Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Climate of the Past , Discussions 1 6,7 , 3 ¨ otl , A. Gerdes 1 , and A. Mangini 8 , C. Sp 2 1688 1687 , D. Scholz , A. Wackerbarth 1 5 , D. K. Richter 8 ¨ oder-Ritzrau , M. Mudelsee 4 , A. Immenhauser 8 , A. Schr 1 This discussion paper is/has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP if available. Heidelberg Academy of Sciences, Heidelberg,Institute Germany for Geosciences, University ofInstitute Mainz, for Mainz, Geology Germany and Palaeontology, UniversityInstitute of for Innsbruck, Geography, University Innsbruck, of Austria Mainz,Climate Mainz, Risk Germany Analysis, Hanover, Germany Institute for Geosciences, Goethe UniversityDepartment Frankfurt, of Frankfurt, Earth Germany Sciences, Stellenbosch University, Private Bag X1, Institute for Geology, Mineralogy and Geophysics, Ruhr-University Bochum, 1 2 3 4 5 6 7 Matieland 7602, South8 Africa Bochum, Germany S. Riechelmann Received: 29 March 2012 – Accepted: 29Correspondence April to: 2012 J. – Fohlmeister Published: ([email protected]) 11 MayPublished 2012 by Copernicus Publications on behalf of the European Geosciences Union. D. F. C. Riechelmann Bunker Cave stalagmites: an archivecentral for European Holocene climate variability J. Fohlmeister Clim. Past Discuss., 8, 1687–1720, 2012 www.clim-past-discuss.net/8/1687/2012/ doi:10.5194/cpd-8-1687-2012 © Author(s) 2012. CC Attribution 3.0 License. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ). Alley Boch Frisia 2009 ; ; Wanner , Wacker- , and ref- Ivy-Ochs ; 2006 1999 , ¨ untgen et al. , 2003 B 2006 , von Grafenstein ; , Boch et al. erent seasons. For ff ; 2002 O, which is explained , 18 δ 2004 Davis et al. ; , Joerin et al. Vollweiler et al. ; ; McDermott et al. er between the warm and cold ff 2004 , Spurk et al. 2005 2005 ; , , 1999 Magny C values and Mg/Ca ratios. We attribute , ; erentiate between di ff 13 δ 1690 1689 1993 O, O signal are interpreted as variations in mete- , Mangini et al. 18 18 ; δ δ Holzhauser et al. 2003 Friedrich et al. , ) showed in a compilation of European pollen data that Guiot et al. 2003 ( ). ). The main reason for this is that enhanced evapo-transpiration during North Greenland Ice Core Project members Niggemann et al. 2011 ; 2010 ) contributed important information on past Holocene climate variability in ). However, none of the currently available speleothem records for Central ; , ), which has been identified in several climate records (e.g. , Davis et al. 1998 2009 2009 2003 2008 1997 erent causes underlying the two climate anomalies. Whereas the Little Ice Age is , , ), lake sediments (e.g. , , , , ff Within the last decade, several Holocene climate reconstructions for central Eu- Various archives for terrestrial past climate variability have been evaluated in order ite stalagmite record fromWe Bunker show Cave, Western high-resolution Germany, stable covering C the and last 10.8 O ka. isotope data as well as Mg/Ca ratios. This Europe covers the entire Holocene. Here we present a Central European compos- et al. et al. temperature variations during theseasons, Holocene with largely larger di fluctuations occurring during winter. rope based on speleothems have been published (e.g. spring and summer months leadsmajor to reduced proportion infiltration of into the thecaves karst drip aquifer. originates water Thus, from the feeding winter thepast precipitation. speleothems In in climate most order variability Central to itexample, European gain comprehensive is insight important into to di erences therein) and glaciers (e.g. et al. Europe. Most of thesetions. archives In are contrast, known speleothems, toto and mainly reconstruct stalagmites climate record in conditions spring during particular,barth to autumn provide et summer and al. the winter condi- opportunity in central Europe ( 2010 ous studies on tree rings (e.g. However, for Europe, several periods duringclimate, the respectively, have Holocene been with reported warm/wetet (see, and al. for cold/dry instance, the summaries in to disentangle the complex patterns of Holocene climate change. For instance, numer- et al. The largest climate anomaly during theet Holocene al. was the short 8.2 ka cold event ( attributed to a pronouncedevent negative was phase triggered of by the cooler NorthThermohaline conditions in Circulation. Atlantic the Oscillation, North the Atlantic 8.2 due ka to a slowdown of the 1 Introduction The Holocene represents an epoch ofticular relatively in stable, comparison warm climate to conditions, the in large, par- rapid changes that occurred during the Last Glacial. stalagmites compare well withfor other central European isotope Holocene records climateLittle and, Ice variability. Age The thus, cold prominent seem events 8.2 areevents representative ka both show event recorded a and in contrasting the the relationshipby Bunker di between cave record. climate However, these and European location, the cavecipitation site and is temperature particularlypresent in well high response suited resolution to to recordschanges record changes of changes in in in the the pre- Mg/Caisotope North composition ratio of Atlantic to the speleothems realm. variationsprecipitation most in We and likely reflects the variations changes meteoric inoric in precipitation precipitation. the vegetation and and The temperature. We stable6.5 found C cold and and 5.5 dry ka, periods 4 between and 9 and 3 ka 7 ka, as well as between 0.7 to 0.2 ka. The proxy signals in our Holocene climate was characterised bytime variability scales. on In multi-centennial central toter. Europe, multi-decadal Here these we fluctuations present a werebased new most on record pronounced four of during speleothems past win- from winter climate Bunker variability Cave, for Western the Germany. last Due 10.8 ka to its central Abstract 5 5 25 20 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , - U O ff 18 238 Ho δ ) and Th/ 2000 232 ( ). The 2011 ( Riechelmann, et al. ; Frank et al. O value of precipitation C, and the mean annual ◦ 18 δ 2010 , . Further details can be found U in secular equilibrium. Age 1 − -free atmosphere in the Heidel- ). All stalagmites have a diame- 238 2 1 ). E in Western Germany (Sauerland, Riechelmann, et al. 00 2011 U and , 53 0 Kluge et al. 234 ; 39 ◦ 1691 1692 Th, 2010 N, 7 , 230 00 level and do not include half-life uncertainties. The σ 03 0 22 ◦ ). 1.9 and Riechelmann, et al. ± ; ). The calibration of the U and Th spikes is described in 2012 ). Correction for detrital contamination assumes a , 2010 2005 , ). Due to the relatively low U content of the samples Th/U-dating ( 2000 ( Immenhauser et al. 2007 ( ¨ unsterer et al. M ¨ ) and belongs to a large cave system, which consists of several closely situated amper et al. ; 1 Cheng et al. Four speleothems, which grew within a maximum distance of 12 m from each other, Wackerbarth et al. berg radiocarbon laboratory using a hand-heldSub-samples dental drill from with a the burr diameter very of 1 top mm. of the stalagmites were milled from the stalagmite concentration ratio of 3.8 uncertainties are quoted at thereference 2- year for all ages given in the study2.2.2 is AD 1950. Radiocarbon dating Samples for radiocarbon dating were drilled in a CO values of the drip water show that the recharge water is well mixed within the aquifer and corresponds to the( infiltration weighted annual mean tion were propagated to theof final age errors. Ages were calculated using the half lives of Holocene speleothems fromTherefore, a Bunker Th Cave solution using withsition the was precisely added TIMS determined to concentration method some sub-samples andto is in isotopic improve order challenging. counting compo- to statistics. increase The the measuredand analysis isotope the time ratios for uncertainties were Th corrected and in accordingly concentration and isotope composition of the added Th solu- ter of about 5 toof 10 the cm investigated and stalagmites