Ž .Global and Planetary Change 21 1999 17–29www.elsevier.comrlocatergloplacha

Geochemistry of Santorini tephra in lake sediments fromSouthwest Turkey

W.J. Eastwood a,), N.J.G. Pearce a, J.A. Westgate b, W.T. Perkins a, H.F. Lamb a,N. Roberts c

a Institute of Geography and Earth Sciences, UniÕersity of Wales, Aberystwyth, Ceredigion, SY23 3DB, UKb Physical Sciences DiÕision, Scarborough College, UniÕersity of Toronto, 1265 Military Trail, Scarborough, Ontario, Canada, M1C 1A4

c Department of Geographical Sciences, UniÕersity of Plymouth, Drake Circus, Plymouth, DeÕon, PL4 8AA, UK

Abstract

Ž .A layer of volcanic ash 4 cm maximum recorded thickness is present at ;250 cm depth in littoral sediments ofGolhisar Golu; a small intramontane lake in Southwest Turkey. The major-element glass chemistry, determined by electron¨ ¨ ¨microprobe, is characterised by a rhyolitic composition. Trace-element data, determined by solution inductively coupled

Ž .plasma mass spectrometry ICP-MS match previously reported results for proximal pumice samples from Santorini and Crete.ŽPeat immediately below the tephra deposit has yielded radiocarbon ages of 3330"70 yr BP and 3225"45 yr BP calibrated

.age range 1749–1406 BC . q 1999 Elsevier Science B.V. All rights reserved.

Keywords: tephra; tephrochronology; trace-element geochemistry; ICP-MS; Turkey

1. Introduction

Tephra layers in Quaternary sediments provideearth scientists and archaeologists with an importanttime-synchronous stratigraphic marker horizon thatallows correlation of sites across entire regionsŽWestgate and Gorton, 1981; Einarsson, 1986; Knox,

.1993 . They also provide an opportunity to deter-mine the age of an eruption, the extent of ashdispersal, and its impact on natural and humanecosystems. One such tephra, the ‘Minoan’ or Z-2tephra, from the seventeenth-century BC eruption ofThera on the Aegean island of Santorini is well

) Corresponding author. Present address: School of Geographyand Environmental Sciences, University of Birmingham, Edgbas-ton, Birmingham, B15 2TT, UK. Tel.: q44-121-414-7960; fax:q44-121-414-5528; e-mail: w.j.eastwood@bham.ac.uk

known in deep-sea sediment cores from the easternŽMediterranean Sea Ninkovich and Heezen, 1965;

Keller et al., 1978; Watkins et al., 1978; Federman.and Carey, 1980; Keller, 1981; Vinci, 1985 . It has

also been discovered in terrestrial sediments on theŽAegean islands of Rhodes Doumas and Papazoglou,

. Ž . Ž1980 , Kos Keller, 1980 and Crete Warren and.Puchelt, 1990 , and in the sediments of Lake Man-

zala, a small lake in the north-eastern section of theŽ .Nile delta Stanley and Sheng, 1986 . The distribu-

tion of these marine and terrestrial records at firstsuggested a south-easterly dispersal direction for the

Ž .Santorini ash plume Ninkovich and Heezen, 1965 ,but more recent discoveries of the tephra on Kos,Rhodes, and in lake-sediment cores from western

Ž .Turkey Sullivan, 1988, 1990 and in deep-sea coresŽ .from the Black Sea Guichard et al., 1993 imply a

Žmore easterly dispersal Pyle, 1990; Sigurdsson et

0921-8181r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved.Ž .PII: S0921-8181 99 00005-3

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–2918

.al., 1990; Fig. 1 . Identification of the Santorinitephra up to now has depended on determinations ofthe major-element chemistry and refractive indicesof the constituent glass shards.

This paper reports the discovery of a 4 cm thicklayer of volcanic ash in the sediments of a smalllake, Golhisar Golu, situated at 3788X N, 29836X E, at¨ ¨ ¨an elevation of 930 m asl in the Lycian Torosmountains of Southwest Turkey, ;400 km east–

northeast of Santorini. We identify the ash as beingfrom the Santorini eruption by comparison of itsgeochemical composition with previously reportedanalyses, and by the radiocarbon age of the underly-ing sediments. Trace-element data have not previ-ously been reported for distal Santorini deposits. Themethod of trace-element analysis used, inductively

Ž .coupled plasma mass spectrometry ICP-MS , allowsanalysis of very small amounts of material to very

Fig. 1. Location of eastern Mediterranean terrestrial sites mentioned in the text. Figures in parentheses for the lake sites in western Turkeyshow thicknesses of tephra in cm.

()

W.J.E

astwood

etal.r

Globaland

Planetary

Change

211999

17–

2919

Fig. 2. Stratigraphy of sediment cores retrieved from Golhisar Golu.¨ ¨ ¨

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–2920

high precision. Our data may be used for moreprecise distinctions between Santorini and othertephras, as well as for comparison with laser-ablation

Ž .ICP-MS see Pearce et al., 1999 .

2. Field sampling, laboratory and analytical meth-ods

Six sediment cores were retrieved from the mar-gin of Golhisar Golu; two with a Livingstone piston¨ ¨ ¨

Ž .corer in 1992 GHA.92 and GHB.92 and four shortŽcores with a Dachnowsky corer Faegri and Iversen,

. Ž1989 in 1993 GHE.93-5; GHE.93-6; GHE.93-7 and.GHE.93-8 . All six cores were taken within 5 m of

each other. Shards of volcanic ash were separatedfrom the peaty matrix by sieving with a series of fine

Ž .mesh polyester sieves 85 mm, 100 mm and 15 mm .The samples were suspended in 30% H O and2 2

placed in a hot water bath until all traces of organicmatter were digested. The shards were then washedin 1% hydrofluoric acid and washed repeatedly incold water, dried and then examined under a petro-

graphic microscope to assess the purity of the sepa-rates. The coarsest size fractions were mounted inresin blocks for major-element analysis at the Uni-versity of Toronto, using a Cameca SX-50 electronprobe fitted with 3 wavelength dispersive spectrome-

Ž .ters WDS . Analyses were carried out using anaccelerating voltage of 15 kV and a beam current of10 nA. The electron beam was either defocused to

Ž5–10 mm diameter to minimise mobilisation of. Ž .alkalis , or scanned 10 K mag. , or focused, depend-

ing on the size of the shards. Peak counting timeswere 20 s for each element. Backgrounds werecounted on both sides of the peak, for the same totaltime as the peak, in all cases except Na, Si, and Al,which were counted on one side only and for half ofthe peak time. Calibration was achieved against natu-

Žral mineral and glass standards described in Pearce.et al., 1999 .

