climatic dependence of stable carbon and oxygen isotope signals recorded in speleothems from soil water to speleothem calcite abstract understanding the relationship between stable isotope signals recorded in speleothems 13 c and 18 o and the isotopic composition of the carbonate species in the soil water is of great importance for their interpretation in terms of past climate variability here the evolution of the carbon isotope composition of soil water on its way down to the cave during dissolution of limestone is studied for both closed and open closed conditions with respect to co 2 the water entering the cave flows as a thin film towards the drip site co 2 degasses from this film within approx 10 s by molecular diffusion subsequently chemical and isotopic equilibrium is established on a time scale of several 10 100 s the 13 c value of the drip water is mainly determined by the isotopic composition of soil co 2 the evolution of the 18 o value of the carbonate species is determined by the long exchange time t ex between oxygen in carbonate and water of several 10 000 s even if the oxygen of the co 2 in soil water is in isotopic equilibrium with that of the water dissolution of limestone delivers oxygen with a different isotopic composition changing the 18 o value of the carbonate species consequently the 18 o value of the rainwater will only be reflected in the drip water if it has stayed in the rock for a sufficiently long time after the water has entered the cave the carbon and oxygen isotope composition of the drip water may be altered by co 2 exchange with the cave air exchange times ex co 2 of about 3000 s are derived thus only drip water which drips in less than 3000 s onto the stalagmite surface is suitable to imprint climatic signals into speleothem calcite deposited from it precipitation of calcite proceeds with time constants p of several 100 s different rate constants and equilibrium concentrations for the heavy and light isotopes respectively result in isotope fractionation during calcite precipitation since t ex p exchange with the oxygen in the water can be neglected and the isotopic evolution of carbon and oxygen proceed analogously for drip intervals t d p the isotopic compositions of both carbon and oxygen in the solution evolve linearly in time the calcite precipitated at the apex of the stalagmite reflects the isotopic signal of the drip water for long drip intervals when calcite is deposited from a stagnant water film long drip intervals may have a significant effect on the isotopic composition of the dic in this case the isotopic composition of the calcite deposited at the apex must be determined by averaging over the drip interval such processes must be considered when speleothems are used as proxies of past climate variability

modification and preservation of environmental signals in speleothems speleothems are primarily studied in order to generate archives of climatic change and results have led to significant advances in identifying and dating major shifts in the climate system however the climatological meaning of many speleothem records cannot be interpreted unequivocally this is particularly so for more subtle shifts and shorter time periods but the use of multiple proxies and improving understanding of formation mechanisms offers a clear way forward

relationship between petrologic processes in the plumbing system of mt etna and the dynamics of the eastern flank from 1995 to 2005 abstract mt etna volcano is located in a complex tectonic setting with large sectors of its eastern flank sliding seaward at different rates according to recent petrologic studies the etna s plumbing system has a multifaceted geometry variable in space and time and consisting of storage zones at different depths where magma ascending to the surface undergoes various processes mainly fractional crystallization and mixing in this framework we investigated a possible cause effect relationship between the flank displacement and pre eruptive magmatic processes in the shallow plumbing system furthermore a comparison between petrologic data and deformative patterns evidences that from 1995 to july 2001 the aforementioned pre eruptive magmatic processes did not significantly influence the volcano eastern flank dislocation which stayed slow and fairly regular by contrast the onset of the 2001 flank eruption leads to an acceleration of the movement as a consequence of the ascent of a primitive volatile rich sub aphyric basaltic magma from a deeper about 10 km b s l reservoir during the 2001 and 2002 03 activity at least for the decade 1995 2005 pre eruptive magmatic processes in the shallow portion

a 9000 year carbon isotopic record of acid soluble organic matter in a stalagmite from heshang cave central china paleoclimate implications abstract organic matter preserved in speleothems has the potential to reflect the changes of the overlying vegetation and soil ecosystem here we report the first near 50 yr resolution acid soluble organic matter asom carbon isotope 13 c asom sequence derived from a laminated stalagmite hs 4 spanning the last 9 ky in heshang cave central china the 13 c asom values vary between 25 8 and 22 0 with lower values from 9 to 4 ka bp and less negative values from 4 to 0 ka bp we postulate that the 13 c asom sequence is mainly controlled by temperature and water balance temperature could affect both vegetation physiology and microbial degradation in soil horizons the influence of temperature on the 13 c asom is supported by the negative correlation r 0 48 p 13 c asom record and the paleotemperature record in the nearby dajiuhu peatland the water balance can affect the retention time of organic matter in soils under drier conditions the soil organic matter will be retained longer and is more likely to be biologically degraded resulting in more negative 13 c asom values our results reveal that 13 c asom in speleothems has the potential to reflect the response of vegetation and or soil processes to paleoclimate changes

strong coupling of centennial scale changes of asian monsoon and soil processes derived from stalagmite δ18o and δ13c records southern china abstract the paleoclimate application of speleothem 13 c is influenced by site specific processes here we present four stalagmite 13 c records from two caves in southern china covering early and late marine isotope stage mis 3 and the holocene to investigate the spatio temporal pattern of calcite 13 c changes and the relationship with asian monsoon am variability in each growth period precessional to millennial scale changes are clear in the 18 o record in contrast millennial variability is absent in the 13 c record which characterizes persistent centennial oscillations however centennial scale 18 o variations agree well with those of 13 c with a larger amplitude in 13 c changes about twice that of 18 o this suggests that soil humidity balance associated with regional hydrological circulations is important for these centennial 13 c changes although evaporation related kinetic fractionation can induce concurrent enrichments in 18 o and 13 c in frequency the detrended 18 o and 13 c records are coupled at a periodicity of about 300 yr during the last glacial period and 150 yr during the holocene those centennial scale 13 c variations are generally consistent with greenland temperature variability indicating a climate response over broad regions thus strong co variation of 18 o and 13 c records should have a climatic origin even if it is amplified by kinetic effects

integrating u th 14c and 210pb methods to produce a chronologically reliable isotope record for the belize river valley maya from a low uranium stalagmite social and environmental changes had great spatiotemporal variability in the maya lowlands during the classic and postclassic periods and stalagmites promise high resolution paleoclimate data that

laboratory calibration of the calcium carbonate clumped isotope thermometer in the 25 250 c temperature range abstract many fields of earth sciences benefit from the knowledge of mineral formation temperatures for example carbonates are extensively used for reconstruction of the earth s past climatic variations by determining ocean lake and soil paleotemperatures furthermore diagenetic minerals and their formation or alteration temperature may provide information about the burial history of important geological units and can have practical applications for instance for reconstructing the geochemical and thermal histories of hydrocarbon reservoirs carbonate clumped isotope thermometry is a relatively new technique that can provide the formation temperature of carbonate minerals without requiring a priori knowledge of the isotopic composition of the initial solution it is based on the temperature dependent abundance of the rare 13c 18o bonds in carbonate minerals specified as a 47 value the clumped isotope thermometer has been calibrated experimentally from 1 c to 70 c however higher temperatures that are relevant to geological processes have so far not been directly calibrated in the laboratory in order to close this calibration gap and to provide a robust basis for the application of clumped isotopes to high temperature geological processes we precipitated caco3 mainly calcite in the laboratory between 23 and 250 c we used two different precipitation techniques first minerals were precipitated from a caco3 supersaturated solution at atmospheric pressure 23 91 c and second from a solution resulting from the mixing of cacl2 and nahco3 in a pressurized reaction vessel at a pressure of up to 80 bar 25 250 c the calibration lines of both experimental approaches overlap and agree in the slopes with theoretical estimates and with other calibration experiments in which carbonates were reacted with phosphoric acid at temperatures above 70 c our study suggests a universal 47 t calibration t in k 47 in 47 0 98 0 01 3 407 10 9 t 4 2 365 10 7 t 3 2 607 10 3 t 2 5 880 t 0 293 0 004 this new 47 t calibration given in the absolute reference frame that extends the experimentally calibrated temperature range for clumped isotopes to 250 c can be applied to carbonates that grew at intermediate temperatures 20 250 c

a multiple cave deposit assessment of suitability of speleothem isotopes for reconstructing palaeo vegetation and palaeo temperature the suitability of speleothems for interpreting palaeoclimate is typically determined by using either the hendy test overlapping analysis or long term cave environment monitoring however in many cases these methods are not applicable because a speleothem lacks clearly traceable layers for the hendy test it is difficult to obtain an overlapping speleothem nearby or long term cave monitoring is impractical the authors propose a multiple cave deposit approach to assess the suitability of speleothems for palaeoclimate study speleothems collected from two sites within raccoon mountain cave tennessee usa exhibit remarkable spatial variation 13c 10 3 to 2 2 over a relatively short distance ca 260 m drip water 18o values exhibit a seasonal precipitation signal at site 1 and an annual signal at site 2 combining field observations water isotope analysis and trace element data the authors propose that the speleothem formation at site 1 and site 2 tapped distinct sources of co2 i co2 derived from overlying soils for site 1 and ii limestone dissolved inorganic carbon induced by ground water dissolution for site 2 using fresh cave deposits modern speleothem 13c 100 c3 vegetation as an analogue a simple model was developed to estimate land surface vegetation for speleothems the speleothem formation temperature estimated using fresh cave deposit 18o values generally reflects the mean annual temperature in this region this study indicates that spatial variations in carbon isotopes could be caused by different carbon sources dominating in different parts of the cave which should be taken into consideration by researchers when using speleothem 13c values to reconstruct temporal palaeo vegetation changes this study demonstrates a practical sampling strategy for verifying suitability of speleothems for palaeo vegetation and palaeo temperature reconstructions by analysing multiple cave deposits especially for cases in which the hendy test parallel sampling and long term monitoring of cave environment are not feasible

