A Holocene paleosecular variation record from the northwestern Barents Sea continental margin

Abstract

A high-resolution paleomagnetic and rock magnetic study has been carried out on sediment cores collected in glaciomarine silty-clay sequences from the continental shelf and slope of the southern Storfjorden trough-mouth fan, on the northwestern Barents Sea continental margin. The Storfjorden sedimentary system was investigated during the SVAIS and EGLACOM cruises, when 10 gravity cores, with a variable length from 1.03 m to 6.41 m, were retrieved. Accelerator mass spectrometry (AMS) 14C analyses on 24 samples indicate that the cores span a time interval that includes the Holocene, the last deglaciation phase and in some cores the last glacial maximum. The sediments carry a well-defined characteristic remanent magnetization and have a valuable potential to reconstruct the paleosecular variation (PSV) of the geomagnetic field, including relative paleointensity (RPI) variations. The paleomagnetic data allow reconstruction of past dynamics and amplitude of the geomagnetic field variations at high northern latitudes (75°-76° N). At the same time, the rock magnetic and paleomagnetic data allow a high-resolution correlation of the sedimentary sequences and a refinement of their preliminary age models. The Holocene PSV and RPI records appear particularly sound, since they are consistent between cores and they can be correlated to the closest regional stacking curves (UK PSV, FENNOSTACK and FENNORPIS) and global geomagnetic model for the last 7 ka (CALS7k.2). The computed amplitude of secular variation is lower than that outlined by some geomagnetic field models, suggesting that it has been almost independent from latitude during the Holocene.

Full text

Article
Volume 12, Number 11
1 November 2011
Q11Z33, doi:10.1029/2011GC003810
ISSN: 1525‐2027
A Holocene paleosecular variation record
from the northwestern Barents Sea continental margin
Leonardo Sagnotti and Patrizia Macrì
Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, I‐00143 Rome, Italy
(leonardo.sagnotti@ingv.it)
Renata Lucchi and Michele Rebesco
Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Borgo Grotta Gigante 42/c, Sgonico,
Trieste I‐34010, Italy
Angelo Camerlenghi
Istitució Catalana de Recerca i Estudis Avançats, E‐08028 Barcelona, Spain
Department d’Estratigrafia, Paleontologia i Geociències Marines, Facultat de Geologia, Universitat de
Barcelona, Martí i Franqués, s/n, E‐08028 Barcelona, Spain
[1]A high‐resolution paleomagnetic and rock magnetic study has been carried out on sediment cores col-
lected in glaciomarine silty‐clay sequences from the continental shelf and slope of the southern Storfjorden
trough‐mouth fan, on the northwestern Barents Sea continental margin. The Storfjorden sedimentary
system was investigated during the SVAIS and EGLACOM cruises, when 10 gravity cores, with a variable
length from 1.03 m to 6.41 m, were retrieved. Accelerator mass spectrometry (AMS)
14
C analyses on
24 samples indicate that the cores span a time interval that includes the Holocene, the last deglaciation phase
and in some cores the last glacial maximum. The sediments carry a well‐defined characteristic remanent
magnetization and have a valuable potential to reconstruct the paleosecular variation (PSV) of the geomag-
netic field, including relative paleointensity (RPI) variations. The paleomagnetic data allow reconstruction
of past dynamics and amplitude of the geomagnetic field variations at high northern latitudes (75°–76° N).
At the same time, the rock magnetic and paleomagnetic data allow a high‐resolution correlation of the
sedimentary sequences and a refinement of their preliminary age models. The Holocene PSV and RPI
records appear particularly sound, since they are consistent between cores and they can be correlated to
the closest regional stacking curves (UK PSV, FENNOSTACK and FENNORPIS) and global geomagnetic
model for the last 7 ka (CALS7k.2). The computed amplitude of secular variation is lower than that
outlined by some geomagnetic field models, suggesting that it has been almost independent from latitude
during the Holocene.
Components: 9900 words, 15 figures, 2 tables.
Keywords: Barents Sea; Holocene; Storfjorden; geomagnetic paleosecular variation; relative paleointensity.
Index Terms: 1521 Geomagnetism and Paleomagnetism: Paleointensity; 1522 Geomagnetism and Paleomagnetism:
Paleomagnetic secular variation; 1560 Geomagnetism and Paleomagnetism: Time variations: secular and longer.
Received 22 July 2011; Revised 30 September 2011; Accepted 3 October 2011; Published 1 November 2011.
Copyright 2011 by the American Geophysical Union 1 of 24

Sagnotti, L., P. Macrì, R. Lucchi, M. Rebesco, and A. Camerlenghi (2011), A Holocene paleosecular variation record from the
northwestern Barents Sea continental margin, Geochem. Geophys. Geosyst.,12, Q11Z33, doi:10.1029/2011GC003810.
Theme: Magnetism from Atomic to Planetary Scales: Physical Principles
and Interdisciplinary Applications in Geoscience
Guest Editors: B. Moskowitz, J. Feinberg, F. Florindo, and A. P. Roberts
1. Introduction
[2]Sedimentary sequences with suitable lithologi-
cal character and good paleomagnetic properties
may provide valuable empirical inputs for the
reconstruction of the geomagnetic field variability over
geological times [e.g., Creer et al., 1972; Thompson,
1973; Verosub, 1977; Tauxe, 1993]. The recon-
struction of the evolution of the magnetic field at
various temporal and spatial scales is key to under-
standing the geodynamo models and the dynamics
of the liquid outer core. The geomagnetic field varies
over timescales from milliseconds to millions of
years. Geomagnetic variations with timescales
longer than 5 years are known as secular variation
(SV) [Thompson and Barraclough, 1982; Bloxham
and Gubbins, 1985]. Variations longer than 22 years,
that is the duration of the turn‐over of solar mag-
netic field, are of internal origin and reflect the
magnetohydrodynamics of the Earth’siron‐rich,
electrically conducting, fluid outer core [e.g., Merrill
et al., 1996]. Paleomagnetic and archeomagnetic data
collected in the last decades allows reconstruction of
geomagnetic paleosecular variation (PSV) for the
past millennia, with the establishment of regional
reference stacked PSV curves [e.g., Turner and
Thompson, 1981, 1982; Hagstrum and Champion,
2002; St‐Onge et al.,2003;Snowball et al., 2007;
Barletta et al., 2010a, 2010b] and global geomag-
netic field models ([e.g., Korte and Constable, 2005;
Korte et al., 2005, 2009; Donadini et al., 2009] for an
updated review see Donadini et al. [2010]). How-
ever, both reference PSV curves and global geo-
magnetic models are mainly based on the compilation
of data collected from low‐and midlatitudes.
[3]As PSV data from high‐latitude regions are still
rare, there is a great interest to collect more widely
distributed high‐latitude PSV data to improve global
geomagnetic field models [see Nilsson et al., 2010].
In particular, there is a lack of PSV data from sites
within the surficial projection of the inner core
tangent cylinder. This is a region of the outer core
where a theoretical cylinder, tangent to the solid
inner core equator and parallel to the axis of rota-
tion, would separate distinct convective regimes.
The tangent cylinder intersects the Earth’s surface
at a latitude of ±69.5°. The theory predicts that a
different process might drive the geomagnetic field
of the polar‐regions: the flow within the tangent
cylinder is thought to be moving as an upwelling
polar vortex similar to that of a hurricane. Thermal
winds and polar vortices within the tangent cylin-
der have been cited as the cause for low radial
magnetic field over the north pole [Olson and
Aurnou, 1999; Hulotetal., 2002; Sreenivasan
and Jones, 2005, 2006] and an increased SV is
predicted (4 times greater than the global average
value for the time period 1870–1990 [Olson and
Aurnou, 1999)]. Therefore PSV data from polar
sites are of critical importance for geomagnetic
field models. Some previous studies on late Pleis-
tocene sediment cores from the Arctic region
pointed out a geomagnetic variability larger than in
intermediate and low latitudes, suggesting that the
magnetic field has been strongly variable during at
least the last 300 ka, with geomagnetic excursions
more frequent and of longer duration than elsewhere
[e.g., Nowaczyk and Antonow, 1997; Nowaczyk and
Frederichs, 1999]. Anyway, recent rock magnetic
studies pointed out that these features of apparent
geomagnetic instability are due to partially self‐
reversed chemical remanent magnetizations acquired
during the oxidation of detrital (titano)magnetite
grains [Channell and Xuan, 2009; Xuan and
Channell, 2010]. Furthermore, there are few Holo-
cene relative paleointensity (RPI) determinations
from marine sediments of the polar regions, limited to
the North America margin for the Arctic region and to
the Antarctic peninsula for the Antarctic region
(Barletta et al. [2010a, 2010b] for the Canadian
region; Lisé‐Pronovost et al. [2009] for the Arctic
Alaskan margin; Brachfeld et al. [2000, 2003] for the
Antarctic peninsula) while a few other studies extend
RPI reconstructions to the Late Pleistocene of the
sub‐Antarctic South Atlantic [Channell et al., 2000;
Stoner et al., 2003] and the peri‐Antarctic margins
[Sagnotti et al., 2001; Macrì et al., 2005, 2006,
2010]. In conjunction with the PSV data, the recon-
struction of detailed RPI records from the European
high northern latitudes may complete the experi-
mental evidence framework for a full understanding
of the overall geomagnetic field variability.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
2of24