Samples for solution ICP-MS analysis were takenfrom each of the size fractions viz -85 mm, 85–150mm, )150 mm and -100 mm. About 0.5 g ofcleaned glass separate was weighed accurately and

Table 1Major-element compositional data of volcanic ash in tephra deposit from Golhisar Golu together with other published data and normalised¨ ¨ ¨to an anhydrous basis. All data in wt.%. One standard deviation given in parentheses

aSite n Method SiO TiO Al O FeO MnO MgO2 2 2 3

b Ž . Ž . Ž . Ž . Ž . Ž .Golhisar Sample A 16 EPMA 73.62 0.49 0.28 0.06 14.04 0.18 1.99 0.10 0.06 0.04 0.27 0.04¨b Ž . Ž . Ž . Ž . Ž . Ž .Golhisar Sample B 18 EPMA 73.57 0.37 0.30 0.06 14.01 0.18 2.07 0.11 0.07 0.04 0.28 0.03¨b Ž . Ž . Ž . Ž . Ž . Ž .Golhisar Sample C 17 EPMA 73.54 0.58 0.29 0.05 14.01 0.13 2.06 0.11 0.07 0.03 0.28 0.02¨b Ž . Ž . Ž . Ž . Ž . Ž .Golhisar Sample D 17 EPMA 73.57 0.50 0.29 0.05 14.01 0.23 2.04 0.15 0.07 0.05 0.27 0.05¨

c Ž . Ž . Ž . Ž . Ž . Ž .Black Sea GGC-79 16 EDS SEM 72.93 0.56 0.32 0.1 13.69 0.28 2.08 0.22 0.07 0.07 0.23 0.12eKoycegiz 8 EPMA 73.53 0.30 14.06 2.21 0.31¨ ˘

fGolcuk 16 EPMA 74.29 0.30 14.12 2.12 0.30¨ ¨g Ž . Ž . Ž . Ž . Ž . Ž .Minoan Pumice 16 EPMA 69.49 1.22 0.48 0.06 15.37 0.22 3.57 0.37 0.10 0.01 1.29 0.22

g Ž . Ž . Ž . Ž .Minoan Ash 3 EPMA 74.92 0.18 0.2 12.94 2.10 2.09 0.12 0.30 0.01h Ž . Ž . Ž . Ž . Ž .Minoan—Land 6 EPMA 73.56 0.19 0.27 0.02 14.17 0.06 1.81 0.06 0.25 0.02

h Ž . Ž . Ž . Ž . Ž .Minoan—Marine 141 EPMA 74.04 1.12 0.27 0.01 13.99 0.41 1.94 0.1 0.27 0.20i Ž . Ž . Ž . Ž . Ž . Ž .Minoan—Marine Z-2 23 EPMA 73.68 0.30 0.30 0.02 14.21 0.18 2.02 0.07 0.06 0.01 0.29 0.01

jNile Delta Core 2 3 EPMA 78.77 0.23 15.20 1.73 0.05 0.12jCore 4 Run 1 – EPMA 81.44 0.19 12.88 3.60 0.05 0.35jCore 4 Run 2 – EPMA 77.64 0.29 15.05 2.07 0.04 0.33jCore 4 Run 3 – EPMA 77.18 0.27 14.42 3.58 0.11 0.43

kKos 3 EPMA 73.36 0.33 14.19 2.08 0.32kRhodes 8 TPD 73.42 0.32 14.02 2.03 0.32

l Ž . Ž . Ž . Ž . Ž . Ž .Knossos, Crete 7 XRF 68.91 1.28 0.41 0.01 14.19 0.27 2.83 0.06 0.08 0.004 0.69 0.06

a b c Ž . d Ž . Ž . e Ž .Iron expressed as total iron. This study. Guichard et al. 1993 . Includes P: 0.01 0.02 and S: 0.19 0.13 . Sullivan 1990 .f Ž . g Ž . h Ž . i Ž . j Ž . k Ž . lSullivan 1988 . Vitaliano et al. 1990 . Federman and Carey 1980 . Vinci 1985 . Stanley and Sheng 1986 . Keller 1980 . Warren

Ž . m Ž . Ž .and Puchelt 1990 . Includes P O : 0.146 0.06 , CO : 1.304 0.59 and SO : -0.01.2 5 2 2

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–29 21

taken into solution using a repeated HFrHClO acid4

attack. Aristar acids were used throughout. The re-sulting solutions were made up to 100 ml in 5%HNO and diluted prior to fully quantitative solution3

ICP-MS analysis. Mixed calibration standards weremade from Aldrich 1000 ppm single element stan-dards. Analyses are the average of 5 acquisitions oneach sample. Detection limits in the solid vary fromelement to element but are normally less than 0.1ppm.

3. Core lithostratigraphy

A tephra layer is present in all of the coresretrieved from Golhisar Golu, varying from 1 to 4¨ ¨ ¨

Ž .cm in thickness Fig. 2 . It is a light grey unit ofsilt-sized particles, clearly identifiable as glass shardswith a low-power optical microscope. There is asharp contact with the underlying peat, suggestingthat the tephra was deposited onto the surface of alake-marginal marsh. The variability in tephra depthand thickness may be a function of the surfacemicrotopography of the marsh. The tephra is overlain

directly, or after a short interval of peat, by calcare-ous silt and clays, suggesting that the local deposi-tional environment changed from marsh to shallowwater at some time following the ash deposition.

