CO C/ · first vacuum-dried at 60 °C overnight. The dry ma ss was between 0.6 and 1. 4 g. For...

RADIOCARBON Vol 46 Nr 2 2004 p 969ndash978 copy 2004 by the Arizona Board of Regents on behalf of the University of Arizona

copy 2004 by the Arizona Board of Regents on behalf of the University of ArizonaProceedings of the 18th International Radiocarbon Conference edited by N Beavan Athfield and R J SparksRADIOCARBON Vol 46 Nr 2 2004 p 969ndash978

969

A 14C CALIBRATION WITH AMS FROM 3500 TO 3000 BC DERIVED FROM A NEW HIGH-ELEVATION STONE-PINE TREE-RING CHRONOLOGY

Franz Dellinger1 bull Walter Kutschera12 bull Kurt Nicolussi3 bull Peter Schieszligling3 Peter Steier1 bullEva Maria Wild1

ABSTRACT High-precision radiocarbon accelerator mass spectrometry (AMS) measurements of a new high-altitude stone-pine tree-ring chronology from the European Alps were performed for a 500-yr stretch in the second half of the 4th millen-nium BC A 14C calibration curve with a typical 1-σ uncertainty of about 20 14C yr was achieved Although the general agree-ment of our data set with INTCAL98 is very good (confirming once more that INTCAL98 is also proper for calibration ofsamples of extraordinary sites) we found small deviations of 17 plusmn 5 14C yr indicating possible seasonal effects of the delayedgrowing season at high altitude

INTRODUCTION

It is well known that 14C calibration with tree rings is an indispensable prerequisite for accurateradiocarbon dating It provides the absolute time reference for 14C content in the atmosphere duringthe past 12000 yr Although the global uniformity of 14C12C isotope ratios in atmospheric CO2 is awell-established fact small deviations from the INTCAL98 calibration curve (Stuiver et al 1998)have been recently reported (Kromer et al 2001 Manning et al 2001 Reimer 2001) In a steep sec-tion of the calibration curve between 850 BC and 750 BC a shift of ~30 yr was obtained by com-paring INTCAL98 with a 14C calibration based on a (floating) tree-ring sequence of junipers fromAnatolia Turkey (Juniperus excelsea and Juniperus foetidissima) Kromer et al (2001) pointed outthat this small shift may have been caused by a regional 14CO2 offset linked to the different growingseason of junipers as compared to German and Irish oaks used for INTCAL98

In the present work we performed high-precision 14C AMS measurements for a new high-altitudetree-ring chronology of stone pines (Pinus cembra L) (Nicolussi and Schieszligling 2001 2002) Stonepines are the typical trees one finds at the timberline in the central parts of the European Alps (Fig-ure 1) Our measurements covered the time period from 3500 BC to 3000 BC On one hand thistime period is interesting since it includes the famous Iceman ldquoOumltzirdquo who lived around 3200 BC inthe same Alpine region where the stone pines were collected On the other hand the calibrationcurve has similar steep sections as the juniper curve mentioned above and a different growing sea-son of the stone pines as compared to the low-altitude German and Irish oaks of INTCAL98 sug-gest another possible observation of a regional 14CO2 offset A prerequisite for such a comparison isa precision of 14C AMS measurements comparable to beta counting How this could be accom-plished at VERA is described separately (Steier et al these proceedings)

THE STONE-PINE TREE-RING CHRONOLOGY

The basis for our investigations was the new high-elevation stone-pine (Pinus cembra L) tree-ringchronology established at the Institute of High Mountain Research of the University of Innsbruck(Nicolussi and Schieszligling 2001 2002) Until recently absolutely dated multi-millennial chronolo-gies (such as those existing for German and Irish oaks) did not exist in the Alps The stone-pine

1Vienna Environmental Research Accelerator (VERA) Institut fuumlr Isotopenforschung und Kernphysik Universitaumlt WienWaumlhringerstrasse 17 A-1090 Wien Austria

2Corresponding author Email walterkutscheraunivieacat3Institut fuumlr Hochgebirgsforschung Universitaumlt Innsbruck Innrain 52 A-6020 Innsbruck Austria

