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QUATERNARY RESEARCH
7,413-427 (1977)
The Gothenburg Magnetic Excursion
NILS-AXEL M~RNER
Geological Institute, University of Stockholm, Box 4801, S-11386 Stockholm, Sweden
September 1, 1976
The Gothenburg Magnetic Excursion in a broad sense ranges from 13,729 to .12,350
years BP and ends with the Gothenburg Magnetic Flip at 12,400-12,3~~y~~trs BP (= the
Fj%r&s Stadial in southern Scandinavia) with an equatorial VGP position in the central
Pacific. The Gothenburg Magnetic Flip is recorded in five closely dated and mutually correlated
In all five cores, the inclination is completely reversed
in
the layer rep-
Bs Stadial dated at 12,400-12,350 years BP. The cores were taken
160 km apart and represent both marine and lacustrine environments. The Gothenburg
Magnetic Flip represents the shortest excursion and the most rapid polar change known at
present. It is also hitherto the far best-dated paleomagnetic event. The Gothenburg Mag-
netic Excursion and Flip are proposed as a standard magnetostatigraphic unit.
INTRODUCTION
The short Late Glacial period of reversed
polarity known as the Gothenburg “Re-
versal” (Miirner er .ul., 1971) or the
Gothenburg Magnetic “Flip” (Morner
and Lanser, 1974) was first found in a core
from Sweden. The discovery was an-
nounced in 1971 (Miimer et al., 1971).
The complete results were presented at
the INQUA IX Congress in New Zealand
in 1973 (Morner, Ed., 1973, 1976). Addi-
tional samples from Sweden, Canada, and
the Atlantic were measured and a summary
report was given in 1974 (Miirner and
Lanser, 1974). The Canadian and Atlantic
results are being published separately
(Morner and,Lanser, 1975; Miirner, 1976a,
d) and a monographic report on the Swedish
results is in preparation. In the summary
paper (Momer and Lanser, 1974), 15 local-
ities are listed where “the chronological con-
trol indicates that the recorded reversals re-
fer to the same event or excursion” and 11
additional localities where “the dating is not
sufficiently precise for direct correlations .”
Recently, the same magnetic anomaly
seems to be well recorded in two Canadian
lake sequences (LaSalle, personal com-
munication).
A comprehensive report on the Gothen-
burg Magnetic Excursion and Flip was
given at the XVI IUGG General Assembly
in Grenoble, 1975 (Momer, 1975d). The
Gothenburg Magnetic Excursion was re-
ported to consist of two parts: (1) a period
of irregular magnetism from 13,750- 12,400
years BP, including at least one Canadian
record of fully reversed polarity (the Port
Dover Excursion), and (2) the Gothenburg
Magnetic Flip from 12,400- 12,350 years BP
(= the Fjaras Stadial), repeatedly re-
corded in Swedish cores as fully reversed
inclination with a corresponding VGP cen-
ter in the central equatorial Pacific.
The Gothenburg Flip is so short and
changes so rapidly that it can only be
recorded in detailed analyses of sediments
with a high sedimentation rate. For reliable
mutual correlations, the dating control must
be unusually accurate. Sweden offers good
possibilities of establishing a very good
dating control, thanks to the glacial stadial/
interstadial chronology, the varve chronol-
ogy, the pollen zonation, and the accessa-
ble uplifted marine deposits, besides nor-
mal radiocarbon dating (Fig. 1).
METHODS
All cores were taken with the Swedish
foil piston corer giving undisturbed (Fig. 2)
413
Copyright 0 1977 by the University of Washington.
All rights of reproduction in any form reserved. ISSN 0033.5894
414
NILS-AXEL MORNER
5800
8000
9700
10000
FIG. 1. Chronostratigraphy of southem Scandinavia. (1) global Epochs; (2) local north European
periods; (3) subdivision of the Postglacial and Late Glacial with (4) corresponding zonation according to
Nilsson (l%l) and Mbmer (1971a), respectively: (5) pollen zonation according to Jessen (1935); (6) radio-
carbon dates (Nilsson, 1964; Mbmer, 1%9); (7) varve dates (Miimer 1%9, 1975a, 1976b); (8) sub-
division of the Kattegatt sediments (Mbmer Wlc, 1975e); and (9) main Baltic stages.