The stratigraphy of the core from Golcuk, which¨ ¨Žcontains a 12-cm-thick tephra deposit Sullivan,

.1988 , is very similar to that at Golhisar Golu,¨ ¨ ¨although the sediments are not calcareous. AtKoycegiz, a 9-cm-thick tephra deposit overlies clay,¨ ˘

Žbut is overlain by about 40 cm of gyttja van Zeist et.al., 1975; Sullivan, 1990 . In all three cases, there-

fore, it seems that the local depositional environmentchanged, apparently by increased water depth, fol-lowing the deposition of the ash. More work isneeded to substantiate this, and to evaluate anypossible role of ash deposition on local or regionalhydrology.

4. Major-element geochemistry

Summary major-element data for this study to-gether with summary data from previously publishedanalyses are listed in Table 1. All analyses have been

CaO Na O K O Cl F O-F,Cl Total Original2 2

analysis total

Ž . Ž . Ž . Ž . Ž .1.40 0.09 4.78 0.54 3.27 0.15 0.31 0.05 0.09 0.08 y0.10 100.0 98.19Ž . Ž . Ž . Ž . Ž .1.41 0.09 4.76 0.23 3.24 0.01 0.31 0.04 0.07 0.10 y0.09 100.0 97.32Ž . Ž . Ž . Ž . Ž .1.41 0.07 4.84 0.61 3.24 0.14 0.31 0.05 0.04 0.06 y0.08 100.0 97.62Ž . Ž . Ž . Ž . Ž .1.40 0.14 4.85 0.49 3.21 0.08 0.31 0.04 0.08 0.10 y0.10 100.0 97.61

dŽ . Ž . Ž . Ž .1.33 0.10 5.01 0.28 3.33 0.11 0.8 0.1 100.0 100.001.39 4.93 3.27 100.0 99.081.43 4.27 3.17 100.0 98.75

Ž . Ž . Ž .2.97 0.50 3.89 0.12 2.84 0.12 100.0 99.62Ž . Ž . Ž .1.28 0.15 4.85 0.10 3.40 0.06 100.0 98.90Ž . Ž .1.41 0.01 5.28 3.25 0.04 100.0 95.98Ž . Ž .1.33 0.10 5.00 3.17 0.20 100.0 97.92Ž . Ž . Ž .1.39 0.05 4.66 0.13 3.38 0.06 100.0 100.00

0.58 0.69 2.65 100.0 86.80.46 0.12 0.93 100.0 86.21.42 2.29 0.87 100.0 91.71.73 0.43 1.84 100.0 92.31.41 4.55 3.40 0.37 100.0 97.131.34 4.65 3.50 0.40 100.0 97.06

mŽ . Ž . Ž .3.45 0.62 4.59 0.11 3.11 0.11 100.0 96.58

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–2922

Table 2Ž . Ž .Major-element analyses wt.% for glass shards Sample A from the tephra layer deposited at Golhisar Golu¨ ¨ ¨

Run Element

SiO TiO Al O FeO MnO MgO CaO Na O K O Cl F O-F,Cl Total2 2 2 3 2 2

1 70.63 0.31 13.55 1.83 0.02 0.25 1.43 4.91 3.24 0.26 0.00 y0.05 96.372 71.93 0.16 13.89 1.72 0.06 0.21 1.15 2.90 3.52 0.21 0.21 y0.13 95.823 72.73 0.27 13.77 1.98 0.08 0.33 1.37 5.00 3.09 0.32 0.10 y0.11 98.924 73.36 0.34 13.92 2.02 0.06 0.32 1.41 5.01 2.99 0.41 0.00 y0.08 99.765 72.27 0.32 13.58 2.04 0.01 0.24 1.39 4.74 3.20 0.33 0.04 y0.08 98.086 72.43 0.23 13.90 2.04 0.04 0.27 1.42 4.00 3.24 0.33 0.04 y0.08 97.887 72.31 0.35 13.80 2.03 0.10 0.30 1.29 5.22 3.15 0.31 0.19 y0.14 98.918 72.15 0.32 13.65 2.05 0.04 0.24 1.29 4.54 3.11 0.31 0.06 y0.09 97.669 73.08 0.26 13.72 1.90 0.08 0.23 1.29 4.91 3.18 0.31 0.17 y0.13 98.99

10 73.34 0.20 14.02 2.08 0.00 0.31 1.55 4.95 3.31 0.35 0.00 y0.07 100.0511 71.75 0.28 13.60 1.94 0.04 0.30 1.40 4.87 3.09 0.28 0.10 y0.10 97.5612 72.44 0.22 13.90 1.77 0.15 0.23 1.37 4.81 3.32 0.34 0.08 y0.10 98.5313 71.36 0.28 13.77 1.88 0.02 0.26 1.31 4.54 3.22 0.25 0.21 y0.14 96.9714 72.58 0.32 14.11 2.10 0.09 0.30 1.53 4.90 3.24 0.32 0.04 y0.08 99.4415 71.93 0.19 13.89 2.03 0.04 0.28 1.45 5.05 3.23 0.32 0.04 y0.08 98.3716 72.22 0.30 13.49 1.88 0.11 0.24 1.30 4.75 3.17 0.25 0.17 y0.12 97.75mean 72.28 0.27 13.78 1.96 0.06 0.27 1.37 4.69 3.21 0.31 0.09 y0.10 98.19S.D. 0.70 0.06 0.18 0.11 0.04 0.04 0.10 0.55 0.12 0.05 0.07

normalised to 100% to enable direct comparison andto remove the variable effects of hydration after

Ž .deposition Smith and Westgate, 1969 . Tables 2–5

show raw major-element analyses for the four sets ofGolhisar volcanic ash samples. Fig. 3 shows a trian-¨

Ž .gular plot of FeO`K O` MgOqCaO .2

Table 3Ž . Ž .Major-element analyses wt.% for glass shards Sample B from the tephra layer deposited at Golhisar Golu¨ ¨ ¨

