Institutionen för naturgeografi

Examensarbete grundnivåNaturgeografi, 15 hp

Peloponnesian Stalagmites and Soda Straw Stalactites as

Climate Archives

Stable Isotopes in New Speleothem Material from Kapsia Cave, Peloponnese, Greece

Linn Haking

NG 632017

Förord

Denna uppsats utgör Linn Hakings examensarbete i Naturgeografi på grundnivå vid

Institutionen för naturgeografi, Stockholms universitet. Examensarbetet omfattar 15

högskolepoäng (ca 10 veckors heltidsstudier).

Handledare har varit Martin Finné, Institutionen för arkeologi och antik historia, Uppsala

universitet. Examinator för examensarbetet har varit Steffen Holzkämper, Institutionen för

naturgeografi, Stockholms universitet.

Författaren är ensam ansvarig för uppsatsens innehåll.

Stockholm, den 4 januari 2018

Steffen Holzkämper

Chefstudierektor

Abstract

This study presents results from stable isotope analyses of amodern stalagmite and

threesodastrawstalactites fromKapsiaCave, thePeloponnese,Greece.The resulting

valuesfromthestalagmiteareputintocontextof localmeteorologicaldata,aswellas

previous research fromKapsiaCave.Thepotential forusing soda straw stalactites as

complementary climate archives on shorter time scales on the Peloponnese is also

explored.Theisotopicvaluesinthestalagmiteconfirmastronglinktotheamounteffect

onanannualscale.Onaseasonalscale,variationsintheisotopicsignalcanbedetected

asaresultofi.e.increasedcaveairtemperatureinsummer.Thestableisotopevaluesin

the soda straw stalactites largely correspond to previous isotopic measurements in

Kapsia Cave. The trend of the isotopic carbon signal in two of the straws also

strengthens earlier theories suggesting a link to CO2 concentrations in the external

atmosphere. Soda straws are, thus, encouraged for use in future climate studies,

although the sampling method should be further explored. The results of this study

contributetoan increasedunderstandingofPeloponnesianspeleothemsinrelationto

environmental processes and new insights are suggested into the use of soda straw

stalactitesasclimatearchives.

KeywordsStableIsotopes;Stalagmite;SodaStrawStalactites;ClimateArchive;ClimateVariability;

TheAmountEffect;IsotopicFractionation;KapsiaCave;Peloponnese;Greece;Mediterranean

Tableofcontent

1. Introduction 1

2. Aimandresearchquestions 2

3. Background 3

3.1 Speleothemformation 3

3.2 Speleothemsasclimatearchives 4

3.2.1 Sodastrawstalactites 5

3.2.2 Stalagmites 6

3.3 Speleothemsandstableisotopesofcarbonandoxygen 7

3.4 Isotopicfractionationandequilibriumconditions 9

3.5 Setting 10

3.5.1 KapsiaCave 10

3.5.2 Localclimate 12

3.5.3 PreviousresearchinKapsiaCave 13

4. Materialandmethod 14

4.1Fieldwork 14

4.2Lab-work 15

5. Results 16

5.1StalagmiteGK02MODERN 16

5.2SodastrawstalactitesKS2,KS3andKS4 18

6. Discussion 19

6.1StalagmiteGK02MODERN 19

6.2SodastrawstalactitesKS2,KS3andKS4 22

7. Conclusion 25

Acknowledgements 26

8. References 26

8.1Electronicreferences 31

1

1.Introduction

Speleothems are calcareous cave deposits that can form and be preserved over long

periods of time making them interesting as natural climate archives. They offer the

possibility to study climate variability through several proxies, for example, oxygen-

andcarbon isotopes, traceelements (e.g.Mg,Sr,Ba),andpetrographicchanges in the

speleothemlaminea,whichcanbeusedincombinationwithpreciseradiometricdating

withUranium-Thorium.Proxyrecordsfromspeleothemscanbeofdifferentresolutions

fromsub-annualtomillennialandsometimescoverextensivetimeseries(upto105of

years)(Fairchildetal.2006).Speleothemstudiesmostlycovertropical-tosub-tropical

regionsoftheworld(e.g.Williamsetal.1999;Bakeretal.2007;Verheydenetal.2008;

Joetal. 2010;Boyd2015;Bergeletal.2017;Scroxtonetal.2017)andare important

complementsasterrestrialarchivesfromlowlatitudestostudiesone.g. icecoresand

oceansedimentscores(Bakeretal.2014).

Several speleothem climate studies have been conducted around the

Mediterranean (e.g. Bar-Matthews et al. 1996; Bard et al. 2002; Bar-Matthews et al.

2003;Frisiaetal.2003;Bakeretal.2007;Verheydenetal.2008;Fleitmannetal.2009;

Zanchetta et al. 2014; Surić et al. 2017). However, they are sparse on the Greek

peninsulaPeloponnese,wherespeleothemmaterialwasfirstpublishedonlyafewyears

ago (Finné et al. 2014). Before 2014 this area constituted a gap in the speleothem

climate research. Furtherwork fromFinné (Finné2014;Finnéetal.2015) aswell as

Boyd(2015),hascontributedwithvaluabledatafortheregion,andongoingwork(e.g.

Finnéetal.inpress)willnotonlycontinuetocontributetotheoverallclimatehistoryof

the Peloponnese and the Mediterranean in general, but also to local archaeological

research(e.g.Kordatzakietal.2016;Weibergetal.2016;Ntinou&Tsartsidou2017).

ThearchaeologyofthePeloponneseisextensiveandcomplexsocietiesstartedto

form as early as 8750BP (6800BC) at the beginning of the Neolithic revolution

(Demoule & Perlès 1993). Current archaeological research of the Peloponnese is

focusingonelucidatinghowpastsocietiesfrom8750BP(6800BC)to1650BP(AD300)

havedevelopedinrelationtoclimatevariabilityandaimstoincreaseourpossibilitiesto

interprethuman-environmentalinteractions(e.g.Weibergetal.2016;DoLPproject).

The overall objective of this study is to contribute to the speleothem climate

recordofthePeloponneseand,hence,increasetheknowledgeaboutclimatevariability

inthisregion.Inparticular,newmodernspeleothemmaterialconsistingofastalagmite

2

(formingwithinthelast5years)fromKapsiaCave,centralPeloponnese,isanalysedfor

stable oxygen- and carbon isotopes in order to investigate how isotopic signals in

speleothemscorrelatewith theexternalclimateof today. Incombinationwithashort

reviewon soda straw stalactite studies, three soda straws fromKapsia Cave are also

analysed for stable isotopes to explore whether this kind of speleothem has the

potentialtobeusedforfutureclimatestudiesonthePeloponnese.