[4]In this study, we present the results of a
high‐resolution paleomagnetic and rock magnetic
analysis on 5 sedimentary cores collected on the
northwestern Barents Sea continental margin in the
framework of the SVAIS and EGLACOM projects.
The results allow us to reconstruct the directional
PSV and the relative paleointensity changes of the
geomagnetic field at high northern latitudes during
the Holocene, thus providing original experimental
constraints for testing models on the geomagnetic
dynamo and the outer core dynamics. The data are
supported by a robust, high‐resolution, correlation
and dating of the cores, and therefore have a valuable
potential for establishing a firm temporal framework
for the observed sedimentological changes and the
inferred paleoenvironmental evolution.
2. Geological Setting and Age
Constraints
[5]The projects SVAIS (The development of an
Arctic ice stream‐dominated sedimentary system:
The southern Svalbard continental margin) and
EGLACOM (Evolution of a GLacial Arctic
COntinental Margin: the southern Svalbard ice
stream‐dominated sedimentary system) were both
conceived within the International Polar Year (IPY)
in 2007–2009. The BIO Hespérides SVAIS cruise
(29 July–17 August 2007) and the R/V OGS‐
Explora EGLACOM cruise (08 July–04 August
2008) investigated the Storfjorden glacial marine
sedimentary system on the NW Barents Sea con-
tinental margin (Figure 1). The seafloor in this area
was shaped by the action of several paleo‐ice
streams flowing into the Storfjorden and Kveithola
glacial throughs, originating from the southern
Svalbard archipelago and Spitsbergen banken.
[6]The overall objective of both projects is to
contribute to the understanding of the evolution of
glacial continental margins in response to ice sheet
dynamics induced by climatic changes, in particu-
lar during the deglaciation phase following the
last glacial maximum. During the SVAIS and
EGLACOM cruises, 10 piston and gravity cores
(SVAIS: 6 piston cores for a total of 26.70 m;
Figure 1. Location of the SVAIS and EGLACOM cores. (a) Location map of the study area in the NW Barents Sea.
TMF: Trough‐Mouth Fan; BY: Byørnøyrenna; KV: Kveithola; SF: Storfjorden. Arrows identify the location of the
major paleo ice streams and paleo ice‐flow direction. Bathymetry from GeoMapApp, http://www.geomapapp.org
(Global MultiResolution Topography Synthesis [Ryan et al., 2009]). The inset at the upper right shows the north-
ern polar region and the surficial projection of the inner core tangent cylinder at 69.5°N (red dashed line). (b) Detail of
the square study area indicated in map A and location of the SVAIS‐EGLACOM sediment cores. Color shaded relief
bathymetric map of the Storfjorden and Kveithola Through Mounth Fans (TMF) area (from combined SVAIS and
EGLACOM multibeam data) superimposed to the International Bathymetric Chart of the Arctic Ocean (IBCAO) gray
scale shaded relief bathymetry after Jakobsson et al. [2008] (http://www.ibcao.org).
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
3of24

EGLACOM: 4 gravity cores for a total of 9.23 m)
were collected either on the continental slope and
shelf (Figure 1), with a variable length from 1.03 m
to 6.41 m (Table 1). We sampled 8 of these cores
collected on the outer continental shelf and on the
slope of Storfjorden and Kveithola throughs‐mouth
fans (TMFs), in water depths between 303 and
1839 m below sea level (bsl). The cores were
retrieved at a latitude of about 75–76°N and are
located within the Earth’s core tangent cylinder
region. Though paleomagnetic and rock magnetic
properties were measured on the whole strati-
graphic interval spanned by the cores, we focused
our analysis on the Holocene interval, since it is
characterized by excellent paleomagnetic proper-
ties. The Holocene record is well preserved in the
continuous fine‐grained homogeneous sediments
of three cores from the mid slope (SV‐04, EG‐02
and EG‐03) and of one core (SV‐06) from the
shelf, where however the sedimentary record
contains hiatuses (Figure 2). An additional core
(EG‐01) from an upper slope gully was also ana-
lyzed, though the Holocene sedimentary record is
very thin. Twenty‐four AMS
14
C calibrated ages
are available for these five cores, and constrain the
age of the sedimentary sequences (Figure 2 and
Table 2). AMS
14
C dating was performed at
NOSAMS (Woods Hole Oceanographic Institu-
tion) on selected stratigraphic intervals, mainly
using foraminifera tests, but also the bulk organic
content of the sediments in the case of core EG‐01
(see Table 2). Radiocarbon ages at NOSAM labo-
ratory were calculated using 5568 years as the half‐
life of radiocarbon and the results were delivered as
raw AMS
14
C (yr BP) without reservoir corrections
or calibration to calendar years. Ages calibration
were then obtained through the calibration software
Calib 6.0 [Stuiver and Reimer, 1993], using the
marine09 calibration curve [Reimer et al., 2009],
and applying an average marine regional reservoir
effect DR of 84 ± 23 obtained from the Marine
Reservoir Correction Database in Calib 6.0 for the
northwestern Barents sea area (south of Svalbard).
The mean values from the calibrated age range of
±1swere then normalized to calendar year (con-
ventionally 1950 AD) and are here reported as
Cal. yr BP (Table 2).
3. Sampling and Measurements
[7]After dividing the cores into working and
archive halves, each core section ‐about 1 m long ‐
was subsampled with u‐channel plastic holders for
continuous paleomagnetic and rock magnetic
measurements. U‐channel samples were collected
from the archive halves of the SVAIS cores
(SV‐03‐04‐05‐06) in January 2008, at the Litho-
teque of the Faculty of Geology, University of
Barcelona. The working halves of the EGLACOM
cores (EG‐01‐02‐03‐04) were sampled in July
2009 at the core repository facility of the Museo
Nazionale dell’Antartide of Trieste.
[8]Palaeomagnetic and rock magnetic measure-
ments were carried out at the palaeomagnetic lab-
oratory of the Istituto Nazionale di Geofisica e
Vulcanologia, in Rome, in a magnetically shielded
room. For each u‐channel, we measured the low‐
field magnetic susceptibility (k) and the natural
remanent magnetization (NRM) at 1 cm spacing.
The NRM was measured on a small access (45 mm
diameter) automated pass‐through “2G Enterprises”
DC 755 superconducting rock magnetometer
(SRM), while k was measured using a Bartington
magnetic susceptibility meter equipped with probe
MS2C and mounted in‐line with the SRM trans-
lating system. For the NRM measurements, we
specify that the half‐width of the response function
of the three orthogonal Superconducting Quantum
Interference Devices (SQUID) sensors of the SRM
system varies between ca. 4.1 cm and ca. 6.7 cm
for the transverse (X and Y axes) and the axial
(Z axis) SQUID pick‐up coils, respectively. It is
Table 1. Location of the SVAIS and EGLACOM Cores
Core Latitude Longitude Water Depth (m) Length (cm)
SV‐01 74° 58′2.82″13° 55′33.00″1813 278
SV‐02 75° 13′42.42″14° 35′57.60″743 641
SV‐03 75° 13′21.12″14° 37′14.94″761 642
SV‐04 74° 57′25.50″13° 53′58.32″1839 303
SV‐05 75° 06′42.18″15° 13′18.42″713 632
SV‐06 76° 05′39.72″17° 43′31.92″303 176
EG‐01 76° 06′12.08″13° 37′37.48″1069 220.5
EG‐02 75° 12′54.44″13° 04′35.26″1722 305.5
EG‐03 75° 50′36.92″12° 58′21.23″1432 291.5
EG‐04 74° 51′53.78″16° 05′36.02″374 105.5
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
4of24