970 F Dellinger et al

chronology can be used as the dating base for the establishment of Alpine event records (egHolocene glacier fluctuations avalanche activity) and the reconstruction of summer temperatures(Nicolussi and Schieszligling 2001) respectively In the Alps there is always enough precipitation attimberline sites and the main limiting factor for tree growth is the summer temperature Thereforefrom the tree-ring-width pattern the information of the summer temperatures can be extracted

In the course of several years about a hundred subfossil logs were collected near the timberlineabove 1900 m above sea level (asl) The logs came from 26 sites in the Hohe Tauern Stubaier AlpsZillertaler Alps Oumltztaler Alps and in the Ortler Group These collecting sites are in the generalvicinity of the location where the famous prehistoric Iceman Oumltzi was found (Kutschera et al 2003)Stone pines were collected almost exclusively the number of spruce (Picea abies) was only about1 of the whole data set

A continuous chronology was established ranging back more than 7000 yr from the present dayuntil 5125 BC (Figure 2) The mean replication of this continuous part is approximately 20 althoughsome weaker replicated sections also exist Including 3 other (floating) sections the Alpine conifertree-ring chronologies now cover nearly the entire Holocene (Figure 2)

Figure 1 Fully-grown stone pine (Pinus cembra L)near the timberline in the European Alps (Photocourtesy of W Kutschera 2003) As seen in thispicture the tree literally grows on a rock hence theterm ldquostonerdquo pine seems appropriate

14C Calibration with AMS from 3500 to 3000 BC 971

SAMPLE EXTRACTION PREPARATION AND PRETREATMENT

All trunks investigated in the present work originated from sites between 2150 and 2300 m asl(Table 1) The samples were selected at the Institute for High Mountain Research from the inside ofthe logs (far away from exposed surfaces) Water was used as a contrast amplifier for tree-ringcounting instead of the usual chalk to exclude possible contamination For each sample severalcubic cm of wood were cut out and sent to the VERA Laboratory For safe storage the samples werefirst vacuum-dried at 60 degC overnight The dry mass was between 06 and 14 g For proper compar-ison with the INTCAL98 data set (Stuiver et al 1998) which is given in decadal steps we used50 decadal tree-ring sections beginning with 3499ndash3490 BC until 3009ndash3000 BC

From each sample material a 1-mm-thick slice was cut from the trunk axis by using a fretsaw The(usually oiled) saw blades were washed in acetone in an ultra-sonic bath for 10 min and then heatedfor 1 hr at 550 degC in the furnace A stick of wood was then cut out with a scalpel for tree rings cov-ering exactly 10 yr A thickness of 1 to 2 mm was chosen so that the mass of the wood stick wasslightly above 10 mg (see Figure 3) In this step care was taken that the chosen wood stick did notcontain any visible resin channels

Our standard acid-base-acid procedure was used for sample pretreatment (1M HCl at 60 degC for 1 hr01 M NaOH at 60 degC for 1 hr 1M HCl at 60 degC for 1 hr) Typically this procedure resulted in a lossof sample weight of a few percent The good state of preservation of the sample was indicated by thefact that very little humic acids were visible The pretreated samples were vacuum-dried overnight

Figure 2 Current state of the central Eastern Alpine tree-ring chronologies The absolutely dated continuousstone-pine chronology is about 7100 yr long and extends back to 5125 BC It is based on approximately 430 sub-fossil logs and also includes more than 300 tree-ring series of living trees and sub-recent logs respectively in thelatest section The temporal positions of the floating chronologies have been assessed by wiggle-matching of 14Cdates These 3 chronologies are based on about 50 subfossil logs of the species Pinus cembra (stone pine) Larixdecidua (European larch) and Picea abies (Norway spruce)

Table 1 Characterization of the tree-ring samples from stone pines used in this workTree logidentifier

Collectionsite

Sitecoordinates

Elevation(m asl)

Tree rings(n)

Tree-ringperiod (yr BC)

Ring-widthrange (mm)

Decadalsections used

KRO-2 KrottenlackeWindachtalStubaier

46deg57prime15PrimeN11deg06prime05PrimeE

2278 118 3508ndash3391 0715ndash2103 9

SSM-84 SchwarzsteinmoorZillertaler Alps


2150 134 3467ndash3334 0136ndash2501 6

EBA-47 Ebenalmdividetztaler Alps


2170 111 3351ndash3241 0637ndash3353 6



2150 307 3312ndash3006 0124ndash0958 10



2170 172 3211ndash3040 0314ndash2733 9

GDM-40 DaunmorpermilnenseeKaunertaldividetztaler Alps


2295 355 3188ndash2834 0416ndash1553 10

0100020003000400050006000700080009000cal BC BC

0 1000 2000AD

floating chronology absolutely dated chronology

[0]