hydrochemical controls on aragonite versus calcite precipitation in cave dripwaters abstract despite the paleoclimatic relevance of primary calcite to aragonite transitions in stalagmites the relative role of fluid mg ca ratio supersaturation and co 3 2 concentration in controlling such transitions is still incompletely understood accordingly we have monitored the hydrochemistry of 50 drips and 8 pools that are currently precipitating calcite and or aragonite in el soplao and torca ancha caves n spain investigating the mineralogy and geochemistry of the caco 3 precipitates on the corresponding natural speleothem surfaces the data reveal that apart from possible substrate effects dripwater mg ca is the only obvious control on caco 3 polymorphism in the studied stalagmites and pools where calcite and aragonite precipitating dripwaters are separated by an initial i e at stalactite tips mg ca threshold at 1 1 mol mol within the analyzed ranges of ph 8 2 8 6 co 3 2 concentration 1 6 mg l supersaturation si aragonite 0 08 1 08 si calcite 0 23 1 24 drip rate 0 2 81 drops min and dissolved zn 6 90 g l we observe no unequivocal influence of these parameters on caco 3 mineralogy despite the almost complete overlapping supersaturations of calcite and aragonite precipitating waters the latter are on average less supersaturated because the waters having mg ca above 1 1 have mostly achieved such high ratios by previously precipitating calcite both calcite and aragonite precipitated at or near oxygen isotopic equilibrium and mg incorporation into calcite was consistent with literature based predictions indicating that in the studied cases caco 3 precipitation was not significantly influenced by strong kinetic effects in the studied cases the calcites that precipitate at 11 c from dripwaters with initial mg ca approaching 1 1 incorporate 5 mol mgco 3 close to the published value above which calcite solubility exceeds aragonite solubility suggesting that aragonite precipitation in high relative humidity caves is favored from a solubility viewpoint we also show that unaccounted caco 3 precipitation in intermediate sampling containers and splash effects may in cases result in underestimating dripwater ca concentration and alkalinity potentially leading to incorrect conclusions regarding the role of fluid mg ca ratio and supersaturation on caco 3 mineralogy a simple way to elude the first effect is by taking water samples directly from stalactites and by titrating alkalinity in the same containers used to collect dripwaters

the evolution of 13 c and 18 o isotope composition of dic in a calcite depositing film of water with isotope exchange between the dic and a co 2 containing atmosphere and simultaneous evaporation of the water implication to climate proxies from stalagmites a theoretical model abstract the most widely applied climate proxies in speleothems are the isotope compositions of carbon and oxygen expressed by 13c and 18o values however mechanisms which are not related to climate changes overlay the climate signal one is the temporal increase of both 13c and 18o values by kinetic processes during precipitation of calcite isotope exchange between dic in the water and the co2 in the surrounding cave atmosphere can also change isotope composition here we present a theoretical model of the temporal isotope evolution of dic in a thin water layer during precipitation of calcite and simultaneous isotope exchange with the cave atmosphere and simultaneous evaporation of water the exchange of oxygen isotopes in the dic with those in the water is also considered for drip times for tdrip dic t drip e c eq c 0 e t drip eq atm 0 t drip in atm eq water 0 e w t drip t ev t drip water the first term on the right hand side is the contribution from precipitation of calcite the second stems from isotope exchange with the co2 of the cave atmosphere and the third results from isotope exchange between oxygen in the dic and the oxygen in the water e are kinetic parameters is the time scale of precipitation eq atm 0 and eq water 0 are the differences between the corresponding initial value 0 and the value eq atm water if dic were in isotope equilibrium with the atmosphere or in the case of oxygen with the water respectively in atm and water are the time scales of approach to isotope equilibrium by the exchange reactions ceq is the concentration of dic in chemical equilibrium with the co2 in the cave atmosphere and c0 is the initial concentration when the water drips to the stalagmite tev is the time needed for complete evaporation of the water layer ew is the fractionation between water vapor and fluid water for times tdrip 0 2 we find a further increase of dic tdrip until a maximum is passed and a final value is reached if eq atm 0 and eq water 0 are both zero exchange has no influence on the isotope composition for drip times tdrip eq atm 0 is about zero in summer time when most of the co2 comes from the vadose zone ground air and about 12 in winter time in well ventilated caves when most of the co2 stems from earth s atmosphere outside the cave therefore 13c may be affected by isotope exchange for the 18o equilibrium between the dic and the oxygen in the water as well as the oxygen in the co2 of the atmosphere is likely in summer time in winter time co2 from the atmosphere outside the cave with of about 6 vpdb may imprint small signals

holocene temperature and hydrological changes reconstructed by bacterial 3 hydroxy fatty acids in a stalagmite from central china abstract to achieve a sufficient understanding of the spatial dynamics of terrestrial climate variability new proxies and networks of data that cover thousands of years and run up to the present day are needed here we show the first gram negative bacterial 3 hydroxy fatty acid 3 oh fa based temperature and hydrological records from any paleoclimate archive globally the data covering the last 9 ka before present bp are generated from an individual stalagmite collected from heshang cave located on a tributary of the yangtze river central china 30 27 n 110 25 e 294 m our results indicate a clear early to middle holocene climatic optimum 8 0 6 0 ka bp followed by a long term monotonic cooling and increasing variability over the last 0 9 ka bp the hydrological record shows two relatively long wet periods 8 8 5 9 ka bp and 3 0 0 ka bp and one relatively dry period 5 9 3 0 ka bp in central china we show that 3 oh fa biomarkers hold promise as independent tools for paleoclimate reconstruction with the potential to deconvolve temperature and hydrological signals from an individual stalagmite

disordering of 13c18o bonds in co2 gas over a heated quartz surface at 50 1100 c insights into the abundance of mass 47 47 in co2 gas at thermodynamic equilibrium abstract the clumped isotope composition or the 47 value of co 2 relates the abundance of 13 c 18 o 16 o among all the co 2 isotopologues to the formation temperature of a carbonate mineral or the equilibration temperature of co 2 gas the 47 data typically requires several standardization steps and one of which heavily relies on true or equilibrium 47 values from different temperatures however they have not yet been experimentally quantified and only theoretically predicted 47 values are available to the community e g wang et al 2004 in this study a series of co 2 gases were cleaned using a custom designed automated co 2 cleaning system baked in a pre cleaned dry quartz tube and then measured for their 47 values the cbm protocol to examine 47 change kinetics of co 2 gas over a heated quartz surface between 50 and 1100 c in another test a series of co 2 gases were baked first cleaned subsequently and finally measured for their 47 values the bcm protocol to evaluate the effect of the co 2 cleaning on the 47 value in a routine 47 measurement our experimental results showed that 47 value of the co 2 gas over a heated quartz surface attained thermodynamic equilibrium in 191 7 0 23 and 0 1 h at 50 100 491 and 1000 c respectively we also reported the first experimentally determined equilibrium 47 t relation in co 2 gas between 50 and 1100 c as follows 47 in t in c r 2 0 99 p absolute 47 0 9791 0 0029 e 0 0045 t the comparison between the two co 2 preparation protocols also revealed that the co 2 cleaning step after the baking in the bcm protocol could alter the original 47 signature of co 2 gas by 0 04 and 0 07 at 100 and 1000 c respectively increasing the empirical transfer function etf slope to 1 therefore the isotope scrambling effect reported in the literature e g dennis et al 2011 might be resulted from co 2 cleaning process because isolating the co 2 cleaning effect before the baking yielded an etf slope of 1 implying that instrumental or analytical artifacts that could affect the measured 47 were not significant we suggest using a set of heated co 2 gases prepared by the bcm protocol from several different temperatures as an alternative for the conventional use of heated and water equilibrated co 2 gases to construct an absolute reference frame and standardize 47

δ 18 o values of cave drip water a promising proxy for the reconstruction of the north atlantic oscillation we present cave monitoring data and two drip water 18o models for the herbstlabyrinth adventhohle hl cave system germany winter climate of the cave region is influenced by the north atlantic oscillation nao as documented by the positive correlations between winter temperature winter rainfall 18o values and the winter nao index cave monitoring data show that recharge of the aquifer at the hl cave system mainly occurs during winter months confirming our drip water model which calculates recharge as the difference between precipitation and potential evapo transpiration cave drip water from the hl cave system should thus be a sensitive proxy for reconstruction of the nao the infiltration models accounting for mixing effects occurring in the karst aquifer show a very good agreement with the monitoring data comparison of the modelled and the monitored drip water 18o values suggests a mean residence time of the water in the aquifer of 12 months and a transmission time of 10 months using these parameters a long term dataset from the nearby meteorological station frankfurt am main and the rainfall 18o data from our monitoring program we model the 18o values of the cave drip water for the last 144 years despite of the favourable conditions of the hl cave system for nao reconstruction the modelled drip water 18o time series only shows a moderate correlation with the winter nao index r 0 33 the major reason for the relatively low correlation is the substantial contribution of precipitation from the remaining seasons to the drip water for instance due to heavy precipitation events occurring during summer these rainfall events bias the seasonality of infiltration and weaken the winter nao signal recorded in the drip water 18o values reconstruction of the nao from speleothems is thus challenging in particular considering further complications arising from chronological uncertainties and calcite precipitation under conditions deviating from isotopic equilibrium these problems may at least in part be avoided by multi proxy studies of annually laminated stalagmites

testing theoretically predicted stalagmite growth rate with recent annually laminated samples implications for past stalagmite deposition annually laminated stalagmites deposited over the last 30 160 years are analysed to determine their growth rate three natural and artificial cave sites in england france and belgium were chosen for their wide range of variability in growth rate determining variables and multiple samples were taken from each site the annual nature of laminae deposition within the stalagmite calcite was confirmed by comparison to the date of cave void opening 14c analyses or by using dated event horizons measured stalagmite growth rate was determined from annual laminae thickness measurements and compared to that theoretically predicted from the chemical kinetics of the calcite precipitation reaction a good agreement is observed between empirical observations and theoretical predictions although two complicating factors variations in calcite porosity and seasonal cessation of the water supply to the samples both affect the growth rate implications for the extraction of palaeoclimate information from stalagmite growth rate are discussed