well known that the different shape and widths of
the response function curves of the three SQUID
pick‐up coils may result in fictitious effects on the
paleomagnetic data, such as inclination shallowing
or steepening [Roberts, 2006]. In our measure-
ments, these spurious effects were corrected directly
by the measuring software, by compensating the
negative regions on the edge of the SQUID
response functions for the X and Y axes and the
broader width of the SQUID response function
along the Z axis. The computed paleomagnetic data
are therefore truly independent every ca. 5 cm and
free from fictitious effects that may arise from
uncompensated raw magnetic moment data. More-
over, we took particular care in avoiding any dis-
turbance effects that may be introduced during the
coring, cutting and sampling procedures and could
result in remanence deflections due to plastic
deformation of the soft sediments. In this study, we
adopted a conservative approach, and disregarded
the paleomagnetic data for ∼5 cm at both ends of
each u‐channel and stratigraphic gap.
[9]After measuring the magnetic susceptibility, the
NRM was progressively subjected to alternating
field (AF) demagnetization in nine steps up to a
maximum peak field of 100 mT (steps: 0, 10, 20,
30, 40, 50, 60, 80, 100 mT), by translating the
samples through a set of three orthogonal AF
demagnetizing coils in‐line with the SRM, with
NRM vectors measured after each demagnetization
step.
[10]After each NRM demagnetization cycle, an
anhysteretic remanent magnetization (ARM) was
imparted on each u‐channel. For producing the
ARM we used an in‐line single‐axis direct current
Figure 2. Lithologic logs and AMS
14
C calibrated ages (red arrows) of the analyzed cores. The present study mostly
refers to the Holocene interval of the sampled sequences, which consists of bioturbated and crudely stratified silty‐
clays with sparse ice rafted debris in the lower part of the sequence. The stratigraphic sequences of the cores collected
from the continental slope appear continuous. Conversely the stratigraphic sequence of core SV‐06, collected from the
continental shelf (see Figure 1) is characterized by two distinct stratigraphic breaks (hiatuses) at depths of 102 (before
1900 yr BP) and 123 cm below seafloor (at 8200 yr BP).
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
5of24

Table 2. AMS
14
C Dating and Calibrated Dates Using Software Calib 6.0
a
Core Lab Ref.
Depth
(cm bsf) Sample Type Description Process
Raw
AMS
14
C
Age
Error ∂13C
Calibrated yr
BP ± 1s
Cal. yr BP
Applied to the
Age Model
EG‐01 OS‐78409 3 Sediment powdered sediment OC 4830 35 −22.38 4890–5046 4968
OS‐78452 102 Sediment powdered sediment OC 28900 190 −24.47 32428–33156 32792
OS‐78453 192 Sediment powdered sediment OC 36700 310 −24.76 41084–41630 41357
EG‐02 OS‐78387 30 Foraminifera Benthic + planktonic HY 4570 130 −25 4501–4829 4665
OS‐78389 90 Foraminifera benthic + planktonic HY 9460 180 0 10001–10469 10235
OS‐78383 182 Forams and
Pteropods
benthic + plankt. + pterop. HY 12100 180 1.41 13300–13662 13481
EG‐03 OS‐78385 90.5 Foraminifera benthic + planktonic HY 4910 120 −25 4957–5279 5118
OS‐78382 160 Foraminifera benthic + planktonic HY 8590 130 0.01 8980–9314 9147
OS‐78324 230.5 Foraminifera benthic + planktonic HY 9740 80 0.73 10421–10595 10508
SV‐04 OS‐77682 0 Foraminifera Nps HY 1100 25 0.44 558–630 594
OS‐77683 25 Foraminifera Nps HY 4000 30 0.83 3840–3952 3896
OS‐82685 62 Foraminifera mixed planktonic HY 7110 30 0.5 7481–7557 7519
OS‐77684 73 Foraminifera Nps HY 7880 45 0.5 8205–8323 8264
OS‐77685 79 Foraminifera Nps HY 8180 35 0.33 8500–8616 8558
OS‐82686 99 Foraminifera mixed planktonic HY 8690 30 −0.44 9222–9362 9292
OS‐82687 134 Foraminifera benthic + planktonic HY 9790 30 0.64 10525–10591 10557
OS‐82688 187 Foraminifera mixed planktonic HY 12050 40 0.09 13328–13450 13388
OS‐77686 304 Foraminifera Nps HY 21800 100 −0.07 25197–25679 25438
SV‐06 OS‐77734 0 Foraminifera benthic + planktonic HY 620 30 −1.22 125–246 186
OS‐77736 60 Foraminifera benthic + planktonic HY 2070 25 −1.11 1500–1598 1549
OS‐77737 83 Foraminifera benthic + planktonic HY 2390 30 −1.2 1869–1970 1920
OS‐77738 123 Foraminifera benthic + planktonic HY 6770 45 −0.22 7161–7264 7213
OS‐77739 124 Mollusc bivalve fragment HY 7800 50 −0.42 8129–8276 8202
OS‐77740 136 Mollusc bivalve fragment HY 8990 60 1.57 9492–9637 9565
a
Abbreviations: bsf: below sea floor; Nps: Neogloboquadrina pachiderma sx; OC: organic carbon; HY: hydrolysis.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
6of24

(DC) coil coupled with the AF coils. We applied
axial 0.1 mT bias DC field and symmetric AF peak
of 100 mT along the Z axis, and translated the
u‐channel through the AF and DC coil system at a
constant speed of 10 cm/s, that is the lowest speed
allowed by the software running the measurements.
This has an effect on the efficiency of the AF
demagnetization and the intensity of the produced
ARM [Sagnotti et al., 2003; Brachfeld et al., 2004].
The adopted procedure equals an AF decay rate
of ca. 67 mT/half‐cycle and results in the highest
ARM intensity achievable with the employed
instrumental setting and management software
[Sagnotti et al., 2003]. From the AF demagnetiza-
tion curves we computed the median destructive
field (MDF) of the NRM (MDF
NRM
) and of the
ARM (MDF
ARM
), which are both almost single‐
component magnetic remanences. The MDF is
defined as the value of the peak AF necessary to
reduce the remanence intensity to half of its initial
value.
4. Results
4.1. Rock Magnetism
[11]The stratigraphic trends of the rock magnetic
parameters are shown in Figure 3. The low‐field
magnetic susceptibility (k) and the ARM intensities
mostly depend on the concentration of ferrimag-
netic minerals. However, these two concentration‐
dependent rock magnetic parameters carry different
information. The magnetic susceptibility values are
determined by the contribution of all the rock
forming minerals, in proportion to their relative
abundance and specific magnetic susceptibility.
The ARM is instead primarily sensitive to the
concentration of fine, single‐domain (SD), ferri-
magnetic grains [King et al. 1982; Maher, 1988].
In the studied cores, the concentration‐dependent
magnetic parameters show values oscillating in a
narrow range of variability especially for the
Holocene interval (Figure 3). The magnetic sus-
ceptibility for the cores from the continental slope
(SV‐04 and the EGLACOM cores) fluctuates
between 20 and 50 (×10
−5
SI), with an average
value between 30 and 40 (×10
−5
SI), whereas it
keeps distinctly lower values in the core from the
continental shelf (SV‐06), where the magnetic
susceptibility profile is remarkably flat around an
average value of 13 × 10
−5
SI. Low magnetic
susceptibility values are related to the composition
of the terrigenous fraction containing diamagnetic
minerals (mainly quartz and feldspars) and organic
rich carbonate rocks deriving from the Mesozoic
sequences of Svalbard, like the Agardhfjellet
Formation [Sigmond, 1992]. In particular, in core
SV‐06 the homogeneously low k values in the upper
130 cm can be related to the abundant biogenic
fraction including foraminiferas, nannofossils, dia-
tomeas, pteropods, ostracods with large bivalve
shells. A larger variability in magnetic susceptibility
values is observed in the pre‐Holocene intervals of
the SV‐04 and EG‐02 cores (Figure 3). The ARM
values mostly oscillates between 0.1 and 0.3 A/m,
with a clear decreasing trend in the lower half of the
cores, which is particularly evident in the pre‐
Holocene interval of all the cores from the conti-
nental slope and in the older part of the SV‐06 core.
Both MDF
NRM
and MDF
ARM
mostly depend on the
coercivity (composition and/or grain size) of the
minerals carrying the remanence. For the cores on
the continental slope (SV‐04 and the EGLACOM
cores), the MDF
ARM
is remarkably constant
throughout the whole stratigraphic sequence, with a
mean value of 33 mT, while the MDF
NRM
is char-
acterized by a step decrease at a depth of 20–30 cm,
from a mean value of 43 mT above the step to a mean
value of 31 mT below the step (Figure 3). For these
cores, both MDF
NRM
and MDF
ARM
show mean
values and range of variability typical for magnetite
grains [Maher, 1988]. For the core on the continental
shelf (SV‐06), the MDF
NRM
and the MDF
ARM
show
similar mean values (46 mT and 47 mT, respec-
tively) and are both remarkably constant throughout
the whole sequence. Finally, the ARM/k ratio
depends on the grain size of ferrimagnetic minerals,
with higher values for finer grained (single domain)
ferrimagnetic particles and lower values for larger
(multidomain) grains. The ARM/k ratio shows for
all cores a downward decreasing trend, indicating a
corresponding increasing trend in the magnetic
minerals grain size, with values passing from ca.
1×10
3
A/m at the top to ca. 0.5 × 10
3
A/m at the
bottom for the cores on the continental slope and
from ca. 2–2.5 × 10
3
A/m at the top to ca. 0.8 ×
10
3
A/m at the bottom for the core on the shelf
(Figure 3). We conclude that the entire set of rock
magnetic data indicate limited variations in the
concentration, composition and grain size of the
magnetic minerals, with a range of variability of
the rock magnetic parameters within each core well
within the same order of magnitude. Magnetic
minerals are more abundant in the cores from the
continental slope, whereas they are less abundant in
the SV‐06 core from the continental shelf. The
MDF parameters show values typical for magnetite
assemblages in the cores from the continental
slope, whereas they likely indicate the presence of
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
7of24