Theresultsofthisstudyincreaseandstrengthentheknowledgeandpotentialof

the Peloponnesian speleothem climate record. It also brings some new insights into

how soda straw stalactites may be used for future climate studies in general, and

further contributes to our understanding of how meteorological data and isotopic

signalsinspeleothemscorrelateinKapsiaCaveinparticular.

2.Aimandresearchquestions

ThisstudyaimstocontributetothePeloponnesianspeleothemclimaterecordthrough

1)stableoxygen-andcarbonisotopeanalysisofnewspeleothemmaterialfromKapsia

Cave, as well as by 2) exploring possibilities in using soda straw stalactites for

Peloponnesian climate studies. The study further aims to relate the stable isotope

resultsfromthestalagmitetolocalmeteorologicaldataandexaminetherelationshipto

previousisotopicmeasurements,withtheambitiontoconfirmandstrengthenexisting

dataandbringmoreinsightintoclimatevariability.

Researchquestions:

- How do the isotopic values analysed in the speleothem material compare to

previousisotopicmeasurementsfromKapsiaCave?

- In what ways does the isotopic signal in the stalagmite respond to external

climatevariabilityandkineticfractionationinthecave?

- Whatpotentialexists inusingsodastrawstalactitesascomplementaryclimate

archives?

3

3.Background

3.1Speleothemformation

Speleothems are calcite deposits created from drip water in karstic caves, cavities

formedthroughdissolutionofcarbonaterockssuchaslimestone(CaCO3)anddolomite

(CaMg(CO3)2). The process of speleothem formation (fig. 1) starts as surface water

percolatesthroughsoilrichincarbondioxideduetorespirationofplantsanddecayof

organic matter, creating acidic water (carbonic acid (H2CO3)). As the acidic water

reaches theepikarst (azoneof fissuredbedrockunderlying thesoilzone) itdissolves

the carbonate bedrock, which in turn makes the calcium concentration rise in the

solution.The calcium-saturatedwater continues through fractures in theporous rock

anddescendsintothecave.Asthecarbondioxidepressure(pCO2)islowerinthecave

than inthesoil-andepikarstzone,degassingofcarbondioxideoccursasthesolution

reachesthecave.Thiscausescalcitedeposition,initiatingtheformationofspeleothems

(Ford&Williams2007;Fairchild&Baker2012).

Figure1.Theprocessofspeleothemformation(createdbyauthorafterFairchildetal.2006).

4

Speleothemsoccurinseveralsizesandshapes(fig.1),forexampleasflowstones,

stalactitesandstalagmites.Flowstonesformaswaterflowsdownthecavewallsandon

the floorcreating layersofcalcite film, sometimesalsohanging likecurtains fromthe

ceiling and wall. Stalactites start as soda straws (thin tubular speleothems) hanging

fromtheceiling,whichwithtimegrowsinlengthandthickness,whilestalagmitesbuild

up from the cave floor. Speleothems growing from the ceiling and the floor may

eventuallymeetandformacolumn(Ford&Williams2007).

3.2Speleothemsasclimatearchives

Even thoughspeleothemshavebeenstudied forover40years it isduring the last20

yearsthattheiruseasclimatearchiveshasincreasedrapidly.Thisincreasecanmainly

betracedtoimprovementsoftheradiometricUranium-Thoriumdatingmethod(U-Th

dating). By calculating the disequilibrium between the parent isotope 234U and its

daughterisotope230Th,thistechniquehasthestrengthtoprovideprecisedatingtothe

speleothemlaminae,upto500,000yearsback intime(Doraleetal.2004;Fairchild&

Baker2012).

Todayspeleothemsarewidelyusedasclimatearchivesthankstothepotentialof

providing detailed time series using U-Th dating as well as counting of regularly

forminglaminae.Inaddition,speleothemshavethecapabilitytogrowcontinuouslyfor

hundreds of thousands of years, thanks to the sheltered cave environment, and

preserveaclimatesignalwithintheirrobuststructure.Asaterrestrialclimatearchive,

speleothemsaswellasicesheetsprovideclimatedatacomparabletootherarchiveslike

ocean sediment cores, covering extensive time periods. The possibility of precise

independentdating,however,iswhatmakesspeleothemsstandoutasaclimatearchive

(McDermott2004;Fairchildetal.2006;Fairchild&Baker2012;Bakeretal.2014).

Proxiesthatarecommonlystudiedinspeleothemsarestableisotopesofcarbon

(δ13C) (e.g.Breecker2016) andoxygen (δ18O) (e.g.McDermott2004; Lachniet2009),

trace elements such as Magnesium (Mg), Strontium (Sr) and Barium (Ba) (e.g.

Desmarchelieretal.2006),aswellasgrowthratesandthicknessoflaminae(e.g.Frisia

et al. 2003; Tan et al. 2006). Though these proxies may be studied to provide an

external climate signal, variations in the depositional environment, such as

temperature, CO2 concentrations, humidity and air circulation in the cave,may affect

thisconnection(seesection3.3and3.4forfurtherdetails)(Fairchildetal.2006).

5

3.2.1Sodastrawstalactites

Sodastrawstalactitesare thevery first

state in the formation of the more

robustconicalstalactites(StPierreetal.

2009). The name soda straw originates

from the tubular shape of this

speleothemresemblingadrinkingstraw

(Desmarchelier et al. 2006). Like all

speleothems, soda straw stalactites

form from supersaturated drip water.

As the water enters the cave and

degassing of CO2 occurs, calcite

precipitates from the drop, which is

hanging from the cave ceiling. Due to

gravity, the drop eventually falls,

leaving a ring of calcite from where it

was hanging. As the straw in this

manner builds towards the cave floor,

thedripwaterwillmoveinthecentreof

theformingtube,increasinginsupersaturation,depositingasmalleramountofcalcite

in its inner canal and a greater amount at the tip as a ring. Because of this calcite

deposition,sodastrawsmanytimesdemonstratehorizontalbandingfrom0.05–0.5mm

thick,interpretedasannuallaminae(fig.2)(Moore1962;Huangetal.2001;Pauletal.

2013). The average diameter of soda straws normally measures around 5mm. The

thicknessof thetubewalls isusually100-300μmat thetipand increasestowardsthe

root,decreasingthewidthof its innercanal.Calcitegrowthbecomes lateralwhenthe

central canal of the straw gets blocked and, thus, begins to form a conical stalactite

(Baldini2001;Fairchild&Baker2012).

Although it is not uncommon to find straws over a metre in length they are

usuallynot longer thana fewdecimetresowing to their fragility (Desmarchelieretal.

2006; Fairchild & Baker 2012). It is commonly believed that soda straws form and

remain intact fora relatively limited timeperiodestimated torangeata fewdecades

butpossiblyuptoacentury.However,growthatthesamepositionmaycontinueafter

Figure 2. Formation and structure of a banded sodastraw stalactite with a suggested sample span forfragments vs. powder (created by author afterPaul et al. 2013, original published inInternationalJournalofSpeleology).