wereprehensive, sampled have long-term under been cave actively monitoring monitored dripping program within sites. the The framework drip sites of a com- Samples for Th/U-datinga diamond-coated were band cut saw. Theis from thickness typically (in 4 the growth mm. direction) All growth(TIMS) of samples individual were at axis samples analysed the by of Heidelberg thermaltion ionisation the and Academy mass mass of stalagmites spectrometry spectrometric Sciences. analysisHolzk using are Methods explained used in detail formann in sample et prepara- al. 2.2 Methods 2.2.1 Th/U dating 2011 were removed from thehas cave for a this length studyBu6 of (Bu1, is Bu2, about a Bu4 65 flowstone cm. and with Bu6). Bu2 a Stalagmite and length Bu1 of Bu4 about are 6 cm approximately (Fig. 20 cm long, whereas 70 cm of soil (inceptisol/alfisolconsists developed from entirely loess of loam). C3 VegetationThe plants, above mean the i.e. cave annual mainly air ashamount temperature and of in beech precipitation in the as the cave wellelsewhere area is as is (e.g. about around scrub 950 10.8 vegetation. mmyr 2.1 Cave site description Bunker cave is locatedFig. at 51 caves. Bunker Cave was discovered inWorld 1926 during War road the works, and entrancethe during the cave area Second is of situated 184 theMiddle m to cave a.s.l. Upper Devonian, on was low-Mg limestone a artificiallyof hosting south-facing thin the enlarged. hill dolomite veins. slope. host The The The thickness rock entrance cave above is to the developed in cave ranges from 15 to 30 m, which is covered by up to ability in Central Europe. 2 Cave site and methods multi-proxy reconstruction enables a robust reconstruction of past winter climate vari- 5 5 25 20 25 15 10 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | - C σ 13 δ ). Dating of ) leading to 1 1 ). Isotope ratios was combusted ). Some samples 2 0.1 ppm). The 2 1 ∼ , Table 2006 1 , − b). These layers probably reflect 3 ). Thin sections revealed that Bu4 2 ¨ otl and Mattey precision is 0.06 and 0.08 ‰ for . The method produces approximately Sp 1 σ − ). 1694 1693 the upper 7 cm) grew between 10.7 and 7.7 ka mode, were subtracted from the raw data. All ∼ ff C. The samples were measured at the MICADAS 1995 ◦ 100 µm) of the stalagmite, which may be contam- , ∼ ). ), which was measured before and after each sample. 2007 , 1996 , ). Element data were continuously acquired using a 60 µm circu- Neuser et al. 2006 , Synal et al. Pearce et al. powder was acidified (HCl) in vacuo, and the resulting CO to C on a Fe catalyst at 575 O, respectively. 2 3 18 δ Gerdes and Zeh is dominated by columnar crystals,rates. which indicates Two small relatively slow detritus andtop layers constant (dft), growth were which observed are identified at as about coralloid 15 layers (Fig. and 17 cm distance from does not resolve amately 17 growth cm stop. dft a Petrographic detritus-rich investigation layer revealing of a Bu1 hiatus. The shows duration of at this approxi- interruption periods of limited growth, which, however, seem to have been short since Th/U dating age uncertainty is between 100contain and elevated 300 amounts a of forsignificant most detritial age samples Th corrections. (Table (between Stalagmite Bu6 2BP, and covers and the the Holocene 3 period ngg part between of 10.7BP. Bu2 Bu4 and (i.e. covers 8.8 ka the last approximately 8.1 ka (Fig. 3.1 Th/U-dating and microscopic analysis Ten sub-samples fromsamples from stalagmite Bu4 Bu1, andthe three four samples sub-samples was sub-samples challenging from due Bu6 from to were the Bu2, dated relatively (Table low eleven U sub- content ( 3 Results 612 glass ( axis, next to the elementin track, order which to were obtain broken a into continuousglass series approximately plates of 4 and cm thin polished sections. long to These pieces pieces 30standard µm were thickness. stuck transmitted-light These on microscopy thin small sections as were(type well examined Lumic using as HC1-LM; using a hot cathode-CL-microscope A continuous sample scan had a maximum length2.2.5 of 2 cm. Microscopy Thin sections were made from all four stalagmites by sawing a thin slice near the growth data are normalized to the Ca content of the calcite and standardized against NIST counts, measured with the laser in o inated due toCaCO exchange with atmosphericwith carbon, H were notat ETH used Zurich for ( analysis. The lar ablation spot and a40 scan data speed points of 10 per µms mm corresponding to a spatial resolution of 25 µm. Background surface. The uppermost layers ( 2.2.3 Stable isotopes The stalagmites were micromilled continuously0.3 mm along for the Bu1 growth and Bu6, axiswere 0.2 at mm measured for increments Bu4 at of and 0.15 the mmthe for triple University Bu2. of collector Stable C Innsbruck. gas and Thecarbonate O source mass isotopes preparation isotope spectrometer system is ratio (for linked details, mass to see spectrometer an of on-line, automated the growth axis. Thetrack. Mg/Ca continuous ratios profile of the isICPMS) speleothems were located at measured the within by Mineralogical Laser 2ultraviolet Institute, mm Ablation ICP-MS laser Frankfurt, of (LA- system, Germany, the using coupled a( stable to New a isotope Wave Themo-Finnigan UP213 Element II sector field ICP-MS and 2.2.4 Mg and Ca analyses The stalagmites weremounted cut in along epoxy the resin growth discs axis and into polished. 2 Mg/Ca cm-long ratios were pieces, measured which parallel were to are reported against the VPDB scale and the 1 5 5 20 25 15 10 25 10 20 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ). 2 b), 3 10 yr 2011 Iscam ± , Levin and C increase. 13 ) the Th/U age ). This method δ 1 2012 , ects can be ruled out, ff Fohlmeister et al. ; ). Thus, it is possible to test 2 2008 Fohlmeister , ). Hence, jumps in the uncertainty 2 C observed for Bu4 is not present in 13 δ 1696 1695 allows to prove if the signals of two archives Mattey et al. ; ). Due to the low U content (Table iscam ) and 1.6 ka BP as well as 4.7 and 6.7 ka BP (Fig. 1999 2004 , , 3.2 40 a BP for the top section of Bu1. ± ). Usually, the age uncertainties in the overlapping periods are ) suggesting that Bu1 stopped growing before the 3 2012 (intra-site correlation age modelling; , Hua and Barbetti , Fig. ; 3.4 iscam Genty and Massault uses the available age information (means and errors) and the variation in 2004 , O signal of the four stalagmites in order to obtain the best age-depth model. ). This suggests that Bu4 was actively growing until its removal, whereas Bu1 10 cm) grew during the Eemian. Thin section analysis of the top of Bu2 and Bu6 2 18 ∼ Fohlmeister δ Iscam For age-depth modelling, both the Th/U ages and the radiocarbon measurements 49 cm dft, it was again impossible to measure reliable dates. The bottom section of C bomb peak is not visible. Thus, the stalagmite definitely stopped growing before smaller than in the periods without overlaps (Fig. We assume an age of 100 the For a detailed descriptiontion of ( the method the reader is referred to the original publica- for the age-depth14 modelling (Bu4 was removed in1950 2007 AD. In AD). addition, ForBu1 the the (Sect. strong top increase of in Bu1, the correlate above significance limits,a common which cause. indicate that the observed variationsare have used. An additionalthe constraint active drip is site. given Therefore, we by prescribed calcite the supersaturated top drip age of water Bu4 from to be 1997 AD bined with correlates dated proxy signals fromage-depth several stalagmites, model determines and the most calculatesenables probable the to age quantitatively uncertainty verifya for whether common the signals combined signal from record. withinwhether two the the resulting individual age correlation stalagmites is errors.of statistically have significant. Furthermore, enlarging This the the provides the signal-to-noise algorithmoverlapping advantage ratio is periods. and In able minimising addition, to the prove