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

variations in the discharge and organic matter content of stalagmite drip waters in lower cave bristol six drip waters which were actively depositing stalagmites in lower cave bristol were analysed both for discharge and luminescence properties drip discharges were determined for two different years and show a complex response to surface precipitation variations inter annual variability in drip discharge is demonstrated to be significantly higher than intra annual variability and discharge was demonstrated both to increase and decrease non linearly with increased precipitation drip waters demonstrate a correlation between their luminescence intensity and drip discharge with increased luminescence in winter as more organic matter is flushed through the aquifer the strength of the relationship between luminescence intensity and discharge increases with increased discharge the results presented here have implications for the palaeoenvironmental interpretation of annual growth laminae and the growth rates of stalagmite samples 1997 john wiley sons ltd

methane in underground air in gibraltar karst abstract little is known about the abundance and geochemical behaviour of gaseous methane in the unsaturated zone of karst terrains the concentrations and 13 c of methane in background atmosphere soil air and cave air collected at monthly intervals over a 4 yr period are reported for st michaels cave gibraltar where the regional climate surface and cave processes are well documented methane concentrations measured in gibraltar soil are lower than the local background atmosphere average of 1868 ppb and fall to 13 c relationships in soil air methane lack strong seasonality and suggest mixing between atmosphere and a 12 c depleted residue after methanotrophic oxidation methane abundances in cave air are also lower than the local background atmosphere average but show strong seasonality that is related to ventilation controlled annual cycles shown by co 2 cave air methane abundances are lowest in the co 2 rich air that outflows from cave entrances during the winter and show strong inverse relationship between ch 4 abundance and 13 c which is diagnostic of methanotrophy within the cave and unsaturated zone anomalies in the soil and cave air seasonal patterns characterised by transient elevated ch 4 mixing ratios with 13 c values lower than 47 suggests intermittent biogenic input dynamically ventilated gibraltar caves may act as a net sink for atmospheric methane

reconstructing high resolution climate using ct scanning of unsectioned stalagmites a case study identifying the mid holocene onset of the mediterranean climate in southern iberia the forcing mechanisms responsible for the mid holocene onset of the mediterranean type climate in south western europe are currently unclear but understanding these is critical for accurate climate projections under future greenhouse gas warming additionally regional studies that present conflicting patterns for the onset and advancement of mediterranean climatic conditions complicate definitively ascribing causality here we use a new high resolution stalagmite density record obtained non destructively using computed tomography ct scanning to reconstruct southern iberian climate between 9 3 and 2 9 ka bp we suggest that stalagmite density can be used as a water excess proxy with lower densities associated with more variable drip rates possibly reflecting increased seasonality consistent with expectations from previous studies of speleothem textures and crystal fabrics our results reveal an early holocene humid interval and mid holocene year round aridity that preceded the onset of mediterranean climate at 5 3 ka bp in southern iberia using this new dataset combined with previously published results we link the gradual advancement of the mediterranean climate to the southward migration of the north atlantic subtropical high induced by an orbitally driven decrease in northern hemisphere insolation future anthropogenic warming could result in a reversal of this trend a northward migration of the north atlantic subtropical high and a return to year round aridity in south western europe

precise timing and rate of massive late quaternary soil denudation strontium isotopes are a unique tool to study soil erosion dynamics changes in sr isotope ratios 87 sr 86 sr provide a record of late quaternary landscape denudation of the edwards plateau of central texas united states the use of sr isotopes as a tracer for soil erosion is based on the observation that in central texas the 87 sr 86 sr ratio of soil correlates with soil thickness plants and animals express the 87 sr 86 sr ratio of exchange able sr in the soil therefore we use changes in sr isotope ratios through a well dated stratigraphic sequence of fossil plants and animals in hall s cave kerr county texas as a proxy for temporal changes in soil thickness by using this record we are able to characterize late quaternary climate driven soil erosion dynamics on the edwards pla teau we find that continuous erosion removed at least 180 cm of soil at a constant min imum rate of 11 cm k y this continuous phase of erosion ended ca 5 ka the sr isotope record of soil erosion is consistent with late quaternary environmental change in central texas that has been independently modeled by using local and regional climate records however the rate of this climate driven soil erosion event was an order of magnitude slower than recent soil erosion caused by human land use these results link erosion to century to millennial scale climate change and are cautionary evidence that even greater landscape degradation may result from coincident climatic variability and anthropogenic influences

intra and inter annual growth rate of modern stalagmites we measure the factors that determine growth rate temperature drip rate calcium ion concentration for 31 waters that feed stalagmites within six cave systems throughout europe water samples were collected at a frequency of at least 1 month to permit the modelling of both inter and intra annual growth rate variations utilising the theory of wolfgang dreybrodt chem geol 29 1980 89 105 chem geol 32 1981 237 245 dreybrodt w 1988 processes in karst systems springer verlag berlin 288 pp inter annual growth rates were measured using the stalagmites that were associated with the analysed water samples growth rate was determined from annual lamina counting specific time markers within the stalagmites and location of bomb 14c when compared to theoretically predicted values a good agreement between theoretical and measured stalagmite growth rates is observed r2 0 69 when compared to site climate and geochemical parameters a good correlation is observed between measured growth rate and mean annual temperature for five sites r2 0 63 and dripwater calcium content r2 0 61 but not drip rate r2 0 09 the good correlation with both calcium and temperature is due to soil co2 production being primarily determined by surface temperature and soil moisture however when we compare our data to that in the grotte de clamouse a site that has little soil cover we observe that the growth rate temperature relationship breaks down due to either the lack of soil co2 production or prior calcite precipitation intra annual data demonstrates that maximum growth rate occurs when calcium concentrations are high and that this occurs under different seasons depending on the hydrology of each site our results demonstrate a stronger dependence of intra annual stalagmite growth rate on dissolved calcium ion concentrations than drip rate for the range of drip rates investigated here 0 01 t 2drip s 1 but for lower drip rates this factor becomes important in controlling growth rate we suggest that for well monitored and understood sites stalagmite growth rate variations can provide useful information for palaeoclimate reconstruction

millennial scale variations in western sierra nevada precipitation during the last glacial cycle mis 4 3 transition abstract dansgaard oeschger d o cycles had far reaching effects on northern hemisphere and tropical climate systems during the last glacial period yet the climatic response to d o cycles in western north america is controversial especially prior to 55 ka we document changes in precipitation along the western slope of the central sierra nevada during early marine oxygen isotope stages mis 3 and 4 55 67 ka from a u series dated speleothem record from mclean s cave the timing of our multi proxy geochemical dataset is coeval with d o interstadials 15 18 and stadials including heinrich event 6 the mclean s cave stalagmite indicates warmer and drier conditions during greenland interstadials giss 15 18 signified by elevated 18o 13c reflectance and trace element concentrations and less radiogenic 87sr 86sr our record extends evidence of a strong linkage between high latitude warming and reduced precipitation in western north america to early mis 3 and mis 4 this record shows that the linkage persists in diverse global climate states and documents the nature of the climatic response in central california to heinrich event 6

a speleothem record of holocene paleoclimate from the northern wasatch mountains southeast idaho usa abstract a speleothem stable isotope record from minnetonka cave located in the northern wasatch mountains is shown to be a winter season biased record of holocene paleoclimate the season specific sensitivity of the record provides an opportunity to more robustly evaluate long term variability in large scale pacific teleconnection patterns such as enso and pdo as precipitation anomalies associated with these teleconnection patterns occur primarily in winter seasonal climate composite maps of high and low snowpack years at the study site demonstrate that winter precipitation is strongly linked to the relative strength of the aleutian low and the associated changes from to more meridional or more zonal steering level wind patterns minnetonka cave data suggest wetter cooler than modern early holocene winters and a dry middle holocene with a consistent warming trend from 7400 to 3800 bp after 4000 bp data suggest a return to wetter and or colder than modern winters for much of the late holocene prolonged winter dry intervals are identified from 7400 to 6000 bp and 4200 bp

