GEOPHYSICALRESEARCH
LETTERS, VOL. 14, NO. 8, PAGES804-807,
AUGUST1987
CORRELATION OF A 3,200 YEAR OLD TEPHRA IN ICE CORES FROM VOSTOK
AND SObWH POLE STATIONS,
ANTARCTICA
J.M.Palais
1,P.R.Kyle
2,E.Mosley-Thompson
3 andE.Thomas
4
Abstract.Tephralayersin two Antarcticicecoresare
correlatedon thebasisof theirchemicalcompositions
and
estimated
ages.We believethetephrawasproduced
about
of theirchemicalcomposition
andestimated
age.We believe
thatthetephraoriginated
in a majorexplosive
eruption
from
3,200yearsagofroma majorexplosiveeruptionof Candlemas
years ago.
Candlemas Island in the South Sandwich Islands about 3,200
Island in the South Sandwich Islands. This is the first time that
SamplingandAnalysis
tephralayershavebeencorrelated
betweentwo widely
separated
ice coresanddemonstrates
thattephralayersmay
serveasstratigraphic
markersfor correlating,
andperhapsin
somecases,datingAntarcticice cores.
Ice samples
containing
thetwo tephralayersweremeltedand
filtered
ontoNucleopore
tm(0.4gmdiameter
poresize)filters
in a Class 100 clean room.
Introduction
A section from each filter was
examinedby scanningelectronmicroscope(SEM) andenergydispersivex-ray analysis(EDAX). A polishedmicroprobe
sectionof eachsamplewaspreparedby washingtheparticles
off of thefilter andmountingthemin epoxy.
Studiesof ice coresamplesfrom GreenlandandAntarctica
providedetailedinformation
aboutpastclimateandthe
chemicalcomposition
of theatmosphere,
for at leastthelast
150,000years(Dansgaardet al., 1981, 1982; Loriuset al.,
1979, 1985;Oeschger,1985). The preservation
of volcanic
deposits
(bothsolubleacidsandinsolublevolcanicash
particles)frombothlocalanddistantvolcanicsources
in
Theenergy-dispersive
x-rayanalyses
use"ZAF"
corrections
AntarcticandGreenlandice (Hammeret al., 1981;Kyle et al.,
1982, 1984; Hammer, 1984; Palais,1985;De Angeliset al.,
1985;Delmaset al., 1985) is of particularinterest.
Eruptions
fromAntarcticvolcanoes
in theMcMurdoVolcanic
GroupandMarie ByrdLand(Keyset al., 1977;Kyle et al.,
1981) andvolcanoesin the SouthSandwichIslands(Nishioet
al., 1984 a,b) arerecordedprincipallyasvisibletephra
(volcanicash)layersin theice cores,whereaseruptions
originatingfromvolcanoes
in themoredistantregionsof Indonesia,
SouthAmerica,andNew Zealandhaveproducedonlylayersof
to calculateoxidepercents(normalizedto 100%), from
elementpeakintensitiesandtheoreticalstandards.The
accuracyof the analyseswascheckedagainstglassandmineral
standards
andtheprecisionof theanalyses
wasdetermined
by
repeatedanalysesof thesesamestandards.The microprobe
analyseswerecorrectedusingtheBence-Albeematrix
correctionprocedure(BenceandAlbee, 1968)andglass
standards
were usedto checkanalyticalprecisionandaccuracy
Themicroprobe
analyses
aremoreprecisethantheEDAX
analyses,
ascanbe seenby comparingthestandard
deviations
of the analyses(Table 1).
Results
elevated
acidity(e.g.H2SO4),recognized
bydetailed
analyses VostokTephra
of the chemicalcompositionof the ice (Delmaset al., 1985).
In Greenland,eruptionsof nearbyIcelandicvolcanoeshave
producedwell-definedlayersof elevatedacidity,identifiedby
increases
in theD.C. electricalconductivityof theice, butno
insolublevolcanicashparticleshaveeverbeenidentified
(Hammeret al., 1981;Hammer, 1984). The only well
confirmedevidenceto date,for long-distance
(> several
thousand
kilometers)transport
of volcanicashparticlesto the
polarice sheets,in eitherhemisphere,is the studyby De
Angeliset al. (1985), in whichvolcanicashparticlesoriginatingin the 1982eruptionof E1Chichon,Mexico,werefound
The Vostoktephrais theinformalnameproposed
by Kyle et
a1.(1982)for a 0.05 m thick,diffusetephralayerfoundat
100.8 m in an ice core drilled in 1979 at Vostok Station in East
Antarctica(Figure1). The depth/agerelationship
(Parkeret
al., 1982)for theVostokcoresuggests
an ageof about3,200 a
B.P. The Vostoktephrais composed
of 55 % lithicmaterial
(mainlywell-rounded,
brown,cryptocrystalline
glass),40 %
clearglassshardsand5 % crystals(mainlyfeldspar)(Figure2
c,d).
in surface snow of the Greenland ice sheet. Further evidence
thattephracanbe transported
f'•r from source,andis therefore
usefulfor correlationpurposes,
is the studyby Kyle and
Seward(1984), in whichtephrafrom New Zealandwas
identifiedin deep-sea
pistoncoresfromtheSouthPacificsector
of the SouthernOceannearthe BallenyIslands.