oxygen isotope variations in rainfall drip water and speleothem calcite from a well ventilated cave in texas usa assessing a new speleothem temperature proxy abstract measurements of the oxygen isotopic composition 18o value of rainfall drip water and associated calcite grown on artificial substrates and in a natural speleothem at multiple drip sites in a well ventilated cave in central texas were conducted to investigate the potential use of speleothem 18o for quantitative temperature reconstructions from 2009 to 2011 rainfall 18o varied by 11 5 10 5 to 1 0 v smow whereas drip waters had a much narrower range of 0 3 4 7 to 4 4 v smow this contrast indicates that mixing processes along flow paths in the vadose zone above the cave produce a well homogenized water reservoir that supplies drip water to the cave the 18o values for calcite grown on substrates over the same time period show seasonal variations summer 6 winter 3 that are strongly correlated with surface air temperatures ta at all three monitored sites r2 0 88 0 96 p

interpretation of orbital scale variability in mid latitude speleothem δ18o significance of growth rate controlled kinetic fractionation effects abstract oxygen isotopes have been the most widely used climate indicator in stalagmites applied to reconstruct past changes in rainfall 18 o and cave temperature however the 18 o signal in speleothems may also be influenced by variable kinetic fractionation effects here conceived broadly as fractionation effects not arising from temperature variation the regional reproducibility of speleothem 18 o signals has been proposed as a way to distinguish the 18 o variations arising directly from changes rainfall 18 o and cave temperature from variations due to kinetic effects which may nonetheless be influenced by climate here we compare isotopic records from 5 coeval stalagmites from two proximal caves in nw spain covering the interval 140 to 70 ka which experienced the same primary variations in temperature and rainfall 18 o but exhibit a large range in growth rates and temporal trends in growth rate stalagmites growing at faster rates near 50 m yr have oxygen isotopic ratios over 1 more negative than coeval stalagmites with very slow 5 m yr growth rates because growth rate variations also occur over time within any given stalagmite the measured oxygen isotopic time series for a given stalagmite includes both climatic and kinetic components removal of the kinetic component of variation in each stalagmite based on the dependence of the kinetic component on growth rate is effective at distilling a common temporal evolution of among the oxygen isotopic records of the multiple stalagmites however this approach is limited by the quality of the age model for time periods characterized by very slow growth and long durations between dates the presence of crypto hiatus may result in average growth rates which underestimate the instantaneous speleothem deposition rates and which therefore underestimate the magnitude of kinetic effects the stacked growth rate corrected speleothem 18 o is influenced by orbital scale variation in the cave temperature and the 18 o of the ocean moisture source but also by temporally variable fractionation in the hydrological cycle the most salient trend is increased hydrological fractionation during the gi 22 period when warmer sea surface temperatures in the subtropical atlantic moisture source region may have favored greater precipitation amounts

a mathematical model for seepage of deeply buried groundwater under higher pressure and temperature summary deeply buried groundwater such as brine is an important industrial raw material with high economic value because brine frequently exists under higher temperature and pressure the quantitative prediction of its seepage field is very difficult here we study the migration of deeply buried groundwater by using a numerical simulation based on laboratory test results in particular we express the pressure and temperature variation of seepage parameters such as hydraulic conductivity k and specific storage coefficient s in terms of the corresponding variation of the solid skeleton s permeability k porosity n compressibility coefficient s and seepage fluid s viscosity and compressibility coefficient w then through mathematical transformation and linearization methods the mathematical model with pressure and temperature dependent coefficients is reduced to the same form as the standard one for seepage flow the results are successfully applied to the moxi structure in sichuan basin the results show that the effect of higher pressure and temperature should be taken into account for quantitative study of deeply buried groundwater and that the effects are easily included by the transformation of the mathematical model to standard form

factors controlling the growth rate carbon and oxygen isotope variation in modern calcite precipitation in a subtropical cave southwest china abstract a prerequisite for using cave speleothems to reconstruct palaeoenvironmental conditions is an accurate understanding of specific factors controlling calcite growth in particular the isotopic partitioning of oxygen 18 o and carbon 13 c which are the most commonly used proxies an in situ monitoring study from april 2008 to september 2009 at xueyu cave chongqing sw china provides insight into the controls on calcite growth rates drip water composition cave air parameters and 18 o and 13 c isotopic values of modern calcite precipitation both cave air p co 2 and drip water hydrochemical characteristics show obvious seasonality driven by seasonal changes in the external environment calcite growth rates also display clear intra annual variation with the lowest values occurring during wet season and peak values during the dry season seasonal variations of calcite growth rate are primarily controlled by variations of cave air p co 2 and drip water rate seasonal 18 o vpdb and 13 c vpdb in modern calcite precipitates vary with more negative values in the wet season than in the dry season strong positive correlation of 18 o vpdb vs 13 c vpdb is due to simultaneous enrichment of both isotopes in the calcite this correlation indicates that kinetic fractionation occurs between parent drip water and depositing calcite likely caused by the variations of cave air p co 2 and drip rate influenced by seasonal cave ventilation kinetic fractionation amplifies the equilibrium fractionation value of calcite 18 o by 1 5 and 13 c by 1 7 which quantitatively reflects surface conditions during the cave ventilation season these results indicate that the cave monitoring of growth rate and 18 o and 13 c of modern calcite precipitation are necessary in order to use a speleothem to reconstruct palaeoenvironment

large kinetic isotope effects in modern speleothems the application of stable isotopes in speleothem records requires an understanding of the extent to which speleothem calcite isotopic compositions refl ect the compositions of the cave waters from which they precipitate to test for equilibrium precipitation modern speleothem calcite was grown on glass plates so that the carbon and oxygen isotope composition of the calcite and the water from which it precipitated could be directly compared the plates were placed on the tops of three actively growing stalagmites that occupy a 1 m 2 area in harrison s cave barbados west indies only some of the plate 13 c values and none of the plate 18 o values correspond to equilibrium values indicating signifi cant kinetic isotope effects during speleothem calcite growth we investigate herein mechanisms that may account for the kinetic isotope effects on each plate speleothem calcite was deposited with distinct 18 o and 13 c compositions that increase progressively away from the growth axis with up to 6 6 13 c and 1 7 18 o enrichments the positive 13 c

remote vs local control on the preboreal asian hydroclimate and soil processes recorded by an annually laminated stalagmite from daoguan cave southern china abstract stable isotopic measurements on the upper 168 cm of stalagmite dg24 from southern china which is annually laminated above 74 8 cm 11 8 ka reconstruct a history of detailed asian summer monsoon asm variability and soil processes between 14 8 and 10 3 ka the climate sequence of bolling younger dryas yd preboreal events is evident in 18 o record in the preboreal four year resolution and annually counted 18 o record reveals that the asm strengthening can be divided into three phases with a prominent and persistent rise initiated at about 11 2 0 3 ka likely in response to interactions between ocean atmosphere and ice sheets in contrast the long term 18 o depletion is absent in the 13 c and annual layer records which characterize persistent centennial oscillations and likely represent relative humidity of the soil at multi decadal scale prominent asm failures are generally consistent with periods of 13 c enrichment and decreased layer thickness when compared with solar proxies centennial scale 13 c changes match well with solar activity regardless of the observed disparity between asm and solar records and common cycles of 130 and 300 years are identified in both the atmospheric 14 c and speleothem 13 c records this implicates that during the preboreal local soil humidity budget and co 2 production indicated by the 13 c and annual layer records is more sensitive to changes in solar output than the regional hydroclimate variability recorded by the 18 o signal

isotopic characterization of cave environments at varying altitudes on the eastern adriatic coast croatia implications for future speleothem based studies abstract an important step in the implementation of paleoclimate reconstructions from speleothems cave carbonate deposits is to evaluate the sensitivity of the host cave environment to regional climate accordingly we studied three caves at different altitudes 74 m 570 m and 1250 m a s l along a transect from the dalmatian islands to velebit mountain peaks in coastal croatia to characterize their environments in terms of each cave s suitability to host speleothems that would be capable of yielding robust paleoclimate reconstructions we conducted cave microclimate 2 years and dripwater 1 year monitoring and analysed the isotopic composition of precipitation cave dripwater and modern spelean calcite as for the water isotopic imprints the isotopic values of meteoric waters reaching the two lower altitude caves in spite of an altitude difference of 500 m lie on local meteoric water lines lmwls of similar slope and intercept 2 h 6 61 18 o 4 92 and 2 h 6 69 18 o 6 86 their slopes lower than that of gmwl indicate enhanced evaporation during the warm season as expected the lmwl of the highest cave region 2 h 7 83 18 o 14 45 resembles the slope of the gmwl but the values of deuterium excess obtained for all three caves between 15 2 and 16 6 match that of western mediterranean sourced waters 15 monthly d excess values suggest atlantic sourced air masses can reach the sites throughout the year but never dominate the rainfall composition the altitude effect was noted both in precipitation and in dripwater isotopic composition but with notably different 18 o 100 m gradients 0 33 and 0 11 respectively stable isotope variations of the dripwaters in all caves were attenuated in relation to the rainwater even those of the drip sites with fracture flow behaviour based on stable cave microclimate conditions relatively steady discharges and modern calcite apparently precipitated at or close to isotopic equilibrium with dripwater the two caves at lower altitudes show the greatest potential for future paleoclimate studies the cave at the highest altitude experiences large cave air temperature amplitudes 5 3 c and pronounced ventilation making the isotopic signal susceptible to kinetic fractionation which might preclude quantification of environmental changes but on the other hand it accentuates isotopic events making them easier to identify