a global model for cave ventilation and seasonal bias in speleothem paleoclimate records cave calcite deposits speleothems provide long and continuous records of paleoenvironmental conditions in terrestrial settings typical environmental proxy measurements include speleothem growth rate and variations in elemental and isotope geochemistry commonly the assumption is made that speleothems grow continuously and at a constant rate throughout the year however seasonal variation of growth rate may be the rule in many caves here we apply observations of modern calcite growth and cave air co2 concentrations and a model of factors controlling cave ventilation to construct a global model predicting where cave calcite growth may be seasonal previous models and measurements of calcite precipitation in caves demonstrate the retardation of speleothem growth by high cave air co2 elevated co2 is commonly dissipated by ventilation driven by density differences between cave and surface air seasonal cycles in atmospheric temperature pressure and humidity commonly drive these density contrasts modeling these changes latitudinally and globally indicates a geographic control on seasonal cave ventilation and thus on a principal controlling factor of speleothem growth the model predicts that given constant water calcium and co2 inputs speleothems from temperate to boreal continental regions commonly accumulate more calcite in the cool season and less or none in the warm season these models predict that proxies from temperate to boreal speleothems may be seasonally biased due to seasonal ventilation whereas tropical and maritime records should not

the role of near surface cavities in the carbon dioxide cycle of karst areas evidence from the carburangeli cave natural reserve italy hydrological chemical and meteorological data collected during the years 2006 2007 at carburangeli cave italy have provided new insights on the near surface cycle of carbon dioxide particularly concerning the role played by fractures and karst conduits carbon dioxide is trapped in the underground atmosphere essentially when its temperature is lower than the outer one by contrast convective air circulation disperses all the excess co2 in the external environment when the thermal differential is inverted the network of fractures and karst conduits then works in the vadose zone as a re circulator of co2 from the soil to the atmosphere the total amount of co2 fixed in the underground is controlled during the wet season by the amount of infiltrating waters which act as the main carrier of co2 in the subsoil by contrast during the dry season gravitational drainage is responsible for the accumulation of carbon dioxide in the underground voids the quantitative balance demonstrated that the degassed co2 amounts are one order of magnitude higher than the dissolved co2 in light of this if the near surface outgassing processes are not taken into account co2 budgets may be affected by significant errors

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

relationship between modern rainfall variability cave dripwater and stalagmite geochemistry in guam usa 1 modern rainwater cave dripwater and cave stalagmite geochemical time series from a cave in guam 13 38 n 144 53 e are used to better understand how changes in cave stalagmite geochemistry relate to aboveground changes in rainfall at a tropical location a scientific field team based in guam collects monthly samples from multiple sites for geochemical analyses at a cave and aboveground rainfall from a nearby location we compute a transfer function between rainfall amount and oxygen isotopic composition 18o of a decrease increase of 0 94 0 3 m year for every 1 increase decrease in rainfall 18o based on data extracted from the international atomic energy agency iaea global networks of isotopes in precipitation gnip database and from data generated in this study dripwater 18o and mg ca ratios show annual cyclicity at some but not all sites accentuating the complex nature of cave hydrology a stalagmite 18o record for the last 160 years indicates the existence of droughts of decadal length when rainfall is estimated to be 0 65 0 3 m year less than average conditions this estimate of rainfall reduction most likely refers to wet season months as these months preferentially contribute to groundwater recharge the proxy based climate record at guam provides new evidence highlighting how a rainy site in the western pacific warm pool today can experience considerable changes in rainfall on decadal timescales

a holocene record of climate and hydrological changes from little llangothlin lagoon south eastern australia we present a new well dated holocene record of environmental change from little llangothlin lagoon in eastern australia derived from aquatic plant macrofossils macroscopic charcoal flux and sediment stratigraphy from multiple cores little llangothlin was an ephemeral freshwater wetland exhibiting frequent dry phases between 9800 and 9300 calendar years before present cal yr bp there was a switch to a more positive water balance after 9300 cal yr bp and by 8000 cal yr bp there was a lake that persisted until 6100 cal yr bp the period between 6100 and 1000 cal yr bp was much drier and there is no evidence for a permanent lake during this period the little llangothlin record provides evidence for a wet phase during the early to middle holocene 9000 6000 cal yr bp from the boundary region between temperate and tropical influences in eastern australia we propose that generally enhanced circulation after 9000 cal yr bp explains the pattern of increasing moisture at the site at this time the later holocene climate at the site is consistent with other sites in south east australia with a switch to generally drier conditions after 6000 cal yr bp

trace metal and carbon isotopic variations in cave dripwater and stalagmite geochemistry from northern borneo we investigate stalagmite trace metal ratios and carbon isotopic composition 13 c as potential paleoclimate proxies by comparing cave dripwaters stalagmites and bedrock composition from gunung mulu and gunung buda national parks in northern borneo a tropical rainforest karst site three year long biweekly time series of dripwater mg ca sr ca and 13 c from several drips at our site are not correlated with rainfall variability indicative of a relatively weak relationship between hydroclimate and dripwater geochemistry at our site however combining all of the dripwater geochemical data gathered over four field trips to our site n 300 samples we find that drips with highly variable mg sr ca have relatively invariable 18 o values close to the mean we hypothesize that increased residence times translate into reduced variance in dripwater 18 o through mixing in the epikarst as well as increased mg sr ca values through increased calcite precipitation in the epikarst mg ca sr ca and 13 c time series from three overlapping stalagmites that grew over the last 27 kyrs are characterized by strong centennial scale variations and bear little resemblance to previously published well reproduced 18 o time series from the same stalagmites the only shared signal among the three stalagmites geochemical time series is a relative decrease of 1 in 13 c from the last glacial maximum to the holocene consistent with a transition from savannah c4 to rainforest c3 conditions documented in nearby records taken together our study indicates that stalagmite mg sr ca ratios are poor indicators of hydroclimate conditions at our site while stalagmite 13 c exhibits some reproducible signals on glacial interglacial timescales

east asian summer monsoon variations during the last deglaciation recorded from a stalagmite at linyi northern china abstract a230th dated stalagmite record from linyi shandong province provides a detailed history of the east asian summer monsoon easm in northern china during the last deglaciation our record reveals changes that are similar to previously published stalagmite records from the east asian monsoon region on centennial and millennial scales although some subtle and detail discrepancies are observed comparisons with other paleoclimate records show that the easm was jointly controlled by the north atlantic climate and low latitude tropical processes during the last deglaciation ocean atmospheric interactions particularly sea surface temperature changes in the tropical pacific might have contributed to the increasing trend of the easm during the bolling allerod and to the lesser weakening in the easm during the younger dryas in addition the significantly higher growth rates of the stalagmite during the heinrich event 1 might have been driven by the co2 degassing processes future studies with long term monitoring of the calcite deposition rate at this site will be needed to support our arguments on the co2 degassing processes