Figure 3
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
8of24

an additional magnetic component of higher coer-
civity in the core from the continental shelf. As
discussed below, the stratigraphic trends of some
rock magnetic parameters can be closely matched
between cores and, together with paleomagnetic
properties of the Holocene intervals, they can
contribute to define a high‐resolution correlation
between cores. In Figure 4 we show the correlation
of the ARM stratigraphic trends for the analyzed
cores. For high‐resolution core correlation and
dating, all stratigraphic depths have been correlated
to depth of core SV‐04, which is the core with the
highest number of available AMS
14
C calibrated
ages.
4.2. Paleomagnetism
[12]The sedimentary sequence is characterized by
excellent paleomagnetic properties. After removal
of a viscous low coercivity remanence component
at AF peaks of 10–20 mT, the paleomagnetic
directions remain remarkably stable, with demag-
netization vectors aligned along linear paths in
orthogonal vector diagrams (Figure 5). This
behavior allows precise identification of the char-
acteristic remanent magnetization (ChRM), whose
direction was computed by principal component
analysis [Kirschvink, 1980] on the individual linear
demagnetization paths, generally in the 10–60 mT
Figure 4. Correlation of the stratigraphic trends of anhysteretic remanent magnetization (ARM) for the analyzed
cores. In the correlation procedure, all data have been transferred to the stratigraphic depth of core SV‐04, which
is the core with the highest number of available AMS
14
C calibrated ages (see Table 2 and Figure 2). The ARM
curves of the SV‐04 and EG‐02 cores match closely, with a correlation coefficient R = 0.94. The correlation looks
also good for the SV‐04 EG‐03 and SV‐04 EG‐01 pairs, with R = 0.80 and 0.67 respectively, whereas it is poor for
the pair SV‐04 SV‐06. The core SV‐06, however is characterized by a lower content of magnetic minerals, as
indicated also by the magnetic susceptibility values (see text and Figure 3) and the correlation between the SV‐04 and
SV‐06 cores was mostly based on the radiometric ages and paleomagnetic data.
Figure 3. Downcore variation of the main rock magnetic parameters measured for the analyzed cores. For each core,
the plots show the stratigraphic trend of the intensity of the ARM after demagnetization in 20 mT AF, the magnetic
susceptibility (k), the ARM/k ratio, the MDF
NRM
and the MDF
ARM
values. The horizontal dashed lines indicate
u‐channel breaks. Lithologic logs and symbols as in Figure 2. See text for discussion.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
9of24

or 10–80 mT AF demagnetization step intervals.
The paleomagnetic results for the analyzed inter-
vals are shown in Figure 6. The maximum angular
dispersion (MAD) is generally very low (<2°) in
the homogeneous fine‐grained sediments, which is
particularly valuable for PSV studies, whereas it
reaches higher values (but less than 10°) for the
lower intervals of cores SV‐04, EG‐01 and EG‐02,
characterized by variable and coarser‐grained
sediments (Figure 6). Since the cores were not
azimuthally oriented, the ChRM declination of
each u‐channel has been arbitrarily rotated to align
the mean value of the uppermost u‐channel section
with true north, and to line up the declination trends
and values across consecutive u‐channel sections.
The ChRM inclination shows limited oscillations
with arithmetic mean values around 70–80°, that
are slightly shallower than the value expected at
about 75° N latitude, where geometric considera-
tions imply a geomagnetic axial dipole inclination
value of 82.4°. The variation in the ChRM incli-
nation values is less pronounced in the homoge-
neous silty clays of the Holocene intervals (with
arithmetic mean ChRM inclination values of 75–
78° for all cores), whereas it markedly increases for
the coarser grained (ice rafted debris‐rich) sedi-
ments of the lower intervals of the cores. A clear
decreasing trend in ChRM inclination values is
evident in the lower half of core EG‐02 and is most
likely due to lithological factors (Figure 6).
4.3. Relative Paleointensity
[13]The NRM intensity may reflect the strength of
the geomagnetic field during the time of the
acquisition of the remanence but it also depends on
the concentration of the natural remanence‐carrying
minerals. Provided that the basic requirements of a
Figure 5. Representative NRM demagnetization orthogonal vector diagrams [Zijderveld, 1967] for selected speci-
mens subjected to AF demagnetization: open and closed symbols represent projections onto vertical and horizontal
planes, respectively. The demagnetization data have been visualized and analyzed using the Remasoft program
[Chadima and Hrouda, 2006].
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
10 of 24

Figure 6. Downcore variation of the paleomagnetic properties of the analyzed cores. For each core, the plots show the
stratigraphic trend of the intensity of the natural remanent magnetization (NRM), ChRM declination and inclination and
maximum angular deviation (MAD). The horizontal dashed lines indicate u‐channel breaks. The vertical red dashed line
in the ChrM inclination plot indicates the value expected using the geocentric axial dipole (GAD) model. Lithologic logs
and symbols as in Figure 2.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
11 of 24

substantial uniformity in lithology and in concen-
tration, composition and grain size of the magnetic
minerals are met [King et al., 1983; Meynadier
et al., 1992; Tauxe, 1993; Valet and Meynadier,
1998; Valet, 2003; Tauxe and Yamazaki, 2007],
curves of relative paleointensity (RPI) variation are
generally reconstructed by normalizing the NRM
intensity for an opportune concentration‐dependent
rock magnetic parameter. To estimate RPI varia-
tion, we normalized the NRM remaining after
demagnetization in 20 mT AF (NRM
20mT
)by
magnetic susceptibility (k) and by the ARM
intensity left after demagnetization in 20 mT AF
(ARM
20mT
). Both methods resulted in a similar
pattern (Figure 7) and therefore support a general
coherency between the two normalization proce-
dures. In particular, the two normalized curves
match closely for the upper part of all the cores
from the continental slope. We notice that the low
magnetic susceptibility values measured in the
SV‐06 core from the continental shelf may result
in unreliable oscillations in the NRM
20mT
/k curve
(Figure 7). Therefore, for all the cores we used the
NRM
20mT
/ARM
20mT
curves as the preferred RPI
proxy.
5. Discussion
[14]As formerly anticipated, in this study we limit
our analyses to the Holocene interval of the sam-
pled sequences. This choice relies on three main
factors:
[15]1. The Holocene interval is characterized by a
homogeneous fine‐grained lithology and a sub-
stantial magnetic homogeneity, as indicated by the
rock magnetic parameters. This represents the
ideal condition for continuous measurements on
u‐channel samples [see Roberts, 2006].
[16]2. The paleomagnetic data for the Holocene
may be correlated to the existing high‐resolution
PSV and RPI reference curves from stacking of
regional paleomagnetic data or from global geo-
magnetic models.
[17]3. The Holocene interval is also characterized
by extremely well defined ChRM directions, with
MAD values below 2° (Figure 6), which are
therefore particularly suitable for PSV reconstruc-
tions and for high‐resolution correlation with the
available coeval reference PSV curves.
[18]Keeping into proper account the constraints
provided by the available AMS
14
C dates, we tried
to match the paleomagnetic record for each of the
analyzed cores to the PSV and RPI variations
expected at the cores location according to the
global geomagnetic model CALS7K.2 [Korte and
Constable, 2005] and to the closest Holocene
PSV and RPI regional stack curves. For this
purpose, we used the PSV and RPI stacks from
7 Fennoscandian lakes (FENNOSTACK and
FENNORPIS of Snowball et al. [2007]) and the
PSV stack from 3 British lakes (UK PSV stack of
Turner and Thompson [1981, 1982]) (Figure 8).
[19]These regional PSV stack records have been
relocated to the EGLACOM and SVAIS core sites
via the virtual geomagnetic pole (VGP) method
[Noel and Batt, 1990]. In this method, the geo-
magnetic field is modeled by an inclined geocentric
dipole and the remanence direction measured at a
given site is converted to the correspondent direc-
tion observed at a reference site via a virtual
magnetic pole. The method allows a direct com-
parison of the obtained paleomagnetic data with the
paleomagnetic declination and inclination expected
at the location of the analyzed cores according to
the UK PSV and FENNOSTACK reference curves.
The core correlation based on paleomagnetic data
(PSV and RPI) has been also adjusted and checked
keeping into account the constraints provided by the
correlation of rock magnetic parameters (Figure 4).
As a result, the PSV and RPI cross‐correlation
allows establishment of an improved age model for
the cores. The available AMS
14
C calibrated ages
have been integrated with constraints derived from
correlation with both PSV and RPI reference curves
(Figures 8 and 9) and rock magnetism (Figure 4).
The comparison of the ChRM declination records
(Figure 8a) indicate similar trends for all curves,
with larger variation in the interval between 2000
and 4000 yr BP. The VGP passed close to the cores
site location at about 2350–2400 yr BP, when the
ChRM is almost vertical (Figure 8b). A few sharp
ChRM declination swings are indicated for ages
older than 7500 yr BP; however, since they are
recorded by a few measurements on single cores it is
doubtful that they represent actual variation of the
geomagnetic field. The comparison of the ChRM
inclination records (Figure 8b) indicate also a good
agreement between the curves and a remarkable
match with the expected trend according to the
global geomagnetic model CALS7K.2. A signifi-
cant inclination shallowing was only recorded for
the second u‐channel, from the top, of the SV‐06
core, spanning around 2500 to 3500 yr BP
(Figure 8b). Similarly, the RPI records from the
EGLACOM and SVAIS cores have been visually
correlated to the available reference RPI curves
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
12 of 24