and continuous cores of up to 11 mm in
length. The corer and cores were carefully
oriented. The 11 m cores, after a brief
field examination, were cut up in 1.5 m
lengths, wrapped up in plastic foils, put into
plastic tubes, and transported to the labora-
tory, where they were subjected to a careful
stratigraphic analysis and finally cut up in
3.6 cm pieces that were sucked into plastic
containers without affecting the sediment
structures. The samples were measured by
Dr. J. Lanser on astetic magnetometers
at the Paleomagnetic Laboratory of Utrecht
University. All samples were treated with
progressive demagnetization in alternating
fields of up to 2006 Oe peak values (50
Hz). A detailed report. on the magnetic
properties and the various analyses applied
is in preparation by Lanser. In general,
demagnetization in 200 Oe does not change
the results to any significant degree. All
VGP calculations were made on the Digico
magnetometer system of the Stockholm
Paleomagnetic Laboratory.
DISCUSSION
Stratigraphically, the Gothenburg Mag-
netic Flip ,falls in the FjLPs Stadial
or zone Fj in Miimer’s climatic zone sys-
tem (Morner, 197la), dated at 12,400-
12,350 years BP (Morner, 1969, 197lb).
The ice marginal position during the
Fjaras Stadial is well established (Fig. 3),
at least for the west coast of Sweden
(Morner, 1969). The Fjlras Stadial
represents the end of the classical Oldest
Dryas biozone (Morner, 1969, 197la, b).
The radiocarbon-dated malacological changes
on the west coast can be correlated with
the ice marginal fluctuations and the climatic
zones (Morner, 1969, p. 167). Figure 1
illustrates the chronostratigraphical control
of south Scandinavian sediments. The
Gothenburg Magnetic Excursion in a broad
sense embraces zones Vi, LB, AG and Fj,
i.e., the time 13,750-12,350 years BP.
In southern Sweden, several sections
(Fig. 3) have been analyzed paleomagneti-
tally specifically for the study of the
GOTHENBURG MAGNETIC EXCURSION
315
FIG. 2.
X-ray photography of parts of cores B 911 and 913 taken when the cores were still in the
plastic tubes. Sampling with the Swedish foil piston corer gives quite undisturbed samples and con-
tinuous cores of up to 11 m long.
Gothenburg Magnetic Excursion and Flip.
Cores B 890, 891, and 893 are discussed
separately (Morner, 1975b, c, e). B 664
refers to clays at the interlobate moraine
of the ktgelholm Phase (Morner, 1969)
and represents the base of the Vintapper
Interstadial (13,750 BP). The other cores
are the important ones for the discussion
of the Gothenburg Magnetic Excursion and
Flip.
Cores B 873, 901, 897, 896, and 892 all
have a well-established chronology that
enables close correlations on grounds other
than the magnetic results. They all include
deposits of the Fjaras Stadial: in cores
B 873, 901, 897, and 986, these beds are
416
NILS-AXEL MGRNER
SOUTHERN SWEDEN
883
FIG. 3. Position of the ice margin in southern Sweden during the Fjib& Stadial dated at 12,400-
12,350 years BP, and location of cores and sections paleomagnetically analyzed specifically for the study of
the Gothenburg Magnetic Flip and Excursion.
directly correlated on stratigraphic and
climatic grounds with the ice marginal posi-
tion along the Fj5rAs line (Fig. 3); in core
B 892, this layer is easily identified as the
top layer of the Oldest Dryas pollen zone.
In the marine deposits of cores B 873,
901, 897, and 896, the Gothenburg Mag-
netic Flip is associated with a characteristic
layer of clayey sandy silt with abundant
molluscs and ice rafted material including
pebbles with attached barnacles and pieces
of Cretaceous chalk and chert from Skine-
Denmark (suddenly appearing in this layer
and not being found on the Swedish west
coast below this level). This layer serves as
a regional marker bed in the marine deposits
along the Swedish west coast (Fig. 4). It
represents a regional environmental change
in the Kattegatt (Miirner, 1969, pp. 169,
174). Extensive exposures in clay pits indi-
cate that this layer was formed by heavy
ice rafting (and not turbidity currents) in
combination with normal setting of particles
washed into the sea. The material is therefore
suitable for paleomagnetic studies, which is
indicated by the results that show consistent
declination and inclination records in all
cores (except for the declination record
of cores B 873 and 901 which represent
an ice marginal environment, where turbid-
FIG.