effect of in stream physicochemical processes on the seasonal variations in δ13c and δ18o values in laminated travertine deposits in a mountain stream channel abstract travertines are potential archives of continental paleoclimate records of stable carbon and oxygen isotopic composition 13 c and 18 o in laminated travertine deposits from endogene spring waters show regular cyclic patterns which may be due to seasonal change in climate determinants such as temperature and rainfall in this study 13 c and 18 o measurements of three travertine specimens that grew naturally over the eight years 2004 2011 at upstream middle and downstream sites in a canal at baishuitai sw china are presented they exhibit clear seasonal variations that generally correlate with biannual laminations specifically 13 c and 18 o values show significant positive correlation with each other for the three travertine specimens with the correlation coefficients increasing downstream along the canal to reveal the factors governing the seasonal and spatial variations in 13 c and 18 o values newly formed travertines precipitated on plexiglas substrates are also examined both 13 c and 18 o of the substrate travertines are low in the summer rainy season and high in the winter dry season showing a great consistency with the patterns in the natural travertines spatially isotope values increase downstream in both seasons with higher increase rates in winter that are related to removal of larger fractions of dissolved inorganic carbon dic from the solution and stronger kinetic isotopic fractionation in winter due to in stream physicochemical processes including caco 3 precipitation and the associated degassing of co 2 seasonal changes in 13 c and 18 o in the travertines are amplified by two times between the upstream and downstream sites this is opposite to trends for epigene meteogene tufas whose seasonal changes in stable isotope compositions are reduced downstream we suggest in stream physicochemical processes are a potential reason for underestimation of annual temperature ranges that are inferred from epigene tufa 18 o data

modelling fractionation of stable isotopes in stalagmites abstract high resolution 13c and 18o profiles recorded in precisely dated speleothems are widely used proxies for the climate of the past both 13c and 18o depend on several climate related effects including meteorological processes processes occurring in the soil zone above the cave and isotope fractionation processes occurring in the solution layer on the stalagmite surface here we model the latter using a stalagmite isotope and growth model and determine the relationship between the stable isotope values in speleothem calcite and cave parameters such as temperature drip interval water p co 2 and a mixing coefficient describing mixing processes between the solution layer and the impinging drop the evolution of 13c values is modelled as a rayleigh distillation process and shows a pronounced dependence on the residence time of the solution on the stalagmite surface and the drip interval respectively the evolution of 18o values in contrast is also influenced by buffering reactions between the bicarbonate in the solution and the drip water driving the 18o value of the bicarbonate towards the value expected for equilibrium isotope fractionation between drip water and calcite this attenuates the dependence of the 18o values on drip interval the temperature dependence of 18o however is more pronounced than for 13c and in a similar range as expected for fractionation under equilibrium conditions we also investigate the isotopic enrichment of the 13c and 18o values along individual growth layers and thus the slopes expected for hendy tests the results show that a positive hendy test is only possible if isotope fractionation occurred under disequilibrium conditions however a negative hendy test does not exclude that isotope fractionation occurred under disequilibrium conditions a more reliable indicator for disequilibrium fractionation is the enrichment of the 13c values along an individual growth layer

new speleothem data from molinos and ejulve caves reveal holocene hydrological variability in northeast iberia new speleothem records from northeastern iberian caves provide data to explore the climatic patterns during the holocene we present 13c and mg ca from three speleothems from two different caves located in the iberian range allowing replication of the climatic signal for several millennia through the integration of those stalagmites covering since the holocene onset to 2 ka the early holocene 11 7 8 5 ka appears as the wettest interval a marked change towards aridity is observed during the middle holocene 8 5 4 8 ka and an increase of humidity afterwards 4 8 2 ka this three part pattern contrasting with other iberian sequences seems to be associated with the different role that seasonality has played in the response of different proxies or records to changes in water availability interpreting our speleothem records as changes in winter spring precipitation along the holocene allows reconciling previous data on hydrological variability from the western mediterranean borderlands

impacts of cave air ventilation and in cave prior calcite precipitation on golgotha cave dripwater chemistry southwest australia abstract speleothem trace element chemistry is an important component of multi proxy records of environmental change but a thorough understanding of hydrochemical processes is essential for its interpretation we present a dripwater chemistry dataset pco2 alkalinity ca sicc mg and sr from an eight year monitoring study from golgotha cave building on a previous study of hydrology and dripwater oxygen isotopes treble et al 2013 golgotha cave is developed in quaternary aeolianite and located in a forested catchment in the mediterranean type climate of southwest western australia all dripwaters from each of the five monitored sites become supersaturated with respect to calcite during most of the year when cave ventilation lowers pco2 in cave air in this winter ventilation mode prior calcite precipitation pcp signals of increased mg ca and sr ca in dripwater are attributed to stalactite deposition a fast dripping site displays less evolved carbonate chemistry implying minimal stalactite growth phenomena which are attributed to minimal degassing because of the short drip interval 30 s we employ hydrochemical mass balance modelling techniques to quantitatively investigate the impact of pcp and co2 degassing on our dripwater initially we reverse modelled dripwater solutions to demonstrate that pcp is dominating the dripwater chemistry at our low flow site and predict that pcp becomes enhanced in underlying stalagmites secondly we forward modelled the ranges of solution mg ca variation that potentially can be caused by degassing and calcite precipitation to serve as a guide to interpreting the resulting stalagmite chemistry we predict that stalagmite trace element data from our high flow sites will reflect trends in original dripwater solutes preserving information on biogeochemical fluxes within our system by contrast stalagmites from our low flow sites will be dominated by pcp effects driven by cave ventilation our poorly karstified system allows us to highlight and quantify these in cave pcp processes which are otherwise masked at sites where karstification is more developed and hydrogeology is more complex our modelling also shows enhanced co2 source production in the unsaturated zone that is attributed to deeply rooted vegetation and increasing bioproductivity which we link to forest recovery after fires impacted our site during 2006 ce

millennial scale climate variability during the last 12 5 ka recorded in a caribbean speleothem abstract we present a speleothem stable oxygen isotope record for the last 12 5 ka based on two stalagmites from western cuba the 18o signal is interpreted to represent past precipitation variability both stalagmites show a pronounced transition from higher 18o values indicating drier conditions to more negative 18o values suggesting wetter conditions between 10 and 6 ka this transition is also visible in a planktonic 18o record off haiti on orbital timescales the 18o value of caribbean precipitation thus strongly resembles the oxygen isotope composition of caribbean surface water on millenial timescales the speleothem 18o record shows a high correlation to a north atlantic sea surface temperature sst record off west africa as well as a similarity with the bond events periods of lower north atlantic sst correspond to less precipitation in the caribbean and vice versa the potential teleconnection to the caribbean may reflect the position of the intertropical convergence zone because a further southward position of the itcz leads to reduced precipitation in the northern caribbean

a review of single sample based models and other approaches for radiocarbon dating of dissolved inorganic carbon in groundwater abstract numerous methods have been proposed to estimate the pre nuclear detonation 14c content of dissolved inorganic carbon dic recharged to groundwater that has been corrected adjusted for geochemical processes in the absence of radioactive decay 14c0 a quantity that is essential for estimation of radiocarbon age of dic in groundwater the models approaches most commonly used are grouped as follows 1 single sample based models 2 a statistical approach based on the observed curved relationship between 14c and 13c data for the aquifer and 3 the geochemical mass balance approach that constructs adjustment models accounting for all the geochemical reactions known to occur along a groundwater flow path this review discusses first the geochemical processes behind each of the single sample based models followed by discussions of the statistical approach and the geochemical mass balance approach finally the applications advantages and limitations of the three groups of models approaches are discussed the single sample based models constitute the prevailing use of 14c data in hydrogeology and hydrological studies this is in part because the models are applied to an individual water sample to estimate the 14c age therefore the measurement data are easily available these models have been shown to provide realistic radiocarbon ages in many studies however they usually are limited to simple carbonate aquifers and selection of model may have significant effects on 14c0 often resulting in a wide range of estimates of 14c ages of the single sample based models four are recommended for the estimation of 14c0 of dic in groundwater pearson s model ingerson and pearson 1964 pearson and white 1967 han plummer s model han and plummer 2013 the iaea model gonfiantini 1972 salem et al 1980 and oeschger s model geyh 2000 these four models include all processes considered in single sample based models and can be used in different ranges of 13c values in contrast to the single sample based models the extended gonfiantini zuppi model gonfiantini and zuppi 2003 han et al 2014 is a statistical approach this approach can be used to estimate 14c ages when a curved relationship between the 14c and 13c values of the dic data is observed in addition to estimation of groundwater ages the relationship between 14c and 13c data can be used to interpret hydrogeological characteristics of the aquifer e g estimating apparent rates of geochemical reactions and revealing the complexity of the geochemical environment and identify samples that are not affected by the same set of reactions processes as the rest of the dataset the investigated water samples may have a wide range of ages and for waters with very low values of 14c the model based on statistics may give more reliable age estimates than those obtained from single sample based models in the extended gonfiantini zuppi model a representative system wide value of the initial 14c content is derived from the 14c and 13c data of dic and can differ from that used in single sample based models therefore the extended gonfiantini zuppi model usually avoids the effect of modern water components which might retain bomb pulse signatures the geochemical mass balance approach constructs an adjustment model that accounts for all the geochemical reactions known to occur along an aquifer flow path plummer et al 1983 wigley et al 1978 plummer et al 1994 plummer and glynn 2013 and includes in addition to dic dissolved organic carbon doc and methane ch4 if sufficient chemical mineralogical and isotopic data are available the geochemical mass balance method can yield the most accurate estimates of the adjusted radiocarbon age the main limitation of this approach is that complete information is necessary on chemical mineralogical and isotopic data and these data are often limited failure to recognize the limitations and underlying assumptions on which the various models and approaches are based can result in a wide range of estimates of 14c0 and limit the usefulness of radiocarbon as a dating tool for groundwater in each of the three generalized approaches single sample based models statistical approach and geochemical mass balance approach successful application depends on scrutiny of the isotopic 14c and 13c and chemical data to conceptualize the reactions and processes that affect the 14c content of dic in aquifers the recently developed graphical analysis method is shown to aid in determining which approach is most appropriate for the isotopic and chemical data from a groundwater system