age uncertainties within the whether the proxy signalsis recorded the in case, individual aand stalagmites dominant the are influence proxy reproducible. signals ofsections likely If local, allow reflect this drip-site to past assemble specific climate a e records variability. composite The of record. temporally We the a overlapping four priori stalagmites assume that represent the one O common isotope signal. The records are com- The growth phases ofvals, all two four stalagmites stalagmites grew contemporaneously cover (i.e. the from last 0 10.8 to ka. 1.6 During ka; from several 4.7 inter- to 6.7 ka; 3.3 Chronology definitely stopped growing before 1950 AD. Table from 7.7 to 8.1 ka and between 8.8 and 10.7 ka, Fig. show a clear bomb-peak,uppermost whereas 2 Bu4 mm reveals as a expected(see typical for increase the e.g. and radiocarbon bomb-pulse decrease captured in in its stalagmites Three radiocarbon analyses were performedBu1. at the This top enabled sections ofthe to stalagmite atmospheric test Bu4 radiocarbon and anomaly whether inKromer the the middle stalagmites of the stopped 20thdata century growing are (e.g. before not precise or enough after to verify/falsify recent speleothem growth. Bu1 does not ∼ Bu1 ( indicate brown layers, which aredata interpreted for as the detrital upper layers 7 highlightingBu6 (Bu2) hiati. as and well Hence, 2 mm as the (Bu6) younger werewhich part discarded. reveal of The relatively Bu1 other slow are parts and solely of constant formed Bu2 growth of and rates. columnar crystals3.2 (Fig. Radiocarbon the interval between 14.6between and the 30 cm top dft. and Hence,between 14 age “pre-modern” cm data (Sect. dft for as Bu1During well the are latter only as period presented from Bu1ment consists 31 mainly with to of the fast 49 cm growing growth dendritic dft rate crystals, including derived in agree- the from periods the age measurements. In the section below of stalagmite growth cannot be determined precisely due to unreliable Th/U dates in 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ). 0.1 ± 2012 , a) show 3 cient of the C values be- c) confirming ffi 3 13 δ Fohlmeister 5 ‰) and the lowest values C. Bu1 generally shows the − 13 δ erent stalagmites are in agree- ff 0.01. This is related to weathering C values of Bu4 decrease. In the re- ± 13 δ a). 3 cients (0.9 for the young parts of Bu1 and ffi O variability during the last 10.8 ka is in the 1698 1697 18 cient between Bu2 and Bu6 is only missed by δ d). ffi 3 O values reflect climate conditions above Bunker 18 ects. This is also supported by the similar absolute ff δ erent (Fig. ff C values of the four Bunker Cave stalagmites is between , and citations therein). However, a sound understanding 13 ). Water in the upper soil zone above Bunker Cave has a very δ a) is required. For this purpose, possible variations of the drip C values of the four Bunker stalagmites show maximum values 3 c). In the early Holocene, Bu2 and Bu6 show 2009 13 3 2011 δ , , O records. For this purpose, all Mg/Ca ratios within the depth range O records in overlapping parts of di 18 10 ‰. As for Mg/Ca, the values of Bu6 are lower than those of Bu2. 18 δ − δ O time series does not exceed the 95 % threshold. The threshold to the d). The high correlation coe 18 3 5 ‰ (Fig. δ O values were used to determine the age model for the composite record. C and − 18 9 and C values of Bu2 increase between 8.5 and 7.5 ka, which is in agreement with 7 ‰ between 8 and 6 ka. After 6 ka, the 13 C values of Bu1 are lower compared to those of Bu4. Furthermore, the rapid δ − − δ 13 13 δ δ O values of all four stalagmites. 7 ‰) recorded around 10 ka (Fig. Modern rain water at the cave location has a maximum Mg/Ca ratio of 0.2 The The total range of the 12 and 18 Riechelmann, et al. − low Ca concentration and a Mg/Ca ratio of 0.13 ( Fairchild and Treble of the geochemical processesfor and each flow cave system, characteristics, isMg/Ca which records mandatory are from for most Bunker the Cave, likelycreasing interpretation first, unique trend an of in explanation this approach the proxy.Middle for Regarding Mg/Ca the Holocene the ratio long-term (Fig. of de- thewater stalagmites sources, Bu2 feeding the and stalagmite, Bu4 must during be considered. the Early to 4 Discussion 4.1 Mg/Ca ratios Previous work suggested that thefor speleothem the calcite amount Mg/Ca ratio of is precipitation a above qualitative the proxy cave or infiltration into the karst aquifer (see ment (Fig. Bu4, 0.79 for the oldBu6) parts of strongly Bu1 suggest and Bu4, thatCave 0.72 rather the for Bu2 than and site Bu4δ and specific 0.76 e for Bu2 and range of 2 ‰, with( the highest values observed at 0.5 ka ( the increase measured in thethat recent Bu1 part stopped of growing before Bu4 this is anomaly not occurred. visible inTherefore, Bu1 the (Fig. cent past, Bu4 shows asame steep pattern increase by as about Bu4, 4 especially ‰ in in the young section of the two stalagmites. However, values than Bu4. Similarly,generally the decreasing Mg/Ca trend patterns – di of Bu1 and Bu4− are – apart from the the Bu4 record. The about a decreasing trend within theapproximately last twice 10.8 ka. as During high theBoth as early the Holocene, in absolute Mg/Ca the Mg/Ca ratios values recent are andBu4 period, the and pattern 0.0033 Bu6 are and suggesting similar in 0.0015, thatcal overlapping all respectively. conditions parts in three of agreement stalagmites Bu2, with experienced findingsratio comparable from of hydrologi- present Bu6 day cave is monitoring. slightly The lower Mg/Ca than that of Bu2. Stalagmite Bu1 shows significantly lower tween The the relatively short overlapping interval between both stalagmites ( 3.4 C and O isotope andGiven Mg/Ca that time-series the spatial resolutionbon of and the oxygen Mg/Ca isotope elemental record, the ratiosof elemental exceeds the proxy that has of been the broughtof car- to the one resolution stable isotope sample have been averaged. The Mg/Ca data (Fig. shaded areas of theBu2 overlapping and periods Bu6 between representaccording Bu4 68 and % Bu2 confidence95 as intervals. % well The interval as correlation for between 0.01. coe the The reason correlation for coe missing the 95 % interval range between Bu2 and Bu4 is related to range may occur at transitions between overlapping and non-overlapping parts. The 5 5 25 20 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ). ). ). ). Hill ) for 2012 2011 1995 2007 , , , , Riechel- 2011 and, thus, , 2 ). ) showed only small Cruz Jr et al. erent drip sites in the ; ff 2004 ( Riechelmann, S. et al. 2011 , 2003 Riechelmann, et al. , Hammerschmidt et al. Riechelmann, et al. Riechelmann, S. et al. ) and contains a further coralloid ecting the Mg/Ca ratio in stalagmites Richter et al. ff 2010 , erent dissolution characteristics of calcite ff 1700 1699 ). Riechelmann, et al. a). This indicates that Bu1 either experienced Tooth and Fairchild 3 a) as precipitation variability above the cave. The 3 2009 , a) is, therefore, interpreted as a proxy for precipitation 4 Frisia and Borsato erent Mg proportions derived from the soil and karst, which may set between stalagmite Bu1 and Bu4 ( ff ff C values of annual drip water collected at di ) reveals that a major process a 13 δ ). The period between 7–8 ka in Bu4 is dominated by columnar fabrics Fairchild and Treble 2011 b). This kind of calcite fabric is formed from aerosols and can therefore , 3 1997 , C values ect of PCP on the Mg/Ca ratio during dry periods is further amplified by an ad- 13 ff δ ). 