origin and palaeoenvironmental significance of lamination in stalagmites from katerloch cave austria the origin and environmental dependencies of lamination in stalagmites from katerloch common in speleothems from other cave sites are examined in detail petrographic observations and chemical analyses including isotopes of stalagmites and modern calcite were combined with multi annual cave monitoring all investigated stalagmites are composed of low mg calcite and show white porous laminae and typically thinner translucent dense laminae the binary lamination pattern results from changes in the calcite fabric white porous laminae are characterized by a high porosity and abundant fluid inclusions and also by enhanced vertical growth and thinning towards the flanks translucent dense laminae exhibit a compact fabric and constant thickness of individual growth layers u th dating supports an annual origin of the lamination and the seasonally changing intensity of cave ventilation provides a robust explanation for the observed relationships between lamination stable c isotopic compositions and trace elements mg sr and ba the seasonally variable air exchange driven by temperature contrasts between the cave interior and outside atmosphere modulates the rate and amount of co2 degassing from the drip water and affects the hydrochemistry and consequently the fabric of the precipitating calcite although cave air composition and drip rate are both major variables in controlling co2 degassing from the drip water the seasonally changing ventilation in katerloch exerts the primary control and the results suggest a secondary amplifying attenuating influence of the drip rate drip rate however might be the controlling parameter for lamina development at cave sites experiencing only small seasonal cave air exchange importantly the seasonally variable composition of drip water does not reflect the seasonal cycle of processes in the soil zone but results from exchange with the cave atmosphere the alternating porous and dense calcite fabric is the expression of a variable degree of lateral coalescence of smaller crystallites forming large columnar crystals the white porous laminae represent partial coalescence and form during the warm season low calcite 13c values are linked to low 13c values of cave air and drip water during that time this observation corresponds to times of reduced cave ventilation high pco2 of cave air low drip water ph lower calcite supersaturation and typically high drip rates in contrast the translucent dense laminae represent more or less complete lateral coalescence inclusion free during the cold season high calcite drip water and cave air 13c values i e times of enhanced cave ventilation low cave air pco2 increased drip water ph relatively high calcite supersaturation and typically low drip rates in essence the relative development of the two lamina types reflects changes in the seasonality of external air temperature and precipitation with a strong control of the winter air temperature on the intensity of cave air exchange thick translucent dense laminae are favoured by long cold and wet winters and such conditions may be related closely to the north atlantic oscillation mode weak westerlies and enhanced mediterranean cyclone activity during the cold season studies of speleothem lamination can thus help to better understand and quantify the role of seasonality changes for example during rapid climate events

hydrogeochemistry and fractionation pathways of mg isotopes in a continental weathering system lessons from field experiments abstract the potential of magnesium isotope records from cave carbonate archives speleothems has been documented but remains underexplored this is due to the limited knowledge regarding the complex suite of physico chemical and biological disequilibrium fractionation processes affecting meteoric fluids in the soil zone the carbonate hostrock and calcite precipitation in the cave this study presents 26 mg data from a monitored cave in germany bunker cave including rain water 26 mg 0 70 0 14 soil water 26 mg 0 51 0 10 and drip waters 26 mg 1 65 0 08 sampled between november 2009 and may 2011 field precipitation experiments i e calcite precipitated on watch glasses 26 mg 3 56 0 26 may 2006 to june 2010 were found to be of limited use this is because of experimental crystallographic and sampling artefacts conversely variations in soil and drip water 26 mg over time are predominantly related to seasonal variations in water availability and air temperature affecting the subtle weathering ratio between mg bearing clay minerals in the soil here mainly chlorite and montmorillonite and the low mg calcite hostrock bunker cave 26 mg drip water values display a significant dependency on the air temperature outside the cave this is because air temperature influences co 2 levels in the soil and hence rock water interaction for fast drip sites the direct correlation of 26 mg soil water and 26 mg drip water documents a relative short residence time of the fluid in the carbonate aquifer and thus limited isotope equilibration and mixing of different reservoirs this result is encouraging and adds new evidence to the poorly understood hydro geochemistry of carbonate aquifers slow seepage flow drip sites display an annual 26 mg drip water pattern that is geochemically unrelated to that of the soil water further research including laboratory experiments must focus on the complex fractionation between drip water and speleothem calcite mg isotope record

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

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

epikarst hydrology and implications for stalagmite capture of climate changes at grotta di ernesto ne italy results from long term monitoring grotta di ernesto is a cave site well suited for palaeoclimate studies because it contains annually laminated stalagmites and was monitored from 1995 to the end of 2008 for microclimate hydrology and hydrochemistry long term monitoring highlighted that cave drips show three different hydrological responses to rainfall and infiltration 1 fast seasonal drips in the upper part of the cave which are mostly fed by fractures 2 slow seasonal drips located at mid depth in the cave characterized by mixed feeding and 3 slow drips mostly located in the deeper gallery which are fed by seepage flow from bulk porosity with a minor fracture fed component the slow drips display daily cycles during spring thaw monitoring also indicated that drip waters are only slightly modified by degassing within the soil zone and aquifer and by prior calcite precipitation hydrochemical studies show a clear seasonality in calcite saturation index which results in most cave calcite precipitation occurring during late autumn and winter with similar amounts of precipitated calcite on most stalagmites regardless of drip rate discharge differences drip rate and drip rate variability therefore has a minor role in modulating the amount of annual calcite formation in contrast drip rate when associated with moderate reduction in calcite saturation index clearly influences stalagmite morphology increasing drip rate yields a passage from candle to cone to dome shaped stalagmites very high drip rates feed speleothems with flowstone morphology in summary monitoring provides information about the karst aquifer and how hydrology influences those physical and chemical characteristics of speleothems which are commonly used as climate proxies copyright 2010 john wiley sons ltd

hydrogeochemical and climatic interpretations of isotopic signals from precipitation to drip waters in liangfeng cave guizhou province china oxygen isotope is a commonly used proxy for paleoclimatic studies on stalagmites in order to understand the transmission of isotopic signals from precipitation to stalagmites meteorological indexes of exterior and interior cave and hydrogeochemical proxies of drip waters in liangfeng cave have been monitored from april 2011 to april 2013 samples of rain and drip waters from three drip sites designated as 1 5 and 6 are collected for hydrogen and oxygen isotopes testing results show that the amount weighted mean 18o value of rain in the first year may 9 2011 to may 1 2012 is lighter than that in the second may 30 2012 to may 2 2013 this may result from different proportions of the pacific indian ocean source moistures the arithmetic mean 18o values of 1 5 and 6 are similar to the multi year amount weighted mean 18o value of precipitation hydrogeochemical analyses of drip waters reveal that the discharge rates increase in the order of 6 1 5 and that water rock reaction fresh old water mixing and co2 degassing exert dominant controls on seepage waters in aquifers hard infiltration of rain during dry season with heavier 18o value due to its small amount may cause lower mean drip water 18o values e g 1 evaporation during the dripping and exuding processes in dry season may result in heavier mean drip water 18o values e g 6 considering calcite depositing mostly during dry season we compare the mean 18o values of drip waters during dry season between the first and second years differences exist and share the same trend with rain the results indicate that drip waters can inherit oxygen isotopic signals of rain but it is critical to have a replication test on 18o records of stalagmites from the same cave for paleoclimatic studies what s more 18o values in stalagmites feeding by drip waters that have no little annual 18o variations may be useful to paleotemperature reconstructions

luminescent microbanding in speleothems high resolution chronology and paleoclimate when illuminated by ultraviolet light many calcite speleothems stalagmites stalactites flowstones display luminescence caused by the presence of organic humic substances occluded in the calcite the amplitude of luminescence varies in a banded pattern parallel to growth layering through 14 c and thermal ionization mass spectrometry uranium series dating we show that cyclical oscillations in the luminescence have periodicities ranging from a few days to 10 5 yr a well defined annual cycle is present in many vadose zone speleothems and can be used to define the chronology of short term events this cycle is probably a response to hydrological events in the recharge to the cave longer term oscillations are inferred to be controlled by climate through its effect on organic activity in the overlying soil