stalagmite growth and palaeo climate the numerical perspective abstract the growth of stalagmites can be approximated by a simple mathematical model which depends on growth rate and equilibrium radius these two parameters are controlled by the climate temperature variations derived from ice and deep sea core data together with models for changes in precipitation and soil cover are used to derive stalagmite stratigraphies which reflect the palaeo climate variations imposed in general stalagmite growth is strongly correlated to temperature and the amount of carbon dioxide available in the soil furthermore precipitation is correlated to the stalagmite diameter however several assumptions need to be made i a functional relationship between temperature on the one hand and precipitation and soil cover on the other needs to be established ii the kinetics of calcite dissolution and precipitation needs to be assigned either under soil and epikarst conditions open to the atmosphere or under fractured rock conditions closed from the atmosphere these assumptions are difficult to access from field data and therefore a stalagmite stratigraphy can be ambiguous and not easily converted back into an unknown palaeo climate signal

variation of the asian summer monsoon since the last glacial interglacial recorded in a stalagmite from southwest china abstract a number of studies proposed a close link between the climate changes in the asian summer monsoon asm the southern hemisphere sh and high latitudes of the northern hemisphere nh but the mechanisms is still an open question although speleothems 18o records have displayed excellent values in the reconstruction of paleoclimate change at centennial millennial to orbital timescales the significance of speleothems 18o and 13c is still debatable here a high precise 230th dated stalagmite from southwestern china was used to reconstruct the changes of asm and regional hydrological conditions since the last interglacial 3 6 118 1 ka bp by the coupled 18o and 13c we found 1 the easm and ism are synchronous changing on the orbital timescale responding to the change of north hemisphere summer insolation nhsi and high latitude climate change there is a teleconnection between antarctic temperature change and asm through the mascarene high and the somali jet 2 during mis 5d the stalagmite 18o in yangzi cave is nearly 1 5 higher than that in mis 2 the maximum of last glacial this should be attributed to the different isotopic compositions in moisture source of ism and easm and the dynamic changes of monsoon circulations 3 from mis 3 to mis 2 the asm showed a stepped pattern in weakening consistent with the decreasing nhsi and increasing global ice volume 4 the changes in stalagmite 13c indicated the changes of local hydrological conditions and closely correlated with climate changes revealed by stalagmite 18o the effective humidity which determined by temperature evaporation and precipitation dominated the regional hydrological conditions the change of effective humidity recorded in stalagmite 13c by influencing surface biomass and soil co2 production

cuban stalagmite suggests relationship between caribbean precipitation and the atlantic multidecadal oscillation during the past 1 3 ka here we present the first high resolution 18o record of a stalagmite from western cuba the record reflects precipitation variability in the northwestern caribbean during the last 1 3 ka and exhib

late holocene monsoon precipitation changes in southern china and their linkage to northern hemisphere temperature abstract observations and models suggest a latitudinal redistribution of precipitation as a result of ongoing global climatic warming however the dynamic link between temperature and regional precipitation in the course of natural climatic variability during the current interglacial period remains unclear especially in the monsoon regions of china here we present a reconstruction of a 5 year resolution summer monsoon rainfall record for the past 3200 years based on 622 pairs of 18o and 13c and 29 230th dates from a stalagmite wu37 from wulu cave in southern china a close similarity between the 18o and 13c records on centennial to decadal timescales suggests that calcite 18o is most likely a proxy associated with monsoon precipitation the record reveals that the little ice age 650 100 yr b p was a relatively humid period with two centennial scale wet events compared with the medieval warm period 1050 650 yr b p in contrast with previous observations in india and northern china monsoon precipitation variations indicated by our record and other cave records nearby were inversely related to changes in northern hemisphere nh temperature over the past two millennia in particular to variations in the thermal gradient between the northern and southern hemispheres this suggests that nh temperature has an important influence on summer precipitation in southern china via the interhemispheric thermal gradient and land ocean thermal contrast in addition we find that variations of monsoon rainfall in southern china on multi centennial to centennial timescales are inversely correlated with observed rainfall in the core monsoon region of india and in the northern fringe of the asian summer monsoon region in china this spatial pattern of rainfall variability can be interpreted as a result of the migration of the intertropical convergence zone that is likely dominated by the interhemispheric thermal gradient via cross equatorial airflows

an extended and higher resolution record of climate and land use from stalagmite mc01 from macal chasm belize revealing connections between major dry events overall climate variability and maya sociopolitical changes abstract the stalagmite mc01 was recovered from macal chasm cave on the vaca plateau of belize in 1995 and an initial paleoclimate interpretation was published in 2007 additional uranium thorium ages have extended the paleoenvironmental record back from 3250 to 5250 cal yr bp and the stable isotope 18o and 13c record is dramatically improved by 660 new values a series of major dry events mdes evident in stable isotopes ultraviolet stimulated luminescence and petrography began 3100 cal yr bp and the initiation of these events coincides with an increase in el nino dominance and southern shift in the intertropical convergence zone three mdes centered at 1750 cal yr bp 200 ce 1100 cal yr bp 850 ce and 850 cal yr bp 1100 ce and found in other regional climate records coincide with maya sociopolitical changes residuals from regression of 13c versus 18o are interpreted as a proxy for maize cultivation and land clearing with residual values gradually increasing at the start of preclassic period settlement 3950 cal yr bp 2000 bce peaking after 2250 cal yr bp 300 bce during major maya development in the late preclassic and classic periods and dropping to pre preclassic values after regional land abandonment 850 cal yr bp 1100 ce regional maya population growth and cultural expansion may have been aided by abnormally low precipitation variability as stable isotope variability suggests the late preclassic through the late classic was the most stable precipitation regime of the past 4000 years this additional research on mc01 complements other regional paleoenvironmental records that suggest that mdes coincided with disruptions in maya society from the preclassic through the postclassic periods although it is clear that not all significant sociopolitical changes can be attributed to the mdes these events likely played an antagonistic role in social stability

anomalous drip in the punkva caves moravian karst relevant implications for paleoclimatic proxies the drips in the punkva caves have been investigated using several methods there was an anomalous drip which differed from regular drips in several parameters including mineralization and isotopic values it has been interpreted as a consequence of prior calcite precipitation above the caves this behavior has implications for the use of speleothems as climatic archives

winter precipitation changes during the medieval climate anomaly and the little ice age in arid central asia abstract the strength of the north atlantic oscillation nao is considered to be the main driver of climate changes over the european and western asian continents throughout the last millennium for example the predominantly warm medieval climate anomaly mca and the following cold period of the little ice age lia over europe have been associated with long lasting phases with a positive and negative nao index its climatic imprint is especially pronounced in european winter seasons however little is known about the influence of nao with respect to its eastern extent over the eurasian continent here we present speleothem records 13c 18o and sr ca from the southern rim of fergana basin central asia revealing annually resolved past climate variations during the last millennium the age control of the stalagmite relies on radiocarbon dating as large amounts of detrital material inhibit accurate 230th dating present day calcification of the stalagmite is most effective during spring when the cave atmosphere and elevated water supply by snow melting and high amount of spring precipitation provide optimal conditions seasonal precipitation variations cause changes of the stable isotope and sr ca compositions the simultaneous changes in these geochemical proxies however give also evidence for fractionation processes in the cave by disentangling both processes we demonstrate that the amount of winter precipitation during the mca was generally higher than during the lia which is in line with climatic changes linked to the nao index but opposite to the higher mountain records of central asia several events of strongly reduced winter precipitation are observed during the lia in central asia these dry winter events can be related to phases of a strong negative nao index and all results reveal that winter precipitation over the central eurasian continent is tightly linked to atmospheric nao modes by the westerly wind systems

coherency of late holocene european speleothem δ18o records linked to north atlantic ocean circulation speleothem 18o records provide valuable information about past continental environmental and climatic conditions although their interpretation is often not straightforward here we evaluate a compilation of late holocene speleothem 18o records using a monte carlo based principal component analysis mc pca method that accounts for uncertainties in individual speleothem age models and for the variable temporal resolution of each 18o record the mc pca approach permits not only the identification of temporally coherent changes in speleothem 18o it also facilitates their graphical depiction and evaluation of their spatial coherency the mc pca method was applied to 11 holocene speleothem 18o records that span most of the european continent apart from the circum mediterranean region we observe a common shared mode of speleothem 18o variability that suggests millennial scale coherency and cyclicity during the last 4 5 ka these changes are likely caused by variability in atmospheric circulation akin to that associated with the north atlantic oscillation reflecting meridionally shifted westerlies we argue that these common large scale variations in european speleothem 18o records are in phase with changes in the north atlantic ocean circulation indicated by the vigour of the iceland scotland overflow water isow the strength of the subpolar gyre spg and an ocean stacked north atlantic ice rafted debris ird index based on a recent modelling study we conclude that these changes in the north atlantic circulation history may be caused by wind stress on the ocean surface driven by shifted westerlies however the mechanisms that ultimately force the westerlies remain unclear