5). The resulting drip water feeding the stalagmite represents, thus, a mixture of the The Mg/Ca ratio of Bu1 and its variability is generally lower than that of Bu4 when We interpret the short-term variations in the Mg/Ca ratios of the Bunker cave sta- Whereas the long-term trend in Mg/Ca is caused by successive decalcification of the = Monitoring of Bunker Cavevariability drip in water the ( monthly collected drip waterThe samples recent from drip the drip raterate sites of of above Bu1 Bu4. the Furthermore, is twois Mg by speleothems. variable isotopes about showing showed di two that orders theexplain of Mg the contribution magnitude Mg/Ca to faster drip o 2012 than waters the drip 4.2 comparing coeval time intervalsa (Fig. faster drip rate resultingresulting in in less a PCP lower orinterpretation Mg a agrees concentration shorter with due residence the to observations time less reported in the intensive in karst ( dolomite aquifer dissolution. This and Forti layer. and dolomite ( result in higher Mg/Ca ratios due to the di ods and vice versa. Based7.7–7.3 ka on this BP interpretation, were periodsthe around characterised findings 0.5, by of 4.5–3.7, relatively 5.6 theBu4 and dry microscopy (Fig. analyses. conditions. At Thisonly 5.6 ka is grow a supported during thin by extrem coralloid dry layer was conditions, found whenindicating in there dryer is conditions ( less drip water available ( lagmites during the Holocene (Fig. detrended Mg/Ca ratio (Fig. amount. Higher Mg/Ca ratios in the detrended record are interpreted as dryer peri- Mg/Ca ratios of meteoric precipitation,resulting soil in zone a clay Mg/Ca contentTowards ratio the and end of host of rock the carbonate the dripThis Last water loess Glacial of may period, 0.02–0.06 have loessthan ( was had today, which deposited a is above sporadically higher Bunker found Cave. proportion in of the host weathered rock late ( diagenetic dolomite During percolation through thehost rock low with, in Mg average, lower Devoniann Mg/Ca limestone, ratios than the the soil water water dissolves (Mg/Ca: 0.004–0.008, the cipitation or infiltration. Themann, extensive et long-term al. monitoring at Bunker Cave ( tion may have led tocausing elution Mg/Ca of ratios the initially in high theweathering Mg stalagmite in components to the of Atlantic decrease. the stage This aeolian as may deposits postulated coincide by with enhanced loess cover, short-term variations in Mg/Ca ratios are attributed to the amount of pre- Weathering and leaching during theof transition the and Mg the bearing Earlyin loess Holocene the removed cover stalagmites some during and the may Early have Holocene. resulted Progressive in weathering and relatively decalcifica- high Mg/Ca ratios is Prior Calcite Precipitationreaches (PCP), the e.g. stalagmite. Lower calcite infiltration which intotion the precipitates of karst before aquifer air the leads compared to solution PCP. Lower to a higher rainfall water propor- amounts in also thecave lead ceiling. host to In rock lower both favouring drip cases,been degassing rates the demonstrated and, of Mg/Ca in thus, CO ratio various foster studies in PCP ( the at stalagmites the should increase as has rillonite and illite. Weathering ofsonal this changes siliceous in soil drip material is water also Mg documented isotope in composition sea- ( ditional process: Longer residence times of the percolating water in the host rock are of the non-carbonate loam fraction of the soil, such as Mg-bearing chlorite, montmo- The e 5 5 25 15 20 10 10 15 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ; ; ) ). C C 2 13 13 δ δ er by Drey- 2008 2005 2011 C val- ff Wurth Scholz ; , , , 13 set in the δ ff 2009 ects. This is , ff 3.5 ‰ ( ¨ otl et al. ), which in turn + C values of Bu4 ) and assuming C values is also Dreybrodt C were detected. C values di 13 13 Sp C values (Cerling, 13 Frisia et al. δ δ 13 13 δ 2012 2012 δ δ ( ects. Higher , ff and set may partly reflect dif- Scholz et al. 2 ff ected the two speleothems, C values of ff ). In addition, variable kinetic 13 C values of the top section of ths et al. δ C signal decreases implying the 13 ffi δ 13 2012 δ , C values ( C values of the Ca-saturated water Gri ). Since monitoring data suggest that C, a higher frequency pattern is vis- 13 Deininger et al. 13 2 δ 13 δ ; δ erences in stalagmite ff 2009 1701 1702 , C, the ). The large increase in the ) or even on the stalactite ( ◦ 23 ‰, host rock erence in − ff 2011 ). 2009 , , c) to changes in the seasonality of calcite precipitation C values (Table erent drip rates may have a 3 14 ff 2012 erences in annual cave air pCO C values of recent calcite precipitates from this drip site , ff Scholz et al. 13 ; C values of about 3 ‰ during the early Holocene and the sub- δ c) may have been caused by several e cult to identify which of these processes dominated the long- 3 ). Today, the drip rate of Bu1 is about two orders of magnitude 13 c) is anomalous and may be related to the artificial opening of C values should be comparable for both drip sites. Thus, the Riechelmann, D. F. C. et al. ffi a). After 6 ka, the stalagmite 3 δ 14 4 C values of the stalagmite record, we hypothesise that more posi- 2009 C value of the drip water. Modern drip water , 13 2011 Tremaine et al. C values of about 13 ; , δ δ C values (Fig. 13 ¨ uhlinghaus et al. erences in PCP and kinetic isotope fractionation. Bu1 has a dead carbon C values modulated by vegetation density was the major influence. This C and δ 13 ff set between both records is ca. 1.3 ‰. This o M 13 δ ff 13 2011 ; δ , δ C values of Bu1 are lower than those of Bu4 during joint growth periods. 13 δ 2009 , ) and a mean temperature of 10 Superimposed on this first-order trend in The increase in the The A similar assessment for the observed di ¨ uhlinghaus et al. Riechelmann, D. F. C. et al. may be related tothe the Mg/Ca relatively ratio dry (Fig. conditions between 7.7 to 7.3 ka BP inferred from faster reaction time ofcally carbonate induced dissolution changes. or Hence, stableto changes isotope changes in fractionation in root to vegetation respirationvalues climati- density probably and due seem microbial to to activity lowerthat soil be due respiration the responsible rates for vegetation between increasing 9 cover and soil above 7 ka air the BP. This cave implies became thinner during this interval, which ues may originate by increasedet kinetic al. isotope fractionation onas the well stalagmite as ( by ation larger and contribution soil of microbial host activity1984). rock-derived resulting Although C in it and/or more is by positiveterm di lower soil trend root gas in respira- the tive soil air assumption is based on the relatively slow adjustment of vegetation compared to the development of a denser vegetationbioproductivity. cover above the cave with concomitant higher soil ible. This patterncave resembles internal the processes second-order suchC signal isotope as fractionation in kinetic is mainly Mg/Ca isotope influenced and fractionation. by variations The is in degree drip attributed rate of to ( kinetic mean soil air 2002 0.7 to 0.8 ‰consistent are with the attributed observed lower toMg/Ca modern ratio PCP drip of rates and the feeding two Bu4 kinetic stalagmites. and isotope the o fractionationsequent e decrease (Fig. reflects changes in karst hydrology and precipitation above the cave. Therefore, high According to similar calculations as described in feeding Bu1 should be about 0.5 to 0.6 ‰ lower than that feeding Bu4. The remaining M the drip water of bothsoil drip sites water originates from theobserved same variability soil water in reservoir, the thedissolution, initial such drip as water the degree shouldas of potential be di open related versus closed tofraction conditions, the respectively, (dcf) as process of well of approximately 7 carbonate %, whereas Bu4 has a dcf of about 12 % (Table The mean o ferences in the approximately 0.13 ‰ ( faster than that ofvalues Bu4, of which Bu1 is and Bu4. consistent with the interpretationpossible of using the the calcite measured which would further increasebrodt the and di Scholz in the last 250 athe (Fig. cave in theBu4 late agree 19th well to with early( the 20th century. The isotope fractionation due to di cave. Similarly, only small di Therefore, we can neither attributespeleothem the long-term trend noror the short-term cave ventilation variations as in hasFrisia et been al. demonstrated for other caves (e.g. 5 5 15 20 10 25 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | O 18 a, b) δ 4 ) esti- ) demon- ) showed O values. ), the cor- er. For ex- 2010 O does not 18 ( ff 18 δ ). In general, Dreybrodt and 2012 2011 δ 2011 ( O values show ; ( , 18 2009 δ O values and vice , C for Bu4 (Fig. 2009 O value. 