Figure 7. Downcore variation of the normalized relative paleointensity (RPI) curves NRM/k and NRM
20mT
/ARM
20mT
of
the analyzed cores. For each core the two curves match closely for the Holocene interval, except for core SVAIS‐06, due to
the low, and poorly defined, values of the magnetic susceptibility in that core. The pre‐Holocene intervals of each core are
characterized by a marked lithological variability; in these stratigraphic intervals the two normalized RPI curves tend to
show similar variations but with different values and amplitudes. Lithologic logs and symbols as in Figure 2.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
13 of 24

(CALS7k.2 and FENNORPIS) (Figure 9). A good
fit is observed between the RPI curve of each core
(but SV‐06) and the expected trend according to
the CALS7k.2 model. The RPI data indicate rela-
tive maxima at about 2500 yr BP and at 9500 yr BP
(Figure 9). RPI record of core SV‐06 appears
essentially flat for ages younger than 8500 yr BP
(Figure 9).
[20]Paleomagnetic data have been furthermore
used to reconstruct VGP paths. In Figure 10 we
show the reconstructed VGP path for the time
interval between 2000 and 5000 yr BP for cores
Figure 8. ChRM (a) declinations and (b) inclinations of the EGLACOM and SVAIS cores plotted as a function of
age and compared with the UK and FENNOSTACK PSV stack curves and with prediction from the global geomag-
netic main field model CALS7k.2 (see text for references and discussion).
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
14 of 24

SV‐04 and EG‐02. This is the period with the
larger PSV variation (see also Figure 8). About
5000 yr BP the VGP was located over the Arctic
Ocean, then a marked swing to lower latitudes is
recorded between 4000 and 3300 yr BP, which
brought the VGP over Siberia, followed by another
fast westerly swing (known as “f‐e event”in the
UK reference PSV curve [Turner and Thompson
1981, 1982]), between 2600 and 2000 yr BP
which brought the VGP over Greenland at about
2000 yr BP.
5.1. Stacking and Holocene VGP Path
[21]The Holocene paleomagnetic data from the
continental slope cores were merged in a stack
curve for declination and inclination. The paleo-
magnetic stack curve was obtained by using Fisher
statistics [Fisher, 1953] on data selected with an
age sliding window of 200 yr. In particular, starting
from 0 yr BP, the mean age of the sliding window
was progressively increased in steps of 200 yr. At
each step the Fisher statistics was computed on the
ChRM directions from all cores, whose estimated
age fall within a range of ± 100 yr relative to the
mean age. This procedure ensured a number of
data N higher than 3 for all the steps in the period
600–10000 yr BP (N values vary between 3 and 22).
Of course, the paleomagnetic stack value was not
computed for time intervals with a number of data
N less than 3 (i.e., for age younger than 600 yr BP).
Core SV‐06 was not included in the stacking for its
anomalous ChRM inclination and RPI records (see
Figures 8 and 9). Figure 11 shows the excellent
match of the SVAIS‐EGLACOM stacked ChRM
declination and inclination with the reference PSV
curves (especially the UK curve for the f‐e event
and the FENNOSTACK and CALS7K.2 for ages
older than 4000 yr BP) and the variations expected
according to the CALS7K.2 model. Analogously,
we reconstructed a RPI stack curve using the data
from the same cores, by computing the arithmetic
mean of the data falling within a sliding window of
the same spacing (200 yr). There is a remarkably
good match with the CALS7K.2 model over the
whole time period (Figure 12). The comparison
with the FENNORPIS stack indicate a remarkable
match for the last 4000 yr, and a similar trend, but
with different values, for ages older than 4000 yr
BP (Figure 12). The RPI stack points out the
occurrence of RPI maxima at 1.8, 2.4 and 8.8,
9.6 kyr BP. The younger RPI maxima matches very
well the features outlined by the FENNORPIS stack
and CALS7K.2 model. The occurrence of a RPI
high for the early Holocene was also pointed out by
the global analysis of Holocene dipole moment
variation carried out by Ohno and Hamano [1993]
and by the paleomagnetic data obtained from dif-
ferent sequences of the Canadian Arctic [Barletta
et al., 2008, 2010b], which however indicated a
Figure 9. Relative paleointensity of the EGLACOM and SVAIS cores plotted as a function of age and compared
with the FENNORPIS stack curve and with prediction from the global geomagnetic model CALS7k.2. For compar-
ison purposes, the magnetic induction values expected at the core location according to the CALS7k.2 global geomag-
netic model and the standardized RPI data of the FENNORPIS stack have been scaled so that a value of 1 was
assigned to their maximum value (see text for references and discussion).
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
15 of 24

single RPI maximum at about 8.5–9.0 krs BP. In
Figure 13, we show the Holocene VGP path
reconstructed form the EGLACOM‐SVAIS PSV
stack. The VGP path in the early Holocene
(10000–8600 yr BP) tends to describe a counter-
clockwise (CCW) loop in the “Pacific”sector of
the Arctic Ocean (Figure 13), with a VGP position
close to the Bering Strait at ca. 9000 yr BP. After a
period of low variation, between 8400 and 7000 yr
BP, with VGP mostly clustered over the “Canadian”
sector of the Arctic Ocean, another CCW loop is
then repeated in the “Pacific”sector of the Arctic
Ocean between 6800 and 5000 yr BP, with again
a VGP position close to the Bering Strait at ca.
6000 yr BP. After another period of low variation
between 5000 and 4000 yr BP, with VGP con-
fined at high latitudes in the “Canadian”sector of
the Arctic Ocean, a marked swing occurred
between 4000 and 3000 yr BP (Figure 13), which
rapidly brought the VGP position at relatively low
latitudes over northern part of western (European)
Russia. A rapid and pronounced westerly swing
then occurred between 2600 and 2000 yr BP,
which corresponds to the well‐known “f‐e”geo-
magnetic feature originally pointed out in the UK
PSV stack. Finally, from 1800 to 600 yr BP the
VGP maintained a nearly polar position, with a
limited oscillation to lower latitudes at about 1200–
1000 yr BP, when the VGP reached a position
close to the northern tip of Novaya Zemlya
(Figure 13). Overall, during the Holocene the
reconstructed VGPs oscillate between 90° and 70°.
This range of variability is larger than that expected
by the CALS7k.2 model [Korte and Mandea,
2008], but, as for the model, the VGP always
maintain within the surface projection of the inner
core tangent cylinder (TC), with the exception of
the large swing at 2.8–3.2 kyr BP when the VGP
slightly exceeded the limit of the TC region
(Figure 13). The swing to relatively low latitudes at
about 2.8–3.2 kyr BP was also pointed out in the
former Holocene global analysis of the geomag-
netic field by Ohno and Hamano [1993], though
the VGP latitude remains well within the TC in
their model. The other major swing of the recon-
structed Holocene VGP path is expressed by a fast
westerly drift of the VGP between 2.6 and 2.0 kyr
BP, which was also pointed out by both the for-
mer models of Ohno and Hamano [1993] and
Korte and Mandea [2008], and brought the VGP
position very close to the sampling sites at about
2.4 kyr BP (Figure 13).
Figure 10. Virtual Geomagnetic Pole (VGP) path reconstructed for cores SV‐04 and EG‐02 for the period 2000–
5000 yr BP. This is the time interval, during the Holocene, characterized by the larger geomagnetic variation. The
VGP path is similar for both cores and implies pronounced swings in paleomagnetic declination and inclination.
The orange dashed circle indicates the surface projection of the inner core tangent cylinder (see text for discussion).
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
16 of 24