4. Zonation, magnetic inclination (upper diagram), stratigraphy (middle diagram) of five Swedish
cores (location in Fig. 3), and corresponding chronology (lower diagram). The distances between the
cores are given at the top. Four cores represent a marine environment and one a lacustrine environ-
ment. In all five cores, there are short, rapid, and fully reversed inclination records exactly in Fj zone
(and only in this zone) corresponding to an equatorial mid-Pacific VGP (Fig. 9). This is known as
the “Gothenburg Magnetic Flip” (Miimer and Lanser, 1974; MBmer, 1975d). The record of the “Flip”
is reproduced, independently of lithology and environment, in exactly the same stratigraphic position in these five
-0
-5
-10
t 15
0 873 0 901 0 097 0 896
GOTHENBURG MAGNETIC EXCURSION
Magnetic Incllnatlon
m 5 Swedish COWS
0 096
417
R i “or”cd c1oy m i cioy [=I i 511t. sord m i gytt,a + i nlorme mor4er bed lzone F,,
FJ
ZO”C2S YD AL
?-dates 950 800
varws 950 800
time xldyrs BP Ill(‘l’(l)lllll/(‘l I
10 11 12 13 1c
cores. The middle diagram gives the zonation and stratigraphy. Ail four marine cores include a distinct marker
bed (+): a thin, silty-sandy, interclay layer with abundant molluscs and ice rafted material (some pebbles
with attached barnacles) that, for the first time in the Late Glacial sediments on the Swedish West Coast, include
Cretaceous chert and chalk from Skilne-Denmark, and corresponds to the ice marginal position along the Fjw
line (Fig. 3). Besides this marker bed (+), cores B 873-901 possess characteristic glacial environmental changes
(varvediice marginaYunvarved/varved), and cores B 897 and B 8% possess characteristic maiacological changes be-
tween arctic (A), boreo-arctic (Ab), and arctic-boreal (AB) faunas (Momer, 1%9, p. 167). A distinct cli-
matic deterioration is recorded in the Fj zone of core B 896. Three samples of molluscs are radio-
carbon dated (x) from the localities of cores B 897 and 8% (they are not corrected for r3C deviation and
the “sea effect,” however). Core B 892 exhibits characteristic stratigraphic changes: 557 glacial varves
of the LB and Vi-max zones, a sudden onset of the organic production at the LB/AG boundary,
and three layers of increased washing in of alluvial Dryas Clay (Fj, OD, YD). The pollen diagram
(Pinus, Betula, NAP) refers to Bergland’s (1971) analysis from the core B 892 locality. The Fj zone
(with increased clay content and reversed inclination) (represents the topmost part of the Oldest Dryas
pollen zone with a corresponding cold peak registered in the Pinus peak and Betula low. The diagram
at the base gives the zonation, the duration of the zones according to the radiocarbon and varve
chronologies, respectively, and the age in years BP.
418
CORE B 873
NILS-AXEL MijRNER
-I-
z
,
--
AL
OD
--
80
z
AG
I
14
c
FIG. 5. Paleomagnetism of core B 873 (taken in the Botanical Garden of Gothenburg), a 14.5 m
stratal sequence ranging from about 12,500 to 8500 years BP (redrawn from Momer, 1973a, PI. 1).
AC cleaning (200 Oe) does not change the NRM values to any significant degree (Hospers et al.,
1973). The investigation of this core is fully described by Miimer et al. (Miimer, Ed., 1973 and 1976).
The paleomagnetic data record a period of reversed polarity in layers 12-13 (=zones Fj-AG) known
as the Gothenburg Event or Excursion. The bedding planes dip southwest. Declination swings around
270” (instead of 360” as is the case in Figs. 6-8). Turbidity currents must at least have affected
the deposition of layers 12 and 13.
ity currents are to be expected, and are also Core B 873 is the original core taken in
indicated by the fossils).’ marine deposits in the Botanical Garden
1 It should be noted that the danger of possible
of Gothenburg in 1970 (Morner et al.,
mechanical disturbance of the magnetic record in the
1971; Hospers
et
al., 1973; Morner, 1973).