18 , 13 δ 18 δ δ a). Bu1 only shows small 3 O values. This is confirmed O values are very similar to Lachniet 18 ) and the Bunker Cave 18 ¨ unsterer et al. δ ). Cold periods as indicated by Wackerbarth et al. δ M 5 Langebroek et al. Langebroek et al. 2001 Scholz et al. ) suggested that this positive rela- ; ; , 2010 2008 ( 2009 , , ect of temperature and precipitation. Heat ff 1703 1704 Bond et al. O signal. However, for the Bunker Cave stalag- 18 ). Therefore, we interpret the observed variations in δ O value of precipitation and atmospheric circulation Cl, that the annual amount of evapo-transpiration is O values reflect cold and dry winters, whereas more Baldini et al. 18 36 2012 18 δ , δ ¨ O values in speleothem calcite). uhlinghaus et al. ect the Wackerbarth et al. 18 M ff O response of individual cave systems might di δ 18 O record of Bu4 (21 point moving average) for the last 8 ka δ 18 δ O values for stalagmite calcite. In addition, in case of kinetic isotope 18 O values ( O values in Bunker Cave. O as changes in both surface winter temperature and amount of winter δ Deininger et al. 18 18 18 ; O values represent warmer and more humid winters. δ δ δ 18 erences in the Mg/Ca ratios of Bu1 and Bu4 (Fig. O values than summer precipitation, leads to lower drip water δ O values ff 2011 O values in precipitation over central Western Europe are influenced by a North 18 c) shows large similarities with the detrended and smoothed Mg/Ca record 18 , a). During relatively dry conditions (high Mg/Ca ratio), the δ O, which provides additional evidence that PCP did not strongly influence the 18 4 4 δ δ 18 C values are assigned to periods of low drip rates and vice versa. The overall simi- δ Data and modelling studies ( The smoothed The relationship between surface air temperature variability and the stable oxygen 13 that Atlantic Oscillation (NAO) like pattern.relation As pattern argued between in the over Europe is aand result moisture of are the mainly transported combinedby to e the the European westerlies. continent Therefore, fromhematite-stained climatic-related the grains signals North (HSG) from Atlantic record; the North Atlantic (e.g. the those of Bu4, which showsfluence relatively of large PCP. Furthermore, variations peaks in inin Mg/Ca Mg/Ca suggesting are a in strong mostspeleothem in- cases not coeval with peaks variations in Mg/Ca indicating negligible PCP, but the precipitation. More positive negative (Fig. amount of winterlarger precipitation amount and of precipitation winterlower contributing temperature. to During the recharge warmerIn water, total, which winters, higher has winter the generally temperaturesresult (and in higher lower mean annual temperatures)fractionation, may, higher thus, drip rates (probablysult due in to lower increased precipitation)Scholz would also re- speleothem more positive values thanpattern is during particularly relatively pronounced humid betweenand 7.8 conditions during and the (low 7.3 LIA. ka, Mg/Ca In 6hold contrast, and ratio). for this 5.5 This ka, relationship the 2.8 of period and highsolution from 2.2 Mg/Ca ka processes 4.5 and and high to PCP 3.5 may ka.Variable be As PCP responsible described may for the above, also observed changesmites, a variability PCP in seems in carbonate not Mg/Ca. dis- to beby of the major di importance for the record are expected to show similar variations (Fig. tionship may not be valid when accounting for the positive relationship between the (Fig. increased percentages of HSGWestern indeed Germany (high coincide in most cases with colder phases in isotope signal of precipitationlower are temperatures well should understoodversa. correspond (e.g. However, to the lowerample, for speleothem central Europe Applying conventional evapo-transpiration equations, mated that about 40–50 %processes. of the Thus, annual precipitation the isaquifer contribution lost is due of to very evapo-transpiration summer lowstrated, precipitation in based the to on cave recharge analysiseven region. higher of of Furthermore, and the maythe karst reach major values proportion between of the 68 cave to drip 88 water %. and Thus, dominates its winter precipitation is δ larity of the detrended and smoothedimplies time that series slow of Mg/Ca drip and rates correspond to periods of4.3 less precipitation. 5 5 25 15 20 25 10 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) 1999 C and Barber , 13 ; O values δ c) are the LeGrande 18 5 O record of ; ) and Span- 1998 δ 1997 18 , , δ O values whose 5 ‰ and broadly 1999 2009 a) suggesting av- − 18 , , 4 δ 7 to ). This event was trig- − O records from Atta Cave Alley et al. O record (Fig. 18 2005 18 δ Boch et al. , δ O values from the Bunker Cave C values of the detrended record ´ ottir 18 13 δ δ von Grafenstein et al. ). O is also recorded in the Bunker Cave ) and a pronounced negative anomaly ´ ustsd 18 von Grafenstein et al. b) over the northern rim of the Alps and ´ δ Ag 5 2009 ), Katerloch ( 2001 , , 1706 1705 O record with the 2003 ). In Central-Northern Europe, this event led to 18 ) with the HSG record from the North Atlantic , 5 δ O values are the highest of the entire record. Ac- O value of the rainfall preserved in the stalagmites. ), a similar structure is observed in all records. This Alley and 18 O value of soil water above Bunker Cave. The signal- 2005 18 δ ; , δ 18 O data allow a consistent reconstruction of past winter Bond et al. Trouet et al. δ 2006 18 O signal reconstructed from Lake Ammersee. However, , δ ¨ 1997 alike 18 , c). Throughout the Holocene, the composite δ 5 C and O data highlight longer periods of high or low Niggemann et al. 13 O values in precipitation ( ). However, the amplitude of the 8.2 ka event in the stalagmite record ). This depletion in rainfall ; 18 ) suggests that the signal from the central European continent may 5 δ δ 18 O values from Lake Ammersee ( δ Alley et al. O value of precipitation (Fig. 18 2008 2000 2001 Rohling and P Vollweiler et al. O excursion. This is ascribed to a negative anomaly in the , 18 δ , , ; δ 18 O record (Fig. δ 18 1999 δ , O values during the last 10.8 ka reflect lower winter temperature and less winter O record (Fig. O in the Bunker record. The Another prominent Holocene cold event was the 8.2 ka event. This abrupt event Ostracod When comparing the Bunker Cave 18 18 18 Bond et al. Niggemann of precipitation over centralcirculation Europe due triggered to by increased changes freshwater in input. the The North Atlantic Ocean A multi-proxy studyThe of Mg/Ca four ratio, Holoceneclimate speleothems variability from in central Bunker Europe.dry Cave High periods Mg/Ca is within values the presented. in Holocene. the Accordingly,are high detrended ascribed record depict toδ low drip ratesrainfall. due An to exception in dry thisnegative context conditions is above the the 8.2 ka cave. cold event, More which positive shows a prominent erage or slightly moreexceptionally dry humid in conditions. central Thus, Europe climate during the conditions 8.2 ka were event. probably not 5 Conclusions is lower than inBunker the Cave Ammersee record precipitation are record. relatively Furthermore, low during Mg/Ca the ratios 8.2 of ka the event (Fig. δ that freshened the North Atlantictailment and influenced of the North Northet Atlantic Atlantic circulation al. Deep by a Water cur- (NADW)more formation negative ( and Schmidt gered by large amounts of melt water originating from the North American continent of the NAO during this period ( brought generally cold andduring dry winter conditions ( to the Northern Hemisphere, in particular observed in the