6

breakage(Williamsetal.1999;StPierreetal.2009;Fairchild&Baker2012).Growth

ratesvarygreatly,butcanbeasfastas40mmperyear(Joetal.2010).

Becauseofthefragilenatureofsodastraws,theyhavemanytimesbeenavoided

for paleoclimate research (Desmarchelier et al. 2006) and, thus, the supply of such

studiesislimited.Still,manyrelevantareasarecovered:dating(e.g.StPierreetal2009;

StPierreetal2012),growthrateandstructure(e.g.Moore1962;Baldini2001;Perrette

&Jaillet2010;Pauletal.2013),traceelements(e.g.Huangetal.2001;Desmarchelieret

al. 2006), and stable isotopes (e.g. Baskaran & Krishnamurthy 1993; Williams et al.

1999;Woo etal.2005). Studies on short-term climate variability and climate change

overthepastcenturyareanimportantstepinunderstandingthecorrelationbetween

stableisotopesinspeleothemsandtheexternalclimate.Thisisanecessarycomplement

topaleoclimateresearchandbecauseanalysesforbothisotopesanddatingtodayallow

small sample size, soda straws stand a potential candidate for this kind of research

(McDermott2004;Wooetal.2005;Fairchildetal.2006;Pauletal.2013).

3.2.2Stalagmites

Stalagmites are used to a great extent in paleoclimate research. Among the climate

proxiesnormallystudiedinstalagmites,morphologyandpetrographycanbeaphysical

indicationtoclimatevariability(Bakeretal.2014).Laminaethicknessandcolourmay,

forexample,provideaninsightintochangesinexternaltemperature(Frisiaetal.2003).

Changesindriplocationandindriprates,largelycontrolledbyrainfall,canbeseenin

thegrowthgeometryandporositiesofthestalagmite(Genty&Quinif1996;Frisiaetal.

2003;McDermott2004;Fairchildetal.2006).Tanetal.(2006)alsodemonstratedthe

possibility of tracing long-term climate changes from the growth structure and

thickness of stalagmite lamination. Although they emphasise that stalagmite laminae

and its sensitivity to the external climate may differ greatly between individual

specimens,theusageofstalagmitesbeforeotherspeleothemsisstillencouraged(Tanet

al.2006).

7

3.3Speleothemsandstableisotopesofcarbonandoxygen

Naturallyoccurringstableisotopesarevariationsofthesameelement,butthenumber

ofneutrons in theatom’snucleidiffersandconsequently constitutesadifferentmass

weight.Thisweightdifferencemaycausephysicalseparationofthedifferentisotopes,

socalledisotopicfractionation,forexamplewhenelementsaretransferredbetweenthe

reservoirsoftheEarthsystemdrivenbysolarenergy.Therelativeabundanceofheavy

andlightisotopesineachreservoirisdependentonthefavouredtransferofoneisotope

overtheotherasaresultofisotopicmassaswellastemperature.Thiscreatesaratioof

heavytolightisotopethatcanbemeasuredandisreportedinrelationtoasetstandard

(v-SMOW:ViennaStandardMeanOceanWater)(Sharp2017).

Theratioofstableoxygenisotopesincarbonatesisdefinedbytheformula:

δ18O‰V-PDB(ViennaPeeDeeBelemnite)=(Rsample/Rstandard-1)×1000whereR=18O/16O.

Similarly,theratioofstablecarbonisotopesincarbonatesisexpressedas:

δ13C‰V-PDB(ViennaPeeDeeBelemnite)=(Rsample/Rstandard-1)×1000whereR=13C/12C

(e.g.Rozanskietal.1993).

The most common stable isotopes that are analysed in speleothems for

paleoclimatological purposes are oxygen and carbon. In nature, oxygen is normally

foundwith8protonsand8neutronsinitsnuclei(16O–abundance:99.76%),whilethe

most common formof naturally occurring carbon contains 6 protons and6 neutrons

(12C–abundance:98.89%).Theheavier isotopesof theseelementsoccurwithoneor

two more neutrons forming: 17O (abundance: 0.04%), 18O (abundance: 0.2%), 13C

(abundance:1.11%)and14C(radioactive).Amongthese,18Oand13Careusedforstable

isotopeanalysisincarbonates(Sharp2017).

Theisotopicsignalinthecavedripwater,capturedwithinthegrowthlaminaeof

speleothems,canunderequilibriumconditionsoriginatefrommeteoricwaterand,thus,

climate-regulatedprocessesonthesurfacecontrolthe18Oabundanceinrelationtothe

set standard. As a simplified example, a warmer climate with high solar energy

increasesoceanwaterevaporationallowingmoreoftheheavieroxygenisotopes(18O)

togetintotheatmosphere.Inturn,heavierisotopesarefavouredduringcondensation,

causing isotopic enrichment with increasing condensation temperature (the

condensation effect). Consequently, meteoric precipitation will hold a high

concentrationoftheheavierisotope18O,eventuallycausinggroundwatertobeenriched

in 18O and, thus, to display relatively enriched δ18O values.This relationship between

8

temperature at the ocean water source and 18O is known as the ocean source effect

(Dansgaard1964;Williamsetal.1999;Sharp2017).Examplesoffurtheralterationsof18Omayoccuraccordingto theamounteffect,whereδ18Oofprecipitation is inversely

related to precipitation amount, or the seasonal effect,where δ18O of precipitation is

more depleted in winter. The distance between precipitation and its source, the

continental effect, also has an impact on δ18O, as the abundance of 18Owill decrease

furtherfromthesource(Rozanskietal.1993;Williamsetal.1999).

The amount of 13C that gets transported into the groundwater is partly

controlled by CO2 concentrations in the atmosphere. In an article from Baskaran &

Krishnamurthy(1993),sodastrawstalactites,conicalstalactitesandstalagmiteswere

analysed for stable isotopes to determine the influence of atmospheric CO2 in calcite

cavedeposits.Theyargued that soda strawsdated to the last century recordedmore

enrichedδ13Cvaluesclosertopreindustrialtimes(anaveragearound−5.9‰(v-PDB)

inAD1920)andmoredepletedvaluestowardsthetipofthestrawdepositedinrecent

times (an average around−8.2‰ (v-PDB) in AD1990), which was interpreted as a

resultofglobalindustrialemissionsofCO2.Williamsetal.(1999)aswellasWooetal.

(2005)confirmthecorrelationbetweenmoreenrichedδ13Cvalueswithdistancefrom

thetipinmodernsodastraws.