carbon dioxide and dissolution rate dynamics within a karst underflow overflow system savoy experimental watershed arkansas usa abstract within numerical models of karst development geochemical and hydrological boundary conditions are typically assumed to be constant however rates of calcite dissolution in natural karst systems can vary substantially in time in particular variation in carbon dioxide co2 concentrations has been shown to produce time variability in dissolution rates in karst streams but controls on co2 variation within karst systems are relatively poorly quantified here we analyze hourly in situ measurements of dissolved co2 discharge and specific conductance at a pair of karst underflow overflow springs and examine potential drivers of variability in co2 and dissolution rates the springs display strong seasonal variability in co2 and saturation state as well as moderate variation during storm events though both springs have elevated co2 concentrations in the summer season the overflow spring experiences a substantial decrease in dissolved co2 below a critical discharge threshold we hypothesize that this decrease results from ventilation within the overflow portion of the system as segments of the flow path transition from full pipe to open channel flow the overflow spring experiences substantially lower average dissolution rates than the underflow spring despite larger discharge and chemical variability during high flow events at the overflow spring though open systems are frequently presumed to have higher dissolution rates because of their ability to replenish co2 that is consumed in the dissolution process these data suggest that dissolution rates within the closed portion of the system may in some cases be higher due to the inability of closed flow paths to ventilate excess co2 to the atmosphere such conditions are likely to occur in conduits where co2 concentrations are elevated above atmospheric levels and average flow through times are short compared to the time scale over which water reaches equilibrium with respect to calcite

changing amounts and sources of moisture in the u s southwest since the last glacial maximum in response to global climate change abstract the u s southwest has a limited water supply and is predicted to become drier in the 21st century an improved understanding of factors controlling moisture sources and availability is aided by reconstruction of past responses to global climate change new stable isotope and growth rate records for a central texas speleothem indicate a strong influence of gulf of mexico gom moisture and increased precipitation from 15 5 to 13 5 ka which includes the majority of the bolling allerod warming ba 14 7 12 9 ka coeval speleothem records from 900 and 1200 km to the west allow reconstruction of regional moisture sources and atmospheric circulation the combined isotope and growth rate time series indicates 1 increased gom moisture input during the majority of the ba producing greater precipitation in texas and new mexico and 2 a retreat of gom moisture during younger dryas cooling 12 9 11 5 ka reducing precipitation these results portray how late pleistocene atmospheric circulation and moisture distribution in this region responded to global changes providing information to improve models of future climate

carbon dioxide ground air and carbon cycling in gibraltar karst we put forward a general conceptual model of co2 behaviour in the vadose zone of karst aquifers based on physical principles of air flow through porous media and caves combined with a geochemical interpretation of cave monitoring data this gibraltar model links fluxes of water air and carbon through the soil with the porosity of the vadose zone the circulation of ground air and the ventilation of caves gibraltar hosts many natural caves whose locations span the full length and vertical range of the rock we report results of an 8 year monitoring study of carbon in soil organic matter and bedrock carbonate dissolved inorganic carbon in vadose waters and gaseous co2 in soil cave and ground air results show that the regime of cave air co2 results from the interaction of cave ventilation with a reservoir of co2 enriched ground air held within the smaller voids of the bedrock the pco2 of ground air and of vadose waters that have been in close contact with it are determined by multiple factors that include recharge patterns vegetation productivity and root respiration and conversion of organic matter to co2 within the soil the epikarst and the whole vadose zone mathematical modelling and field observations show that ground air is subject to a density driven circulation that reverses seasonally as the difference between surface and underground temperatures reverses in sign the gibraltar model suggests that cave air pco2 is not directly related to co2 generated in the soil or the epikarstic zone as is often assumed ground air co2 formed by the decay of organic matter om washed down into the deeper unsaturated zone is an important additional source of pco2 in gibraltar the addition of om derived co2 is the dominant control on the pco2 of ground air and the ca hardness of waters within the deep vadose zone the seasonal regime of co2 in cave air depends on the position of a cave in relation to the density driven ground air circulation pattern which is itself determined by the topography as well as by the high permeability conduits for air movement provided by caves themselves in the steep topography of gibraltar caves in the lower part of the rock act as outflow conduits for descending ground air in summer and so have higher pco2 in that season caves in the upper rock have high pco2 in winter when they act as outflow conduits for rising currents of co2 enriched ground air understanding seasonal flows of ground air in the vadose zone together with the origins and seasonal regimes of co2 in cave air underpins robust interpretation of speleothem based climate proxy records

limited hydrologic response to pleistocene climate change in deep vadose zones yucca mountain nevada abstract understanding the movement of water through thick vadose zones especially on time scales encompassing long term climate change is increasingly important as societies utilize semi arid environments for both water resources and sites viewed as favorable for long term disposal or storage of hazardous waste hydrologic responses to pleistocene climate change within a deep vadose zone in the eastern mojave desert at yucca mountain nevada were evaluated by uranium series dating of finely layered hyalitic opal using secondary ion mass spectrometry opal is present within cm thick secondary hydrogenic mineral crusts coating floors of lithophysal cavities in fractured volcanic rocks at depths of 200 to 300 m below land surface uranium concentrations in opal fluctuate systematically between 5 and 550 g g age calibrated profiles of uranium concentration correlate with regional climate records over the last 300 000 years and produce time series spectral peaks that have distinct periodicities of 100 and 41 ka consistent with planetary orbital parameters these results indicate that the chemical compositions of percolating solutions varied in response to near surface climate driven processes however slow micrometers per thousand years relatively uniform growth rates of secondary opal and calcite deposition spanning several glacial interglacial climate cycles imply that water fluxes in the deep vadose zone remained low and generally buffered from the large fluctuations in available surface moisture during different climates

interpretation of speleothem calcite δ13c variations evidence from monitoring soil co2 drip water and modern speleothem calcite in central texas we studied the sources and transport of carbon in two active karst systems in central texas inner space cavern is and natural bridge north and south caverns nb to provide new insights into the interpretation of speleothem cave calcite deposit carbon isotope compositions we have determined the 13c values of soil co2 13cs in grassland and savanna above these caves with 13c values of cave drip water 13chco3 and modern speleothem calcite grown on artificial substrates 13ccc we compare 13chco3 values from direct drip sites where water was sampled immediately upon discharging from the cave ceiling to values from indirect sites where water was sampled after flowing along a prolonged path within the cave that allowed for longer co2 degassing and have found that direct drip sites yield consistently lower 13chco3 values the 13chco3 values of direct drip water below savanna 10 6 0 5 and 12 6 0 2 in nb and is respectively are indistinguishable from is or similar to nb calculated 13chco3 values in equilibrium with measured soil co2 beneath trees 13 5 to 11 3 for juniper trees above nb and 13 6 to 12 6 for mixed oak and elm trees above is respectively at is the 13chco3 values of direct drip water are higher below grassland 9 7 0 3 than below savanna 12 6 0 2 these results suggest that the 13chco3 values of drip waters that initially enter the caves are controlled by deep rooted plants where present and are minimally influenced by host rock dissolution and or prior calcite precipitation pcp the 13chco3 values of indirect drip water vary seasonally with relatively low values during the summer 10 8 0 8 and 9 2 0 4 under juniper savanna at nb and under grassland at is respectively that are similar to the direct drip 13chco3 values 10 6 0 5 and 9 7 0 3 under savanna at nb and under grassland at is respectively the relatively high 13chco3 values of indirect drip sites during the winter 13chco3 8 6 0 8 at nb and 8 0 0 1 at is result from co2 degassing of water along in cave flow paths we also present decade long records of modern calcite 13c values from direct and indirect drip sites at is the 13ccc values vary seasonally with lower values during the summer and higher values during the winter and with smaller amplitude variations at the direct drip site such seasonal variations can be used as a geochronological tool in some speleothems that do not contain visible lamina the summer 13ccc values of direct drip calcite are similar to 13ccc values predicted from soil co2 collected beneath trees above that drip site the occurrence of highest 13ccc values during the winter when cave co2 concentrations are low highlights the significance of ventilation driven changes in cave air pco2 modern calcite 13c values are also negatively correlated with drip rate which suggests that 13ccc variations are controlled by kinetic effects during degassing and calcite precipitation associated with the drip water exposure time to a low pco2 environment in all at the caves we investigated variability in speleothem 13ccc values primarily reflect presence absence of deep rooted vegetation and kinetic isotope effects we therefore infer that increased aridity may result in higher 13c values of vegetation lower drip rates and more drip water degassing and thus higher 13ccc values of speleothem calcite