In thispaperwe reportthefirst correlation
of tephralayers
between
twoicecoresin Antarctica.The,visible
tephr,
a layers
in icecoresfromVostokStation(78ø 28 S, 106ø 48 E) and
SouthPoleStation(90ø S), havebeencorrelated
onthebasis
Kyle et a1.(1984)considered
threepossiblesourceregions
(theSouthShetlandIslands,the SouthSandwichIslandsand
theSouthern
Andes)for theVostoktephraandconcluded
that
the SouthSandwichIslandswere the mostlikely source.
Rocks from the South Shetland Islands and the Southern
Andeshavehighertotalalkalicontentandlowerironcontents,
respectively,
thantheVostoktephra.TheVostoktephra(I able
1, sample3,4) is mostsimilarin composition
to anaphyric
andesitefrom thenorthernpartof Candlemas
Islandin the
SouthSandwichIslands,which is one of the youngestof the
SouthSandwichIslands(Table 1, sample5)(Baker, 1978;
Tomblin,1979). Lavasfrom Candlemas
Islandareexception-
1Graduate
School
ofOceanography,
Univ.ofRhode
Island, allylowinpotash
(K20),a characteristic
feature
oftheVostok
Narragansett,R.I.
2 Dept.
ofGeoscience,
NewMexico
Institute
ofMining
and
tephra.
CoPyright1987by theAmericanGeophysical
Union.
Grainsizeanalyses
of theVostoktephraindicate
initial
deposition
of coarse
particles
(meandiameter
of about45 gm)
followedbydeposition
of muchfinerparticles
(meanof about
7 gm),composing
thebulkof thetephra(Figure3) Themass
concentration
of tephrain meltwatersamples
gradually
increases
froma background
of about1 gg/mlto a peakof
about14 gg/ml. The originalthickness
of thetephrais
Papernumber7L7157.
makes it difficult to calculate a mass accumulation rate
T•chnology,
Socorro,
N.M.
a Byrd PolarResearchCenter,Ohio SateUniversity,
Columbus, Ohio
4 Lamont-Doherty
Geological
Observatory,
Palisades,
N.Y.
unknownasthe diffusenatureof the Vostoktephrain thecore
(mg/cm2/1000a),
asisdone
indeep
seacores.
0094-8276/87/007L-7157503.00
804
Palaiset al.-Correlation
Of TephraIn Ice Cores
South
Atlantic
'•Ocean' ':South
Sandwich
•o
Islands
805
Table1.Majorelement
analyses
(wt.%)of tephra
fromtheSouth
Pole andVostokcores,anda rock from the SouthSandwich
Islands.
ß
n
- '•'•'•,t•
•
i
R
Mt
Ex
4
Mt
o
Te
ice•,•/
c•s•[,•n•rc•,,c •
•Shelf• /
........
•
Indian
Ocean
x Tephra exposed in blue ice
ß Cenozoic volcanic rocks
0
•
3
5
11
9
SiO2
E•slAnarctic
T
3
2
4
5
.
........ AU
o•n_e•,•/•
TARCTIC"•,,,•.
2
1
km
1000
59.98(1.21)t 60.1(3.02) 60.56(0.42)
TiO2
0.78(0.9)
0.3(0.22) 0.74(0.07)
A1203 16.03(0.94) 17.6(3.40) 14.92(0.82)
FeO* 7.37(1.14) 9.0(3.79) 9.15(0.57)
0
MnO
0.16(0.8)
0.23(0.04)
MgO 1.71(0.28) 3.5(1.91) 2.39(0.34)
6.72(0.26)
CaO
6.79(0.42) 5.5(•.35)
Na20
5.94(0.83) 3.6(0.89) 3.31(0.38)
0.44(0.05)
K20
0.39(0.09) 0.](0.]5)
n.d.
P205
0.08(0.09) 0.3(0.13)
Total
South
Pacific
99.23
100
98.46
37
59.73(1.79)
0.90(0.16)
14.84(0.66)
10.25(1.23)
0.15(0.12)
2.44(0.48)
6.64(0.76)
4.46(0.57)
0.63(0.19)
60.9
0.95
14.8
8.34
0.11
2.35
6.09
3.67
0.39
n.d.