North Atlantic ( ( anomalously cold and dry winter conditions in agreement with the cold conditions even be representative for the North Atlantic region and4.3.1 large parts of Little Europe. Ice Age vs. 8.2Two ka prominent event features in8.2 the ka composite event and Bunker the Cave LittleLIA Ice is Age characterized (LIA), which byδ occurred high between Mg/Ca 0.7 to ratios 0.2 ascording ka to BP. well The our interpretation, as this prominent shows that maxima during in the LIA, central Europe experienced nagel Cave ( indicates that the signalregional encoded climate. in A the comparisonEuropean Bunker of stalagmite Cave the archives stalagmites composite (Fig. represents Bunker supra- Cave record and the other reflect the the four Bunker Cave stalagmitesfollows shows the values ranging precipitation from the Bunker cave amplitude is also larger thanin soil that and of cave the may AmmerseeIn modify particular, record, the variations suggesting in that the (degree processes influence. of) kinetic isotope fractionation may have a strong ( are here used to constrain the to-noise ratio of theCave Ammersee data is comparable to that of the composite Bunker 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ects on the car- mann, S., Lotti- ff 1699 ff 1720 , 1692 1700 1706 1706 , 1705 1690 , 1700 , 1704 1698 1702 1717 , variability: implications for stalagmite growth 2 1697 , 1708 1707 C levels via stalagmites, Radiocarbon, 53, 99–115, 14 1703 1696 , 1720 , mann, D. L., Richards, D. A., and Clipson, N.: Very high- 1690 ff 1690 1702 , J., Gallup, C. D., Richards, D. A., and Asmerom, Y.: The half- 1705 ff , 1703 , 1690 solution and the related isotopic composition of calcite in stalagmites, ´ ottir, A. M.: The 8k event: cause and consequences of a major Holocene 1701 3 This work was funded by DFG research grant FG 668 (DAPHNE). ´ ustsd ´ -CaCO Ag 2 1706 ¨ otl, C., and Kramers, J.: High-resolution isotope records of early Holocene rapid 1695 1692 1704 O-CO 1706 2 , alpine stalagmites records the influencewinter of climate, solar Earth activity Planet. and Sci. the Lett., North 216, Atlantic 411–424, oscillation 2003. on 1690 bon and oxygen isotopemochim. composition Ac., of submitted, 2012. speleothems – a model approach, Geochim. Cos- travertine during the last interglaciation2000. in Southern Germany, Quaternary Res., 54, 38–48, the Holocene reconstructed from pollen data, Quaternary Sci. Rev., 22, 1701–1716, 2003. Geochim. Cosmochim. Ac., 72, 4712–4724, 2008. recorded in speleothems: From soil75, water 734–752, to 2011. speleothem calcite, Geochim. Cosmochim. Ac., change, Quaternary Sci. Rev., 28, 449–468, 2009. on the reconstruction of2011. atmospheric radiocarbon calibration asQuatern. derived Int., from 61, 27–39, lateglacial/early 1999. Holocene tree-ring chronologies, Sci. Rev., 29, 1005–1016, 2010. lives of uranium-234 and thorium-230, Chem. Geol., 169, 17–33, 2000. ing H per, J.: Tree-ring indicators of German summer drought over the last millennium, Quaternary of rainfall variations in SouthernPleistocene Brazil stalagmite, from Geochim. trace Cosmochim. element Ac., ratios 71, (Mg/Ca 2250–2263, and Sr/Ca) 2007. in a rate Quat. Geochronol., submitted, 2012. Bond, R., Hajdas,during I., the and Holocene, Bonani, Science, 294, G.: 2130–2136, Persistent 2001. solar influence on North Atlantic climate abrupt climate change, Quaternary Sci. Rev., 24, 1123–1149, 2005. 1689 climate change from two coeval stalagmites28, of Katerloch 2527–2538, Cave, 2009. Austria, Quaternary Sci. Rev., climatic instability: A prominent, widespread event 8200 yr ago, Geology, 25, 483–486, 1997. frequency and seasonal cave atmosphere pCO and oxygen isotope-based2008. paleoclimate records, Earth Planet. Sci.Bilodeau, Lett., G., 272, McNeely, R., 118–129, Southon,cold J., event Morehead, M. of D., 8200 and yr348, Gagnon, 1999. ago J.-M.: by Forcing catastrophic of the drainage of Laurentide lakes, Nature, 400, 344– ¨ untgen, U., Trouet, V., Frank, D., Leuschner, H. H., Friedrichs, D., Luterbacher, J., and Es- Frisia, S., Borsato, A., Preto, N., and McDermott, F.: Late Holocene annual growth in three Frisia, S. and Borsato, A.: Karst, Devel. Sedimentol., 61, 269–318, 2010. Deininger, M., Fohlmeister, J., and Mangini, A.: The influence of evaporation e Frank, N., Braum, M., Hambach, U., Mangini, A., and Wagner, G.: Warm period growth of Davis, B. A. S., Brewer, S., Stevenson, A. C., and Guiot, J.: The temperature of Europe during Fohlmeister, J., Kromer, B., and Mangini, A.: The influence of soil organic matter age spectrum Friedrich, M., Kromer, B., Spurk, M., Hofmann, J., and Kaiser, K. F.: Paleo-environment and Fairchild, I. J. and Treble, P. C.: Trace elements in speleothems as recorders of environmental Cheng, H., Edwards, R. L., Ho Dreybrodt, W.: Evolution of isotopic composition of carbon and oxygen inDreybrodt, a W. and calcite Scholz, precipitat- D.: Climatic dependence of stable carbon and oxygen isotope signals B Fohlmeister, J.: A statistical approach to construct composite climate records of dated archives, Cruz Jr, F. W., Burns, S. J., Jercinovic, M., Karmann, I., Sharp, W. D., and Vuille, M.: Evidence Bond, G., Kromer, B., Beer, J., Muscheler, R., Evans, M., Showers, W., Ho Alley, R. B. and Acknowledgements. References Boch, R., Sp records from the North7 ka, Atlantic. 6.5 and Cold 5.5 ka, and 4 dry and 3 periods ka are as well observed as between between 0.7 9 to and 0.2 ka. Alley, R. B., Mayewski, P. A., Sowers, T., Stuiver, M., Taylor, K. C., and Clark, P. U.: Holocene Barber, D. C., Dyke, A., Hillaire-Marcel, C., Jennings, A. E., Andrews, J. T., Kerwin, M. W., stalagmites agree well with other central European climate archives as well as with Baldini, J. U. L., McDermott, F., Ho 5 5 30 20 15 10 25 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1695 1690 O, textural and C time series of ¨ 18 oder-Ritzrau, A., ¨ uchter, C.: Latest 13 δ δ 1690 1699 C and 14 1695 1695 1695 1690 ¨ ultenfuß, J., Schr C data for carbon cycle modeling and ¨ otl, C., and Borsato, A.: Carbon mass- 14 1692 ¨ level in mid-latitudes of the Northern Hemi- otl, C., S 2 1702 , CO 1703 1701 1709 1710 14 1701 ¨ uhl, H. J.: Glacier and lake-level variations in West- 1706 ¨ uchter, C.: Multicentury glacier fluctuations in the Swiss , 2012. ¨ ohlenkd. Westf., 1, 1–154, 1995. 1692 , 2008. O stalagmite record, Earth Planet. Sci. Lett., 235, 741–751, 2005. 18 δ et, J., Fisher, R., Hodge, E., and Frisia, S.: A 53 yr seasonally resolved 1700 ff 1690 ¨ otl, C., and Mangini, A.: High-precision constraints on timing of alpine warm 1691 ¨ otl, C., and Verdes, P.: Reconstruction of temperature in the Central Alps during 1691 ¨ amper, S., Sp ths, M. L., Fohlmeister, J., Drysdale, R. N., Hua, Q., Johnson, K. R., Hell- ¨ ohlen in Iserlohn, Schr. Karst. H mann, D. L., Prytulak, J., Richards, D. A., Elliott, T., Coath, C. D., Smart, P. L., and ffi ff and Schulte, U.: Magnesium-isotope fractionation during low-Mg calcite precipitation in a Hawkesworth, C. J., Borsato, A., Keppens, E.,and Fairchild, I. Selmo, J., E. van M.: der Borg, Holocene K., climate Verheyden, S., variability in Europe: evidence from doi:10.1029/2008PA001610 the past 2000 yr from a 1690 oxygen and carbon isotopewater record and from relationship a to modern local precipitation, Gibraltar Earth speleothem: Planet. reconstructed Sci. drip Lett., 269, 80–95, 2008. H Scholz, D.: Procedures for accurateICPMS, U Int. and J. Th Mass isotope Spectrom., measurements 264, by 97–109, high 2007. precision MC- periods during the middle to lateSci. Pleistocene Lett., using 236, speleothem 751–764, growth periods, 2005. Earth Planet. age calibration purposes, Radiocarbon, 46, 1273–1298, 2004. Quaternary Sci. Rev., 28, 412–432, 2009. isotopic composition of precipitation in1704 Europe, Earth Planet. Sci. Lett., 311, 144–154, 2011. eral circulation modeling insights into the 8.2 kasphere event, (1959–2003), Paleoceanography, Radiocarbon, 46, 23, 1261–1272, PA3207, 2004. and its probable impact1690 on prehistoric human settlements, Quatern. Int., 113, 65–79, 2004. in Europe using pollen and lake-level data, Quaternary Res., 40, 139–149, 1993. Central Europe over the last 3500 yr, Holocene, 15, 789–801, 2005. Niggemann, S., and Aeschbach-Hertig, W.: Dating396–406, cave 2010. drip water by tritium, J. Hydrol., 349, Huntsville, AL, 1997. zircons: comparison with SHRIMParmorican and metasediment new in constraints1693 Central for Germany, the Earth provenance and Planet. age Sci. of Lett., an strom, 249, 41–67, J. 2006. carbon C., content Gagan,doi:10.1016/j.quageo.2012.04.001 of M. a K., Holocene and tropical Zhao, J.