Consequently,higherconcentrationof13Candmoreenrichedδ13Cvaluesindrip

wateraregeneratedwhenCO2concentrationsarelowintheatmosphere,forinstance,

on longer time scales during periods of colder climate (glacial conditions) when

vegetationisforcedtoabsorbeventheheavierCO2molecules(13CO2).Otherfactorsthat

affect δ13C in speleothems are photosynthesis in C3versus C4 plants, microbiological

processesandhumanlanduse(Wooetal.2005;Ford&Williams2007;Sharp2017).

Hence,theδ18Osignal incavedripwatercanbeinterpretedasanindicatorfor

changes in thehydrological cycleandpropertiesofprecipitation, suchasamountand

temperature,whiletheδ13CsignalisrelatedtoatmosphericCO2,vegetationcoverand

biological activity in the soil zone (Williams et al. 1999; Woo et al. 2005; Ford &

Williams2007;Sharp2017).

9

3.4Isotopicfractionationandequilibriumconditions

Eventhoughtheoxygenandcarbonisotoperatioincavedripwateroriginatesfromthe

externalenvironment,thisclimatesignalmaybecompromisedifthespeleothemdoes

notdepositin,ornear,equilibrium.EquilibriumreferstothestatewhereHCO-3andCO2

ofthecavedripwaterremainsunfractionatedduringcalciteprecipitation(Hendy1971;

Mickleretal.2004;Sharp2017).

SincetheworkofHendy(1971),theprocessesthatimpactisotopicfractionation

haveremainedanongoingdebate.Inhisarticle,Hendydiscussespossiblekineticeffects

onthedripwateras itentersthecave,causingcalcitetoprecipitate indisequilibrium

withitsparentwater,possiblycompromisinganyclimatesignal.Processesthatcanlead

to enriched isotopic values compared to equilibrium are, for example, (1) rapid

degassingofCO2ifpCO2inthedripwatersolutionismuchhigherthanpCO2inthecave

atmosphere,enrichingbothδ18Oandδ13C,aswellas(2)evaporationofthedripwaterif

the relativehumidityof the cave is low, causingδ18O in the solution tobecomemore

enriched(Hendy1971).

Subsequentstudieshavefurtherexploredthisconcept(e.g.Bar-Matthewsetal.

1996;Mickleretal.2004;Dietzeletal.2009;Lachniet2009;Tremaineetal.2011;Stoll

et al.2015). Mickler et al. (2004) examined kinetic fractionation and equilibrium in

modern speleothems in relation to contemporary climatology and groundwater

chemistry.Althoughmost speleothemsat thecavesitewereexpected todepositnear

equilibrium because of a stable depositional environment and high humidity, their

results showed that especially δ18O values were far from what they predicted. They

argued that several fractionating processesmust have acted on the dripwater since

isotopicvalueswerebothenrichedanddepletedindifferentplacesinthecave.Mickler

et al. (2004) concluded that enriched isotopic values were seen close to the cave

entrance where stronger air ventilation lowered the CO2 concentrations and caused

increaseddegassingofCO2inthedripwater,aswellasincreasingtheevaporationdue

toamorevariedhumidity.Lateron, the studyofTremaineetal. (2011)also showed

that a linear enrichment in calcite δ13C could be detectedwith closer distance to the

caveentrance.Mickleretal.(2004)furtherarguedthatrapidorlargevariabilityinrates

ofcalciteprecipitationcouldhaveadepletingeffectonδ13C,butalsoenrichδ18O.

Alterationof the δ18Omay also occur according to the cavetemperatureeffect,

wherefractionationofthedripwateroccursasaneffectofthecaveairtemperatureby

10

−0.24‰per °C increase in cooler temperatures (around 10°C), and−0.22‰per °C

increaseintemperaturesaround20°C(Friedman&O’Neil1977;Williamsetal.1999).It

has been suggested, however, that the cave temperature effect is largely

counterbalanced by the condensation effect in the atmosphere causing enrichment of

δ18O by 0.2-0.3‰ per °C. This is especially evident on longer time scales since a

warming of the atmosphere also will lead to warming of the cave air over time

(Williams et al. 1999; Finné et al.2014).Williams et al. (1999) argued that the cave

temperatureeffectislikelytobecomemoredominantwithincreaseddistancefromthe

moisturesource.

Itisgenerallybelievedthatpaleoclimaterecordsfromspeleothemsshouldonly

be considered reliable if modern calcite precipitation occurs in or near equilibrium,

whichistobedeterminedbysite-specificmonitoring(e.g.Mickleretal.2004;Dietzelet

al.2009; Lachniet 2009; Tremaine etal.2011).Nevertheless, it is acknowledged that

themanydifferentfractionatingprocessesrarelyofferperfectequilibriumdepositionof

calcite, and that the existent of such a state is highly questionable. Although this

complicates the possibility of interpreting an isotopic signal in speleothems, external

climate signalsmay still be retrieved (Sharp 2017). If, however, kinetic fractionation

occurs,complementarystudiesareneededtofurtherinvestigatetheprocessesbehind

theobserveddisequilibrium inorder toobtainareliable interpretationof the isotope

signal(e.g.Lachniet2009;McDermottetal.2011).

3.5Setting

3.5.1KapsiaCave

KapsiaCave(N37.623°,E22.354°), centralPeloponnese,Greece,(fig.3)liesbeneath20-

30mofTriassic-EoceneGavrovo-Tripolitzazonelimestonebedrockandisstretchingfor

about200m.It is locatedontheMantineaPlainat thebaseof theMainaloMountains.

Abovethecave,patchesofsoil,exposedbedrockanddeadjunipertrunks,showthatthe

vegetation is sometimes subject to burning (last noted in AD1997). Further, the

vegetationiscomprisedof2mhighoakshrubs,grassspecies,LamiaceaeandEuphorbia.

KapsiaCavehasanaturalentranceandanartificialentrance,constructedin2004,both

about700ma.s.l. Since2010partsof the cave areopen to tourists.Themeanannual

temperature measured over the last 3.5 years is 11.9°C ±0.52°C and mean annual

11

relativehumidity is≥95%.Anunusually lowrelativehumidityof89%wasmeasured

duringthewinterof2012(Finnéetal.2014;Finné2014).

The many varied and impressive speleothems in Kapsia Cave (stalactites,

stalagmites,flowstones,curtainsetc.)arepartlycoveredbyalayerofclay,indicatinga

high-watermark from flooding events occurring both in the distant past (e.g. 500BC,

70BC, andAD450) andmore recently (last noted in AD2001). Low-lying parts of the

cavehavemeter-thickdepositsofclaysuggestingrepeatedflooding.Thisisalsoevident

from a previous speleothem study in Kapsia Cave by Finné (2014), where a sliced

stalagmite showed clayhorizons in its laminae.These floodingshaveoccurred as the

drainagecapacityof5sinkholes(oneadjacent to thenaturalentranceof thecave)on

theMantinea Plain has been exceeded by the surfacewater input (Finné etal.2014;

Finné2014).