Run Element

SiO TiO Al O FeO MnO MgO CaO Na O K O Cl F O-F,Cl Total2 2 2 3 2 2

1 71.87 0.26 13.71 2.06 0.05 0.24 1.45 4.76 3.03 0.31 0.00 y0.06 97.672 69.61 0.30 13.23 2.05 0.01 0.27 1.36 4.26 3.02 0.27 0.00 y0.05 94.323 72.47 0.38 14.06 2.02 0.10 0.32 1.49 4.97 3.19 0.27 0.39 y0.22 99.464 72.17 0.30 14.01 2.02 0.00 0.27 1.47 4.41 3.25 0.33 0.10 y0.11 98.225 69.78 0.24 13.28 2.05 0.09 0.24 1.42 4.34 3.20 0.38 0.00 y0.08 94.966 71.98 0.22 13.24 1.96 0.06 0.26 1.22 4.77 3.20 0.29 0.08 y0.09 97.197 69.61 0.29 13.46 1.84 0.14 0.23 1.34 4.06 3.11 0.29 0.21 y0.14 94.438 72.63 0.22 13.60 1.92 0.09 0.29 1.31 5.00 3.14 0.23 0.02 y0.06 98.409 71.33 0.29 13.58 2.06 0.09 0.29 1.53 4.32 3.21 0.29 0.00 y0.06 96.92

10 71.08 0.34 13.47 1.83 0.07 0.26 1.34 4.50 3.24 0.30 0.02 y0.07 96.3811 72.33 0.28 13.50 1.91 0.07 0.21 1.30 4.71 3.31 0.24 0.00 y0.05 97.8312 70.52 0.27 13.25 2.07 0.03 0.33 1.34 4.40 3.05 0.31 0.02 y0.07 95.5213 72.79 0.40 13.79 2.13 0.05 0.27 1.44 4.74 3.14 0.28 0.00 y0.06 98.9614 73.34 0.21 13.84 2.07 0.07 0.24 1.32 4.94 3.34 0.37 0.08 y0.11 99.7215 73.06 0.28 14.32 2.24 0.07 0.34 1.44 5.18 3.27 0.34 0.10 y0.11 100.5316 70.37 0.29 13.43 2.07 0.06 0.25 1.36 4.54 3.05 0.28 0.00 y0.06 95.6417 72.01 0.28 13.61 1.86 0.02 0.25 1.20 4.80 3.05 0.28 0.06 y0.08 97.3318 71.82 0.41 14.09 2.15 0.09 0.27 1.44 4.77 3.00 0.34 0.06 y0.09 98.34mean 71.60 0.29 13.64 2.02 0.06 0.27 1.38 4.64 3.16 0.30 0.06 y0.09 97.32S.D. 1.19 0.06 0.33 0.11 0.03 0.04 0.09 0.30 0.11 0.04 0.10

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–29 23

Table 4Ž . Ž .Major-element analyses wt.% for glass shards Sample C from the tephra layer deposited at Golhisar Golu¨ ¨ ¨

Run Element

SiO TiO Al O FeO MnO MgO CaO Na O K O Cl F O-F,Cl Total2 2 2 3 2 2

1 69.03 0.26 13.16 2.04 0.07 0.25 1.36 4.21 3.14 0.39 0.00 y0.08 93.842 72.45 0.22 13.74 2.03 0.06 0.32 1.41 5.18 3.37 0.29 0.08 y0.09 99.073 72.25 0.31 13.71 1.94 0.03 0.26 1.31 4.77 3.15 0.28 0.00 y0.06 97.964 72.87 0.20 13.78 1.87 0.05 0.27 1.38 2.47 3.34 0.34 0.00 y0.07 96.485 71.70 0.24 13.56 2.10 0.11 0.33 1.35 4.79 3.18 0.25 0.04 y0.07 97.586 71.95 0.33 13.75 1.89 0.06 0.29 1.47 5.04 3.18 0.29 0.13 y0.11 98.277 71.02 0.32 13.54 2.11 0.03 0.25 1.42 4.79 3.30 0.24 0.02 y0.06 96.988 72.31 0.30 13.83 2.15 0.01 0.28 1.35 4.90 3.00 0.33 0.02 y0.08 98.429 72.67 0.17 13.84 2.02 0.13 0.27 1.34 5.05 3.18 0.33 0.02 y0.08 98.93

10 71.60 0.31 13.70 1.97 0.04 0.28 1.39 4.91 3.00 0.34 0.00 y0.07 97.4811 72.30 0.31 13.75 2.11 0.08 0.29 1.37 5.07 3.14 0.28 0.06 y0.08 98.6712 70.94 0.27 13.72 2.10 0.10 0.28 1.39 4.84 2.97 0.30 0.19 y0.14 96.9613 72.13 0.32 13.83 2.12 0.06 0.27 1.40 4.83 3.17 0.34 0.00 y0.07 98.3914 71.47 0.30 13.98 2.06 0.10 0.26 1.53 5.13 3.06 0.30 0.08 y0.10 98.1815 71.69 0.30 13.37 1.81 0.03 0.25 1.22 4.77 3.39 0.26 0.00 y0.05 97.0416 70.53 0.34 13.33 1.88 0.06 0.28 1.37 4.58 2.91 0.30 0.00 y0.06 95.5317 73.51 0.27 13.92 1.95 0.12 0.29 1.31 4.99 3.26 0.21 0.00 y0.04 99.80mean 71.79 0.28 13.68 2.01 0.07 0.28 1.38 4.72 3.16 0.30 0.04 y0.08 97.62S.D. 1.03 0.05 0.22 0.10 0.03 0.02 0.07 0.63 0.14 0.04 0.05

There is an excellent agreement between analysesof the Golhisar tephra with the data from the tephra¨deposits from Golcuk, Koycegiz, Black Sea, and ash¨ ¨ ¨ ˘

Žfrom Thera and the deep-sea cores Minoan marine.and Z-2 . Major-element compositional differences