Figure 3 Typical decadal wood samples (a) 2 pieces of wood with different tree ring widths from which sticks shownin (b) were cut for sample preparation The sticks were converted into graphite samples for the AMS measurementThe contribution of the various tree rings to the sample mass depends on the ring width


The combustion of the sample material took place at 900 degC for 4 hr in a flame-sealed quartz tubecontaining 1g CuO as oxidant and some silver wire The sample CO2 was then reduced to elementalcarbon at 610 degC using H2 and an iron catalyst (Vogel et al 1984) The mixture of graphite and cat-alyst was divided and pressed into 2 aluminium target holders suitable for our 40-position MC-SNICS ion source Both sputter targets were measured

AMS MEASUREMENTS

The measurement of the stone-pine samples was performed in 5 separate AMS beam times (runs)Run 1 only contained material of the ldquoKRO-2rdquo tree slice while in run 2 3 and 4 material of allother tree slices was used An additional run (run 5) was performed for samples which showed adeviation of more than 2 σ from INTCAL98 in the preliminary evaluation of runs 1 to 4 Sampleswhich got lost in chemical pretreatment were also measured in run 5

In run 1 IAEA C-3 cellulose (12941 plusmn 006 pMC) and IAEA C-5 wood (2305 plusmn 002 pMC) wereused as standard materials (Rozanski et al 1992) It turned out to be advantageous to use wood of10 tree rings (3239ndash3230 BC) of the dendro-dated FIRI-D wood as standard material instead of theC-5 wood in the remaining runs The FIRI-D wood from the Fourth International Radiocarbon Inter-comparison (Scott 2003) has a higher pMC value (5717 plusmn 006) and the wood chips of FIRI-Dbehave more similar to the actual samples than the powdered C-5 wood For each run 2 chemicallyindependent standards were produced from FIRI-D wood and C-3 cellulose respectively For thestandards splits from the same graphite were exchanged between the runs to increase the diversityof standard material After run 2 the idea arose to permute also the doublets of the samples withanother wheel Hence we decided to mount single samples in the target wheel of run 3 and measureall the doublets in run 4

Compared to routine measurements which usually take 24 hr the stone-pine measurements lastedapproximately 3 days per run For such long measurement periods it is necessary to retune the AMSfacility once per day (Steier et al 2004)

DATA EVALUATION AND RESULTS

Each run is evaluated separately using the present version of the program ldquoEVALGENrdquo (Pucheggeret al 2000) which is also used for routine measurements For yet unknown reasons the quality ofthe data varied for the different ldquotuningsrdquo of 1 run judged from the reproducibility of the sampleresults and from the agreement of the standards with the nominal values The evaluation programtakes this into account by assigning additional uncertainties to the measured isotope ratios So thefinal precision may even improve if data from such a tuning are left out In some cases the reasonfor the uncertainty can be identified and a workaround can be found For example the first tuningof run 5 could be used after normalizing to the low energy 12Cndash current instead of the usual 12C3+ cur-rent Obviously the accelerator transmission of the 12Cndash beam was not constant for this setup but the13C and 14C were not affected

From 12 chemically independent ABA pretreatments of the standards one was rejected as an outlierbecause all targets of this material showed a consistent deviation of ~50 14C yr (which is more than2 σ) in all 3 runs where this graphite was used We think that contamination during the pretreatmentis the most likely reason Additionally 1 single standard target was excluded in run 4 The samegraphite in run 3 showed regular results A possible reason for a deviation of 1 single target may becontamination during target pressing


The exclusion of certain standards is no problem for measurement precision At least 8 standards aremounted in each target wheel Even if 2 standards are excluded (run 4) the 6 remaining are suffi-cient to calculate external uncertainties

The final results of all stone-pine measurements are listed in Table 2 The dendro date in column 2is the medium of the respective 10-yr tree-ring section The 14C ages of run 3 and run 4 are combinedby building the weighted mean treated as 1 measurement (run 3+4) in the following

For most samples a total 1-σ uncertainty of less than 20 14C yr could be achieved corresponding toan overall precision of 25permil for the 14C determination Compared to routine 14C measurements thisprecision is mainly due to longer measurement times and the larger number of standards and theirarrangement