speleothem calcite farmed in situ modern calibration of δ18o and δ13c paleoclimate proxies in a continuously monitored natural cave system abstract understanding the relationships between speleothem stable isotopes 13 c 18 o and in situ cave forcing mechanisms is important to interpreting ancient stalagmite paleoclimate records cave studies have demonstrated that the 18 o of inorganically precipitated low temperature speleothem calcite is systematically heavier than the 18 o of laboratory grown calcite for a given temperature to understand this apparent offset rainwater cave drip water groundwater and modern naturally precipitated calcite farmed in situ were grown at multiple locations inside hollow ridge cave in marianna florida high resolution micrometeorological air chemistry time series and ventilation regimes were also monitored continuously at two locations inside the cave supplemented with periodic bi monthly air gas grab sample transects throughout the cave cave air chemistry and isotope monitoring reveal density driven airflow pathways through hollow ridge cave at velocities of up to 1 2 m s 1 in winter and 0 4 m s 1 in summer hollow ridge cave displays a strong ventilation gradient in the front of the cave near the entrances resulting in cave air that is a mixture of soil gas and atmospheric co 2 a clear relationship is found between calcite 13 c and cave air ventilation rates estimated by proxies pco 2 and 222 rn calcite 13 c decreased linearly with distance from the front entrance to the interior of the cave during all seasons with a maximum entrance to interior gradient of 13 c caco3 7 a whole cave hendy test at multiple contemporaneous farming sites reveals that ventilation induces a 1 9 0 96 13 c offset between calcite precipitated in a ventilation flow path and calcite precipitated on the edge or out of flow paths this interpretation of the hendy test has implications for interpreting 13 c records in ancient speleothems calcite 13 c caco3 may be a proxy not only for atmospheric co 2 or overlying vegetation shifts but also for changes in cave ventilation due to dissolution fissures and ceiling collapse creating and plugging ventilation windows farmed calcite 18 o was found to exhibit a 0 82 0 24 offset from values predicted by both theoretical calculations and laboratory grown inorganic calcite unlike 13 c caco3 oxygen isotopes showed no ventilation effects i e 18 o caco3 appears to be a function of growth temperature only although we cannot rule out a small effect of unmeasured gradients in relative humidity evaporation accompanying ventilation our results support the findings of other cave investigators that water calcite fractionation factors observed in speleothem calcite are higher that those measured in laboratory experiments cave and laboratory calcite precipitates may differ mainly in the complex effects of kinetic isotope fractionation combining our data with other recent speleothem studies we find a new empirical relationship for cave specific water calcite oxygen isotope fractionation across a range of temperatures and cave environments 1000 ln 16 1 10 3 t 1 24 6 with a fractionation temperature dependence of 18 o t 0 177 c lower than the currently accepted 0 206 c

oxygen isotope fractionation in travertine depositing pools at baishuitai yunnan sw china effects of deposition rates abstract travertine 18o values can be used to reconstruct paleo temperatures if the oxygen isotope fractionation factors between travertine and water are accurately understood for this purpose the 18o values of pool travertine and its parent water and the deposition rates of the calcite were investigated at baishuitai yunnan sw china over the course of the full hydrological year april 23 2006 april 25 2007 the results show that the travertine water isotope fractionation factors are close to the commonly accepted equilibrium line of kim and o neil 1997 this differs from the results obtained by yan et al 2012 who found that the oxygen isotope fractionation factors in the travertine depositing pools were close to the line suggested as equilibrium relationship by coplen 2007 the average calcite deposition rate 2 30 mg cm 2 d 1 in the present study is six times larger than that 0 38 mg cm 2 d 1 in yan et al 2012 if slower calcite precipitation leads to equilibrium oxygen isotopic fractionation then the results of this study support the results of coplen 2007 that indicate that the equilibrium fractionation factor may be greater than the commonly accepted one derived by kim and o neil 1997 the relationship between oxygen isotope fractionation factor and calcite deposition rate in our study also agrees with the results of dietzel et al 2009 who found that the kinetic isotope effect favors preferential incorporation of 16o in solid calcite as the calcite deposition rate increases there was a threshold for calcite precipitation rate control on oxygen isotopic equilibrium in our case of travertine depositing pools when the calcite deposition rate was lower than 0 38 mg cm 2 d 1 oxygen isotopic equilibrium between calcite and water was attained therefore calcite deposition rate is a potentially important consideration when using 18o in natural carbonates as a proxy for terrestrial and ocean temperature

timing and duration of the east asian summer monsoon maximum during the holocene based on stalagmite data from north china we present a continuous c o isotope series that shows the detailed variability of east asian summer monsoon easm since 11 0 ka bp the series is based on two stalagmites namely dsy1 and lm2 wh

the coupled δ13c radiocarbon systematics of three late glacial early holocene speleothems insights into soil and cave processes at climatic transitions abstract the coupled 13 c radiocarbon systematics of three european stalagmites deposited during the late glacial and early holocene were investigated to understand better how the carbon isotope systematics of speleothems respond to climate transitions the emphasis is on understanding how speleothems may record climate driven changes in the proportions of biogenic soil carbon and limestone bedrock derived carbon at two of the three sites the combined 13 c and 14 c data argue against greater inputs of limestone carbon as the sole cause of the observed shift to higher 13 c during the cold younger dryas in these stalagmites gar 01 from la garma cave n spain and so 1 from sofular cave turkey the combined changes in 13 c and initial 14 c activities suggest enhanced decomposition of old stored more recalcitrant soil carbon at the onset of the warmer early holocene alternative explanations involving gradual temporal changes between open and closed system behaviour during the late glacial are difficult to reconcile with observed changes in speleothem 13 c and the growth rates in contrast a stalagmite from pindal cave n spain indicates an abrupt change in carbon inputs linked to local hydrological and disequilibrium isotope fractionation effects rather than climate change for the first time it is shown that while the initial 14 c activities of all three stalagmites broadly follow the contemporaneous atmospheric 14 c trends the younger dryas atmospheric 14 c anomaly can be clearly discerned subtle changes in speleothem initial 14 c activities are linked to climate driven changes in soil carbon turnover at a climate transition

modelling stalagmite growth and δ13c as a function of drip interval and temperature abstract growth and stable isotope composition of stalagmites are affected by climate changes to understand the underlying mechanisms we developed a time dependent multi box model that describes stalagmite growth and stable isotope fractionation of carbon under disequilibrium conditions the model takes variations of the drip interval temperature and the amount of mixing between the impinging drops and the solution on top of the stalagmite into account which allows to quantify the influence of these parameters to calculate the variations of 13c the multi box model was calibrated by comparison with an existing growth model the results show that drip interval temperature and the mixing coefficient do have a significant influence on 13c however considering the higher natural variability of the drip interval this parameter might have the largest influence

drip water isotopes in semi arid karst implications for speleothem paleoclimatology abstract we report the results of the first multi year monitoring and modelling study of the isotopic composition of drip waters in a semi arid karst terrane high temporal resolution drip rate monitoring combined with monthly isotope drip water and rainfall sampling at cathedral cave australia demonstrates that drip water discharge to the cave occurs irregularly and only after occasional long duration and high volume rainfall events where the soil moisture deficit and evapotranspiration is overcome all drip waters have a water isotopic composition that is heavier than the weighted mean annual precipitation some fall along the local meteoric water line others trend towards an evaporation water line it is hypothesised that in addition to the initial rainfall composition evaporation of unsaturated zone water as well as the time between infiltration events are the dominant processes that determine infiltration water isotopic composition we test this hypothesis using a soil moisture balance and isotope model our research reports for the first time the potential role of sub surface evaporation in altering drip water isotopic composition and its implications for the interpretation of speleothem o 18 records from arid and semi arid regions

cosmogenic 36cl in karst waters from bunker cave north western germany a tool to derive local evapotranspiration abstract monthly rain and drip waters were collected over a period of 10 months at bunker cave germany the concentration of 36 cl and the 36 cl cl ratios were determined by accelerator mass spectrometry ams while stable 35 37 cl concentrations were measured with both ion chromatography ic and ams the measured 36 cl fluxes of 0 97 0 57 10 4 atoms cm 2 month 1 0 97 atoms m 2 month 1 in precipitation were on average twice as high as the global mean atmospheric production rate this observation is consistent with the local fallout pattern which is characterized by a maximum at mid latitudes the stable chloride concentration in drip waters ranging from 13 2 to 20 9 mg l and the 36 cl concentrations ranging from 16 9 10 6 to 35 3 10 6 atoms l are a factor of 7 and 10 above the values expected from empirical evapotranspiration formulas and the rain water concentrations respectively most likely the additional stable cl is due to human impact from a nearby urban conglomeration the large 36 cl enrichment is attributed to the local evapotranspiration effect which appears to be higher than the calculated values and to additional bomb derived 36 cl from nuclear weapons tests in the 1950s and 60s stored in the soil above the cave in the densely vegetated soil above bunker cave 36 cl seems not to behave as a completely conservative tracer the bomb derived 36 cl might be retained in the soil due to uptake by minerals and organic material and is still being released now based on our data the residence time of 36 cl in the soil is estimated to be about 75 85 years

climatic and environmental controls on speleothem oxygen isotope values variations in speleothem oxygen isotope values d 18 o result from a complicated interplay of environmental controls and processes in the ocean atmosphere soil zone epikarst and cave system as such the controls on speleothem d 18 o values are extremely complex an understanding of the processes that control equilibrium and kinetic fractionation of oxygen isotopes in water and carbonate species is essential for the proper interpretation of speleothem d 18 o as paleoclimate and paleoenvironmental proxies and is best complemented by study of site specific cave processes such as infiltration flow routing drip seasonality and saturation state and cave microclimate among others this review is a process based summary of the multiple controls on d 18 o in the atmosphere soil epikarst and speleothem calcite illustrated with case studies primary controls of d 18 o in the atmosphere include temperature and relative humidity through their role in the multiple isotope effects variability and modifications of water d 18 o values in the soil and epikarst zones are dominated by evaporation mixing and infiltration of source waters the isotopically effective recharge into a cave system consists of those waters that participate in precipitation of caco3 resulting in calcite deposition rates which may be biased to time periods with optimal dripwater saturation state recent modeling experimental and observational data yield insight into the significance of kinetic fractionation between dissolved carbonate phases and solid caco3 and have implications for the hendy test to assist interpretation of speleothem d 18 o time series quantitative and semi quantitative d 18 o climate calibrations are discussed with an emphasis on some of the difficulties inherent in using modern spatial and temporal isotope gradients to interpret speleothems as paleoclimate proxy records finally several case studies of globally significant speleothem paleoclimate records are discussed that show the utility of d 18 o to reconstruct past climate