Žfor pumice analyses from Knossos and Thera Upper

Table 5Ž . Ž .Major-element analyses wt.% for glass shards Sample D from the tephra layer deposited at Golhisar Golu¨ ¨ ¨

Run Element

SiO TiO Al O FeO MnO MgO CaO Na O K O Cl F O-F,Cl Total2 2 2 3 2 2

1 71.21 0.30 13.78 2.04 0.00 0.30 1.45 4.68 3.04 0.37 0.06 y0.10 97.132 73.34 0.34 13.70 1.98 0.05 0.24 1.20 5.08 3.21 0.22 0.06 y0.07 99.343 72.00 0.28 13.65 2.05 0.10 0.25 1.39 4.93 3.04 0.29 0.04 y0.08 97.944 70.90 0.29 13.53 1.96 0.04 0.23 1.47 4.57 3.09 0.30 0.00 y0.06 96.325 72.15 0.30 13.87 1.83 0.02 0.28 1.28 4.84 3.21 0.35 0.13 y0.12 98.136 72.36 0.32 14.05 2.18 0.05 0.22 1.49 3.05 3.20 0.31 0.06 y0.09 97.207 71.80 0.23 13.59 2.07 0.10 0.30 1.37 4.85 3.08 0.30 0.37 y0.22 97.858 69.82 0.38 14.00 2.18 0.04 0.37 1.69 4.97 3.03 0.30 0.08 y0.10 96.779 70.03 0.33 13.25 2.05 0.11 0.30 1.34 4.23 3.15 0.29 0.00 y0.06 95.03

10 71.80 0.30 13.75 2.01 0.06 0.26 1.43 5.12 3.10 0.35 0.00 y0.07 98.1011 72.00 0.27 13.23 1.66 0.03 0.16 1.20 4.83 3.31 0.28 0.08 y0.09 96.9612 72.11 0.28 13.68 2.15 0.11 0.30 1.40 4.52 3.16 0.28 0.00 y0.06 97.9413 71.90 0.22 13.74 1.88 0.08 0.24 1.36 4.89 3.12 0.37 0.00 y0.07 97.7214 72.11 0.31 13.96 2.08 0.05 0.32 1.34 5.04 3.07 0.30 0.12 y0.11 98.5915 72.04 0.26 13.65 1.97 0.17 0.29 1.29 4.81 3.12 0.31 0.00 y0.06 97.8516 72.62 0.26 13.54 1.82 0.09 0.24 1.34 5.10 3.09 0.31 0.21 y0.15 98.4617 72.49 0.21 13.50 1.86 0.14 0.20 1.11 4.97 3.17 0.31 0.17 y0.13 98.00mean 71.80 0.29 13.67 1.99 0.07 0.27 1.36 4.73 3.13 0.31 0.08 y0.10 97.61S.D. 0.88 0.04 0.23 0.14 0.04 0.05 0.13 0.49 0.07 0.04 0.10

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–2924

Ž .Fig. 3. FeO)`K O` CaOqMgO of tephra deposit from Golhisar Golu together with other Minoan samples. FeO) refers to total iron¨ ¨ ¨2Ž .FeOq Fe O . See text for explanation and Table 2 for references.2 3

.pumice may be due to the heterogeneity betweenŽ . Žproximal pumice and distal ash see Druitt in dis-

.cussion of Sullivan, 1990, p. 119 . Major-element

compositional data for ash from the Nile delta tephraŽ .deposit Stanley and Sheng, 1986 are not consis-

tent with the Minoan eruption in terms of

Table 6Ž .Major-element data of glass shards from Lake Manzala, Nile Delta after Stanley and Sheng 1986

Sample SiO Al O FeO MgO CaO K O Na O TiO MnO Total2 2 3 2 2 2

aCore 2 68.4 13.2 1.5 0.1 0.5 2.3 0.6 0.2 0.04 86.8Core 4: run 1 70.2 11.1 3.1 0.3 0.4 0.8 0.1 0.16 0.04 86.2Core 4: run 2 71.2 13.8 1.9 0.3 1.3 0.8 2.1 0.27 0.04 91.7Core 4: run 3 71.2 13.3 3.3 0.4 1.6 1.7 0.4 0.25 0.10 92.3

aAverage of data from three samples.

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–29 25

Ž . Ž .FeO`K O` MgOqCaO Fig. 3 . Na OqK O2 2 2Žfor the tephra from the Nile Delta analyses average

.2.46 wt.% are very low when compared with theŽ .Golhisar data average 8.05 wt.% which suggests¨

that glass shards from the Nile Delta tephra are no

longer ‘rhyolitic’. Poor analytical procedure resultingŽin alkali loss or mobility, or extreme hydration up to

.about 14% H O which has leached alkalis from2Žthese glasses could account for the low totals Table

. Ž .6 . Stanley and Sheng 1986 recognise this and also

Table 7Trace-element analyses for separated glass shards from the tephra layer deposited at Golhisar Golu by solution nebulisation ICP-MS.¨ ¨ ¨Trace-element data for pumice from Thera and Knossos, Crete also shown. One standard deviation given in parentheses. The Golhisar data¨

Ž .have been normalised to an anhydrous basis using H O by difference 2.315% . Concentrations in ppm2

a a a a b cSample Golhisar Golhisar Golhisar Golhisar Thera Knossos¨ ¨ ¨ ¨-100 mm )150 mm -85 mm 85–150 mm

dMethod ICP-MS sol ICP-MS sol ICP-MS sol ICP-MS sol ICPrSSMS ICP-MSe e e en 1 1 1 1 5 7

Ž .Li 24.85 26.78 25.55 27.16 20.04 2.29Ž .Be 1.38 1.85 1.83 1.87 1.57 0.09Ž .B 10.80 4.97 3.17 3.31 0.93 0.69

P 644.5 354.5 441.1 372.5Sc 8.59 6.22 6.63 6.23Ti 2947 1771 1931 1864V 65.04 34.88 31.68 25.80