varves is higher than commonly assumed. Recent
A total of 123 samples were analyzed
repetitive sampling of thick varves in the Stockholm
with 1 sample in the Fj zone and 11 in the
area (Miirner and Kukla, in preparation; Momer,
1976e) has demonstrated large inconsistencies in the
AG zone (Fig. 5). The bedding planes
orientation of the magnetic vector in a single year
show a clear dip to the southeast. The
layer. Declination values, in particular, are strongly
declination swings around 270”, instead of
affected. The disturbance is due to a mechanical
360” as is the case in cores B 890, 892,
contortion of the thick and sandy
basal
parts of the
896, and 897, which seems to be the effect
varves. To produce an apparent record of Gothenburg
Magnetic Flip, however, any mechanical disturbence
of some orientation error, the sediment
would have to change the original dip of strata by
dip, or turbidity currents. Turbidity cur-
at least 90”. The bedding planes in Cores B 873 and
901 and the extension and appearance of the marker versed inclination record of the Gothenburg Magnetic
bed exposed in clay pits close to Cores B 8% and Flip is, therefore, considered to record true geomag-
897, do not show any such deformation. The re- netic field behavior.
GOTHENBURG MAGNETIC EXCURSION
419
rents must at least have affected the
deposition of layers 12 and 13 (and may
explain the declination values in B 873
and 901 that do not agree with those found
in the other cores; the inclination values
are consistent in all cores). In order to
duplicate the original record and prove the
validity of the “Gothenburg Reversal” of
Morner et al. (1971), a new core, B 901,
was taken 60 cm from the old bore hole of
B 873. The stratigraphic units were easily
identified. A total of 78 samples were
analyzed (ranging from the AG zone to the
base of the OD zone) with 6 samples in
the Fj zone and 25 samples in the AG zone
(Lanser , in preparation).
Core B 897 corresponds to the Tors-
garden clay pit described by Miirner
(1969, p. 167) which includes a radiocarbon
date from the top of the LB zone. A total
of 49 samples were analyzed, with 4 samples
in the Fj zone and 7 samples in the AG
zone (Fig. 6).
Core B 896 corresponds to the Agard
clay pit-the type locality of the Agkd
Interstadial-described by Miimer (1%9,
p. 168); it includes two radiocarbon dates
from the AG zone and clear malacological
indications of a subsequent climatic de-
terioration representing the Fjk&s Stadial
(Miirner, 1969, 1971b). Two additional
dates were recently made of shells from
the AG zone: 12,700 + 150 years BP (outer
fraction of sample l), 13,040 -+ 155 years
BP (inner fraction of sample 1) and 12,770
it 190 years BP (sample 2), with 13C correc-
tion corresponding to 12,340, 12,745, and
12,505 years BP, respectively. A total of
54 samples were analyzed, with 1 sample
(No. 52) in the Fj zone and 51 in the AG
zone (Fig. 7).
Core B 982 corresponds to the lacustrine
sequence from Bjiirkerods Mosse, closely
analyzed for pollen by Berglund (1971),
which exhibits the Oldest Dryas/BGlling
pollen zone boundary, i.e., the Fjaras/
Boiling (Fj/Bb) boundary in Momer’s
system (1971a). A total of 181 samples were
analyzed (Fig. 8), with 3 samples (57-59)
in the Fj zone and 20 samples in the AG
zone (60-79). Below the AG zone, there are
557 varves representing the LB zone (varves
210-557 and the Vi zone (varves l-210).
Figure 4 gives the inclination records,
the zonation, the lithology, and the chrono-
stratigraphic characteristics of the five
cores. It should be noted that the zonation
and correlations were established before the
magnetic results were known, in accordance
with the information referred to in the pre-
vious paragraphs. Short and rapid reversed
inclination is recorded in all five cores ex-
actly in the Fj zone (and only in this zone).
The inclination is completely reversed.
This, indeed, is good evidence of the
Gothenburg Magnetic Flip for it is recorded
in five cores with a spacing of 160 km,
includes both marine and lacustrine en-
vironments, and was correlated prior to and
on other grounds than the magnetic results.
This is the fundamental basis for the es-
tablishment of the Gothenburg Magnetic
Flip and for its global correlations (Miimer
and Lanser, 1974). The mutual correlations
between the five cores, the close dating
control, and the individual magnetic records
are superior to all other records supposed
to represent a magnetic excursion at about
13,000 years BP. The Gothenburg Magnetic
Excursion and Flip are therefore proposed
as a standard magnetostratigraphic unit in
global correlations.