0.12
100.04
97.72
Ocean
180 ø
I
Fig.1.Mapof Antarctica
showing
corelocations
andprobable
pathsof atmospheric
transport
fromtheSouthSandwich
Islands to the Antarctic ice sheet.
Key:
* FeO, total Fe as FeO;
? one standarddeviation.d. indicatesnot detected;n is number
of samples.
1. SouthPoleTephra-Electron
microprobe
analyses,
Univ.of RhodeIsland,(Analyst,
J. Palais).
SouthPol• Tcphr•
2. SouthPoleTephra-Energy-dispersive
x-rayanalysis,
In 1983/84 a 361 m ice core was drilled at the South Pole
with a distincttephralayer(3mmthick) at 303.44m. The
tephrais composed
primarilyof vesicular
glassshards
and
lithicmaterial
witha smallpercentage
of crystals,
including
quartz,pyroxene
andplagioclase
of intermediate
composition
(Figure2 a,b). Majorelement
analyses
of theglassshards
in
theSouthPoletephra(Table1,analyses
1,2)compare
well
OhioStateUniv.(Analyst,
T. Leonardi).
3. VostokTephra-Electron
microprobe
analysis,
LosAlamos
NationalLaboratory
(Analyst,J. Palais)(Kyle
et al., 1984).
4. VostokTephra-Energydispersive
x-rayanalysis,
Arizona
StateUniversity(Analyst,
E. Thomas)(Kyle
et al., 1984).
5. Candlemas
Island-Aphyric
andesite,
Cauldron
Lakelava,
northern
Candlemas
Island.Wetchemical
analysis
(Tomblin,
•979).
I
Fig.2. Scanning
electron
micrographs
oftephra
fromtheSouth
PoleandVostok
icecores.
a)South
Pole
tephra
blocky,
moderately
vesicular,
partially
altered
shard
withshallow
spherical
vesicles.
Fineadhering
dust.
2400x; 1cm=4gm.b)South
Poletephra
highly
vesicular,
fresh
shard
withdelicate
square
to
rectangular
vesicles.
2400x;1cm=4gm.c)Vostok
tephra
subrounded,
blocky,
moderately
vesicular
shard,
partially
altered,
withshallow
spherical
vesicles.
Fineadhering
dust.
Compare
witha).l110x;1cm=9 gm
d)Vostok
tephra
blocky
shards
withfineadhering
dust,
fewvesicles.
1110x; lcm= 9 gm.
806
Palaiset al.: CorrelationOf TephraIn Ice Cores
al. (1982), suggests
an ageof 3,250a B.P. at 300 m in the
SouthPolecore. Thiscompares
well with theestimated
age
(3,200a B.P.) for theVastoktephra(Parkeret al., 1982).
Total Mass Concentration(•g/ml)
0
4
8
12
Ioo.75
I,,,,,,
]
NO3-
SO,•
II
!
L
I
30-
,1. 20-
40- -- 5
7
9
li
L
:
•
•;
Discussion
i-
30-
......................
! 0o 1• , ,';- , , , ,
.s
• ••
• 100.80
•
2.':
Total
Mass
I
:...............
,o:
•
30
5
7
0
I
:
II
:1
9
II
--
o
,oo.s5[•
-,.....
,
I
I
I
8
layers
in theYamatoMountains
arenotwellconstrained,
they
areof thecorrectorderof magnitude
to becorrelative
withthe
associated
withthesetephralayers,suggest
thattheageof the
3o579II
I
(theMeteorite
IceField)of theYamatoMountains,
Queen
MaudLand,EastAntarctica(Figure1) (Nishioet al., 1984;
Katsushima
et al., 1984).Althoughtheagesof thetephra
Vastok
andSouth
Pole
tephras.
36C1
analyses
ofice
d, 20-
4
Tephrasimilarin composition
tothatin theVastokandSouth
Polecoresalsooccursin layersat thesurfacein blueiceareas
ice in the Meteorite Ice Field of the Yamato Mountains is less
than
one36C1
half-life
(3x 105 a)(Nishiizumi
etal.,1979).