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

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

controls on the spatial and temporal variability of vadose dripwater geochemistry edwards aquifer central texas abstract a 4 yr study of spatial and temporal variability in the geochemistry of vadose groundwaters from caves within the edwards aquifer region of central texas offers new insights into controls on vadose groundwater evolution the relationship between vadose and phreatic groundwaters and the fundamental influence of soil composition on groundwater geochemistry variations in sr isotopes and trace elements mg ca and sr ca ratios of dripwaters and soils from different caves as well as phreatic groundwaters provide the potential to distinguish between local variability and regional processes controlling fluid geochemistry and a framework for understanding the links between climatic and hydrologic processes the sr isotope compositions of vadose cave dripwaters mean 87sr 86sr 0 7087 and phreatic groundwaters mean 87sr 86sr 0 7079 generally fall between values for host carbonates mean 87sr 86sr 0 7076 and exchangeable sr in overlying soils mean 87sr 86sr 0 7088 dripwaters have lower mg ca and sr ca ratios and higher 87sr 86sr values than phreatic groundwaters dripwater 87sr 86sr values also inversely correlate with both mg ca and sr ca ratios mass balance modeling combined with these geochemical relationships suggest that variations in fluid compositions are predominantly controlled by groundwater residence times and water rock interaction with overlying soils and host aquifer carbonate rocks consistent differences in dripwater geochemistry i e 87sr 86sr mg ca and sr ca between individual caves are similar to compositional differences in soils above the caves while these differences appear to exert significant control on local fluid evolution geochemical and isotopic variations suggest that the controlling processes are regionally extensive temporal variations in 87sr 86sr values and mg ca ratios of dripwaters from some sites over the 4 yr interval correspond with changes in both aquifer and climatic parameters these results have important implications for the interpretation of trace element and isotopic variations in speleothems as paleoclimate records as well as the understanding of controls on water chemistry for both present day and ancient carbonate aquifers

very high frequency and seasonal cave atmosphere pco2 variability implications for stalagmite growth and oxygen isotope based paleoclimate records abstract cave air p co 2 at two irish sites varied dramatically on daily to seasonal timescales potentially affecting the timing of calcite deposition and consequently climate proxy records derived from stalagmites collected at the same sites temperature dependent biochemical processes in the soil control co 2 production resulting in high summer p co 2 values and low winter values at both sites large large amplitude high frequency variations superimposed on this seasonal cycle reflect cave air circulation here we model stalagmite growth rates which are controlled partly by co 2 degassing rates from drip water by considering both the seasonal and high frequency cave air p co 2 variations modeled hourly growth rates for stalagmite cc bil from crag cave in sw ireland reach maxima in late december 0 063 m h 1 and minima in late june early july 0 033 m h 1 for well mixed diffuse flow cave drips such as those that feed cc bil high summer cave air p co 2 depresses summer calcite deposition while low winter p co 2 promotes degassing and enhances deposition rates in stalagmites fed by well mixed drips lacking seasonal variations in 18 o integrated annual stalagmite calcite 18 o is unaffected however seasonality in cave air p co 2 may influence non conservative geochemical climate proxies e g 13 c sr ca stalagmites fed by seasonal drips whose hydrochemical properties vary in response to seasonality may have higher growth rates in summer because soil air p co 2 may increase relative to cave air p co 2 due to higher soil temperatures this in turn may bias stalagmite calcite 18 o records towards isotopically heavier summer drip water 18 o values resulting in elevated calcite 18 o values compared to the equilibrium values predicted by calcite water isotope fractionation equations interpretations of stalagmite based paleoclimate proxies should therefore consider the consequences of cave air p co 2 variability and the resulting intra annual variability in calcite deposition rates

a stepwise screening system to select storm sensitive stalagmites taking a targeted approach to speleothem sampling methodology a stepwise stalagmite sample screening process was applied in order to select a stalagmite as a sensitive recorder of recent tropical cyclone rainfall events near belize field and laboratory criteria were combined in series to screen out candidate stalagmites whose characteristics indicated lower sensitivity to stormwater infiltration the approach described here was designed to increase the likelihood that selected stalagmites would increase the signal noise ratio of the target phenomenon in the resulting proxy records this four stage method for sample selection may be an important methodological consideration for researchers attempting to use speleothems for stable isotope paleotempestology hallmarks of this approach include 1 establishing a priori scientific targets 2 applying sample criteria in the form of contra indicators and 3 organizing the sample screening protocol into a series of practical stages the overall approach to stalagmite selection presented here supports cave conservation and can be adapted readily by others in support of different scientific goals it is hoped that other investigators will also publish field and laboratory sample selection schemes as increased transparency will provide new information invaluable to replication efforts and to advancing the field of speleothem paleo environmental studies

model evaluation of the coherence of a common source water oxygen isotopic signal recorded by tree ring cellulose and speleothem calcite oxygen isotopic compositions 18o of tree rings and speleothems inherit 18o of precipitation 18oppt and are used to reconstruct past variations in the amount of precipitation or temperature integration of 18o records of both the proxies for a multiproxy climate reconstruction necessitates understanding of the extent to which the initial 18oppt is modified in both the proxies before getting preserved in them a forward modeling approach assuming both the proxies have access to a common source water 18o signal is employed to assess the expected maximum correlation between the 18o records of the two proxies on interannual time scale and the factors influencing the correlation variations in the leaf temperature relative humidity 18o of atmospheric water vapor introduce variations in 18o of tree ring cellulose while the variations in the cave temperature and oxygen isotopic equilibrium disequilibrium conditions between calcite and drip water influence 18o of speleothem calcite variation introduced by these factors in 18o of individual proxies as compared to the variation in 18oppt is crucial in deciding the correlation between 18o records of the two proxies when the former is higher than or comparable with the latter finding one to one correspondence between the 18o records of the two proxies could be challenging modeling exercise revealed a favorable climatic condition at jagdalpur 19 08 n 82 03 e a potential tropical location for tree ring and speleothem based climate reconstruction for inheriting a common source water 18o signal in both the proxies 18o records of tree ring and annually resolved speleothem from jagdalpur could be integrated for the multiproxy climate reconstruction

cave air ventilation and co2 outgassing by radon 222 modeling how fast do caves breathe abstract in general the rate and timing of calcite precipitation is in part affected by variations in cave air co2 concentrations knowledge of cave ventilation processes is required to quantify the effect variations in co2 concentrations have on speleothem deposition rates and thus paleoclimate records in this study we use radon 222 222rn as a proxy of ventilation to estimate co2 outgassing from the cave to the atmosphere which can be used to infer relative speleothem deposition rates hollow ridge cave a wild cave preserve in marianna florida is instrumented inside and out with multiple micro meteorological sensor stations that record continuous physical and air chemistry time series data our time series datasets indicate diurnal and seasonal variations in cave air 222rn and co2 concentrations punctuated by events that provide clues to ventilation and drip water degassing mechanisms average cave air 222rn and co2 concentrations vary seasonally between winter 222rn 50 dpm l 1 where 1 dpm l 1 60 bq m 3 co2 360 ppmv and summer 222rn 1400 dpm l 1 co2 3900 ppmv large amplitude diurnal variations are observed during late summer and autumn 222rn 6 to 581 dpm l 1 co2 360 to 2500 ppmv we employ a simple first order 222rn mass balance model to estimate cave air exchange rates with the outside atmosphere ventilation occurs via density driven flow and by winds across the entrances which create a venturi effect the most rapid ventilation occurs 25 m inside the cave near the entrance 45 h 1 1 33 min turnover time farther inside 175 m exchange is slower and maximum ventilation rates are 3 h 1 22 min turnover time we estimate net co2 flux from the epikarst to the cave atmosphere using a co2 mass balance model tuned with the 222rn model net co2 flux from the epikarst is highest in summer 72 mmol m 2 day 1 and lowest in late autumn and winter 12 mmol m 2 day 1 modeled ventilation and net co2 fluxes are used to estimate net co2 outgassing from the cave to the atmosphere average net co2 outgassing is positive net loss from the cave and is highest in late summer and early autumn about 4 mol h 1 and lowest in winter about 0 5 mol h 1 modeling of ventilation net co2 flux from the epikarst and co2 outgassing to the atmosphere from cave monitoring time series can help better constrain paleoclimatic interpretations of speleothem geochemical records