Recently, an even more remarkable con-
firmation of the magnetic results in figure
4 was established when the polar position
(VGP) was calculated: all the data from the
Fj zone give an equatorial VGP position
in the central Pacific (Fig. 9). Canadian
glacial clays postdating the ParisiGalt
Moraines and predating the Niagara Mo-
raines give a similar VGP (Morner, 1976d).
The same applies for some of the data of
Easterbrook (1975) when calculated to VGP
(Fig. 9). The excursion at 13 m depth in
Lake Biwa (Nakajima et al., 1973) gives a
similar VGP. Recently, samples predating
the Gschnitz Moraine in Austria have
yielded a similar central equatorial Pacific
VGP center (Morner, in preparation).
Canadian clays predating the Paris/Gait
B 897, TorsgZlrden
Declination
310 330 350 0 10 3
I , . , I
0.
7
Inclination
-50 -30 0 +20 40 +60 l BO
I ’ . I 1 . ’
Intensity
rnP 1nP
.- I”
I----
FIG. 6. Paleomagnetism of core B 897. The stratigraphy and dating is discussed by Miimer (1969, p. 167). Sample 10 in the Fj zone
exhibits a fully reversed inclination corresponding to an equatorial mid-Pacific VGP position (2” S Lat., 164” E Long.).
B 896,
Agdrd
(Sweden)
Declination
310 330 350 0 20 LO
T
I I . 1 . 1
-
86
FJ
-
T
inclination
-40 -20 0 l 20 'LO l 60 l 60
I I . ’ 1 ’ ’
/
intensity
, , , , ( 1’y , , , , , I’pr6 ]
FIG. 7. Paleomagnetism of core B 8%. taken at the type locality of the Aglrd Interstadial (Mrner 1969, p. 168). Shells from the i(G zone
are radiocarbon dated at 12,575 2 235 years BP and 12,930 ? 270 years BP. Sample 52. right in the Fj zone, exhibits a fully reversed
inclination corresponding to an equatorial mid-Pacific VGP (9” N Lat.. 186” E Long.). The mean values of the AG zone give VGP
positions in the Pacific at about latitude 43-W’ N.
422
NILS-AXEL MGRNER
8 892
Declination Inclination
iuLoww Intensity
3”.’ VI-5
FIG.
8. Paleomagnetism (NRM) of core B 892 from Bjorkeriids Mosse (an overgrown lake).
The same locality has been pollen analyzed by Berglund (1971) who established a detailed pollen zona-
tion back to the layers H/I boundary corresponding to the Biilling/Oldest Dryas boundary. The layer
L/K boundary represents a sudden organic increase and corresponds to the climatic amelioration at the
LB/AG boundary. Layer L includes 5’57 varves representing the Vi zone (varves l-210) and the LB
zone (varves 210-557) and dating the free melting and onset of the sedimentation at about 13,460
years BP. Sample 57 from the middle of the Fj zone (layer I) exhibits very low intensity, which after
AC cleaning changes over to fully reversed inclination (all other samples remain normal) corresponding
to an equatorial mid-Pa&c VGP position. Samples 4 and 5 (at the top of the YD zone) exhibit
reversed declination corresponding to a low-latitude VGP in West Africa. This is known as the “Omii
Declination Departure,” is recorded in eight other cores, and is dated by varves at 150 & 10 varves
prior to the Pleistocene/Holocene boundary (Mbmer, Ed., 1976, Chap. XX; Momer, 1976c).
GOTHENBURG MAGNETIC EXCURSION
423
0 90'E 180" 9O'W 0
80
60
LO
20
0
20
LO
60 - 00
Larchmw B -60
"13s _
80 - - 80
I, I,,,,,,, ,r,,,t,, ,,,,,,I,
0 90'E 180' 9O"W 0
FIG.
9. Virtual geomagnetic pole (VGP) migration 13,700-l 1,500 years BP (zones Vi-AL) according
to Swedish data: dashed lines and hatched areas with zone letters. All Swedish records of the Gothen-
burg Magnetic Flip fall within the hatched equatorial mid-Pacific area (i.e., the reversed inclination
samples of cores B 897, 8%, and 892, and B 873 and 901 after correction of the declination values).