Ž .Cr 17.09 2.90 2.90 1.78 10.05 4.12Ž .Mn 611.1 4.12Ž .Co 4.86 2.37 2.76 2.46 3.94 0.41Ž .Ni 8.84 2.54 1.77 16.65 5.93 2.43Ž .Cu 9.51 8.97 16.76 9.42 15.38 1.97Ž .Zn 55.37 44.20 53.07 55.97 59.41 3.05Ž .Ga 26.27 26.23 26.11 25.89 15.19 0.61Ž .Se 1.98 0.69Ž .Rb 86.93 97.51 97.48 92.32 94.80 2.88

Ž . Ž .Sr 107.7 66.66 73.38 69.30 136.4 62.47 102.9 6.18Ž .Y 36.23 36.37 35.90 36.37 35.10 0.95

Ž . Ž .Zr 242.0 279.8 266.9 276.5 267.0 9.75 258.4 10.89Ž . Ž .Nb 11.76 9.32 12.80 11.82 12.60 1.67 8.33 0.75Ž . Ž .Mo 2.40 0.50 2.49 0.14

Ž .Ag 0.36 0.08Ž .Cd 0.37 0.09

Ž . Ž .Sn 4.76 0.46 2.78 0.31Ž .Sb 1.00 0.10

Ž . Ž .Cs 2.33 2.58 2.49 2.48 2.36 0.30 2.71 0.11Ž . Ž .Tl 0.46 0.11 0.70 0.14Ž . Ž .Ba 518.7 523.0 506.0 514.3 480.6 44.27 488.9 12.92Ž . Ž .Hf 6.55 7.91 7.39 7.64 7.13 0.54 6.73 0.44

Ta 1.04 0.86 1.67 1.52Ž . Ž .W 1.10 0.27 1.34 0.16Ž . Ž .Pb 34.15 19.15 17.96 18.79 13.80 2.17 18.56 3.85Ž . Ž .Bi 0.13 0.05 0.24 0.02Ž . Ž .Th 15.59 17.58 16.75 17.49 16.04 1.89 16.00 1.18Ž . Ž .U 4.84 5.56 5.26 5.49 4.75 0.73 4.64 0.47

a This study.b Ž .Vitaliano et al. 1990 .c Ž .Warren and Puchelt 1990 .dSpark Source Mass Spectrometry.eAverage of five acquisitions from one sample digestion.

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–2926

that problems related to the vesicular nature of thetephra and to the polishing of small, silt-sized parti-cles may also have led to low analytical totals.However, whilst the data from these Nile delta de-posits have similar Al:Si ratios to our and other dataŽ .0.18–0.19 , the four Nile Delta ashes are highlyvariable and, solely on the basis of major-elementanalyses, their provenance cannot be assigned un-equivocally.

5. Trace-element geochemistry

The trace-element and rare earth element data areshown in Tables 7 and 8 respectively. Also shownare data from analyses of pumice samples from

Ž . ŽThera Vitaliano et al., 1990 and Knossos Warren.and Puchelt, 1990 . All of the trace-element data,

and in particular data for the relatively immobileŽ .trace-elements REE, Zr, Nb, Hf, Y are virtually

indistinguishable from the published analyses fromKnossos and Thera. In addition the remaining, poten-

Ž .tially more mobile elements such as Rb, Cs, Sr, Ba

are also almost identical to the published data indi-cating that very little alteration of the Golhisar glasses¨has taken place. This is consistent with the major-element data. There can be no doubt that the Golhisar¨samples are from the same source as the samplesanalysed from Knossos and Thera, and are thussourced from the Santorini eruption. A study of theimmobile trace-elements of the tephras from the NileDelta may enable more confident correlation of thiswith other Santorini ashes.

Fig. 4 shows chondrite-normalised rare earth ele-ments from Golhisar Golu compared to data for¨ ¨ ¨

Ž .pumice samples from Thera Vitaliano et al., 1990Ž .and Knossos Warren and Puchelt, 1990 . There is

an excellent agreement in the shape of the rare earthelement patterns from all four size fractions analysedwhen compared to samples from Knossos and Thera.

6. Radiocarbon age

Radiocarbon ages of two peat samples from justbelow the tephra are indistinguishable within the one

Table 8Rare earth element analyses for separated glass shards from the tephra layer deposited at Golhisar Golu by solution nebulisation ICP-MS. REE¨ ¨ ¨data for pumice from Thera and Knossos, Crete also shown. One standard deviation given in parentheses. The Golhisar data have been¨

Ž .normalised to an anhydrous basis using H O by difference 2.315% . Concentrations in ppm2

a a a a b cSample Golhisar Golhisar Golhisar Golhisar Thera Knossos¨ ¨ ¨ ¨-100 mm )150 mm 85–150 mm -85 mm

eMethod ICP-MS sol ICP-MS sol ICP-MS sol ICP-MS sol ICPrSSMS ICP-MSd d d dn 1 1 1 1 5 7

Ž . Ž .La 28.4 29.1 29.2 30.3 25.2 2.63 26.3 1.08Ž . Ž .Ce 56.1 55.5 55.8 57.7 51.3 4.74 55.9 1.42Ž . Ž .Pr 6.75 6.60 6.80 6.95 5.63 0.27 6.17 0.28Ž . Ž .Nd 24.8 26.0 25.4 26.4 23.3 1.49 23.2 0.98Ž . Ž .Sm 5.71 5.77 5.49 5.86 5.05 0.30 5.06 0.15Ž . Ž .Eu 1.25 0.99 1.01 1.13 0.95 0.05 1.02 0.03Ž . Ž .Gd 6.55 6.61 6.66 6.74 5.21 0.18 5.76 0.18Ž . Ž .Tb 0.83 1.06 1.06 1.06 0.94 0.06 1.02 0.06Ž . Ž .Dy 6.75 6.96 7.10 6.99 6.20 0.34 5.98 0.20Ž . Ž .Ho 1.54 1.60 1.55 1.63 1.35 0.04 1.37 0.06Ž . Ž .Er 4.34 4.84 4.63 4.73 4.15 0.13 4.23 0.21

Ž .Tm 0.71 0.75 0.72 0.78 0.75 0.02Ž . Ž .Yb 4.92 5.14 5.17 5.25 4.31 0.20 4.48 0.21

Ž .Lu 0.79 0.79 0.84 0.84 0.79 0.03

a This study.b Ž .Vitaliano et al. 1990 .c Ž .Warren and Puchelt 1990 .dAverage of five acquisitions from one sample digestion.eSpark Source Mass Spectrometry.