DATA INTERPRETATION AND ANALYSIS

The overall agreement of the stone-pine measurements with INTCAL98 is very good (see Figure 4)However by taking a closer look at the curve small offsets in certain sections can be recognizedFirst the whole data set of run 1 tends to be shifted to older 14C ages Second in the section of approx-imately 3410ndash3260 BC (ie the steep decline of the calibration curve) the data are shifted to younger14C ages independent from the measurement in which they were obtained For the data of run 5 thistrend to younger values remains for the calendar section 3260ndash3000 BC while the data points of run2 and run 3+4 are distributed almost equally to older and younger ages Although these shifts can beclearly seen they have to be carefully interpreted Such offsets may come from systematic errors inthe measurements and would then not be meaningful in terms of a paleoclimatic interpretation

Figure 4 Comparison of the results from the present work (run 1 2 3+4 and 5) with the INTCAL98 calibration curve

4300

4350

4400

4450

4500

4550

4600

4650

4700

4750

30003050310031503200325033003350340034503500

Rad

ioca

rbon

Age

BP

Dendro Age BC

INTCAL98run 1run 2

run 3+4run 5


Table 2 Comparison of the 14C results for stone-pine samples with INTCAL 98Dendro data VERA data INTCAL 98

Tree log identifier Date BC VERA nr Run δ13C (permil) 14C age (BP) INTCAL 98 (BP)KRO-2-1 3495 V23841 1 ndash187 plusmn 05 4688 plusmn 18 46507 plusmn 105KRO-2-2 3485 V23851 1 ndash186 plusmn 06 4651 plusmn 15 46291 plusmn 96KRO-2-3 3475 V23861 1 ndash183 plusmn 04 4651 plusmn 23 46272 plusmn 107KRO-2-4 3465 V23871 1 ndash189 plusmn 06 4636 plusmn 18 46568 plusmn 90KRO-2-4 3465 V23872 5 ndash222 plusmn 03 4639 plusmn 21 46568 plusmn 90KRO-2-5 3455 V23881 1 ndash195 plusmn 05 4675 plusmn 16 46729 plusmn 123KRO-2-6 3445 V23891 1 ndash187 plusmn 08 4690 plusmn 30 46737 plusmn 94KRO-2-7 3435 V23901 1 ndash197 plusmn 11 4699 plusmn 23 46700 plusmn 90KRO-2-8 3425 V23911 1 ndash182 plusmn 05 4714 plusmn 16 46984 plusmn 95KRO-2-9 3415 V23921 1 ndash197 plusmn 06 4707 plusmn 15 46976 plusmn 141SSM-84-1 3405 V23931 2 ndash198 plusmn 06 4683 plusmn 19 47058 plusmn 127SSM-84-2 3395 V23941 3+4 ndash218 plusmn 04 4671 plusmn 18 47115 plusmn 92SSM-84-3 3385 V23951 3+4 ndash222 plusmn 03 4678 plusmn 16 47137 plusmn 134SSM-84-4 3375 V23961 2 ndash228 plusmn 10 4643 plusmn 24 46559 plusmn 102SSM-84-5 3365 V23971 3+4 ndash212 plusmn 03 4577 plusmn 17 46064 plusmn 121SSM-84-6 3355 V23981 3+4 ndash216 plusmn 03 4552 plusmn 15 45710 plusmn 126EBA-47-1 3345 V23991 2 ndash227 plusmn 04 4531 plusmn 18 45393 plusmn 84EBA-47-2 3335 V24001 3+4 ndash215 plusmn 03 4507 plusmn 18 45203 plusmn 99EBA-47-3 3325 V24011 3+4 ndash221 plusmn 03 4489 plusmn 16 44931 plusmn 122EBA-47-4 3315 V24021 5 ndash231 plusmn 02 4461 plusmn 