Open circles give VGP of localities 75, 90, 94; and 95 in Ontario (Canada). Additional data: X = VGP
of some of Easterbrook’s data from Washington (dated within 12,900-11,000 years BP), cube = VGP
according to data at the YM boundary in core Kl38 of Clark and Kennett (1973), rombs = VGP
according to Laschamp data of Bonhommet and ZSihringer (1%9), and encircled cross = VGP of the
excursion at I3 m in Lake Biwa (Nakajima et al., 1973). The data cluster around two low-latitude
regions marked by dotted circles: (1) a Pacific center, the Gothenburg Excursion and Flip at 12,90612,350
years BP ranging from the equator up to 55-60” N Lat. and including the Swedish AG and Fj
data. the Canadian Lot. 95, 90, and 94:15 data, several of Easterbrook’s data, and the Lake Biwa
datum, and (2) a southeast Pacific center, the Port Dover Excursion at about 13,300 years BP in-
cluding the Canadian Lot. 75 and l5:l data (dashed lines from this center indicate its chronological
position within the Vi zone).
Moraines, hence dating about 13,300 years
BP, give a VGP in the southeast Pacific
Ocean (Fig. 9) for which the term “Port
Dover Excursion” has preliminarily been
used (Morner, 1976d).
The magnetic records from the AG zone
give a midlatitude VGP position in the
north Pacific (Fig. 9). This position is
also valid for the Swedish east coast cores
(Mbrner, 1975b, e) and a varved clay se-
quence taken in Leningrad (Morner and
Krasnov, in preparation).
The Swedish cores discussed above all
have a very well established chronology.
However, layers of the Fjariris Stadial
are so thin that the Gothenburg Magnetic
Flip is only established in one or a few
samples per core. Core B 938, a piston
core recently taken off southeast Sweden,
is interesting in this respect (Fig. 10)
because it exhibits constantly reversed in-
clination in seven samples (the upper five
being constantly normal). The switch from
reversed to normal takes place within 7
cm in a reddish-brown clay that shows
not the slightest trace of any lithological
changes and shows, from X-ray analyses,
unchanged mineralogical composition. The
corresponding VGP position is in the
Pacific (at low and midlatitudes, respec-
tively) agreeing well with the VGP curve
in figure 9. From the stratigraphy, the
varves. and the position in the deglaciation
history, core B 938 cannot yet be more
precisely dated than about 12,800-12,000
years BP (12,400+400 years BP) which,
however, is enough to assure that the re-
versed inclination in core B 938 is a new
record of the Gothenburg Magnetic Excur-
sion (Flip).
The Fjaras Stadial lasted for about 50
years (Mbrner, 1969; 1971a, b), possibly
85 years (Morner, 1975c), which means
that the magnetic “flip” only covers some
tens of years and that the inclination
switches only took some years (cf. Momer,
1977).
During the Vi and LB zones, cores B
664, 892, and 893 (like the Canadian sam-
ples of the same age; Morner, 1976d)
u
J38
-LO.0 In
lntenstty
200 300
I I I I
2
I.
Declination , Inclination
7
FIG. IO. Core B 938 is an unoriented piston core (hence the declination is relative) taken in the Bay of Hanobukten. Intensity and
declination are measured on the Digico long core system. Inclination is measured of 12 separate samples (black rectangles). The stratig-
raphy is typical for this area of the Baltic. The change from unvarved (grey) to varved (reddish-brown) clay represents a regional climatic-
environmental change. Chronologically, the core represents a short period sometime between 12,800 and 12,000 years BP. Future varve
chronological studies will sharpen the dating control. The inclination record shows a rapid switch (within 7 cm) in the upper part of the
thick and uniform reddish-brown clay. X-ray analyses indicate that the minerology remains unchanged across the switch.
inclination represents the Gothenburg Magnetic Flip. The reversed
GOTHENBURG MAGNETIC EXCURSION
425
10,000 shift to the Canadian ArctIc
-- ------_
5 Ix normal
.-
5 Slberla 8, Slberlan Archc Ocean
5
12.350 -
s
.-
5 III $ 2 4 equatorial
* k Central Paclflc
:: iiT
.- 12,LOO ~
m P
2 G s $ the Paclflc region
2 II 0) ZiTii
f b (13.250 BP Canadian clay gives
is i - E theVGP In the SE Pacific)
13,750 .