The14Cterrestrial
ageofchondrite
Yamato
75102,
collected
near
tephra
layer
C-32,
indicates
anage
of3.0+1.2x 103a
I
(Nishio,personal
communication,
!985).Theterrestrial
ages
12
of four otherYamato meteoritesare believedto be in the range
concentration (pEq/I)
Fig. 3. Depth variationof massconcentration
of tephrain a
0.10 m sectionof the Vastokcore.Histogramsshowthegrain
sizedistributionof tephrain the samplesthatwereanalyzedfor
massconcentration.Sulfateandnitratedatafrom Kyle et
al.(1982).
with thoseof the Vastok tephra(Table 1, analyses3,4), which
suggests
thattheymightbe fromthesameeruption.Thisis
furthersupported
by theestimatedageof theice enclosing
theselayers,asdiscussed
below.
of 3,000-22,000a. Calculation
of flow linesin theMeteorite
IceFieldsgivesanagefor theiceupstream
of MotoiNunatak,
neartephralayerC-32,in therangefromoneto several
thousand
yearsold (Nishioet al., 1984).
Tephra
layersinpiston
cores
fromtheSouthAtlanticOcean
(Ninkovich
et a1.,1964;
Federman
et al., 1982)werebelieved
tobeerupted
fromtheSouthSandwich
Islands
withinthelast
30,000years.Basedona sedimentation
rateof 8 cm/1000a, a
tephralayerat0.20m in coreV 14-56wouldbe2,500years
old (Federman
et al., 1982). Thisis probablya minimum
estimate,however,sinceerosionby AntarcticBottomWater
mayhaveremoved
someof thesediments
in thecore(Ledbetter
Depth-AgeRelationships
andCiesielski,1986).The tephrahasa similarcomposition
Thereis no absolutedatingof eitherthe SouthPoleor
Vastok cores,but two linesof evidencesuggestthatthe tephra
theYamatoMountainsandmay correlatewith them.
andageto thetephralayersfromVastok,SouthPoleandfrom
layers(Vastoktephra-100m;
SouthPoletephra-3oom)
are
coeval. First,a roughestimateof the ageof thesetwo layersis
madeby assuming
a similardepth-density
profilefor thetwo
locations
andaccumulation
rates
v•hich
differbyafactor
of
aboutthree(Vastok2.0-2.5 g/cm•/a (Younget al., 1982;
Lorius
etal.,1985);South
Pole7-9g/cm2•(Jouzel
etal.,
1983)).Secondly,ourestimated
depth-age
profilefor the
SouthPolecore(Figure4), basedondepth-age
estimates
of
Schwander
(1984),Mosley-Thompson
(1980)andKuivinenet
Depth/Age
104•
Profile-South
Conclusions
Theseanalyses
andinferences
areconsistent
withthe
conclusion
thatthetephralayersin theSouthPoleandVastok
coresarecoevalandrepresent
deposition
froma [najor
explosive
volcanic
eruption
in theSouthSandwich
Islands
(probably
fromCandlemas
Island)about3,200aB.P. Forthe
firsttimetephralayersfromtwowidelyseparated
icecores
havebeencorrelated,whichreinforcestheutility of
tephrochronolgy
foricecorestudies.
Thistephralayer
provides
anexcellent
stratigraphic
markerforAntarctic
ice
coresandshouldbe soughtat otherlocations.Furthermore,
a
detailed
studyof thedispersal
of thistephralayermayprovide
information
onthetransport
of atmospheric
particles
in thispart
of thesouthern
hemisphere.
Theoccurrence
of anapparently
widelydispersed
tephra
layerin EastAntarctica,
possibly
originating
fromtheSouthSandwich
Islands,
is consistent
withthepathsof atmospheric
transport
proposed
byAlt et al.
(1959),Carleton(1981)andThompson
andMosley-
Pole
-
n'103=
Thompson(1982).
• 02
=
)-1
Acknowledgements.
We wouldliketothankthePolarIce
CoringOffice(PICa), University
of Nebraska
for drillingthe
-
--
[] Schwander
(1984)
I
ßMosley-Thompson
(1980)
lOOm
Vastok and South Pole ice cores. We also wish to thank Grant
Kuivinen
lO
I
100
I
et al. (1982)
I
I
200
I
200m
I
300
I
400
Depth (m)
Fig.4. Estimated
depth-age
relationship
fortheSouthPole
core basedon data from Schwander(1984), Mosley-
Thompson
(1980)andKuivinenet al (1982).
Heikenfor useof theElectronMicroprobeat theLosAlamos
NationalLaboratory
andPeterBusekfor useof theScanning
ElectronMicroscope
at theArizonaStateUniversity.Dave
Mann(MannPetragraphic
Inc.)madethemicroprobe
mounts
of bothtephrasamples.
TonyLeonardi
of theOhioState
University
andDavidBrowning
of theUniversity
of Rhode
Islandassisted
with theSEM andEDAX analyses
of the South
Poletephra.Thisworkwassupported
bytheNationalScience
Foundation
grantDPP-8021402,DPP-8519122
Palaiset al.: CorrelationOf TephraIn Ice Cores
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(Received
accepted
March 17,
April
27,
1987;
1987.)