-X.: speleothem, Hydrological Quat. control Geochronol., on in the press, dead- a laminated stalagmite fromrecords, SW Geochim. Cosmochim. France Ac., – 63, modeling 1537–1548, and 1999. comparison with other stalagmite limestone cave – field2010. study and experiments, Geochim. Cosmochim. Ac., 74, 4346–4364, 2137–2149, 2009. Alps during the Holocene, Holocene, 16, 697–704, 2006. Pleistocene and Holocene glacier variations in the European Alps, Quaternary Sci. Rev., 28, balance modelling andCosmochim. carbon Ac., isotope 75, 380–400, exchange 2011. processes in dynamic caves, Geochim. Immenhauser, A., Buhl, D., Richter, D. K., Niedermayr, A., Riechelmann, D. F. C., Dietzel, M., McDermott, F., Frisia, S., Huang, Y., Longinelli, A., Spiro, B., Heaton, T. H. E., Mangini, A., Sp Mattey, D., Lowry, D., Du Hammerschmidt, E., Niggemann, S., Grebe, W., Oelze, R., Brix, M. R., and Richter, D. K.: Holzk Hua, Q. and Barbetti, M.: Review of tropospheric bomb Levin, I. and Kromer, B.: The tropospheric Lachniet, M. S.: Climatic and environmental controls on speleothem oxygen-isotope values, LeGrande, A. N. and Schmidt, G. A.: Ensemble, water isotope-enabled, coupled gen- Ho Langebroek, P. M., Werner, M., and Lohmann, G.: Climate information imprinted in oxygen- Magny, M.: Holocene climate variability as reflected by mid-European lake-level fluctuations Guiot, J., Harrison, S. P., and Prentice, I. C.: Reconstruction of Holocene precipitation patterns Holzhauser, H., Magny, M., and Zumb Kluge, T., Riechelmann, D. F. C., Wieser, M., Sp Hill, C. and Forti, P.: Cave minerals of the world, Vol. 2, National speleological society, Gerdes, A. and Zeh, A.: Combined U-Pb and Hf isotope LA-(MC-)ICP-MS analyses of detrital Gri Joerin, U. E., Stocker, T. F., and Schl Genty, D. and Massault, M.: Carbon transfer dynamics from bomb- Ivy-Ochs, S., Kerschner, H., Maisch, M., Christl, M., Kubik, P. W., and Schl Frisia, S., Fairchild, I. J., Fohlmeister, J., Miorandi, R., Sp 5 5 30 30 25 15 25 10 15 20 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 1699 , 1703 , 1698 1690 , 1702 1701 , ¨ oder-Ritzrau, A., 1692 1701 , ¨ activated cathodolu- otl, C., Richter, D. K., + 1703 O in the solution layer on 1691 , 18 δ 1694 ¨ oder-Ritzrau, A., Alfimov, V., 1702 and Mn2 1701 1703 ¨ aologie I, edited by: Richter, D. K. + , C and 13 δ ¨ at- und postglazialen Stalagmiten aus 1691 1720 a, K. R., and Friedrich, M.: Depositional ff ¨ otl, C., Riechelmann, D. F. C., Richter, D. K., Cl in karst waters from Bunker Cave, North 1690 ¨ age zur Spel 36 , 2012. 1699 1706 1711 1712 1693 1701 1720 , 1700 1720 , 1705 , ¨ oder-Ritzrau, A., Sp 1699 1705 C paleoclimate proxies in a continuously-monitored natural cave , 13 ¨ otze, J., Habermann, D., and Richter, D. K.: Kathodolumineszenz: ¨ oder-Ritzrau, A., Scholz, D., Fohlmeister, J., Sp O data, Geochim. Cosmochim. Ac., submitted, 2012. δ 18 1690 δ 1706 1693 ¨ alike, H.: Centennial-scale climate cooling with a sudden cold event around mann, D.: StalAge – an algorithm designed for construction of speleothem O and ff 18 C and 1699 doi:10.1016/j.gca.2012.03.008 δ ¨ ohlen des Sauerlandes, in: Beitr 13 ¨ δ uhlinghaus, C., and Mangini, A.: Modelling 1694 ¨ otl, C., Richter, D. K., Immenhauser, A., and Mangini, A.: Disequilibrium carbon and oxy- ¨ ¨ otl, C. and Mattey, D.: Stable isotope microsampling of speleothems for palaeoenvironmental otl, C., Faichild, I. J., and Tooth, A. F.: Cave air control on dripwater geochemistry, Obir Cave minescence in lateglacial and Holoceneprocesses?, stalagmites Holocene, of 14, Central 759–768, Europe: 2004. evidence for climatic and Chenery, S.: A compilationSRM of 610 new and and NIST published SRM major 6121996. glass and reference trace material, element Geostandard data Newslett., 21, for 115–144, NIST and Mangini, A.: Monitoring ofcave the environmental Bunker Cave parameters, (NW J. Germany):1700 Hydrol., assessing the 409, complexity 682–695, of 2011. Sp climate extending into the last interglacial period, Nature, 431, 147–151, 2004. Nucl. Instrum. Meth. B, 259, 7–13, 2007. calibration of system, Geochim. Cosmochim. Ac., 75, 4929–4950, 2011. positive North Atlantic Oscillation324, mode 78–80, dominated 2009. the medieval climate anomaly, Science, gen isotope fractionation in recentical cave model calcite: comparison of cave precipitates and numer- Kluge, T., Marx, T., and Immenhauser,Mg A.: isotopes Hydrogeochemistry and in fractionationGeol., a pathways 300, of continental 109–122, 2012. weathering system: Lessons from8200 yr field ago, experiments, Nature, 434, Chem. 975–979, 2005. stalagmite surfaces, Geochim. Cosmochim. Ac., 73, 2592–2602, 2009. studies: a comparison of235, 48–58, microdrill, 2006. micromill and laser ablation techniques,(Austria): Chem. implications Geol., for speleothemCosmochim. deposition Ac., in 69, dynamically 2451–2468, ventilated 2005. caves, Geochim. frequency of German subfossil oaks:the climatically Holocene, and Holocene, non-climatically 12, induced 707–715, fluctuations 2002. in evolution of speleothem-forming drip waters,51–68, Crag 2003. Cave, Southwest Ireland, J. Hydrol., 273, age models, Quat. Geochronol., 6, 369–382, 2011. climatic cycles in Holocene216, stalagmites 539–547, from 2003. Sauerland, Germany, Earth Planet. Sci. Lett., lagmites, Geochim. Cosmochim. Ac., 71, 2780–2790, 2009. 86, 138–149, extension-rate variations in three speleothems,1690 Quaternary Sci. Rev., 18, 1021–1038, 1999. Ivy-Ochs, S., and Mangini,Western A.: Germany Cosmogenic – a tool to derive local evapotranspiration?, Geochim. Cosmochim.Methodik Ac., und Anwendung, Zbl. Geo. Pal., 1/2, 287–306, 1995. Massenkalkh and Wurth,Bochum, G., Bochum, 5–129, 2000. Bochumer geologische und geotechnische Arbeiten, Ruhr-University ¨ ¨ uhlinghaus, C., Scholz, D., and Mangini, A.: Modelling fractionationunsterer, of C., stable Fohlmeister, isotopes J., in Wackerbarth, sta- A., Christl, M., Schr Richter, D., Gotte, T., Niggemann, S., and Wurth, G.: REE3 Pearce, N. J. G., Perkins, W. T., Westgate, J. A., Gorton, M. P., Jackson, S. E., Neal, C. N., Riechelmann, D. F. C., Schr Riechelmann, D. F. C., Deininger, M., Scholz, D., Riechelmann, S., Schr North Greenland Ice Core Project members: High-resolution record of Northern Hemisphere Synal, H.