a,
3
normal Slberla 8 Slberlan Arctlc Ocean
15,500 I - - -
(no data)
23,000
FIG. 11. Summary of the main paleomagnetic stages and the polar migration during the late Wiscon-
sin-Weichsel according to our Swedish and Canadian data. Columns: (2) radiocarbon dates in years BP;
(3) subdivision into four main paleomagnetic stages; (4) paleomagnetic characteristics; and (5) mean VGP
positions. The Gothenburg Excursion, in a broad sense (II-III), covers a period of 1400 years rang-
ing from 13,750 to 12,350 years BP, during which the VGP was in the Pacific region (in opposition
to stages I and IV).
display irregular magnetic records (Figs. 8
and 9) including some “flips” to equatorial
and low latitude VGP positions (e.g., the
Port Dover Excursion at about 13,300 years
BP). The entire Gothenburg Magnetic Ex-
cursion is therefore considered to cover a
period of 1400 years from 13,750 to 12,350
years BP (zones Vi, LB, AG, and Fj
in Scandinavia) with the VGP migrating in
the Pacific region (in opposition to the
periods before and after) and being charac-
terized by (1) a period of irregular mag-
netism from 13,750-12,400 years BP, in-
cluding at least one rapid “flip” (the Port
Dover Excursion), and (2) the rapid
Gothenburg Flip at 12,400- 12,350 years
BP, recorded as fully reversed inclination
in the Fj zone in northern Europe and cor-
responding to an equatorial VGP position
in the central pacific. This is illustrated
in Fig. 11, which is based on our Swedish
(this paper) and Canadian (Morner, 1976d)
data.
The Gothenburg Magnetic Flip rep-
resents the shortest interval of reversed
polarity and the most rapid polarity switches
known at present. Unlike most paleomag-
netic records, it is very closely fixed in age.
This makes it a useful marker level for
global correlations (cf. Mbrner, 1974,
Fig. 1; Morner and Lanser, 1975, Fig. 3).
It also makes it important for the under-
standing of the nature and causation of
magnetic changes and geomagnetic dynamo
theories (Mot-net-, 1977).
CONCLUSIONS
1. Chronostratigraphy and zonation
offer unique dating control for the Late Qua-
ternary sediments in southern Scandinavia.
2. The Fj zone (Fjaras Stadial) in
southern Scandinavia, closely dated at
12,400- 12,350 years BP, is characterized
by fully reversed inclination corresponding
to a central equatorial Pacific VGP position.
This period is known as the Gothenburg
Magnetic Flip. .
3. The record of the Gothenburg Mag-
netic Flip is reproduced (quite independ-
ently of lithology) in exactly the same
stratigraphic position in five different cores
(within 160 km; two cores were taken
0.6 m apart) that represent both marine
and lacustrine environments. Consequently,
the investigation meets the requirement
426
NILS-AXEL MGRNER
of the 1974 Tokyo conference that the
netic field during the Brunhes Epoch. IAGA
only valid proof is to reproduce the results
Butterin 36, 174.
in the same stratigraphic position, inde-
Hospers, .I., Lanskr, .I. P., Vollers, Y., and Momer,
pendently of lithology.
N. -A. (1973). In Morner, Ed. (1973), Chapt. XIV,
4. The zones AG, LB, and Vi (12,400- pp.
120-133.
Jesse& K. (1935). Archaeological dating in the history
13,750 years BP) are characterized by ir-
of north Jutland’s vegetation. Actu Archaeotogica 5.
regular,. but generally normal, magnetism
with the corresponding VGP migrating
in the Pacific region. This is defined as
part one of the Gothenburg Magnetic
Excursion, in a broad sense. Canadian clays
dating to about 13,300 BP give a southeast
Pacific VGP, preliminarily labeled the Port
Dover Excursion.
5. The zones BG, OD, AL, and YD
(12,350- 10,000 years BP) are characterized
by generally normal magnetism. Canadian
clays covering the period of about 16,000-
13,750 years BP indicate normal magnetism.
The corresponding VGP positions were in
Siberia and the Siberian Arctic Ocean
with a shift to the Canadian Arctic region
during the YD zone.
6. Low latitude and equatorial VGP
positions are well documented. This is im-
portant for understanding the nature and
causation of magnetic changes, including
geodynamo theories.
ACKNOWLEDGMENTS
This paper was prepared in connection with the
workshop conference on “Late Cenozoic Magneto-
stratigraphy” held in Tokyo in 1974. It is contribu-
tion No. 88 in the author’s series and No. 13 of the
Stockholm Paleomagnetic Laboratory. The field work
and data compilation were financed by grants from
the Swedish National Research Council.
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