Figure 11. Comparison of the SVAIS‐EGLACOM stacked ChRM (a) inclination and (b) declination curves with the
reference UK and FENNOSTACK PSV stack curves and with the trends expected according to the global geomag-
netic model CALS7k.2. For the stack curves, the red diamonds indicate the mean value computed with Fisher statis-
tics on data selected with a sliding window of 200 yr, and the error bars indicate the uncertainty at the 95% confidence
level.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
17 of 24

5.2. Implications for Holocene
Geomagnetic Models
[22]Finally, we analyzed the VGP scatter for the
4 cores with more than 100 data points through the
Holocene. We computed the VGP scatter value (S)
for the Holocene interval of each core, expressed as
the angular standard deviation of the VGP data
distribution [McFadden et al., 1988; McElhinny
and McFadden, 1997], both considering all the
available VGP data and by using the iterative
cut‐off method proposed by Vandamme [1994]
(S
cut‐off
). The cores are characterized by relatively
low S values, which are remarkably similar around
16° for cores SV‐04, SV‐06 and EG‐02 and slightly
lower (12°) for core EG‐03. The S
cut‐off
values are
lower and range between 7 and 14 (Figure 14).
These VGP scatter values are considerably lower
than those predicted for the latitudinal dependence
of VGP scatter by various geomagnetic field models
at such high latitudes (Figure 15). In particular, the
phenomenological model G of McFadden et al.
[1988] and McElhinny and McFadden [1997]
defines a quadratic curve fitting a set of VGP
scatter data plotted against paleolatitude and
predicts that at the latitude of the SVAIS and
EGLACOM cores the S values should be of about
21° (Figure 15). In the TK03.GAD statistical model
of Tauxe and Kent [2004] the time varying geo-
magnetic field is described as a “Giant Gaussian
Process”following Constable and Parker [1988]
(i.e., assuming that the gauss coefficients g
l
m
and
h
l
m
, except for the axial dipole term g
1
0
and in some
models also the axial quadrupole term g
2
0
, have zero
mean and standard deviations that are a function of
degree l). The TK03.GAD model predicts that VGP
distributions are circularly symmetric and the VGP
scatter increases with latitude, with S values of
about 23° when no cut‐off is applied and about 19°
with the cut‐off criterion of Vandamme [1994]
(Figure 15). Finally, Johnson et al. [2008] tried to
reconstruct the characters of the time average
geomagnetic field during the last 5 Ma on the basis
of a synthesis of paleomagnetic data collected from
various lava flows at 17 distributed locations and
8 additional regional data sets, and indicated that
the Brunhes data are compatible both with models
that predict a flat VGP dispersion with latitude
[e.g., Constable and Parker, 1988] and with
models predicting an increase in VGP dispersion
Figure 12. Comparison of the SVAIS‐EGLACOM stacked RPI normalized curve with the FENNORPIS stack curve
and with expected trends from the global geomagnetic model CALS7k.2. For comparison purposes, the magnetic
induction values expected at the core location according to the CALS7k.2 global geomagnetic model and the stan-
dardized RPI data of the FENNORPIS stack have been scaled so that a value of 1 was assigned to their maximum
value. For the stack curve the red diamonds indicate the arithmetic mean value computed on data selected with a slid-
ing window of 200 yr, and the error bars indicate the standard deviation.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
18 of 24

Figure 13
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
19 of 24

with increasing latitude, such as those discussed
above. Johnson et al. [2008] indicated that the
Brunhes data show little variation of S with latitude
and computed a mean Brunhes VGP scatter value
of 16°, which is just the value computed for three
of our cores. In any case, Johnson et al. [2008]
pointed out the need of new paleomagnetic data
from high northern latitudes to discriminate
between the different models.
[23]The paleomagnetic data collected from the
SVAIS and EGLACOM cores hence indicate that
they can be used to trace the PSV and RPI variation
occurred at high latitude sites during the Holocene
and allows a reliable correlation with existing ref-
erence curves and models. At the same time, they
indicate that the range of geomagnetic field varia-
tion, as expressed by VGP dispersion during the
same time interval, has been relatively low and
comparable to that observed at low‐latitude sites
Figure 14. Equal area plots of Holocene VGP positions computed for the four cores (SV‐04 and 06, EG‐02 and
EG‐03) with more than 100 data points (N > 100). The small circle indicates the cut‐off angle estimated by the
Vandamme [1994] method and the red points outside such small circles indicate the data discarded according to
such cut‐off angle. For each core, we indicate the number of data selected according to the Vandamme cut‐off versus
the total number of data and the computed VGP scatter with and without the Vandamme cut‐off (S
cut‐off
and S,
respectively).
Figure 13. The Holocene VGP path reconstructed form the EGLACOM‐SVAIS PSV stack, shown in 6 time win-
dows. The orange dashed circle indicates the surface projection of the inner core tangent cylinder. The data indicate
periods of relatively low geomagnetic variation (i.e., between 7000 and 8500 yr BP) and periods of large geomagnetic
variation (i.e., between 3500 and 4000 yr BP and between 2800 and 2000 yr BP; see text for discussion).
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
20 of 24

(Figure 15). This may be partly due to the
smoothing effects associated with the acquisition of
a depositional remanent magnetization, but it sug-
gests that geomagnetic variability within the tan-
gent cylinder was no higher than elsewhere during
the last 10 kyr.
6. Conclusions
[24]The paleomagnetic properties of the EGLACOM
and SVAIS cores provide an excellent record that
allows us to:
[25]1. Reconstruct the paleosecular variation
(PSV) and the relative paleointensity (RPI) of the
geomagnetic field at high northern latitudes for the
Holocene (extension to older ages is possible but it
is hampered by the effects of lithologic changes
and the lack of PSV reference curves). We propose
new Holocene PSV and RPI reference stack curves
for the region.
[26]2. Achieve a high‐resolution correlation and
dating of the cores, with a substantial improvement
of previous age models. This is critically important
for the reconstruction of timing and rates of
paleoenvironmental changes which followed the
last deglaciation, as documented by sedimento-
logical facies and trends. This allows us to develop
a sound chronological framework for paleoclimatic
studies that are the subject of ongoing and future
researches on the same cores.
[27]3. Recognize that the VGP scatter amplitude
for the studied cores is lower than that predicted by
some geomagnetic field models. This observation
suggests that the amplitude of secular variation has
been almost independent of latitude during the
Holocene. This study provides direct evidence of
geomagnetic field dynamics over a ten thousand
year time scale at latitudes of 75°–76° N. The data
provide constraints for the geodynamo models and
do not support presumptions about an increased
geomagnetic SV within the inner core tangent
cylinder.
Acknowledgments
[28]This study has been supported by Spanish IPY projects
SVAIS (POL2006–07390/CGL) and IPY‐NICE STREAMS
(CTM2009‐06370‐E/ANT),andbyIPY‐related Italian pro-
jects OGS EGLACOM and PNRA MELTSTORM. The
authors wish to acknowledge the cooperation of captains Pedro
Luis de la Puente García‐Ganges (BIO Hespérides), Franco
Sedmak and Carmine Teta (OGS‐Explora)andtheircrew,
and of the technical staff at the UTM (CSIC, Barcelona) and
the RIMA Department (OGS, Trieste). We thank the careful
reviewers by Stefanie Brachfeld and Francesco Barletta. Their
comments and suggestions allowed us to improve considerably
the manuscript.
Figure 15. VGP scatter values (S) of the SVAIS and EGLACOM cores versus latitude, compared with the values
from the PSV database of Johnson et al. [2008] for the last 5 Ma, including standard deviation bars, and with
predictions according to the model G of McElhinny and McFadden [1997] and the model TK03.GAD [Tauxe and
Kent, 2004], computed with and without the cut‐off criterion of Vandamme [1994]. For model predictions, the
dashed lines denote 95% error bounds.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
21 of 24