24 44970 plusmn 105EBA-47-5 3305 V24031 3+4 ndash230 plusmn 03 4466 plusmn 17 44814 plusmn 108EBA-47-6 3295 V24041 3+4 ndash226 plusmn 03 4465 plusmn 15 44837 plusmn 96SSM-102-1 3285 V24051 2 ndash233 plusmn 02 4465 plusmn 17 44838 plusmn 87SSM-102-2 3275 V24061 3+4 ndash208 plusmn 02 4455 plusmn 16 44822 plusmn 102SSM-102-2 3275 V24062 5 ndash228 plusmn 04 4443 plusmn 21 44822 plusmn 102SSM-102-3 3265 V24071 3+4 ndash234 plusmn 03 4450 plusmn 19 44846 plusmn 77SSM-102-4 3255 V24081 2 ndash243 plusmn 03 4490 plusmn 18 44612 plusmn 99SSM-102-4 3255 V24082 5 ndash247 plusmn 18 4444 plusmn 22 44612 plusmn 99SSM-102-5 3245 V24091 3+4 ndash217 plusmn 03 4479 plusmn 17 44641 plusmn 117SSM-102-6 3235 V24101 3+4 ndash220 plusmn 03 4474 plusmn 16 44921 plusmn 77SSM-102-7 3225 V24111 2 ndash227 plusmn 02 4506 plusmn 16 44972 plusmn 76SSM-102-8 3215 V24121 3+4 ndash212 plusmn 03 4523 plusmn 19 45087 plusmn 82SSM-102-9 3205 V24131 3+4 ndash225 plusmn 03 4523 plusmn 16 45317 plusmn 95SSM-102-9 3205 V24132 5 ndash224 plusmn 02 4499 plusmn 22 45317 plusmn 95SSM-102-10 3195 V24141 2 ndash229 plusmn 05 4508 plusmn 15 45279 plusmn 122EBA-46-1 3185 V24151 3+4 ndash235 plusmn 04 4494 plusmn 19 45071 plusmn 125EBA-46-2 3175 V24161 3+4 ndash246 plusmn 03 4465 plusmn 16 45030 plusmn 140EBA-46-2 3175 V24162 5 ndash255 plusmn 08 4481 plusmn 24 45030 plusmn 140EBA-46-3 3165 V24171 2 ndash261 plusmn 08 4495 plusmn 19 44747 plusmn 126EBA-46-4 3155 V24181 3+4 ndash247 plusmn 03 4477 plusmn 18 45142 plusmn 141EBA-46-4 3155 V24182 5 ndash244 plusmn 05 4475 plusmn 22 45142 plusmn 141EBA-46-5 3145 V24191 3+4 ndash231 plusmn 03 4492 plusmn 16 45370 plusmn 139EBA-46-6 3135 V24201 2 ndash253 plusmn 05 4487 plusmn 19 45163 plusmn 142EBA-46-7 3125 V24211 3+4 ndash220 plusmn 03 4511 plusmn 16 45164 plusmn 141EBA-46-8 3115 V24221 3+4 ndash240 plusmn 04 4509 plusmn 18 44881 plusmn 129EBA-46-9 3105 V24231 2 ndash249 plusmn 04 4493 plusmn 16 45008 plusmn 158GDM-40-1 3095 V24241 3+4 ndash229 plusmn 03 4413 plusmn 17 44471 plusmn 126GDM-40-2 3085 V24251 3+4 ndash221 plusmn 03 4460 plusmn 16 44336 plusmn 158GDM-40-3 3075 V24261 2 ndash246 plusmn 02 4413 plusmn 23 44004 plusmn 97GDM-40-4 3065 V24271 3+4 ndash233 plusmn 03 4407 plusmn 19 44276 plusmn 141GDM-40-5 3055 V24281 5 ndash236 plusmn 08 4437 plusmn 22 44439 plusmn 121GDM-40-6 3045 V24291 2 ndash229 plusmn 02 4442 plusmn 17 44404 plusmn 114GDM-40-7 3035 V24301 3+4 ndash241 plusmn 03 4429 plusmn 17 44355 plusmn 117GDM-40-8 3025 V24311 3+4 ndash231 plusmn 04 4411 plusmn 19 44112 plusmn 120GDM-40-8 3025 V24312 5 ndash236 plusmn 13 4387 plusmn 23 44112 plusmn 120GDM-40-9 3015 V24321 2 ndash235 plusmn 02 4424 plusmn 15 43845 plusmn 142GDM-40-9 3015 V24322 5 ndash222 plusmn 08 4368 plusmn 23 43845 plusmn 142GDM-40-10 3005 V24331 3+4 ndash218 plusmn 03 4366 plusmn 17 43698 plusmn 133