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–29 27

Fig. 4. Chondrite-normalised rare earth element compositions for: A: the various size fractions of glass shards in tephra deposit fromŽGolhisar Golu, B: mean REE pattern for the Golhisar glass shards shown alongside data for pumice from Knossos, Crete Warren and¨ ¨ ¨ ¨

. Ž . Ž .Puchelt, 1990 and Thera Upper pumice—Vitaliano et al., 1990 . Chondrite normalising factors from Boynton 1984 . The Golhisar data¨Ž .have been normalised to an anhydrous basis using H O by difference 2.315% . Concentrations in ppm.2

Ž .sigma range Table 9 . Following the calibrationŽprocedure of Stuiver and Reimer 1993: CALIB rev.

.3.0.3.c produces an age range of 1749–1406 BC attwo standard deviations. A precise date for the erup-

Ž .tion of Santorini Thera is still a matter of someŽcontroversy Manning, 1989, 1990a,b; Kuniholm,

.1990 . Reported dates range from the mid-sixteenth

century to the mid-seventeenth century BC. Radiocar-bon dates from the volcanic destruction levels ofThera itself display a wide range and have beenquestioned on the basis of possible contamination oforganic material by volcanic carbon and inappropri-

Ž .ate selection of material Kuniholm, 1990 . Dates onpeat associated with the distal ash layer have the

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–2928

Table 9Radiocarbon age of sediments underlying the tephra layer at Golhisar Golu¨ ¨ ¨

13Ž .Laboratory Core segment Depth cm Conventional age d C Calendar years BCPDB14Ž .number C years BP"1s "0.1‰ at 2s

Beta-56673 GHA.92-3 59–63 3330"70 no data 1749–1434SRR-5188 GHE.93-7 13–21 3225"45 y25.8 1604–1406

Ž .Calendar years derived from CALIB rev. 3.0.3.c after Stuiver and Reimer 1993 .

advantage of being far-removed from any volcanicŽ .contaminating influence cf. Manning, 1989, 1990b .

Ž .Sullivan 1988 reported a radiocarbon age of 3110"160 yr BP for peat 30 cm above the tephra atGolcuk Golu, thus providing a terminus ante quem¨ ¨ ¨ ¨for the Minoan eruption. Although the dates reportedhere are on peat immediately beneath the tephra,they are unlikely to help break the present impasseon agreement for a calendrical date for the eruption,because of the radiocarbon age uncertainty and thenature of the calibration curve for this age range.

7. Conclusions

The major- and trace-element geochemical analy-ses undertaken on the volcanic ash from Golhisar¨Golu together with the radiocarbon age determina-¨ ¨tions leave little doubt that the provenance of this

Ž .tephra is the Minoan eruption of Santorini Thera at;3300 yr BP. Trace-element data, reported here forthe first time on the distal ash, provide a moreprecise identification than major element data alone.Laser ablation techniques for analyzing single sand-

Ž .sized ash shards see Pearce et al., 1999 offer theopportunity of avoiding the problem of contamina-tion of bulk samples by detrital, non-volcanic mate-rial. Increased knowledge of the ash distribution indistal areas will result in better total ash volume

Žestimates and improved volcanological models Pyle,.1990; Sigurdsson et al., 1990 . The presence of

visible tephras in lake sediments in Southwest Turkeyindicates that other tephras may be found. Furtherstudy should be devoted to the microscopic examina-tion of lacustrine sediments for the identification ofdisseminated or low mass-loading tephras in theEastern Mediterranean. Identification of other tephrasin Near-Eastern lake sediments is an essential step

towards constructing a regional tephrochronology forpalaeoecological and archaeological research.

Acknowledgements

Fieldwork was funded in part by the NationalGeographic Society. WJE acknowledges the supportof a University of Wales studentship. One of theradiocarbon dates was provided by NERC ScientificServices Radiocarbon Laboratory. Permission for ourwork was kindly granted by the General Directorateof Monuments and Museums, Burdur Province,Southwest Turkey. Thanks are also due to the BritishInstitute of Archaeology at Ankara for the loan ofthe Dachnowsky corer.

References

Boynton, W.V., 1984. Geochemistry of the rare earth elements:Ž .meteorite studies. In: Henderson, P. Ed. , Rare Earth Element

Geochemistry. Elsevier, pp. 63–114.Doumas, C., Papazoglou, L., 1980. Santorini tephra from Rhodes.

Nature 287, 322–324.Ž .Einarsson, T., 1986. Tephrochronology. In: Berglund, B.E. Ed. ,

Handbook of Holocene Palaeoecology and Palaeohydrology.Wiley, Chichester, pp. 329–342.

Faegri, K., Iversen, J., 1989. Textbook of Pollen Analysis. Wiley,Chichester, 328 pp.

Federman, A.N., Carey, S.N., 1980. Electron microprobe correla-tion of tephra layers from Eastern Mediterranean abyssalsediments and the island of Santorini. Quaternary Research 13,160–171.

Guichard, F., Carey, S., Arthur, M.A., Sigurdsson, H., Arnold,M., 1993. Tephra from the Minoan eruption of Santorini insediments of the Black Sea. Nature 363, 610–612.

Keller, J., 1980. Prehistoric pumice tephra on Aegean islands. In:Ž .Doumas, C. Ed. , Thera and the Aegean World II. Volume

Two. Papers and Proceedings of the Second InternationalScientific Congress on Thera and the Aegean World. TheThera Foundation, London, pp. 49–56.