the potential of near entrance stalagmites as high resolution terrestrial paleoclimate proxies application of isotope and trace element geochemistry to seasonally resolved chronology abstract sub annually resolved environmental proxies can be valuable archives of climate change but they are rare in terrestrial settings and it can be difficult to verify their annual nature we suggest that speleothems that grow in well ventilated zones of caves may preserve such high resolution records near entrance cave environments are characterized by year round near atmospheric co2 concentrations and are significantly influenced by surface air temperature fluctuations particularly in temperate latitudes previous monitoring studies of a well ventilated temperate latitude cave westcave preserve central texas have documented seasonal variations in the oxygen isotope composition of calcite grown on glass substrates with winter 18o maxima and summer 18o minima as well as seasonal variations in drip water trace element compositions extending this work to a stalagmite wc 3 from the same drip site we find that stalagmite 18o variations are similar in magnitude to the seasonal 18o variations previously observed for calcite grown on glass substrates that stalagmite mg variations have a similar seasonal period with winter minima and summer maxima and that geochemical variations follow stalagmite growth fabric as mm scale couplets comprising thin slow growing compact sparry calcite laminae winters and thicker fast growing porous elongate columnar calcite laminae summers we interpret a high resolution weekly to monthly 52 year record of 18o mg sr and ba in wc 3 and report new monthly measurements of drip water and associated calcite grown on glass substrates we find drip water 18o and mg ca are essentially invariant and that seasonal variations in wc 3 calcite 18o and mg concentration agree well with predicted temperature dependent fractionation between water and calcite wc 3 calcite sr and ba also vary but with higher and more variable frequencies compared to 18o and mg the annual nature of 18o and mg cycles is supported by monitoring and 14c bomb peak chronology we suggest that stalagmite 18o and mg vary primarily in response to large seasonal temperature changes in this setting allowing for unambiguous differentiation between summer and winter calcite growth from such 18o and mg derived sub annual chronologies the timing of enrichments in other geochemical species that are less directly coupled to external cave temperature e g calcite sr and ba can be considered as proxies of other important processes such as water rock interaction in the epikarst precipitation events or subsurface respiration rates the potential for this kind of multi proxy seasonally resolved dating may add near entrance stalagmites to the list ice cores lake varves tree rings of high resolution terrestrial proxies available for paleoclimate studies

reconstructing palaeoprecipitation from an active cave flowstone several drill cores were obtained from a laminated actively forming flowstone from a shallow cave in austria highly resolved petrographic and geochemical analyses combined with multi annual cave monitoring reveal a distinct sensitivity of flowstone growth and composition to late holocene meteoric precipitation the regular sub millimetre scale lamination consists of thicker translucent laminae and thinner organic inclusion rich laminae there is also a macroscopic millimetre scale banding of darker and lighter bands comprising several laminae stable isotope analyses of drill cores and modern calcite precipitates show a pronounced positive covariation of 13c and 18o values indicative of kinetic isotope effects comparing the isotope values with petrography shows gradual changes across several of the annual laminae i e changes of several per mille on a multi annual to decadal timescale the stable isotope and trace element composition as well as the flowstone petrography are mainly controlled by the variable drip water discharge controlling the water film thickness and water residence time on the flowstone surface and consequently the intensity of co2 degassing kinetic isotope enrichment and concomitant calcite precipitation drill core pfu6 provides an isotope record of the last ca 3000 years at near annual resolution a distinct phase of low c and o isotope values interpreted as increased discharge and hence higher meteoric precipitation occurred from ca 300 to 140 a b2k second half of the little ice age and another wet interval occurred around 700 a corresponding to reported medieval glacier advances the roman warm period was also dominated by relatively wet conditions although significant decadal variability prevailed increased precipitation further characterized the intervals from ca 2480 to 2430 and 2950 to 2770 a dry conditions persisted during the medieval climate anomaly although this trend towards reduced precipitation started earlier the highest c isotope values of the last 2 ka are recorded around 750 a and another dry phase is centred at 1480 a this new record shows that inter annual to decadal oscillations are a dominant mode of variation during the last 3 ka in the alps copyright 2011 john wiley sons ltd

i stal a model for interpretation of mg ca sr ca and ba ca variations in speleothems and its forward and inverse application on seasonal to millennial scales 1 trace element ratios mg ca sr ca and ba ca are readily measured in speleothems and may be closely related to hydrological balance enhancing paleoclimate information inferred from stable isotope measurements we develop a model which simulates the variation in dripwater chemistry resulting from variable degree of water rock interaction and prior calcite precipitation pcp with the latter process depending both on drip interval and drip oversaturation with respect to caco3 partition coefficients between speleothem and dripwater are dependent on temperature for mg and on speleothem growth rate for sr and ba as observed in laboratory experiments the drip oversaturation state regulated both by cave pco2 and the dilution and soil karst dissolution processes strongly affects stalagmite trace element concentrations by modulating the extent of pcp and speleothem growth rates application of an inverse model confirms that seasonal co2 cycles can explain the uncorrelated seasonal cycles in mg ca and sr ca observed in our speleothem records from nw spain for which high co2 coincides with dry season in absence of seasonal variations in drip interval cycles in cave pco2 can produce seasonal covariation in sr ca mg ca and ba ca in long time series 104 yr where seasonal sampling resolution is not obtained in stalagmites a change from dominance of summer to winter rainfall can shift the season of strongest stalagmite deposition to one of lower mean co2 and hence greater pcp and higher mg ca sr ca and ba ca ratios caves best suited to record a dominantly water balance signal such as mean drip intervals are those with minimal seasonal variation in cave pco2

speleothem trace element signatures a hydrologic geochemical study of modern cave dripwaters and farmed calcite trace element variations in ancient cave speleothems are often interpreted as indicators of changes in paleo rainfall and hydrologic conditions however these records are difficult to interpret without an understanding of the physicochemical controls on stalagmite chemistry plus site specific calibration of changes in net rainfall to variations in dripwater and speleothem chemistry in this study we examine geochemical relationships between net rainfall precipitation minus evapotranspiration p et drip rates drip water chemistry and contemporaneous calcite chemistry to test the hypothesis that speleothem mg ca and sr ca records are proxies for rainfall amount hrc is contained within four low magnesium limestone units capped sporadically by a remnant dolomitic limestone aqueous concentrations of magnesium post evapotranspiration decrease with increasing vertical travel distance between the soil zone and the point of in cave drip emergence drip path length dpl as dissolved high mg solutions sourced from the dolomitic caprock are diluted with dissolved low mg limestone waters sourced from the host limestone dripwater mg ca and sr ca ratios covary and provide diagnostic indicators of the two dominant mechanisms controlling dripwater chemistry 1 mixing of post evaporative solutions derived from two geochemical endmembers dissolution of dolomite and limestone and 2 evolution of hydrochemistry away from dissolved bedrock compositions due to prior calcite precipitation pcp above the drip sites by resolving the linear mixing relationships for drip water mg ca and sr ca sources and the distribution coefficients for trace element transfer in the pcp dripwater to calcite precipitation reactions and applying these principles to our time series we find that the extent of pcp production within the karst is directly controlled by the balance between precipitation p and evapotranspiration et higher net rainfall p et 1 wet conditions reduces pcp and lower net rainfall with increased evapotranspiration p et 1 increases pcp farmed calcite x ca ratios faithfully track hydrologically influenced seasonal variations in dripwater chemistry for x mg sr and na however the relationship between changes in net rainfall and changes in mg ca and sr ca ratios in modern calcite is unique at each site and differs significantly at closely spaced drip stalagmite locations this suggests that in situ modern hydrochemical calibrations should be performed atop individual speleothems prior to harvesting for paleoclimate investigations and that such calibrations may not reflect past conditions as drip paths change we apply this understanding to published dripwater data and speleothem time series from other caves a major implication is that in order to interpret stalagmite sr ca and mg ca ratios as wet vs dry proxies speleothem sr ca and mg ca variations must be coherent and in phase over all time periods i e sr mg ratios must be constant these criteria will help to distinguish rainfall amount versus rainfall source in speleothem 18o records