References
Barletta, F., G. St‐Onge, J. E. T. Channell, A. Rochon,
L. Polyak, and D. Darby (2008), High‐resolution paleomag-
netic secular variation and relative paleointensity records from
the western Canadian Arctic: Implication for the Holocene
stratigraphy and geomagnetic field behavior, Can. J. Earth
Sci.,45, 1265–1281, doi:10.1139/E08-039.
Barletta, F., G. St‐Onge,J.E.T.Channell,andA.Rochon
(2010a), Dating of Holocene western Canadian Arctic sedi-
ments by matching paleomagnetic secular variation to a geo-
magnetic field model, Quat. Sci. Rev.,29, 2315–2324,
doi:10.1016/j.quascirev.2010.05.035.
Barletta, F., G. St‐Onge, J. S. Stoner, P. Lajeunesse, and
J. Locat (2010b), A high‐resolution Holocene paleomagnetic
secular variation and relative paleointensity stack from eastern
Canada, Earth Planet. Sci. Lett.,298, 162–174, doi:10.1016/j.
epsl.2010.07.038.
Bloxham, J., and D. Gubbins (1985), The secular variation of
Earth’s magnetic field, Nature,317, 777–781, doi:10.1038/
317777a0.
Brachfeld, S. A., G. D. Acton, Y. Guyodo, and S. K. Banerjee
(2000), High‐resolution paleomagnetic records from Holo-
cene sediments from the Palmer Deep, western Antarctic
Peninsula, Earth Planet. Sci. Lett.,181, 429–441,
doi:10.1016/S0012-821X(00)00211-9.
Brachfeld, S. A., E. W. Domack, C. Kissel, C. Laj,
A. Leventer, S. E. Ishman, I. M. Gilbert, A. Camerlenghi,
and L. B. Eglinton (2003), Holocene history of the Larsen‐A
Ice Shelf constrained by geomagnetic paleointensity dating,
Geology,31, 749–752, doi:10.1130/G19643.1.
Brachfeld, S. A., C. Kissel, C. Laj, and A. Mazaud (2004),
Viscous behavior of u‐channels during acquisition and
demagnetization of remanences: Implications for paleomag-
netic and rock‐magnetic investigations, Phys. Earth Planet.
Inter.,145,1–8, doi:10.1016/j.pepi.2003.12.011.
Chadima, M., and F. Hrouda (2006), Remasoft 3.0–Auser‐
friendly paleomagnetic data browser and analyzer, Trav.
Geophys.,XXVII,20–21.
Channell, J. E. T., and C. Xuan (2009), Self‐reversal and
apparent magnetic excursions in Arctic sediments, Earth
Planet. Sci. Lett.,284, 124–131, doi:10.1016/j.epsl.2009.
04.020.
Channell, J. E. T., J. S. Stoner, D. A. Hodell, and C. D. Charles
(2000), Geomagnetic paleointensity for the last 100 kyr from
the sub‐antarctic South Atlantic: A tool for inter‐hemispheric
correlation, Earth Planet. Sci. Lett.,175, 145–160,
doi:10.1016/S0012-821X(99)00285-X.
Constable, C. G., and R. L. Parker (1988), Statistics of the geo-
magnetic secular variation for the past 5 m.y, J. Geophys.
Res.,93, 11,569–11,581, doi:10.1029/JB093iB10p11569.
Creer, K. M., R. Thompson, L. Molyneux, and F. J. H.
Mackereth (1972), Geomagnetic secular variation recorded
in the stable magnetic remanence of recent sediments, Earth
Planet. Sci. Lett.,14, 115–127, doi:10.1016/0012-821X(72)
90090-8.
Donadini, F., M. Korte, and C. G. Constable (2009), Geomag-
netic field for 0–3 ka: 1. New data sets for global modeling,
Geochem. Geophys. Geosyst.,10, Q06007, doi:10.1029/
2008GC002295.
Donadini, F., M. Korte, and C. G. Constable (2010), Millen-
nial variations of the geomagnetic Field: From data recovery
to field reconstruction, Space Sci. Rev.,155, 219–246,
doi:10.1007/s11214-010-9662-y.
Fisher, R. A. (1953), Dispersion on a sphere, Proc.R.Soc.
London, Ser. A,217, 295–305, doi:10.1098/rspa.1953.0064.
Hagstrum, J. T., and D. E. Champion (2002), A Holocene
paleosecular variation record from
14
C‐dated volcanic rocks
in western North America, J. Geophys. Res.,107(B1), 2025,
doi:10.1029/2001JB000524.
Hulot, G., C. Eymin, B. Langlais, M. Mandea, and N. Olsen
(2002), Small‐scale structure of the geodynamo inferred
from Oersted and Magsat satellite data, Nature,416,
620–623, doi:10.1038/416620a.
Jakobsson, M., R. Macnab, L. Mayer, R. Anderson,
M. Edwards, J. Hatzky, H.‐W. Schenke, and P. Johnson
(2008), An improved bathymetric portrayal of the Arctic
Ocean: Implications for ocean modeling and geological, geo-
physical and oceanographic analyses, Geophys. Res. Lett.,
35, L07602, doi:10.1029/2008GL033520.
Johnson, C. L., et al. (2008), Recent investigations of the
0–5 Ma geomagnetic field recorded by lava flows, Geochem.
Geophys. Geosyst.,9, Q04032, doi:10.1029/2007GC001696.
King, J. W., S. K. Banerjee, J. Marvin, and Ö. Özdemir (1982),
A comparison of different magnetic methods for determining
the relative grain size of magnetite in natural materials: Some
results from lake sediments, Earth Planet. Sci. Lett.,59,
404–419, doi:10.1016/0012-821X(82)90142-X.
King, J. W., S. K. Banerjee, and J. Marvin (1983), A new
rock‐magnetic approach to selecting sediments for geomag-
netic paleointensity for the last 4000 years, J. Geophys. Res.,
88(B7), 5911–5921, doi:10.1029/JB088iB07p05911.
Kirschvink, J. L. (1980), The least‐squares line and plane and
the analysis of paleomagnetic data, Geophys. J. R. Astron.
Soc.,62, 699–718.
Korte, M., and C. G. Constable (2005), The geomagnetic
dipole moment over the last 7000 years—New results from
a global model, Earth Planet. Sci. Lett.,236, 348–358,
doi:10.1016/j.epsl.2004.12.031.
Korte, M., and M. Mandea (2008), Magnetic poles and dipole
tilt variation over the past decades to millennia, Earth Planets
Space,60, 937–948.
Korte, M., A. Genevey, C. G. Constable, U. Frank, and
E. Schnepp (2005), Continuous geomagnetic field models
for the past 7 millennia: 1. A new global data compilation,
Geochem. Geophys. Geosyst.,6, Q02H15, doi:10.1029/
2004GC000800.
Korte, M., F. Donadini, and C. Constable (2009), Geomag-
netic field for 0–3 ka: 2. A new series of time‐varying global
models, Geochem. Geophys. Geosyst.,10, Q06008,
doi:10.1029/2008GC002297.
Lisé‐Pronovost, A., G. St‐Onge, S. Brachfeld, F. Barletta, and
D. Darby (2009), Paleomagnetic constraints on the Holocene
stratigraphy of the Arctic Alaskan margin, Global Planet.
Change,68(1–2), 85–99.
Macrì, P., L. Sagnotti, J. Dinarès‐Turell, and A. Caburlotto
(2005), A composite record of Late Pleistocene relative
geomagnetic paleointensity from the Wilkes Land Basin
(Antarctica), Phys. Earth Planet. Inter.,151,223–242,
doi:10.1016/j.pepi.2005.03.004.
Macrì, P., L. Sagnotti, and R. G. Lucchi (2006), A stacked
record of relative geomagnetic paleointensity for the past
270 kyr from the western continental rise of the Antarctic
Peninsula, Earth Planet. Sci. Lett.,252,162–179, doi:10.1016/
j.epsl.2006.09.037.
Macrì, P., L. Sagnotti, J. Dinarès‐Turell, and A. Caburlotto
(2010), Relative geomagnetic paleointensity, excursions
and the Brunhes‐Matuyama precursor as recorded in a sedi-
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
22 of 24