stalagmite carbon isotopes and dead carbon proportion dcp in a near closed system situation an interplay between sulphuric and carbonic acid dissolution in this study the dead carbon proportion dcp calculated from combined u th and radiocarbon analyses was used to explore the carbon isotope systematics in corchia cave italy speleothems using the example of stalagmite cc26 which grew during the last 12 ka the dcp values in cc26 are among the highest ever recorded in a stalagmite spanning the range 44 8 68 8 a combination of almost closed system conditions and sulphuric acid dissolution sad are proposed as major drivers in producing such a high dcp with minor contribution from old organic matter from the deep vadose zone the long term decrease in both dcp and 13c most likely reflects post glacial soil recovery above the cave with a progressive increase of soil co2 contribution to the total dissolved inorganic carbon dic pronounced millennial scale shifts in dcp and relatively small coeval but antipathetic changes in 13c are modulated by the effects of hydrological variability on open and closed system dissolution sad and prior calcite precipitation hence the dcp in corchia cave speleothems represents an additional proxy for rainfall amount

palaeo climate reconstruction from stable isotope variations in speleothems a review abstract speleothems are now regarded as valuable archives of climatic conditions on the continents offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores they are ideal materials for precise u series dating yielding ages in calendar years thereby circumventing the radiocarbon calibration problems associated with most other continental records stable isotope studies in speleothems have shifted away from attempting to provide palaeo temperature reconstructions to the attainable goal of providing precise estimates for the timing and duration of major o isotope defined climatic events characterised by high signal to noise ratios e g glacial interglacial transitions dansgaard oeschger oscillations the 8200 year event unlike the marine records speleothem data sets are not tuned and their independent chronology offers opportunities to critically assess leads and lags in the climate system that in turn can provide important insights into forcing and feedback mechanisms improved procedures for the extraction and measurement of stable isotope ratios in fluid inclusions trapped in speleothems are likely to provide in the near future a much enhanced basis for the quantitative interpretation of o isotope ratios in speleothem calcite the latter developments open up once again the tantalising prospect of palaeo temperature estimates but more importantly perhaps provide a direct test for a new generation of general circulation models whose hydrological cycles will incorporate the water isotopes the literature is reviewed briefly to provide for the reader a sense of the current state of the art and to provide some pointers for future research directions

devils hole paleotemperatures and implications for oxygen isotope equilibrium fractionation subaqueous calcite in devils hole nevada was growing continuously from slightly super saturated groundwater providing a 570 kyr long o18 paleoclimate record due to its very slow growth it has been assumed to have grown under conditions of isotopic equilibrium however its holocene o18 value is 1 5 higher than predicted by laboratory precipitation based oxygen isotope thermometer calibrations the suggestion that devils hole calcite anchors the isotope thermometer to more 18o enriched values has stirred a debate as to which paleothermometer calibration is relevant for paleoclimate and casts doubt on the validity of o18 based paleotemperatures we used clumped isotopes to test the assumptions of the devils hole alternative 18o thermometer carbonate clumped isotopes are a temperature proxy that measures the abundance of 13c18o bonds in caco3 this proxy is independent of the water composition and therefore gives independent estimates of temperatures when calcite forms at thermodynamic and isotopic equilibrium we find that devils hole water paleotemperatures were constant at 30 6 2 6 c between 27 and 180 ka similarly to the modern groundwater temperature of 32 8 34 3 c the proximity of the devils hole clumped isotope data to values expected based on modern groundwater temperatures supports the notion that devils hole calcite grew under equilibrium conditions therefore the commonly used laboratory based o18 temperature calibrations should be reconsidered the constant water temperature over the glacial interglacial cycles indicates that the long devils hole o18 record reflects only variations in the groundwater o18 values and as such represents a valuable archive of paleoclimate and isotope paleohydrology

the nature of annual lamination in carbonate flowstones from non karstic fractures vinschgau northern italy abstract the vinschgau is an inneralpine valley in the southern alps whose steep flanks are composed of strongly sheared gneisses and schists affected by deep seated gravitational slope deformations fractures generated by these movements host a groundwater system characterised by high amounts of dissolved solids which reflect long residence times and water rock interactions driven by sulphide oxidation this in combination with high air and soil temperatures on the south facing slope sonnenberg of the valley favoured the deposition of calcite and aragonite flowstone in shallow parts of this fractured non karstic aquifer about 5 of these speleothems exhibit well developed regular lamination whose annual origin was confirmed by radiometric dating a stable isotope petrographic and trace element study combined with u th dating was undertaken to disentangle the processes controlling lamina formation a succession of darker and lighter laminae forms distinct macroscopic couplets 0 2 2 mm wide in three of the samples while one sample comprises alternating white and translucent laminae microscopically the darker and white laminae show a higher abundance of opaque particles whose organic origin is confirmed by their strong epifluorescence the crystal fabric is dominated by the fascicular optic type the calcite shows regular 18 o oscillations with an amplitude of up to 1 2 with the exception of one sample 13 c lacks such a regular pattern and only shows smaller variations which do not correlate with 18 o in a consistent way all samples exhibit regular low amplitude mg sr ba and u cycles in three samples mg shows oscillations similar to the 18 o cycles in their frequency but opposite in phasing 18 o and mg oscillations are primarily attributed to surface temperature variations that are transmitted to the shallow subsurface by thermal conduction low amplitude trace element cycles mg sr ba and u are most probably driven by intra annual variations in the degree of prior aragonite precipitation in the seepage path which relates to seasonal changes in evaporation

stalagmite records of hydroclimate in central california during termination 1 abstract the last deglaciation is marked by large and abrupt hydroclimatic changes in the great basin and the american southwest however comparatively little is known about how hydroclimate varied on the western side of the sierra nevada we present new evidence for abrupt changes in precipitation amount in the central sierra nevada during the last deglaciation our new record from mclean s cave overlaps with a previously published record from nearby moaning cave oster et al 2009 and extends the record of hydroclimatic change in the region through heinrich stadial 1 mclean s cave speleothem 18o 13c mg ca and sr ca indicate a shift to drier conditions at the beginning of heinrich stadial 1 from 16 1 to 17 5 ka followed by wetter conditions at the end of heinrich stadial 1 when the majority of great basin lakes reached their deglacial highstands during the last deglaciation coincident shifts in the moaning and mclean s cave proxy records indicate drier conditions in the western sierra nevada during millennial scale intervals of warming at high latitudes such as the bolling and allerod and wetter conditions during cooler intervals such as the older and younger dryas thus the sierra nevada speleothem records are consistent with other regional records that document increased winter rainfall during millennial scale cold periods of the last deglaciation however regional differences exist in the hydroclimatic response to the younger dryas with central californian and interior southwestern sites indicating an increase in winter storms that is not apparent in southern california dynamic simulations of atmospheric circulation indicate that wetter conditions during the younger dryas relative to the bolling at mclean s cave may have resulted from a stronger storm track in the north pacific at the latitude of northern california

seasonal variations in modern speleothem calcite growth in central texas u s a variations in growth rates of speleothem calcite have been hypothesized to reflect changes in a range of paleoenvironmental variables including atmospheric temperature and precipitation drip water composition and the rate of soil co2 delivery to the subsurface to test these hypotheses we quantified growth rates of modern speleothem calcite on artificial substrates and monitored concurrent environmental conditions in three caves across the edwards plateau in central texas within each of two caves different drip sites exhibit similar annual cycles in calcite growth rates even though there are large differences between the mean growth rates at the sites the growth rate cycles inversely correlate to seasonal changes in regional air temperature outside the caves with near zero growth rates during the warmest summer months and peak growth rates in fall through spring drip sites from caves 130 km apart exhibit similar temporal patterns in calcite growth rate indicating a controlling mechanism on at least this distance the seasonal variations in calcite growth rate can be accounted for by a primary control by regional temperature effects on ventilation of cave air co2 concentrations and or drip water co2 contents in contrast site to site differences in the magnitude of calcite growth rates within an individual cave appear to be controlled principally by differences in drip rate a secondary control by drip rate on the growth rate temporal variations is suggested by interannual variations no calcite growth was observed in the third cave which has relatively high values of and small seasonal changes in cave air co2 these results indicate that growth rate variations in ancient speleothems may serve as a paleoenvironmental proxy with seasonal resolution by applying this approach of monitoring the modern system speleothem growth rate and geochemical proxies for paleoenvironmental change may be evaluated and calibrated