Though no systematic excavations have been made so far, traces from many

archaeological periods have been identified in Kapsia Cave. Undated human remains

from50individualsofallagesarescatteredinthecave,aswellastracesofhumanmade

fires,whichdatetotheNeolithic(6500-3000BC).It isstilldiscussedwhetherthecave

wasusedasaburialgroundorifthesepeoplewerevictimsofafloodingevent(Finnéet

al.2014 and references therein). Further, artefacts from the Hellenistic period (323-

31BC) and the 4th-6th century AD have been found deep in Kapsia, among the things

somebronzecoinsandfibulaefromthe2ndhalfofthe6thcenturyAD(Finnéetal.2014).

Figure3. LocationofKapsiaCaveontheGreekpeninsulaPeloponnese (afterFinné2014).

12

3.5.2Localclimate

Meteorological data from AD2010 to 2017 (fig. 4) has been collected from a

meteorological station in Tripoli (N37.509°, E22.418°, 10 km south of Kapsia, 646m

elevation). Previousmeteorological data, also displayed in figure 4,was presented in

the study by Finné (2014), which likewise was collected from a station in Tripoli,

although a different one. The meteorological data indicates a characteristic

Mediterraneanclimatewheresummersarehotanddryandwintersaremildandwet.

Themeanannual temperaturebetweenAD1980-2004andAD2010-2016combined is

13.7°C±0.4°Cwithaslightlycoldermeantemperature in themostrecentperiod.The

meantotalprecipitationforthewetseason(ONDJFMA)betweenAD1980and2017is

around580mm.Duringthewetseason,70-80%oftheyearlyamountfalls(Dotsikaet

al.2010). The limited amount of rainfall in the dry season is commonly occurring as

heavy rain showers, which is clear when going through the monthly meteorological

reports during the last seven years. In earlier studies (e.g. Finné et al. 2014; Finné

2014), the contribution of dry season (MJJAS) precipitation to the karstic aquifer has

been considered to be negligible since these rain showers cause fast runoff and no

significant percolation of rainwater into deeper soils occur. Therefore, the cave drip

waterinKapsiaisassumedtoprimarilyoriginatefromwetseasonprecipitation(Finné

2014);hencethisstudyisbasedonthesamepremises.

Figure4.AnnualwetseasonprecipitationdatacompiledfromFinné(2014)andTripoliMeteosearch.

13

3.5.3PreviousresearchinKapsiaCave

EventhoughspeleothemsfromseveralcountriesaroundtheMediterraneanhavebeen

analysed for paleoclimate research since many years back (e.g. Bar-Matthews et al.

1996;Bardetal.2002;Bar-Matthewsetal.2003;Frisiaetal.2003;Bakeretal.2007;

Verheydenetal.2008;Fleitmannetal.2009),noextensivestudieshadbeenconducted

on thePeloponneseuntil2009whenKapsiaCaveandGlyfadaCave firststarted tobe

monitored for a PhD project by Martin Finné (2014). By establishing the first

stalagmite-basedrecord for thePeloponnese, thisproject, in2014,couldpresentnew

data on changes in the local environment covering a period from 2900 to 1120BP

(950BCtoAD830),aswellasregionalclimatechanges.Periodswithwetterclimatethan

averagewereidentified2800,2650,2450,2350-2050,1790-1650,and1180BPthrough

stableoxygenisotopevariations(δ18O),whichcontributedtotheoverallpictureofthe

paleoclimateof theMediterraneanaswell as to archaeological research in the region

(e.g. Weiberg et al. 2016; DoLP project). Variations in stable carbon isotopes (δ13C)

couldfurtherbeassociatedwithbiologicalactivityandlocalhumanlanduse(Finnéet

al.2014;Finné2014).

Stable isotopeanalyseswerealsoconductedforthelaminatedmoderntopofa

stalagmite (GK02) from Kapsia Cave. Lamina counting suggests that the top formed

from the 1980’s until collection in 2009. The topwas analysed for stable isotopes at

sub-annual resolution. These high-resolution δ18O valueswere binned into individual

years and an annual averagewas calculated. These annual average δ18O valueswere

then correlated to the total amount ofwet season rainfall (Finné 2014). This data as

well asmonitoringofKapsiaCave fromSeptember2009 toMarch2013has revealed

thatdripwater is supersaturated all year aroundanda strong seasonal variability in

driprate.Thereisalsoarelativelystrongcorrelationbetweenprecipitationamountand

variationsinδ18O,i.e.theamounteffect,whenconsideringalagof1-2years,i.e.thetime

ittakesforwatertopassthroughtheaquifer.Thisisseenasdepletedδ18Ovalueswhen

rainfall increases during wet season (Finné 2014). A correlation between δ13C and

rainfallhasnotbeendetectedinthemodernlaminaeofGK02,noristhereacorrelation

inδ18Oandδ13Ctosurfacetemperature(Finné2014).

Although the risk of kinetic fractionation has been noted to increase since the

openingoftheartificialentrancein2004(Finné2014),inaccordancewiththestudyof

Mickleretal.(2004)andTremaineetal.(2011),calculationsindicatethatspeleothems

14

inKapsiaCavearelikelytodepositnearequilibrium(Finnéetal.2014;Finné2014).

Further climate studies for the Peloponnese and Kapsia Cave, using both past

andrecent timeseries, canhelp toprovidemoreknowledgeon thecorrelationof the

externalclimateandisotopicsignalscapturedwithinspeleothems,aswellasknowledge

ofkineticeffects. Inthisway,correlationsso farobservedcanhopefullybeconfirmed

andstrengthenedand,thus,provideastrongerpaleoclimaterecord(Finné2014).

4.Materialandmethod

4.1Fieldwork

Forthisstudy,fieldworkwascarriedoutduringonedayonthe25thofSeptember2017,

inKapsiaCave, central Peloponnese.The initial objectivewas to cleanoutpreviously

installed monitoring equipment and to collect an actively growing stalagmite

(GK02MODERN,acontinuationofstalagmiteGK02 collected in2009)thatwasdepositing

onaplasticfilmontopofadripsensorplacedinabucketsinceMarch2013(fig.5a&

5b).Unfortunately, the installationhad fallenand,hence, theonlypresent calcitehad

formedontheartificialbasebeneaththefallensensorandbucket.Thestalagmitewas,

nevertheless, collected for furtheranalysis.However, thestartdateof its formation is

unknown.

Figure5.a)SamplesiteforstalagmiteGK02MODERNandlocationofpreviouslysampledsodastraws(KS2,KS3andKS4)inKapsiaCave(afterFinnéetal.2014).b)InstallationfortheformationofGK02MODERN(Finné2014).