In the statistical analysis we wanted to investigate the significance of the deviations of the stone-pine data In the first step we calculated the difference between every stone-pine data point and theassociated INTCAL98 data point Subsequently the mean deviation for every run was determined+151 14C yr for run 1 ndash07 14C yr for run 2 ndash151 14C yr for run 3+4 and ndash253 14C yr for run 5These offsets may originate in a systematic error which is correlated for all samples in a whole runThis error cannot be reduced by averaging and is the same for each individual sample and for theaverage of a complete measurement However this uncertainty cancels out if the average bias of arun is subtracted from the data points In the corrected data it can be explored if there are significantdifferences between the flat part of the calibration curve and the region with the steep declineUnfortunately the samples of run 1 cover only a short calendar period and not even 1 single datapoint lies in the steep part of the curve As a consequence these data could not be utilized in the cal-culations above

In Figure 5 the deviation of the offset-corrected data points from the INTCAL98 curve are plottedThe error bars include the internal uncertainty of the stone-pine data points and the uncertainty ofINTCAL98 The plot suggests that deviations from INTCAL98 may exist For a statistical checkwe divided the data set into 2 parts The data points in the steep part between 3410 and 3260 BC gen-erally seem to be located below the average while in the flatter region from 3260 to 3000 BP thedeviation is slightly positive The solid lines in the plot are the weighted mean values in the 2regions The mean values confirm the visual impression the resulting difference of the 2 regions of166 plusmn 48 yr is statistically significant at 34 σ

Figure 5 Difference between the 14C calibration from the stone pine and INTCAL98 For details of the procedurefor how to arrive at the different offsets indicated by the horizontal lines (plusmn1 σ) see text

-50

-40

-30

-20

-10

0

10

20

30

40

50

60

3000305031003150320032503300335034003450

Rad

ioca

rbon

Yea

rs

Dendro Age BC

run 2 - meanrun 3+4 - meanrun 5 - mean


To investigate whether the uncertainties of the data points in each of the 2 regions are realistic a χ2

test was performed For the region 3410ndash3260 BC consisting of 16 data points a χ2 of 586 wasdetermined (250 is allowed for 95 confidence) Concerning the region 3260ndash3000 BC the testresulted in a χ2 of 391 (450 is allowed at 95 confidence for 32 data points)

POSSIBLE EXPLANATION FOR THE SMALL SHIFT IN CALIBRATION

Interestingly similar deviations have been observed by Kromer et al (2001) and Manning et al(2001) in Turkish junipers At a sharp drop of the calibration curve around 800 BC the data of Turk-ish junipers were shifted by about 30 yr towards older 14C ages relative to the (mainly) German oaksof INTCAL98 It is argued that the reason for this deviation lies in the seasonal variability of atmo-spheric 14C In Figure 6 our understanding of the emerging deviations based on the discussion inKromer et al (2001) is illustrated

From modeling bomb 14C (Hesshaimer 1997) and from present-day tropospheric 14C monitoringnetworks (Levin and Hesshaimer 2000) variations of 4permil between low winterspring and maximumsummer activity have been deduced (Kromer et al 2001) Depending on the rate of carbon uptakeduring the growing season and the phase relation of the growing seasons between the different

Figure 6 Our understanding of Kromer et al (2001) The preindustrialprebomb seasonal variability of 14C is shown foratmospheric conditions similar to the present ones (a) and for deep solar minima which are also episodes of widespreadatmospheric cooling (b) The different growth cycles of the various tree species is manifested in the ∆14C In (b) the sea-sonal variability is larger and the colder climate causes later growth of the stone pine whereas higher precipitation allowsearlier growth of the Turkish juniper This increases the differences between the 3 species

German oak

German oak

a

b


regions different parts of this seasonal cycle are seen Turkish junipers for instance start their mainwood production earlier in spring than German oaks do Hence due to the intra-annual variations ofthe seasonal cycle the wood of the Turkish junipers is depleted in 14C compared to the wood of Ger-man oaks As the amplitude of the seasonal cycle is proportional to the 14C influx from the strato-sphere the effect of intra-annual variations should be best observable during times of ldquodeeprdquo solarminima In these times the amplitude of the seasonal cycle is supposed to be twice as large as in theaverage of the 11-yr solar cycle (Kromer et al 2001 Masarik and Beer 1999) Such periods ofenhanced 14C production appear as a steep decline in the calibration curve