Keller, J., 1981. Quaternary tephrochronology in the Mediter-

( )W.J. Eastwood et al.rGlobal and Planetary Change 21 1999 17–29 29

Ž .ranean region. In: Self, S., Sparks, R.S.J. Eds. , TephraStudies. Reidel, Dordrecht, pp. 227–244.

Keller, J., Ryan, W.B.F., Ninkovich, D., Altherr, R., 1978. Explo-sive volcanic activity in the Mediterranean over the past200,000 yr as recorded in deep-sea sediments. GeologicalSociety of America Bulletin 89, 591–604.

Knox, R.W.O’B., 1993. Tephra layers as precise chronostrati-Ž .graphical markers. In: Hailwood, E.A., Kidd, R.B. Eds. ,

High Resolution Stratigraphy. Geological Society Special Pub-lication 70, London, pp. 169–186.

Kuniholm, P.I., 1990. Overview and assessment of the evidencefor the date of the eruption of Thera. In: Hardy, D.A., Ren-

Ž .frew, A.C. Eds. , Thera and the Aegean World III. VolumeThree: Chronology. Proceedings of the Third InternationalCongress, Santorini, Greece. The Thera Foundation, London,pp. 13–18.

Manning, S., 1989. The Santorini eruption: an up-date. Journal ofŽ .Mediterranean Archaeology 2 2 , 303–313.

Manning, S., 1990a. The eruption of Thera: date and implications.Ž .In: Hardy, D.A., Renfrew, A.C. Eds. , Thera and the Aegean

World III. Volume Three: Chronology. Proceedings of theThird International Congress, Santorini, Greece. The TheraFoundation, London, pp. 29–40.

Manning, S., 1990b. The Thera eruption: The Third Congress andŽ .the problem of the date. Archaeometry 32 1 , 91–100.

Ninkovich, D., Heezen, B.C., 1965. Santorini tephra. In: Proceed-ings of the Seventeenth Symposium of the Colston ResearchSociety. Colston Research Papers 17 Butterworths ScientificPublications, London, pp. 413–452.

Pearce, N.J.G., Westgate, J.A., Perkins, W.T., Eastwood, W.J.,Shane, P., 1999. The application of laser ICP-MS to the analysisof volcanic glass shards from tephra deposits: bulk glass andsingle shard analysis. Global and Planetary Change 21, 153–173.

Pyle, D.M., 1990. New estimates for the volume of the Minoaneruption. In: Hardy, D.A., Keller, J., Galanopoulos, V.P.,

Ž .Flemming, N.C., Druitt, T.H. Eds. , Thera and the AegeanWorld III. Volume Two: Earth Sciences. Proceedings of theThird International Congress, Santorini, Greece. The TheraFoundation, London, pp. 113–121.

Sigurdsson, H., Carey, S., Devine, J.D., 1990. Assessment ofmass dynamics and environmental effects of Santori volcano.In: Hardy, D.A., Keller, J., Galanopoulos, V.P., Flemming,

Ž .N.C., Druitt, T.H. Eds. , Thera and the Aegean World III.Volume Two: Earth Sciences. Proceedings of the Third Inter-

national Congress, Santorini, Greece. The Thera Foundation,London, pp. 100–112.

Smith, D.G.W., Westgate, J.A., 1969. Electron microprobe tech-nique for characterising pyroclastic deposits. Earth and Plane-tary Science Letters 5, 313–319.

Stanley, D.J., Sheng, H., 1986. Volcanic shards from SantoriniŽ .Upper Minoan ash in the Nile Delta, Egypt. Nature 320,733–735.

Stuiver, M., Reimer, P.J., 1993. Extended 14C data base andrevised CALIB 3.0 14C age calibration program. Radiocarbon

Ž35, 215–230, CALIB rev. 3.0.3.c Department of Geological.Sciences, University of Washington, Seattle, 1994 .

Sullivan, D.G., 1988. The discovery of Santorini Minoan tephra inwestern Turkey. Nature 333, 552–554.

Sullivan, D.G., 1990. Minoan tephra in lake sediments in westernTurkey, dating eruption and assessing the atmospheric disper-

Ž .sal of ash. In: Hardy, D.A., Renfrew, A.C. Eds. , Thera andthe Aegean World III. Volume Three: Chronology. Proceed-ings of the Third International Congress, Santorini, Greece.The Thera Foundation, London, pp. 114–119.

Vinci, A., 1985. Distribution and chemical composition of tephralayers from Eastern Mediterranean abyssal sediments. MarineGeology 64, 143–155.

Vitaliano, C.J., Taylor, S.R., Norman, M.D., McCulloch, M.T.,Nicholls, I.A., 1990. Ash layers of the Thera Volcanic Series:Stratigraphy, Petrology and Geochemistry. In: Hardy, D.A.,Keller, J., Galanopoulos, V.P., Flemming, N.C., Druitt, T.H.Ž .Eds. , Thera and the Aegean World III. Volume Two: EarthSciences. Proceedings of the Third International Congress,Santorini, Greece. The Thera Foundation, London, pp. 53–78.

Warren, P.M., Puchelt, H., 1990. Stratified pumice from BronzeŽ .Age Knossos. In: Hardy, D.A., Renfrew, A.C. Eds. , Thera

and the Aegean World III. Volume Three: Chronology. Pro-ceedings of the Third International Congress, Santorini, Greece.The Thera Foundation, London, pp. 71–81.

Watkins, N.D., Sparks, R.S.J., Sigurdsson, H., Huang, T.C., Fed-erman, A., Carey, S., Ninkovich, D., 1978. Volume and extentof the Minoan tephra from Santorini volcano: new evidencefrom deep-sea cores,. Nature 271, 122–126.

Westgate, J.A., Gorton, M.P., 1981. Correlation techniques inŽ .tephra studies. In: Self, S., Sparks, R.S.J. Eds. , Reidel,

Dordrecht, pp. 73–94.van Zeist, W., Woldring, H., Stapert, D., 1975. Late Quaternary

vegetation and climate of southwestern Turkey. Palaeohistoria17, 55–143.