15

In addition, the positions of three previously collected soda straws were

analysed (KS2, KS3 and KS4). They had been noted to actively drip at the tip and

seeminglydepositingcalciteunderneathuponcollection.Thiscouldalsobenotedinthe

field,andsothesethreestrawswereselectedforfurtheranalysesinthisstudy.

Point measurements of temperature (12.9°C) and relative humidity (96%)

duringthefieldworkfallswithintherangeofearliermeasurementsfrommonitoringof

thecavebetween2009-2013.

4.2Lab-work

Both the stalagmite (GK02MODERN) and the three soda straw stalactites (KS2, KS3and

KS4) were prepared for stable isotope analysis in the lab of the Physical Geography

Department,StockholmUniversity.

StalagmiteGK02MODERNwas cut in half,with a diamond-coatedwire, across the

centre where it was thickest. The height of the stalagmite wasmeasured to roughly

1.5mm in cross-section. Three layers could be distinguished when looking at the

specimen in microscope (fig. 6a). It is not clear whether these have been deposited

annually.

FoursampleswereextractedfromGK02MODERNbyscrapingwithahandhelddrill

(Dremmel)withadiamond-coateddrillbit(fig.6a&6b).Sample1wasextractedfrom

theuppermosthalfoflayer1,whilesample2wastakenfromthelowesthalfoflayer1.

Sample3representslayer2andsample4representslayer3.

Figure6.a)SamplesinGK02MODERNindicatedbynumberswithapproximatespan(picturebyauthor).b)GK02MODERNaftersampling(picturebyauthor).

16

ThesodastrawstalactitesKS2,KS3andKS4werestudiedunderamicroscopein

order to identify any banding. Since no unambiguous banding or structure could be

distinguished, thestrawsweredivided into5mmintervals,starting fromthetip, from

which samples were extracted. The straws measured 45 to 60mm in length (KS2≈

45mm,KS3≈60-70mm,andKS4≈55-60mm).

StrawKS2andKS3weresimilarinstructure,beingmorefragileinthefirsthalf

from the tip and becomingmore solid towards the root of the straw.KS4 wasmore

fragileandthethicknessof itswallsdidnot increasewithdistance fromthetipalong

thepartremovedfromthecave,despitebeingaboutthesamelengthastheothertwo

straws.

Samples were extracted from the 5mm intervals starting from the tip of the

straws,excludingtherootofKS2andKS3.Thiswasdonebyscrapingthesurfaceusinga

handheld drill (Dremmel) with a diamond-coated drill bit. In the more fragile parts

(closertothetip),fragmentswereinsteadcollectedandlatergroundtoapowderwith

anagatemortar.StrawKS2yielded8samples,KS3yielded10samplesandKS4yielded

11samples.However,sampleKS4:7didnotyieldenoughmaterialforthestableisotope

analysis(yieldedlessthan0.2mg)andwasconsequentlyexcluded.

The material was sent to the stable isotope laboratory in Geo Zentrum

Nordbayern at theUniversity of Erlangen-Nuremberg, Germany,where aGasbench II

connectedtoaThermoFisherDeltaVPlusmassspectrometerwasused.Reproducibility

forδ13Candδ18Owas±0.04and±0.05(1standarddeviation),respectively.

5.Results

5.1StalagmiteGK02MODERN

The stable oxygen isotope values in the four samples extracted from stalagmite

GK02MODERNrangefrom−4.35‰(v-PDB)to−4.82‰(v-PDB),withincreaseddepletion

towardsthetop(fig.7).

17

The stable carbon isotope values in GK02MODERN, ranging from−9.13‰ (v-PDB) to

−9.97‰(v-PDB), shows a similar, but not the exact same pattern as δ18O, due to a

slightenrichmentfromsample4tosample3,andthenmovestowardsdepletion(fig.8).

Figure7.StableoxygenisotopevaluesfromGK02MODERNwithindicationofsamplespansinrelationtodepth.

Figure8.StablecarbonisotopevaluesfromGK02MODERNwithindicationofsamplespansinrelationtodepth.

18

5.2SodastrawstalactitesKS2,KS3andKS4

ThethreesodastrawstalactitesKS2,KS3andKS4yieldedstableoxygenisotopevalues

ranging from−4.03‰ (v-PDB) to−5.30‰ (v-PDB). A couple of sample points are

withinthemeasureduncertaintyofonestandarddeviation(±0.05‰)ofeachother(fig.

9).

Asforthestablecarbonisotopevalues,KS2andKS3areclosetoparallelwitha

fewsamplepointswithinornearthemeasureduncertaintyofonestandarddeviation

(±0.04‰).However,KS4yieldedmoredepletedstablecarbonvaluesthananysample

pointoftheotherstrawsandalsohasasmootherisotopiccurve(fig.10).Valuesrange

from−6.16‰(v-PDB)to−11.13‰(v-PDB).

Figure9.StableoxygenisotopevaluesfromthesodastrawstalactitesKS2,KS3andKS4,withindicationofonestandarddeviation.SampletypedisplayedwiththelettersP(powder)andF(fragment).ThemissingsampleKS4:7isseenasagapinKS4.

Figure10.(Nextpage)StablecarbonisotopevaluesfromthesodastrawstalactitesKS2,KS3andKS4,withindicationofonestandarddeviation(notvisibleonthisscale).SampletypedisplayedwiththelettersP(powder)andF(fragment).ThemissingsampleKS4:7isseenasagapinKS4.

19

6.Discussion

6.1StalagmiteGK02MODERN

StalagmiteGK02MODERN that has been analysed in this study has been growing in the

same place as a stalagmite (GK02) collected in Kapsia Cave in 2009 for paleoclimate

research of the Peloponnese (Finné etal.2014; Finné 2014). Themaximum possible

time of formation forGK02MODERN is 4.5 years (March 2013 to September 2017), but

since the installation on which this stalagmite grew had tipped over causing the

stalagmitetorestartitsgrowth,theactualtimeperiodisshorter,butunknown.

The calculated growth rate in the fossil part (2900 to 1120BP) of stalagmite

GK02was0.15mm/year(Finnéetal.2014),whilethemostrecentlaminae(AD1996to

2008) indicateagrowthrateof0.9mm/year inaverage(calculatedafterFinné2014).

CalculatingthegrowthrateinGK02MODERNbasedonitsthicknessandthemaximumtime

periodof formationresults inagrowthrateof0.33mm/year,which is closer to fossil

rates rather than modern rates. If instead the recent growth rate of 0.9mm/year is

appliedto thestalagmite,consideringthemodernandactivedepositionofcalcite, the

timeperiodofformationiscalculatedto1yearand8months.Althoughtherearesome

uncertaintiesconcerningthegrowthrate,themodernratehasbeenconsideredtobea

morelikelyestimateandis,thus,usedastheagemodelinthisstudy.