Following the previous argument the stone pines should be higher in 14C than German oaks andappear younger due to the later growing season at high elevation sites That agrees with the observedoffset in our measurement

CONCLUSIONS

To our knowledge this is the first high-altitude calibration curve which has been established byAMS In our measurements we achieved a typical 1-σ uncertainty of about 20 14C yr (25permil) at areasonable increase of effort The results of the stone-pine measurements confirm once more thatINTCAL98 is also proper for calibration of samples of extraordinary sites such as the timberline inthe Alps Although the agreement of our data set with INTCAL98 is very good at the edge of sta-tistical analysis we found small deviations of 17 plusmn 5 14C yr Considering the argumentation ofKromer et al (2001) this shift seems reasonable

REFERENCESHesshaimer V 1997 Tracing the global carbon cycle

with bomb radiocarbon [PhD dissertation] Heidel-berg University of Heidelberg

Kromer B Manning S Kuniholm P Newton M SpurkM Levin I 2001 Regional 14CO2 offsets in the tropo-sphere magnitude mechanism and consequencesScience 2942529ndash32

Kutschera W Muumlller W 2003 ldquoIsotope languagerdquo of theAlpine Iceman investigated with AMS and MSNuclear Instruments and Methods in PhysicsResearch B 204705ndash19

Levin I Hesshaimer V 2000 Radiocarbonmdasha uniquetracer of global carbon cycle dynamics Radiocarbon42(1)69ndash80

Manning S Kromer B Kuniholm P Newton M 2001Anatolian tree rings and a new chronology for the EastMediterranean Bronze-Iron Ages Science 2942532ndash5

Masarik J Beer J 1999 Simulation of particle fluxes andcosmogenic nuclide production in the earthrsquos atmo-sphere Journal of Geophysical Research 104D12099ndash111

Nicolussi K Schieszligling P 2001 Establishing a multi-millennial Pinus cembra chronology for the centralEastern Alps Conference ldquoTree Rings and Peoplerdquo22ndash26 September 2001 Davos Switzerland httpwwwwslchforestdendro2001

Nicolussi K Schieszligling P 2002 A 7000-year-long con-

tinuous tree-ring chronology from high-elevation sitesin the central Eastern Alps Dendrochronology Envi-ronmental Change and Human History Abstracts251ndash252 6th International Conference on Dendro-chronology Quebec City Canada 22ndash27 August2002

Puchegger S Rom W Steier P 2000 Automated evalua-tion of 14C AMS measurements Nuclear Instrumentsand Methods in Physics Research B 172274ndash80

Reimer JR 2001 A new twist in the radiocarbon taleScience 2942494ndash5

Rozanski K Stichler W Gonfiantini R Scott EM Beu-kens R Kromer B van der Plicht J 1992 The IAEA14C intercomparison exercise 1990 Radiocarbon34(3)506ndash19

Scott EM 2003 The Fourth International RadiocarbonIntercomparison (FIRI) Radiocarbon 45(2)135ndash291

Steier P Dellinger F Kutschera W Rom W Wild EM2004 Pushing the precision limit of 14C measure-ments with AMS Radiocarbon these proceedings

Stuiver M Reimer PJ Bard E Beck JW Burr GS HughenKA Kromer B McCormac G van der Plicht J SpurkM 1998 INTCAL98 radiocarbon age calibration24000ndash0 cal BP Radiocarbon 40(3)1041ndash83

Vogel JS Southon JR Nelson DE Brown T 1984 Per-formance of catalytically condensed carbon for use inaccelerator mass spectrometry Nuclear Instrumentsand Methods in Physics Research B 5289ndash93


chronology can be used as the dating base for the establishment of Alpine event records (egHolocene glacier fluctuations avalanche activity) and the reconstruction of summer temperatures(Nicolussi and Schieszligling 2001) respectively In the Alps there is always enough precipitation attimberline sites and the main limiting factor for tree growth is the summer temperature Thereforefrom the tree-ring-width pattern the information of the summer temperatures can be extracted

In the course of several years about a hundred subfossil logs were collected near the timberlineabove 1900 m above sea level (asl) The logs came from 26 sites in the Hohe Tauern Stubaier AlpsZillertaler Alps Oumltztaler Alps and in the Ortler Group These collecting sites are in the generalvicinity of the location where the famous prehistoric Iceman Oumltzi was found (Kutschera et al 2003)Stone pines were collected almost exclusively the number of spruce (Picea abies) was only about1 of the whole data set