modeling speleothem δ13c variability in a central sierra nevada cave using 14c and 87sr 86sr abstract carbon isotopes in speleothems can vary in response to a number of complex processes active in cave systems that are both directly and indirectly related to climate progressing downward from the soil zone overlying the cave these processes include soil respiration fluid rock interaction in the host limestone degassing of co2 and precipitation of calcite upflow from the speleothem drip site and calcite precipitation at the drip site here we develop a new approach to independently constrain the roles of water rock interaction and soil processes in controlling stalagmite 13c this approach uses the dead carbon proportion dcp estimated from coupled 14c and 230th u measurements in conjunction with sr isotope analyses on stalagmite calcite from a central sierra nevada foothills cave in california a region characterized by a highly seasonal mediterranean type climate to determine the roles of water rock interaction and soil processes in determining stalagmite 13c increases in stalagmite dcp between 16 5 and 8 8 ka are coincident with decreased 13c indicating a varying yet substantial contribution from the soil organic matter som reservoir likely due to significantly increased average age of som in the soil veneer above the cave during wet climatic intervals we use geochemical and isotope mixing models to estimate the host carbonate contribution throughout the 13c time series and determine the degree of degassing and calcite precipitation that occurred prior to precipitation of stalagmite calcite the degree of degassing and prior calcite precipitation we calculate varies systematically with other climate indicators with less degassing and prior calcite precipitation occurring during wetter climatic intervals and more during drier intervals modeled 13c values and degassing calculations suggest that some degree of prior calcite precipitation is necessary at all time intervals to explain measured stalagmite 13c values even during relatively wet intervals these results illustrate the importance of constraining degassing and prior calcite precipitation in the interpretation of speleothem 13c records particularly those from caves that formed in seasonal semi arid to arid environments

northwest european palaeoclimate as indicated by growth frequency variations of secondary calcite deposits a compilationn for the northwest of europe of over 500 uranium series speleothen and travertine dates is presented using a cumulative distributed error frequency approach these secondary carbonate deposits require both significant groundwater supply and a biogenic soil carbon dioxide source for their growth during glacial periods soil co2 production is inhibited and the water supply is ice locked therefore growth is slowed significantly if not stopped thus deposits can be used on a chronological basis to give a signal of glacial and non glacial periods however sensitivity to the groundwater supply modifies this signal with growth also limited in times of high aridity the palaeoclimatic signal is thus complex the compilation presented is used both as a chronology for comparison with the orbitally tuned marine oxygen isotope record and as a palaeoclimatic indicator attention is focused on two periods of the last glacial interglacial cycle where the record provides a significantly different palaeoclimatic record to other terrestrial and oceanic records these are the isotope stages 5 4 transition for which a relatively low cumulative growth frequency indicates an earlier increase in aridity than observed elsewhere and isotope stage 3 the pleniglacial where both statistically significant high 49 62 ka and low 22 35 44 46 ka levels of growth are observed and can be used to constrain the timing of many of the interstadial events within this period

response of cave air co2 and drip water to brush clearing in central texas implications for recharge and soil co2 dynamics 1 brush removal is commonly conducted to increase water availability in arid areas such as central texas where water resources are stressed the effectiveness of brush clearing to enhance recharge however remains uncertain as numerous studies have yielded contradictory results this study assesses the effects of brush clearing on recharge to a cave at natural bridge caverns central texas by evaluating changes in drip rate drip water compositions cave air co2 concentrations and calcite growth in a cave underlying an area cleared of brush drip sites were monitored for 3 years preclearing and 2 years postclearing at five drip sites beneath and seven drip sites not beneath the surface cleared of brush physical and chemical drip water parameters exhibit preclearing and postclearing variability postclearing drip rate characteristics reflect an initial interval of anomalously heavy rainfall then a longer dry period drip water 87sr 86sr values do not exhibit preclearing to postclearing variation at sites beneath the cleared area and indicate no change in postclearing water residence time significant decreases in postclearing cave air co2 are observed at seven of nine drip sites in the cave beneath the clearing decreases in cave air co2 influence calcite growth which impacts postclearing drip water mg ca and sr ca decreases in cave air co2 immediately following brush clearing suggest that a significant portion of soil co2 respiration is from tree root respiration rather than from soil microbial activity seasonal calcite growth patterns linked to cave air co2 also exhibit variability postclearing and suggest that cave mineral deposits may record historical changes in vegetative cover

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

geochronology of late pleistocene to holocene speleothemsfrom central texas implications for regional paleoclimate a detailed chronology for four stalagmites from three central texas caves separated by as much as 130 km provides a 71 000 yr record of temporal changes in hydrology and climate mass spectrometric 238 u230 th and 235 u231 pa analyses have yielded 53 ages the accuracy of the ages and the closedsystem behavior of the speleothems are indicated by interlaboratory comparisons concordance of 230 th and 231 pa ages and the result that all ages are in correct stratigraphic order over the past 71 000 yr the stalagmites have similar growth histories with alternating periods of relatively rapid and slow growth the growth rates vary over more than two orders of magnitude and there were three periods of rapid growth 71 60 ka 39 33 ka and 24 12 ka these growth rate shifts correspond in part with global glacial interglacial climatic shifts paleontological evidence indicates that around the last glacial maximum 20 ka climate in central texas was cooler and wetter than at present this wetter interval corresponds with the most recent period of increased growth rates in the speleothems which is consistent with conditions necessary for speleothem growth the temporal shift in wetness has been proposed to result

holocene climate variability in texas usa an integration of existing paleoclimate data and modeling with a new high resolution speleothem record abstract delineating the climate processes governing precipitation variability in drought prone texas is critical for predicting and mitigating climate change effects and requires the reconstruction of past climate beyond the instrumental record we synthesize existing paleoclimate proxy data and climate simulations to provide an overview of climate variability in texas during the holocene conditions became progressively warmer and drier transitioning from the early to mid holocene culminating between 7 and 3 ka thousand years ago and were more variable during the late holocene the timing and relative magnitude of holocene climate variability however is poorly constrained owing to considerable variability among the different records to help address this we present a new speleothem nbj reconstruction from a central texas cave that comprises the highest resolution proxy record to date spanning the mid to late holocene nbj trace element concentrations indicate variable moisture conditions with no clear temporal trend there is a decoupling between nbj growth rate trace element concentrations and 18o values which indicate that i the often direct relation between speleothem growth rate and moisture availability is likely complicated by changes in the overlying ecosystem that affect subsurface co2 production and ii speleothem 18o variations likely reflect changes in moisture source i e proportion of pacific vs gulf of mexico derived moisture that appear not to be linked to moisture amount