20

With an assumed growth rate of 0.9mm/year the start of deposition in

GK02MODERN ismodelled toJanuary2016.Theconstructedagemodelsuggests that the

top sample consists of calcite deposited during the summermonths of 2017 (June -

September). The material in sample 2 has been deposited between February – May

2017, while sample 3 and 4 cover a longer time span; material in sample 3 was

depositedJuly2016–January2017,andsample4wasdepositedJanuary2016–June

2016.

Even though the isotopic values of these samples arewellwithin the range of

previous measurements, both fossil and recent, from Kapsia Cave (mean−4.9‰ (v-

PDB)foroxygenand−9.3‰(v-PDB)forcarbonforthelast30years)(fig.11)(Finné

2014 for further details), the top sample clearly shows more depleted oxygen- and

carbonvaluesthantheothersamplesinGK02MODERN.

Inpreviousresearch(Finné2014)theamounteffecthasproventoberelatively

strong(R2=0.30)onanannualscale(AD1989-2009).Anapproximateannualaverageof

thesamplevaluesfromthisstudy,yieldingδ18O−4.62‰(v-PDB)andδ13C−9.65‰(v-

PDB)for2017,andδ18O−4.36‰(v-PDB)andδ13C−9.15‰(v-PDB)for2016,suggest

a climate trend towards wetter conditions with richer vegetation and increased

biologicalactivity,i.e.towardsdepletionofδ18Oandδ13C.Thecorrelationbetweenδ18O

andprecipitationamountdoes,however,slightlydecrease(R2=0.28)whenaddingthe

valuesfromthisstudytotheearlierregressionanalysis(fig.12).

Even though the monitoring of Kapsia Cave has shown that the environment

remainsrelativelystablethroughouttheyear,an increaseof thecaveair temperature

has been recorded in summer. Since the top sample inGK02MODERN is suggested as a

summerdepositionalsignal itcouldhavebeenaffectedbythecavetemperatureeffect,

drivingtheoxygenvaluestowardsdepletionwithincreasedcaveairtemperature.The

reason for the depleted carbon value is not as clear, but could possibly be related to

higherCO2concentrationsinthecaveinsummer.Inwinter,isotopicvaluesmayinstead

become slightly enriched due to lower CO2 concentrations in the cave atmosphere

(Finné 2014). Hence, if the top sample in GK02MODERN also would include winter

depositionofcalciteliketheothersamples,theisotopicvaluewouldbelessdepleted.

Sincenoextremevariations in theenvironmenthavebeenobserved inKapsia,

these fractionating processes are probably acting on a smaller scale that cannot be

observed when examining isotopic values at multi-annual resolution. Instead, the

21

amounteffectiscontrollingthegeneraltrend.Althoughtheannualaverageδ18Ovalues

calculated for GK02MODERN does not show a strong correlation to the wet season

precipitation with the response time of 1-2 year that has been estimated for Kapsia

Cave(Finné2014),itislikelythattheaverageisotopicvaluefor2017willbecomeless

depleted,sincethefall/winter(OND)depositionsignalisnotincluded.Asthepotential

cavetemperatureeffectisreduced,leadingtomoreenrichedδ18Ovalues,theimprintof

theamounteffect on the isotopic signalwill becomemore pronounced. Addingmore

datapoints to this regressionanalysiswouldbevaluable in the future. In accordance

withthestudyofFinné(2014), thisstudyneither indicates thatexternal temperature

stronglycorrelatestoδ18Oandδ13C,northatastrongcorrelationexistsbetweenδ13C

andrainfall.

Figure11.StableisotopevaluesfromGK02(AD1989-2009)(afterFinné2014)andGK02MODERN(afteragemodel,AD2016-2017)

22

6.2SodastrawstalactitesKS2,KS3andKS4

Thethreesodastrawswereofunknownageandhadnotbeenmonitored in thecave

beforebeingcollectedatthesametime.Eventhoughthetimeperiodcoveredbysoda

straws normally do not exceed a century, approaching this issue by, for example,

correlating the oxygen isotope signal to precipitation from the last hundred years to

find a dating is not reliable in this case. First, the risk of kinetic fractionation may

compromise the δ18O correlation to the amount effect. Second, even under near

equilibriumdepositionandanexpectedrelationshipwiththeamounteffect,thegrowth

ratesareunknownandalsohavebeenshowntovaryconsiderablyinstraws.Hence,the

oxygenisotopecurvemayberespondingtoprecipitationonamonthly,annual,decadal

orcentennialbasis.Withtheseuncertainties,theisotopicsignalcouldpossiblyfitatany

Figure12.CorrelationbetweenprecipitationamountandstableoxygenisotopesinGK02(afterFinné2014)andGK02MODERN.

23

placeinthelastcoupleofhundredyears.Consequently,theoriesondatingofthesoda

strawsKS2,KS3andKS4havebeendeliberatelyavoidedinthisstudy.

It is stillpossible todiscusswhether the threestrawsarecoeval, regardlessof

theexactdate.AlthoughstrawKS4measuredaroundthesamelength(~55-60mm)as

KS2andKS3(~45-65mm),itclearlydifferedinappearance.KS2andKS3hadfragiletips

andincreasingthicknessofthetubewallstowardstheroot.Despitethattheveryrootof

KS4wasnevercollected itexhibiteda fragilestructurealong itswhole lengthwithout

increasingsolidityandthicknessofthetubewalls.Itcould,forexample,bearguedthat

thewholecollectedlengthofKS4depositedfasterthanKS2andKS3andiscoevalwith

the tips of the other two straws. Still, there is not any additional evidence for this

conclusionandeventhoughKS4wasdripping, liketheothertwostraws,when itwas

collected,itmaynothavebeendepositingatthetimeofKS2andKS3ifthewaterwas

notsupersaturatedwithcalcite.

The stable isotopes analysedmay further reveal the relationship between the

three straws. KS2 and KS3 seem to follow a general trend towards more depleted

isotopicvaluestowardsthetips,morepronouncedincarbon,whichisnotseeninKS4

(fig. 9 & 10). Despite that only a few sample points in KS2 and KS3 are within the

measureduncertaintyofonestandarddeviation(±0.05‰foroxygenand±0.04‰for

carbon), their common trend possibly indicates thatKS2andKS3are coeval. This is

furtherstrengthenedbythesimilarappearanceinthetwostrawsaswellastheactive

drippingwhentheywerecollected.

Theδ18Ovaluesinallthreestrawsarewithintherangeofearliermeasurements

onstalagmites(Finné2014forfurtherdetails).Likewise,thisistruefortheδ13Cvalues

inKS2andKS3. Their general trend in δ13C also strengthen the theory presented by

Baskaran & Krishnamurthy (1993), indicating a correlation between increasing CO2

concentrations in the external atmosphere and depletion of carbon values in soda

straws.SuchanalysesareencouragedforfurtherstudiesonmaterialfromKapsiaCave

andthePeloponnese,aswellasforsodastrawstudiesingeneral.