A continuous chronology was established ranging back more than 7000 yr from the present dayuntil 5125 BC (Figure 2) The mean replication of this continuous part is approximately 20 althoughsome weaker replicated sections also exist Including 3 other (floating) sections the Alpine conifertree-ring chronologies now cover nearly the entire Holocene (Figure 2)

Figure 1 Fully-grown stone pine (Pinus cembra L)near the timberline in the European Alps (Photocourtesy of W Kutschera 2003) As seen in thispicture the tree literally grows on a rock hence theterm ldquostonerdquo pine seems appropriate








Collectionsite

Sitecoordinates

Elevation(m asl)

Tree rings(n)






2278 118 3508ndash3391 0715ndash2103 9



2150 134 3467ndash3334 0136ndash2501 6



2170 111 3351ndash3241 0637ndash3353 6



2150 307 3312ndash3006 0124ndash0958 10



2170 172 3211ndash3040 0314ndash2733 9



2295 355 3188ndash2834 0416ndash1553 10

0100020003000400050006000700080009000cal BC BC

0 1000 2000AD


[0]





AMS MEASUREMENTS














4300

4350

4400

4450

4500

4550

4600

4650

4700

4750

30003050310031503200325033003350340034503500

Rad

ioca

rbon

Age

BP

Dendro Age BC

INTCAL98run 1run 2

run 3+4run 5








-50

-40

-30

-20

-10

0

10

20

30

40

50

60

3000305031003150320032503300335034003450

Rad

ioca

rbon

Yea

rs

Dendro Age BC









German oak

German oak

a

b




CONCLUSIONS


























Collectionsite

Sitecoordinates

Elevation(m asl)

Tree rings(n)






2278 118 3508ndash3391 0715ndash2103 9



2150 134 3467ndash3334 0136ndash2501 6



2170 111 3351ndash3241 0637ndash3353 6



2150 307 3312ndash3006 0124ndash0958 10



2170 172 3211ndash3040 0314ndash2733 9



2295 355 3188ndash2834 0416ndash1553 10

0100020003000400050006000700080009000cal BC BC

0 1000 2000AD


[0]





AMS MEASUREMENTS














4300

4350

4400

4450

4500

4550

4600

4650

4700

4750

30003050310031503200325033003350340034503500

Rad

ioca

rbon

Age

BP

Dendro Age BC

INTCAL98run 1run 2

run 3+4run 5








-50

-40

-30

-20

-10

0

10

20

30

40

50

60

3000305031003150320032503300335034003450

Rad

ioca

rbon

Yea

rs

Dendro Age BC









German oak

German oak

a

b




CONCLUSIONS























AMS MEASUREMENTS














4300

4350

4400

4450

4500

4550

4600

4650

4700

4750

30003050310031503200325033003350340034503500

Rad

ioca

rbon

Age

BP

Dendro Age BC

INTCAL98run 1run 2

run 3+4run 5








-50

-40

-30

-20

-10

0

10

20

30

40

50

60

3000305031003150320032503300335034003450

Rad

ioca

rbon

Yea

rs

Dendro Age BC









German oak

German oak

a

b




CONCLUSIONS


























4300

4350

4400

4450

4500

4550

4600

4650

4700

4750

30003050310031503200325033003350340034503500

Rad

ioca

rbon

Age

BP

Dendro Age BC

INTCAL98run 1run 2

run 3+4run 5








-50

-40

-30

-20

-10

0

10

20

30

40

50

60

3000305031003150320032503300335034003450

Rad

ioca

rbon

Yea

rs

Dendro Age BC









German oak

German oak

a

b




CONCLUSIONS


























-50

-40

-30

-20

-10

0

10

20

30

40

50

60

3000305031003150320032503300335034003450

Rad

ioca

rbon

Yea

rs

Dendro Age BC









German oak

German oak

a

b




CONCLUSIONS


























German oak

German oak

a

b




CONCLUSIONS






















CONCLUSIONS



















CO C/ · first vacuum-dried at 60 °C overnight. The dry ma ss was between 0.6 and 1. 4 g. For...

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Transcript of CO C/ · first vacuum-dried at 60 °C overnight. The dry ma ss was between 0.6 and 1. 4 g. For...