inverse modelling of the 14c bomb pulse in stalagmites to constrain the dynamics of soil carbon cycling at selected european cave sites the decomposition of soil organic matter som is temperature dependent but its response to a future warmer climate remains equivocal enhanced rates of decomposition of som under increased global temperatures might cause higher co2 emissions to the atmosphere and could therefore constitute a strong positive feedback the magnitude of this feedback however remains poorly understood primarily because of the difficulty in quantifying the temperature sensitivity of stored recalcitrant carbon that comprises the bulk 90 of som in most soils in this study we investigated the effects of climatic conditions on soil carbon dynamics using the attenuation of the 14c bomb pulse as recorded in selected modern european speleothems these new data were combined with published results to further examine soil carbon dynamics and to explore the sensitivity of labile and recalcitrant organic matter decomposition to different climatic conditions temporal changes in 14c activity inferred from each speleothem was modelled using a three pool soil carbon inverse model applying a monte carlo method to constrain soil carbon turnover rates at each site speleothems from sites that are characterised by semi arid conditions sparse vegetation thin soil cover and high mean annual air temperatures maats exhibit weak attenuation of atmospheric 14c bomb peak a low damping effect d in the range 55 77 and low modelled mean respired carbon ages mrca indicating that decomposition is dominated by young recently fixed soil carbon by contrast humid and high maat sites that are characterised by a thick soil cover and dense well developed vegetation display the highest damping effect d c 90 and the highest mrca values in the range from 350 126 years to 571 128 years this suggests that carbon incorporated into these stalagmites originates predominantly from decomposition of old recalcitrant organic matter som turnover rates cannot be ascribed to a single climate variable e g maat but instead reflect a complex interplay of climate e g maat and moisture budget and vegetation development

cave air control on dripwater geochemistry obir caves austria implications for speleothem deposition in dynamically ventilated caves there are very few process studies that demonstrate the annual variation in cave environments depositing speleothems accordingly we initiated a monitoring program at the obir caves an austrian dripstone cave system characterized by a seasonally changing air flow that results in a predictable pattern of high pco2 during summer and low pco2 in winter although similar seasonal changes in soil pco2 occur they are not directly connected with the changes in the subsurface since the dripwaters are fed from a well mixed source showing little seasonal variation cold season flushing by relatively co2 poor air enhances degassing of co2 in the cave and leads to a high degree of supersaturation of dripwater with regard to calcite forced calcite deposition during the cold season also gives rise to a pronounced pattern of synchronous seasonal variations in electrical conductivity alkalinity ph ca and 13cdic which parallel variations recorded in 13ccave air chemical components unaffected by calcite precipitation e g d 18o sio2 so4 lack a seasonal signal attesting to a long residence in the karst aquifer modeling shows that degassing of co2 from seepage waters results in kinetically enhanced c isotopic fractionation which contrasts with the equilibrium degassing shown from the soreq cave in israel the obir caves may serve as a case example of a dripstone cave whose seepage waters and speleothems show intra annual geochemical variability that is primarily due to chemical modification of the groundwater by a dynamic bidirectional subsurface air circulation

stable isotope variations in modern tropical speleothems evaluating equilibrium vs kinetic isotope effects applications of speleothem calcite geochemistry in climate change studies require the evaluation of the accuracy and sensitivity of speleothem proxies to correctly infer paleoclimatic information the present study of harrison s cave barbados uses the analysis of the modern climatology and groundwater system to evaluate controls on the c and o isotopic composition of modern speleothems this new approach directly compares the 18 o and 13 c values of modern speleothems with the values for their corresponding drip waters in order to assess the degree to which isotopic equilibrium is achieved during calcite precipitation if modern speleothems can be demonstrated to precipitate in isotopic equilibrium then ancient speleothems suitable for paleoclimatic studies from the same cave environment may also have been precipitated in isotopic equilib rium if modern speleothems are precipitated out of isotopic equilibrium then the magnitude and direction of the c and o isotopic offsets may allow specific kinetic and or equilibrium isotopic fractionation mechanisms to be identified carbon isotope values for the majority of modern speleothem samples from harrison s cave fall within the range of equilibrium values predicted from the combined use of 1 calcite water fractionation factors from the literature 2 measured temperatures and 3 measured 13 c values of the dissolved inorganic carbon of drip waters calcite samples range from 0 8 higher to 1 1 lower than predicted values the 13 c depletions are likely caused by kinetically driven departures in the fractionation between hco3 aq and caco3 from equilibrium conditions caused by rapid calcite growth 13 c enrichments can be accounted for by rayleigh distillation of the hco3 aq reservoir during degassing of 13 c depleted co2 modern speleothems from harrison s cave are not in o isotopic equilibrium with their corresponding drip waters and are 0 2 to 2 3 enriched in 18 o relative to equilibrium values 18 o variations in modern calcite are likely controlled by kinetically driven changes in the fractionation between hco3 aq and caco3 from equilibrium conditions to nonequilibrium conditions consistent with rapid calcite growth in contrast to 13 c 18 o values of modern calcite may not be affected by rayleigh distillation during degassing because co2 hydration and hydroxylation reactions will buffer the o isotopic composition of the hco3 aq reservoir if the effects of rayleigh distillation manifest themselves in the o isotopic system they will result in 18 o enrichment in the hco3

clumped isotope thermometry of cryogenic cave carbonates abstract freezing of cave pool water that is increasingly oversaturated with dissolved carbonate leads to precipitation of a very specific type of speleothems known as cryogenic cave carbonates ccc at present two different environments for their formation have been proposed based on their characteristic carbon and oxygen isotope ratios rapidly freezing thin water films result in the fast precipitation of fine grained carbonate powder cccfine this leads to rapid physicochemical changes including co2 degassing and caco3 precipitation resulting in significantly 13c enriched carbonates alternatively slow carbonate precipitation in ice covered cave pools results in coarse crystalline ccc ccccoarse yielding strongly 18o depleted carbonate this is due to the formation of relatively 18o enriched ice causing the gradual depletion of 18o in the water from which the ccc precipitates cryogenic carbonates from central european caves were found to have been formed primarily during the last glacial period specifically during times of permafrost thawing based on the oxygen isotope ratios and u th dating information about the precise conditions of ccccoarse formation i e whether these crystals formed under equilibrium or disequilibrium conditions with the parent fluid however is lacking an improved understanding of ccccoarse formation will increase the predictive value of this paleo permafrost archive here we apply clumped isotopes to investigate the formation conditions of cryogenic carbonates using well studied ccccoarse from five different cave systems in western germany carbonate clumped isotope measurements yielded apparent temperatures between 3 and 18 c and thus exhibit clear evidence of isotopic disequilibrium although the very negative carbonate 18o values can only be explained by gradual freezing of pool water accompanied by preferential incorporation of 18o into the ice clumped isotope derived temperatures significantly above expected freezing temperatures indicate incomplete isotopic equilibration during precipitation of ccc

younger dryas to early holocene paleoclimate in cantabria n spain constraints from speleothem mg annual fluorescence banding and stable isotope records abstract the younger dryas yd stadial represents the most abrupt climate change of the earth s recent history thus understanding its causes and different local responses is relevant for quaternary paleoclimatology we present a speleothem high resolution proxy record of the lateglacial to early holocene paleoclimate of the cantabrian cordillera n spain a strategic location to evaluate the influence of north atlantic events such as the yd on south western europe fluorescence lamination growth rate stable isotope and mg records from stalagmite sir 1 were dated using an age depth model constrained by u th dates and annual lamina counting the yd is recorded as a prominent positive 13c excursion whose chronology 12 95 0 14 to 11 62 0 16 ka and shape closely agree with the gs 1 stadial as defined in greenland ice supporting the event synchronicity in both areas a colder and drier yd climate limited soil productivity and dripwater availability leading to higher 13c and mg reduced growth rate and virtually absent fluorescence lamination the early yd record until 12 5 ka reflects increasing aridity whereas the late yd from 12 2 ka on shows the opposite trend at the yd boundaries temperature changes influenced the mg record by modifying the mg partition into calcite however this effect was superseded by major changes in dripwater mg ca linked to rainfall variations during the early holocene the arnero sierra was forested and had a relatively warm and humid seasonal climate indicated in sir 1 by higher growth rates lower 13c and mg and well developed fluorescent lamination similar to other high resolution stalagmitic records of the cordillera from 8 5 to 8 0 ka sir 1 reflects a temporary trend of increasing aridity

comment on stoll h et al 2015 interpretation of orbital scale variability in mid latitude speleothem δ18o significance of growth rate controlled kinetic fractionation effects quat sci rev 127 215 228

contrasts in variations of the carbon and oxygen isotopic composition of travertines formed in pools and a ramp stream at huanglong ravine china implications for paleoclimatic interpretations abstract water samples and modern endogenic thermogene travertine calcite deposited on plexiglass substrates in travertine pools and a ramp stream were collected along the huanglong ravine sichuan sw china at regular 10 day intervals from early may to early november in 2010 including both wet and dry conditions temporal and spatial variations in the 13 c and 18 o values of the modern travertine were examined to understand their potential for paleoclimatic and paleoenvironmental interpretations it was found that 13 c and 18 o of travertine formed in the ramp stream were low in the warm rainy season and high in the cold dry season their positive correlation was mainly due to dilution and rainfall seasonal effects on 13 c and 18 o values respectively i e low 13 c values were caused by dilution by overland flow with depleted 13 c values and reduced co 2 degassing in the warm rainy season while low 18 o values of travertine were because of low 18 o values of water induced by seasonal variation in oxygen isotopic ratios of rainwater meanwhile kinetic effect on oxygen isotopic fractionation during ramp travertine deposition existed and reduced this positive correlation in contrast the 13 c and 18 o values of the pool travertines displayed a converse behavior which was caused mainly by the temperature effect low 18 o values and high 13 c values in the warm rainy season were correlated chiefly with the higher water temperatures therefore the 13 c and 18 o values of the travertine may be used for paleo rainfall or paleotemperature reconstruction respectively this study demonstrates that endogenic travertine like epigenic meteogene tufa may be a suitable candidate for high resolution paleoclimatic and paleoenvironmental reconstructions however since travertines deposited under differing hydrodynamic conditions e g pools with still water contrasted to fast flow streams have different climatic responses it is necessary to check the depositional facies of fossil travertine samples before they can be used for palaeoclimate temperature and or rainfall reconstruction