UnlikestrawKS2andKS3,KS4 showsδ13Cvaluesnotonlymoredepleted than

those in the other two straws, but also more depleted values than in any of the

previously presented speleothems from Kapsia Cave, both in modern- and fossil

laminae (Finné 2014 for further details). The reasons for the significantly depleted

valuesinstrawKS4couldbemany.Fractionatingprocessessuchasrapidorvarieddrip

24

ratescouldleadtoδ13Cdepletion.WiththeopeningoftheartificialentranceinKapsia

Caveitisalsoprobablethatairventilationbecamestronger,increasingdegassingofthe

dripwaterasCO2concentrationsgetlower,aswellasalteringthehumidityinthecave

and, thus, increasing evaporation. However, these processes have previously been

associatedwithisotopicenrichmentandcannotexplainthedepletionofcarboninKS4.

Anotherpossibility is thatKS4 formeda fewyearsafter the latestwild fireabove the

cave(AD1997).Atfirst,isotopiccarbonvalueswouldbecomeenrichedduetotheloss

ofvegetation.Afewyearslaterasvegetationisestablishedagain,theremainsfromthe

firemayhaveafertilisingeffectincreasingthebiologicalactivityanddepletingisotopic

carbonvalues.Still,thisstrongdepletionincarbonhasnotbeenobservedinanyofthe

previouslyanalysedspeleothemscoveringthisperiod.Thereasonforthedepletedδ13C

inKS4istoovaguetoargueandwillbeleftunansweredinthisstudy.

In the case of the soda straw stalactites it is important to highlight the way

sampleswereextracted since a standard techniquehasnotbeen clearlypresented in

previousstudiesandthiskindofspeleothemhasnotbeenusedforclimatestudieson

the Peloponnese. As for the fragile parts of the straws it was not possible to obtain

samplesbyscrapingoffpowderfromthesurface,buthadtobecollectedasfragments,

whichwerelatergroundtopowder.Thesesamplesrepresentthewholethicknessofthe

tube wall, unlike powder samples that only represent the outer surface. Since some

calcite also deposits inside the central canal during formation, several yearsmay be

includedinonesample(fig.2).Thiscouldpossiblyresultinagreatersmoothingofthe

isotopicsignal,if,forexample,thereisamixingofwinterandsummerdepositionlikein

GK02MODERN. It is also possible that calcite deposited inside the canal yield different

valuesduetoe.g.alessexposeddepositionalenvironmentthanatthetipofthestraw.

A smoother isotopic curve, both for oxygen and carbon in all three straws, is

presentwheresampleswerecollectedasfragmentsincontrasttopowder(fig.9&10).

This could possibly explain some existing differences between KS2 and KS3, if they

happen to be coeval, as well as the remarkably smooth carbon curve for KS4.

Nevertheless, this phenomenon should be further examined in future studies to

increase the possibility of interpreting the isotopic signal in soda straw stalactites.

Dating of soda straws from Kapsia Cave and the Peloponnese is also encouraged in

combination with stable isotope analyses and analyses of trace elements, to further

explorethepossibilitiesofusingthesespeleothemsasahigh-resolutionclimatearchive.

25

7.Conclusions

Thisstudycontributes toan increasedandstrengthenedunderstandingofhowstable

isotopes in Peloponnesian speleothems correlate to climate variability and their

depositionalcaveenvironment.Thestudyfurtherelucidateshowsodastrawstalactites

canbeusedinclimateresearch,locallyaswellasingeneral.Thefollowingconclusions

havebeenestablishedonthebasisoftheresearchquestionsofthisstudy:

- Theassumedannualaveragesaswellasthemeasuredindividualsamplevalues

inGK02MODERNarewellwithintherangeofpreviouslymeasuredisotopicvalues

inKapsiaCave.

- The newdata points added fromGK02MODERNsupport the relatively strong link

between isotopicdepletionandwetseasonprecipitation(linkedto theamount

effect) thathasbeenpreviouslyestablished forKapsiaCave. It is likely that an

averageoxygenisotopevalueassumedfor2017willbecomeenriched,asparts

ofthewetseason(OND)havenotbeenincluded.Thisenrichmentwouldleadto

a stronger correlationbetween rainfall andδ18O in speleothems,possibly than

whatpreviouslyhasbeenshown.

- The top sample from the stalagmite should be regarded as a summer

depositionalsignal, likelydepositedduringthesummerof2017.It issuggested

thathighertemperaturesduringsummercausethissampletobemoredepleted.

This is not observable in the same way in the other samples, which are less

depleteddue to themixof summerandwinterdeposition.Thus, onanannual

scalecalciteδ18Oisstronglylinkedtotheamounteffect.

- The results from the stable isotopeanalysisof the soda strawstalactites show

potential in using this speleothem as a climate archive, as they yielded values

thatarewithin the rangeofpreviousmeasurements,with theexceptionof the

δ13CinstrawKS4.Theδ13CtrendinKS2andKS3isalsoinaccordancewithwhat

hasbeenconcludedinearlierstudiesonsodastraws,suggestingthatthecarbon

valuescorrespondtoexternalatmosphericCO2.

- Thesamplingtechniqueinsodastrawstalactitesmayaffecttheisotopicvalues,

wheresampling fragments fromstraws incontrast topowder fromthesurface

yields a smoothed isotopic signal. If this relationship is further explored, soda

straws may provide a complementary high-resolution climate archive on a

shortertimescaleonthePeloponneseandingeneral.

26

Acknowledgement

Firstofall,specialthankstomysupervisorMartinFinnéforlettingmetakepartinhisresearchandfor

interesting discussions, an inspiring field trip and supportive and dedicated supervision. I also thank

SteffenHolzkämper,HeadDirectorof Studies and lecturer at theDepartmentofPhysicalGeographyat

Stockholm University, for providing me with the opportunity to work on this project with Martin as

supervisor.FurtherthankstomyamazingfriendsResaandKristerDavénforproof-readingmyEnglish.

Many thanks tomyother friendsand family forencouragementandsupport, and last,butnot least, to

Alexwhoalwaysmanagestomakemehappyfromanypartoftheworld.

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8.1Electronicreferences

DoLP (Domesticated Landscapes of the Peloponnese, Uppsala University), project plan:

http://www.arkeologi.uu.se/Research/Projects/domesticated-landscapes-en/ (6thofDecember2017)

TripoliMeteosearch,meteorologicaldataforTripoli,Greece:

http://meteosearch.meteo.gr/stationInfo.asp

(6thofNovember2017)