-A., Stocker, M., and Suter, M.: MICADAS: a new compact radiocarbon AMS system, Tremaine, D. M., Froelich, P. N., and Wang, Y.: SpeleothemTrouet, calcite V., farmed Esper, in J., Graham, situ: N. modern E., Baker, A., Scourse, J. D., and Frank, D. C.: Persistent Riechelmann, S., Buhl, D., Schr Scholz, D., M Sp Tooth, A. F. and Fairchild, I. J.: Soil and karst aquifer hydrological controls on the geochemical Rohling, E. J. and P Sp Scholz, D. and Ho Spurk, M., Leuschner, H. H., Baillie, M. G. L., Bri Niggemann, S., Mangini, A., Mudelsee, M., Richter, D. K., and Wurth, G.: Sub-Milankovitch M M Neuser, R. D., Bruhn, F., G Niggemann, S.: Klimabezogene Untersuchung an sp 5 5 20 25 30 30 25 15 10 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 1692 , 1720 , ¨ at Bochum, 1690 0.23 0.59 0.41 0.15 0.36 0.21 0.14 0.16 0.48 0.30 0.28 0.29 0.46 0.18 0.19 0.15 0.15 0.18 0.20 0.27 0.14 0.13 0.19 0.16 0.18 0.26 0.16 0.34 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± corrected O value of cave 1705 , 18 age δ 1690 0.22 8.03 0.59 6.64 0.37 7.14 0.16 6.40 0.24 5.89 0.140.16 1.09 0.46 1.53 0.13 4.66 0.25 4.98 0.23 5.78 6.36 0.180.19 10.11 10.65 0.11 5.02 0.130.16 2.46 0.15 3.35 3.89 0.21 0.56 0.25 7.66 0.15 0.83 0.16 8.78 0.18 0.60 0.27 9.20 0.14 1.09 0.18 10.04 0.080.14 1.42 1.76 0.30 10.59 1690 1690 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 1.9. uncorrected analytical errors. Corrected ± ¨ otl, C.: A precisely dated cli- σ , 2006. ¨ uckiger, J., Goosse, H., Gros- Th ages for Bunker Cave stalag- ). U) age 238 230 2.2 0.0029 8.11 0.0065 6.81 0.0051 7.45 0.0017 6.42 0.0034 6.39 0.00230.0017 0.72 0.0019 1.11 0.0052 1.57 0.0014 5.02 0.0026 5.50 0.0025 6.00 6.70 0.00330.0021 9.24 0.0025 10.20 10.68 0.0016 5.20 0.00110.0020 1.89 0.0018 1.91 0.0022 2.52 0.0021 3.53 3.96 0.0032 10.86 0.0027 0.57 0.0029 8.39 0.0022 0.85 0.0017 8.93 0.0019 1.10 0.0018 10.08 Th/ ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 230 ¨ uller, S. A., Prentice, I. C., Solomina, O., 9 0.1103 6 0.0759 6 0.0735 9 0.0989 7 0.0888 88 0.0139 4 0.0193 5 0.0547 9 0.0581 4 0.0653 0.0737 75 0.1174 4 0.1288 0.1469 7 0.0157 5 0.1127 7 0.0724 77 0.0204 0.0256 8 0.0361 7 0.0569 6 0.1190 4 0.0996 U( 1720 10 0.1027 11 0.0078 24 0.0135 10 0.0082 10 0.0480 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± , 234 ± ± ± ± ± δ 1713 1714 ¨ at-bis postglazialen Stalagmiten des Sauerlandes, 1705 1701 ¨ uller, J., Jouzel, J., and Johnsen, S.: The cold event 8 271 2 390 1 278 8 277 11 332 8 336 8 292 4 283 6 252 287 33 437 2 442 564 0 501 2 271 94 514 2 548 582 2 598 , 30 537 41 600 19 440 33 662 27 664 29 354 27 587 31 558 14 275 Th ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Th concentration ratio of 3.8 ¨ 232 uttel, M., M doi:10.1029/2006GL027662 1689 232 Th/ U 0.2 368 0.1 891 0.1 1200 0.4 1437 0.1 2099 0.1 54 0.1 36 0.2 100 0.1 2019 0.1 274 0.10.10.1 74 1004 0.1 1403 0.1 661 1317 0.2 221 0.2 304 0.2 47 0.4 333 0.1 57 0.1 597 0.2 1038 0.2 1881 0.10.2 592 390 0.5 2779 0.10.1 590 227 238 230 [ppb] [ppt] [‰] act. ratio [ka BP] [ka BP] ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ¨ uhlinghaus, C., Mangini, A., and Sp 69 66 84.1 69.1 57.7 48.08 102.9 ¨ utikofer, J., Crowley, T., Cubasch, U., Fl ∗ ∗ ∗ ∗ ∗ ∗ ∗ 1720 , ¨ atsbibliothek, Bochum, 2002. Bu4 – 19.25 cm Bu1 – 49 cm 120.6 Bu4 – 17.1 cm Bu1 – 46 cm 90.7 Bu6 Bu6 – 0.8 cm 219.1 Bu2 Bu2 – 1 cm 57.1 Bu4 Bu4 – 1.45 cm Sample ID Bu1 Bu1 – 2 cm 44.4 Bu1 – 3.3 cm Bu1 – 14 cmBu1 – 31 cmBu1 – 35 cmBu1 – 39.5 39.8 cmBu1 – 42 61.5 cm 60.4 68.6 84.6 Bu2 – 4 cmBu2 – 7 cm 116.6 191.6 Bu4 – 3 cm 79.5 Bu4 – 15.1 cm Bu6 – 2.5 cm 199.4 Bu1 – 9 cm 58.5 Bu2 – 5.5 cm 135.9 Bu4 – 5.5 cmBu4 – 75.4 10.15 cm Bu4 – 12 cmBu4 – 13.6 cm 95.8 Bu6 – 3.8 cm 237.0 Bu4 – 7 cmBu4 – 9 cm 72.0 68.6 Uranium and thorium isotopic compositions and ¨ 1706 ankischen Alb und der Bayerischen Alpen, Ph.D. thesis, Ruhr-Universit , Th ages assume an initial der Fr Universit drip water and speleothem calcite,1703 Earth Planet. Sci. Lett., 299, 387–397, 2010. jean, M., Joos,Stocker, T. F., F., Kaplan, Tarasov,change: P., J., an Wagner, overview, M., K Quaternary Sci. and Rev., 27, Widmann, 1791–1828, M.: 2008. Mid-to late Holocene climate decadal isotope-climate record from 151705 500 to 5000 yr BP, Science, 284, 1654–1657, 1999. Holocene cold events, Quaternary Sci. Rev., 30, 310–3123, 2011. mate record for theGeophys. last Res. 9 Lett., kyr 33, from L20703, three high alpine stalagmites,8200 yr Spannagel ago Cave, documented in Austria, oxygenClim. isotope records Dynam., of 14, precipitation 73–81, in 1998. Europe and Greenland, Wurth, G.: Klimagesteuerte Rhythmik in sp * Samples marked by an asterisk indicate addition of extra Th (see Sect. Wackerbarth, A., Scholz, D., Fohlmeister, J., and Mangini, A.: Modelling the Wanner, H., Beer, J., B Wanner, H., Solomina, O., Grosjean, M., Ritz, S. P., and Jetel, M.: Structure and origin of Table 1. von Grafenstein, U., Erlenkeuser, H., Brauer, A., Jouzel, J., and Johnsen, S. J.: A mid-European 230 mites Bu1, Bu2, Bu4 and Bu6 measured by TIMS. Errors are 2 von Grafenstein, U., Erlenkeuser, H., M Vollweiler, N., Scholz, D., M 5 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | error σ C activity 1 14 1716 1715 0.10.30.5 29116 291170.5 266070.5 91.35 91.81 28404 91.14 0.25 28405 0.24 100.15 0.25 87.83 0.26 0.23 0.05 28403 97.44 0.27 ± ± ± ± ± ± sampleBu1 xixBu1 xx depthBu1 x HD analysis 0.1 Bu4 Top 0.5 Bu4 1 mm 0.05 Bu4 1.0 2 mm 0.6 1.6 name [mm] number [pm C] [pm C] C activity of the top sections from stalagmites Bu1 and Bu4. 14 Map of Central Europe showing the location of Bunker Cave. Central Europe is strongly influenced by the westerlystalagmites wind from system Bunker (indicated cave bysample are is the shown shown. black on solid the arrow). right. The For four Bu2, studied only the Holocene part of the Fig. 1. Table 2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | -uncertainty σ ).The for Bu1 2012 (d) , O 18 δ and Fohlmeister ( (c) C 13 δ iscam , (b) -uncertainties as well as the age-depth σ 19 -uncertainties as well as the age-depth models (solid line) for 1718 1717 σ , petrographic logs (Fohlmeister, submitted).The shaded areas define the 2 (a) iscam -uncertainty range. The thin dotted lines denote periods that are σ erent fabrics are: blue: columnar; grey: elongated columnar; aqua: short colum- ff Time series of 100*Mg/Ca Th/U ages (solid squares) and associated 2 Map of Central Europe showing the location of Bunker Cave. Central Europe is strongly influenced by Th/U ages (solid squares) and associated 2 Fig. 3. (grey), Bu4 (red), Bu2scale (blue) and European Bu6 cold (magenta). eventscode The (i.e. for vertical the the light di 8.2 ka greynar; lines event, yellow: represent 8.2 open ka, large- columnar; and pink: the dendritic; orange: Little coralloids Ice and/or Age, detrital LIA). layers. Colour models (solid line) for the four stalagmites calculated using Fig. 2. shaded areas define thecontained 2 in two stalagmites (i.e. overlapping sections). Fig. 2. Fig. 1. the westerly wind system (indicated by theare black shown solid on the arrow). right. The For four Bu2, studied only stalagmites the from Holocene Bunker part cave of the sample is shown. the four stalagmites calculated using range. The thin dotted lines denote periods that are contained in two stalagmites (i.e., overlapping sections). Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 1998 ). Thin , of Bu4. (c) C record 2006 , 13 δ hematite-stained O record (a) ). 18 δ 2011 , Vollweiler et al. von Grafenstein et al. O record from stalagmite AH1 18 δ mann ff (e) ), Lake Ammersee (about 550 km south- (b) 2009 , ), Scholz and Ho 21 ( 1720 1719 2001 O record (c) of Bu4. The vertical light grey boxes represent ) from the Atta Cave (about 50 km south of Bunker , 18 δ Boch et al. 2003 , O of meteoric precipitation ( StalAge 18 δ Bond et al. O record from Bunker Cave in comparison to 18 with the smoothed (21 point moving average) δ O record from the Austrian Alps (COMNISPA, (b) Niggemann et al. 18 ; δ O record from Katerloch ( the 2000 , Composite 18 C record (f) δ 13 Comparison of the detrended and smoothed (21 point moving average) Mg/Ca ratio (a) and Comparison of the detrended and smoothed (21 point moving average) Mg/Ca ratio δ (d) ), and Fig. 4. the 8.2 ka event and theby LIA. elevated The Mg/Ca yellow ratios. boxes represent periods of below average precipitation as indicated (b) with the smoothed (21 point moving average) Niggemann Cave) and grey lines represent the(coloured original thick data, lines). which The Ammersee were8.5 data smoothed and between with 6 5.35 ka and an BP 0.8 are 11-point kaon not moving and a smoothed the average due new AH1 to age-scale data their calculated between low with temporal resolution. The AH1 data are shown grains from the North Atlantic ( 1999 ( Fig. 5. (c) east of Bunker Cave) a proxy of Fig. 4. (a) The vertical light grey boxes representperiods the of 8.2 ka below event average and precipitation the as LIA. indicated The by yellow boxes elevated represent Mg/Ca ratios.