annually laminated sequences in the internal structure of some belgian stalagmites importance for paleoclimatology abstract fifteen stalagmites from four caves and one sealed tunnel in southern belgium are composed of alternations of annually deposited white porous and dark compact laminae this is demonstrated by comparing the number of laminae with the local history of the site for modern stalagmites and with radioisotopic ages for late glacial and holocene stalagmites annual cyclicity in the internal structure of these speleothems is explained by the highly seasonal variations of the water excess which influences underground water flow comparison between climatic data and modern stalagmites of a closed tunnel shows that growth laminae can record climatic variations 1 there is a good correlation r 0 84 between lamina thickness in a stalagmite and water excess 2 during years with a high water excess dark compact laminae are more developed which makes the speleothem darker vertical successions of several laminae represent microsequences that may have recorded climatic variations with a time resolution of 1 2 year in a late glacial stalagmite successive laminae microsequences form very regular cycles of 11 years separated by a thick darkcompact lamina it is supposed that as for modern stalagmites the thick dark compact lamina corresponds to a period of high water excess hence this 11 year cycle may reflect a climatic cycle

multiple proxy analyses of a u th dated stalagmite to reconstruct paleoenvironmental changes in northwestern madagascar between 370 ce and 1300 ce abstract the timing and causes of paleoenvironmental changes in madagascar have been debated specifically in respect to human activity following the settlement in the late holocene here we present 18o 13c layer bounding surfaces layer specific width mineralogy and distribution of macroholes from stalagmite ma3 from anjohibe cave to provide a detailed understanding of the paleoenvironmental changes in northwestern madagascar between 370 ce and 1300 ce the stable isotope records of stalagmite ma3 are compared with stable isotope records of stalagmites anj94 5 and ma2 detailed examination of the proxies suggests three distinct intervals of changes 1 prior to 795 ce changes in vegetation seem to have responded to changes in monsoonal rainfall linked to the relative position of the itcz the period between ca 755 ce and 795 was the driest and the stalagmite ma3 record is consistent with sediment records pollen and lithology from lake mitsinjo northwestern madagascar and with sediment records fossil pollen and charcoal from sainte luce southeastern madagascar 2 between 795 ce and 870 the environmental conditions became more favorable when vegetation recovered from the driest interval the new conditions must have been suitable for community development in the region as suggested by archaeological evidence around lake mitsinjo and the boeny region and the establishment of the stone town of mahilaka 3 after 870 ce a gradational change in plant communities from c3 to c4 marks the record until around 1130 ce after which vegetation was dominated by c4 plants this change cannot be explained by climate alone as there is no clear relationship in the climate sensitive proxies instead it could have been caused by tavy a variety of swidden agriculture practiced in the region

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

dating and characterization of polymorphic transformation of aragonite to calcite in pleistocene bivalves from rhodes greece by combined shell microstructure stable isotope and electron spin resonance study absolute dating of diagenesis is a challenging yet significant problem reconstructing the depositional and diagenetic history of a late pleistocene coralligene type red algal reef and overlying maerl red algal sand from the plimiri coastal cliff se island of rhodes greece is enabled using a combination of microstructure stable isotope analyses and electron spin resonance of large bivalve shells partially altered by diagenesis these shells consisting of both original shell aragonite and polymorphic transformed rims now consisting of neomorphic spar provide the opportunity to date the primary age when the shells were precipitated as well as the age of their polymorphic transformation the contamination of samples presented a significant problem for interpreting ages based on data from electron spin resonance esr alone however sample contamination was evaluated with quantitative xrd providing the opportunity to apply corrections which increased reliability of the ages the carbon and oxygen stable isotope values and the neomorphic spar microtexture suggested that the polymorphic transformation at plimiri took place in a meteoric environment with a high and increasing fluid rock ratio the electron spin resonance dates combined with the vertical sedimentary evolution allowed to assign the formation of the red algal reef to the marine isotope stages 6 to 5e transgressive event ca 135 to 120 ka and to identify meteoric diagenetic phases during possibly the marine isotope stage 5d and the upper marine isotope stage 5c to lower 3 the use of electron spin resonance dating of neomorphic spar and age correction for sample contamination is presented herein for the first time and the results suggest that it might provide a useful tool to date late pleistocene diagenesis

response of a modern cave system to large seasonal precipitation variability abstract speleothems are capable of providing information on the response of middle and low latitude terrestrial environments to global climate change during the pleistocene and holocene multiproxy speleothem studies however have demonstrated that complex interactions can occur in cave settings between processes that are directly and indirectly related to climate change thorough and extended monitoring of modern cave environments is necessary in order to fully understand how each cave responds to these processes on seasonal and interannual timescales and how environmental signals are preserved in speleothem carbonate regular environmental monitoring began at black chasm cavern in the sierra nevada foothills california during the winter of 2006 2007 monthly measurements of cave air temperature humidity and p co 2 in black chasm demonstrate that the cave is ventilated in the winter months when cold dense surface air sinks into the cave cave drip water flow nearly ceases during the late summer and autumn increases substantially during the winter and spring and responds within hours to storm events during the height of the rainy season rainwater and drip water 18 o and 2 h are controlled by variations in surface air temperature and moisture source while rainfall source influences rainwater isotopes through individual storm events it has less influence on drip water isotopic composition due to mixing of recharge waters delivered by different rainfall events in the epikarst variations in drip water chemistry 13 c mg ca and sr ca indicate that the greatest level of calcite precipitation upflow from the drip water collection site prior calcite precipitation occurs during the autumn october november when drip rates are slow and cave air p co 2 is low the least prior calcite precipitation occurs during the summer july august when drip rates are slow but cave air p co 2 is at a maximum while p co 2 is a primary control on prior calcite precipitation during all seasons the predominant influence of drip rate variability on prior calcite precipitation is evident when considering only those seasons winter spring and autumn characterized by low cave air p co 2 thus drip rate variability and in turn rainfall amount should provide the primary control on trace element variations ultimately captured in speleothem calcite the isotopic and chemical variability observed in black chasm drip waters supports previous interpretations of speleothem paleoclimate proxy records from a nearby cave where such monitoring is not feasible observations of the modern cave environment at black chasm provide a reference point for the interpretation of stalagmite proxy records from similar seasonal mediterranean climates

tracking regional and global teleconnections recorded by western north american speleothem records abstract speleothem proxy records are useful for interrogating past climates in the low and mid latitudes given their ability to provide continuous high resolution and long lived records that can be dated with high precision several speleothem oxygen isotope records from western north america have recently been developed that highlight the importance of this archive in documenting past changes in atmospheric circulation taken individually these records hint at teleconnections between western north american hydroclimate and climate changes in the high northern latitudes and tropics however there has been no systematic investigation of global climate teleconnections to this region that draws upon the body of north american speleothem records as a whole here we review the dominant controls on precipitation oxygen isotopes across the region and conduct statistical comparisons and network visualizations of high resolution speleothem oxygen isotope records from western north america to investigate the regional response to pronounced climate changes of the last deglaciation and to determine the pattern of global teleconnections to this region we find that most western north american speleothem oxygen isotope records demonstrate a robust and consistent response to the events of the last deglaciation despite differing controls on the oxygen isotope ratio of precipitation across the region one record that receives a strong influence from the gulf of mexico exhibits a contrasting pattern in oxygen isotopes relative to most of the other records which are dominated by westerly storms generated in the pacific during the studied interval major shifts in western north american speleothem records appear broadly synchronous at least within the uncertainty of age models we also find strong statistical linkages between western north american speleothem records and speleothem records of asian monsoon variability and other records from regions directly influenced by movement of the intertropical convergence zone demonstrating that nearly synchronous changes in atmospheric circulation measurably altered precipitation dynamics in these regions during the last deglaciation further multi proxy investigations are needed to determine how such changes in atmospheric circulation recorded by speleothem oxygen isotope ratios influenced precipitation amounts in drought prone western north america