ment core from Wilkes Land Basin (Antarctica), Phys. Earth
Planet. Inter.,179,72–86, doi:10.1016/j.pepi.2009.12.002.
Maher, B. A. (1988), Magnetic properties of some synthetic
sub‐micron magnetites, Geophys. J. R. Astron. Soc.,94,
83–96.
McElhinny, M. W., and P. L. McFadden (1997), Palaeosecular
variation over the past 5 Myr based on a new generalized
database, Geophys. J. Int.,131, 240–252, doi:10.1111/
j.1365-246X.1997.tb01219.x.
McFadden, P. L., R. T. Merrill, and M. W. McElhinny (1988),
Dipole/quadrupole family modelling of paleosecular varia-
tion, J. Geophys. Res.,93,11,583–11,588, doi:10.1029/
JB093iB10p11583.
Merrill, R. T., M. W. McElhinny, and P. L. McFadden (1996),
The Magnetic Field of the Earth, 531 pp., Academic, San
Diego, Calif.
Meynadier, L., J.‐P. Valet, R. Weeks, N. J. Shackleton, and
V. L. Hagee (1992), Relative geomagnetic intensity of the
field during the last 140 ka, Earth Planet. Sci. Lett.,114,
39–57, doi:10.1016/0012-821X(92)90150-T.
Nilsson, A., I. Snowball, R. Muscheler, and C. B. Uvo (2010),
Holocene geocentric dipole tilt model constrained by sedi-
mentary paleomagnetic data, Geochem. Geophys. Geosyst.,
11, Q08018, doi:10.1029/2010GC003118.
Noel, M., and C. M. Batt (1990), A method for correcting geo-
graphically separated remanence directions for the purpose
of archeomagnetic dating, Geophys. J. Int.,102,753–756,
doi:10.1111/j.1365-246X.1990.tb04594.x.
Nowaczyk, N. R., and M. Antonow (1997), High resolution
magnetostratigraphy of four sediment cores from the
Greenland Sea–I. Identification of the Mono Lake excursion,
Laschamp and Biwa I/Jamaica geomagnetic polarity events,
Geophys. J. Int.,131,310–324, doi:10.1111/j.1365-246X.
1997.tb01224.x.
Nowaczyk, N., and T. Frederichs (1999), Geomagnetic events
and relative paleointensity variations during the last 300 ka
as recorded in Kolbeinsey Ridge sediments, Iceland Sea,
indication for a strongly variable geomagnetic field, Int. J.
Earth Sci.,88, 116–131, doi:10.1007/s005310050250.
Ohno, M., and Y. Hamano (1993), Global analysis of the geo-
magnetic field; time variation of the dipole moment and the
geomagnetic pole in the Holocene, J. Geomagn. Geoelectr.,
45, 1455–1466, doi:10.5636/jgg.45.1455.
Olson, P., and J. Aurnou (1999), A polar vortex in the Earth’s
core, Nature,402, 170–173, doi:10.1038/46017.
Reimer, P. J., et al. (2009), IntCal09 and Marine09 radiocarbon
age calibration curves, 0–50,000 years cal BP, Radiocarbon,
51(4), 1111–1150.
Roberts, A. P. (2006), High‐resolution magnetic analysis of
sediment cores: Strengths, limitations and strategies for max-
imizing the value of long‐core magnetic data, Phys. Earth
Planet. Inter.,156, 162–178, doi:10.1016/j.pepi.2005.
03.021.
Ryan, W. B. F., et al. (2009), Global Multi‐Resolution Topog-
raphy synthesis, Geochem. Geophys. Geosyst.,10, Q03014,
doi:10.1029/2008GC002332.
Sagnotti, L., P. Macrí, A. Camerlenghi, and M. Rebesco
(2001), Environmental magnetism of Antarctic Late Pleisto-
cene sediments and interhemispheric correlation of climatic
events, Earth Planet. Sci. Lett.,192,65–80, doi:10.1016/
S0012-821X(01)00438-1.
Sagnotti, L., P. Rochette, M. Jackson, F. Vadeboin, J. Dinarès‐
Turell, and A. Winkler (2003), “Mag‐Net”Science Team,
Inter‐laboratory calibration of low field and anhysteretic
susceptibility measurements, Phys. Earth Planet. Inter.,
138,25–38, doi:10.1016/S0031-9201(03)00063-3.
Sigmond, E. M. O. (1992), Bedrock map of Norway and adja-
cent ocean areas, scale 1:3 million, Geol. Surv. of Norway,
Trondheim.
Snowball, I., L. Zillén, A. Ojala, T. Saarinen, and P. Sandgren
(2007), FENNOSTACK and FENNORPIS: Varve dated
Holocene paleomagnetic secular variation and relative
palaeointensity stacks for Fennoscandia, Earth Planet. Sci.
Lett.,255, 106–116, doi:10.1016/j.epsl.2006.12.009.
Sreenivasan, B., and C. A. Jones (2005), Structure and
dynamics of the polar vortex in the Earth’s core, Geophys.
Res. Lett.,32, L20301, doi:10.1029/2005GL023841.
Sreenivasan, B., and C. A. Jones (2006), Azimuthal winds,
convection and dynamo action in the polar region of the
planetary cores, Geophys. Astrophys. Fluid Dyn.,100,
319–339, doi:10.1080/03091920600807864.
St‐Onge, G., J. S. Stoner, and C. Hillaire‐Marcel (2003),
Holocene paleomagnetic records from the St. Lawrence
Estuary, eastern Canada: Centennial to millennial‐scale geo-
magnetic modulation of cosmogenic isotopes, Earth Planet.
Sci. Lett.,209,113–130, doi:10.1016/S0012-821X(03)
00079-7.
Stoner, J. S., J. E. T. Channell, D. A. Hodell, and C. D. Charles
(2003), A ∼580 kyr paleomagnetic record from the sub‐
Antarctic South Atlantic (Ocean Drlling Program Site 1089),
J. Geophys. Res.,108(B5), 2244, doi:10.1029/2001JB001390.
Stuiver, M., and P. J. Reimer (1993), Extended
14
Cdata
base and revised Calib 3.0
14
C age calibration program,
Radiocarbon,35, 215–230.
Tauxe, L. (1993), Sedimentary records of relative paleointensity
of the geomagnetic field: Theory and practice, Rev. Geophys.,
31, 319–354, doi:10.1029/93RG01771.
Tauxe, L., and D. Kent (2004), A simplified statistical model
for the geomagnetic field and the detection of shallow bias
in paleomagnetic inclinations: Was the ancient magnetic
field dipolar? in Timescales of the Internal Geomagnetic
Field,Geophys. Monogr. Ser.,vol.145,editedbyJ.E.T.
Channell et al., pp. 101–115, AGU, Washington, D. C.
Tauxe, L., and T. Yamazaki (2007), Paleointensities, in Treatise
on Geophysics,vol.5,editedbyG.Schubert,pp.509–563,
Elsevier, Oxford, U. K., doi:10.1016/B978-044452748-
6.00098-5.
Thompson, R. (1973), Palaeolimnology and palaeomagnetism,
Nature,242, 182–184, doi:10.1038/242182a0.
Thompson, R., and D. R. Barraclough (1982), Geomagnetic
secular variation based on Spherical harmonic and cross
validation analyses of historical and archaeomagnetic data,
J. Geomagn. Geoelectr.,34,245–263, doi:10.5636/jgg.
34.245.
Turner, G. M., and R. Thompson (1981), Lake sediment record
of the geomagnetic secular variation in Britain during Holo-
cene times, Geophys. J.,65,703–725, doi:10.1111/j.1365-
246X.1981.tb04879.x.
Turner, G. M., and R. Thompson (1982), Detransformation of
the British geomagnetic secular variation record for Holo-
cene times, Geophys. J.,70, 789–792.
Valet, J. P. (2003), Time Variations in geomagnetic intensity,
Rev. Geophys.,41(1), 1004, doi:10.1029/2001RG000104.
Valet, J.‐P., and L. Meynadier (1998), A comparison of differ-
ent techniques for relative paleointensity, Geophys. Res.
Lett.,25,89–92, doi:10.1029/97GL03489.
Vandamme, D. (1994), A new method to determine paleo-
secular variation, Phys. Earth Planet. Inter.,85, 131–142,
doi:10.1016/0031-9201(94)90012-4.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
23 of 24

Verosub, K. L. (1977), Depositional and post‐depositional
processes in the magnetization of sediments, Rev. Geophys.
Space Phys.,15, 129–143, doi:10.1029/RG015i002p00129.
Xuan, C., and J. E. T. Channell (2010), Origin of apparent
magnetic excursions in deep‐sea sediments from the
Mendeleev‐Alpha Ridge, Arctic Ocean, Geochem. Geophys.
Geosyst.,11, Q02003, doi:10.1029/2009GC002879.
Zijderveld, J. D. A. (1967), A. C. demagnetization of rocks:
Analysis of results, in Methods in Palaeomagnetism, edited
by D. W. Collinson, K. M. Creer, and S. K. Runcorn,
pp. 254–286, Elsevier, Amsterdam.
Geochemistry
Geophysics
Geosystems
G3
G3
SAGNOTTI ET AL.: HOLOCENE PSV FROM NW BARENTS SEA 10.1029/2011GC003810
24 of 24