplanktonic foraminiferal datums
The age of the last occurrence of Neogloboquadrinaatlantica (sinistral) in the Nordic Atlantic region has ahistory of conflicting interpretation. North Sea zona-tions have most often referred it to an age of 2.3 Ma,based on the temperate northern North Atlantic bio-magnetostratigraphy of DSDP Leg 94 (Weaver andClement 1986). This study shows this bioevent to beclearly time-transgressive across the region, but withthree age clusters recorded at ca. 1.8 Ma, ca. 2.3 Maand ca. 3.1 Ma (Appendix 1).
The oldest age assignment for the LO N. atlantica (s)of ca. 3.1 Ma was recorded at sites that show evidenceof a significant Mid-Pliocene warm-water influx:Vøring Plateau ODP Sites 642 & 643 (?C2r.1r) and Yermak Plateau ODP Site 910 (slightly older than thestandard Pl3/Pl4 planktonic foraminiferal zonal bound-ary of Berggren et al. 1995). The ‘Mid-Pliocene globalwarmth’ is evident here in the warm-temperate to sub-tropical planktonic foraminiferal assemblage at ODPSite 910 (including Dentoglobigerina altispira andGloborotalia (Menardella) limbata), and the acmes ofGlobigerina bulloides and the dinocyst Achomo-sphaera andalousiensis on the Vøring Pla teau. Knies et al. (2002) identified a seasonally ice-free period inthe eastern Arctic, contemporaneous with the ‘Mid-Pliocene global warmth’.
The ca. 2.3 Ma age assignment for the LO N. at-lantica (s) applies to the northern North Atlantic sitescurrently overlain by the warm surface waters of theNorth Atlantic Drift (ODP Sites 981, 982,?984) and forthe Vøring Plateau ODP Site 644, currently overlainby the warm Norwegian Coastal Current. At these lo-cations the LO N. atlantica (s) occurs within the pale-omagnetic Subchron C2r.2r.
The youngest age assignment for the LO N. atlanti-ca (s) of ca. 1.8 Ma (straddling the Pliocene-Pleis-tocene boundary) was recorded at sites currently over-lain by cold to mixed surface currents: Irminger BasinODP Site 918 (upper C2n), Iceland Sea ODP Sites 985(?C1r.3r) and 907 (mid C2n), Svalbard Margin ODPSite 986 (?C1r.3r) and Yermak Plateau ODP Site 911(mid C2n). The complete absence of this bioevent andpoor preservation encountered at Greenland Sea ODPSite 987 is probably due to dissolution as a result of theoverlying cold East Greenland Current. The presenceof this bioevent at the more northerly sites could be
42 Erik D. Anthonissen
due to the contemporaneous inception of the warmProto-Norwegian Current at ca. 1.9 Ma (Henrich et al.2002). Poore and Berggren (1974) observed this eventin the Labrador Sea at Deep Sea Drilling Project Site113 as a very rare occurrence at the same level as theLO Discoaster brouweri (1.9 Ma astronomically cali-brated age in Lourens et al. 2004). At other LabradorSea sites, the event occurred lower in the UpperPliocene, also possibly due to dissolution by the coldLabrador Current.
The age of the first common occurrence of Neo -globoquadrina pachyderma (sinistral) appears to belargely synchronous across the region, ranging from1.7–1.9 Ma (mid C2n to lower C1r.3r) in the majorityof the sites investigated. The only exceptions to thisrecord are the anomalously young ages of 1.0–1.1 Marecorded at East Greenland ODP Site 918 (upperC1r.2r) and Greenland Sea ODP Site 987 (mid C1r.1r).Both sites are presently overlain by the cold EastGreenland Current, which may have resulted in calcitedissolution of the lower parts of the N. pachyderma (s)acme. The inception of the warm Proto-NorwegianCurrent at ca. 1.9 Ma might have been responsible forthis sudden acme event. Since these warmer-water in-cursions are believed to have been confined to the east-ern and southern Nordic Seas, the Greenland Seawould not have experienced the same ameliorated sur-face-water conditions (Henrich et al. 2002). The ano -malously younger age does, however, coincide withthe globally synchronous first occurrence of the largermodern N. pachyderma (s) morphotype (Kucera andKennett, 2002).
6. Conclusions
The correlation of deep-sea cores in the Nordic At-lantic region highlights the geographical extent andstratigraphic range of a number of high-latitude mar-ker species. This has resulted in the identification ofsynchronous and diachronous bioevents, together withthe best biostratigraphic approximations to the stan-dard chronostratigraphic boundaries of this time peri-od. Although many of these taxa have been know toshow diachronous local ranges, this regional correla-tion allows for a better quantification of the degree ofthis diachroneity. This has resulted in identification ofthe best biostratigraphic approximations to the stand -ard Late Pliocene – Pleistocene chronostratigraphicboundaries at these high latitudes. In addition, thisstudy highlights biostratigraphic trends on both a re-
gional scale and on a more local scale between sub-basins.
Possible explanations for the diachronous record ofthe last occurrence Neogloboquadrina atlantica (sinis-tral) in the Nordic Atlantic region are: calcite dissolu-tion under cold ocean currents (results in a depressedrange); ice-rafting or other reworking (results in an ar-tificially extended range); sites located under warmsurface water from the Gulf Stream/North AtlanticDrift might have experienced unfavourable environ-mental conditions for this apparently cold-adapted,sinistrally-coiled N. atlantica morphotype (results in adepressed range). At locations dominated by cold ormixed ocean currents, the last occurrence of Neo -globoquadrina atlantica (s) occurs together with thefirst common occurrence of N. pachyderma (s).
The first common occurrence of N. pachyderma (s)is a largely synchronous datum in the region, and agood biostratigraphic approximation for the base ofthe Pleistocene. The exception occurs at locationsdominated by cold ocean currents such as the EastGreenland Current, where only the uppermost part ofthe acme is present. The earlier onset of this acmeevent in the southern and eastern parts of the regionmay be related to the inception of the warm Proto-Nor-wegian Current (Henrich et al. 2002).
The continuing efforts of the Integrated Ocean Dril -ling Program (IODP) and further advances in amino-acid dating, OSL and isotope dating methods may im-prove linking these high-latitude microfossil recordsto the standard Neogene chronostratigraphic defini-tions of the Mediterranean.
Acknowledgements. This study, under the supervisionof Felix M. Gradstein, is part of an ongoing project at theNatural History Museum in Oslo (Norway) to calibrateNordic Upper Cenozoic biozones relative to the standardglobal time scale. Support comes from the Natural HistoryMuseum, University of Oslo and the Norwegian InteractiveLithostratigraphic Lexicon (NORLEX Project).
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Manuscript received: March 13, 2008, rev. version received:April 8, 2008, accepted for print: April 9, 2008.
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47Late Pliocene and Pleistocene biostratigraphy of the Nordic Atlantic region
48 Erik D. Anthonissen
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