bomb 14c time history recorded in two modern stalagmites importance for soil organic matter dynamics and bomb 14c distribution over continents carbon 14 activity measurements made by accelerator mass spectrometry on two modern stalagmites from the han sur lesse cave belgium and from the postojna cave slovenia permit the construction of 14c activity a14c time series over the last 50 years a high precision chronology is given by annual laminae in the first stalagmite and by a specific mark explosion in the postojna cave in 1944 in the second one in both stalagmites 14c activity increase due to nuclear tests in the atmosphere is remarkable however instead of a sharp peak like the one observed in the atmosphere around 1963 1964 the 14c activities of the stalagmite caco3 show an abrupt increase with an offset of 1 10 years followed by a high activity plateau for the han sur lesse sample and a slight decrease for the postojna sample for both stalagmites the variation of the a14c amplitude between pre and post bomb period is much lower than the atmospheric record which demonstrates the damping effect of the soil carbon reservoir we have modeled the caco3 activities using fractionation processes between atmosphere co2 soil co2 and organic matter om dissolved inorganic carbon and stalagmite caco3 in both cases studied the model and former soil studies suggest that co2 from soil organic matter som decomposition which has a slow turnover i e 1 y is of major importance in winter when the development of speleothem is the most important combined with the fact that 80 90 of the stalagmite carbon comes from soil co2 this produces a damping effect on the speleothem a14c consequently the geochemical time resolution at least for speleothem carbon is much lower than the structural resolution given by annual laminae alternations and is mainly controlled by soil carbon dynamics a14c and 13c are smoothed over several years differences between the 14c time series of the han sur lesse and postojna stalagmites are likely to be due to the double amount of precipitation in postojna which produces a faster soil om turnover and thus a system which is more sensitive to atmospheric changes

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

interaction of low level flow with the western ghat mountains and offshore convection in the summer monsoon abstract seven year averaged values of percent frequency of occurrence of highly reflective cloud for the months june july and august indicate that offshore convection is a major component of the cloudiness of the southwest monsoon principal areas of convection occur off of the western coats of india burma thailand and the philippines this study concentrates on the area upstream of the western ghats mountains of india analysis of a special boundary layer mission flown during the wmo icsu summer monsoon experiment leads us to believe that partial deceleration of the monsoon flow by upstream blocking effects of the mountains initiates and maintains a vertical and horizontal motion field that could support the observed convection data obtained on this mission allow a large scale momentum budget computation for the subcloud layer which shows pressure deceleration to be significant the budget dominated by advection predicts an increase of average wind speed which is observed the pressure decelera

three dimensional effects in high drag state flows over long ridges abstract numerical simulations of nonrotating flow with uniform basic wind and stability past long three dimensional 3d ridges are compared to the corresponding two dimensional 2d limit to reveal the importance of 3d effects for mountain heights smaller than the threshold for breaking waves the low level flow over the interior of the ridge is well described by 2d theory when the horizontal aspect ratio is roughly 10 or greater by contrast in flows with wave breaking significant discrepancies between 2d and 3d results remain apparent even for 12 it is found that the onset of wave breaking and the transition to the high drag state is accompanied in 3d by an abrupt increase in deflection of the low level flow around the ridge the increased flow deflection is produced at least in part by upstream propagating columnar disturbances forced by the transition to the high drag state the deflection of the incident flow reduces the amplitude of the mountain wave aloft relative to 2d and acts as a neg

trace element distribution in annual stalagmite laminae mapped by micrometer resolution x ray fluorescence implications for incorporation of environmentally significant species abstract stalagmite er78 from grotta di ernesto cave in ne italy displays clear annual lamination consistent with its shallow depth below a forest ecosystem subject to autumnal peaking of water infiltration synchrotron radiation scanning micro x ray fluorescence analyses of heavy elements at european synchrotron radiation facility beamline id22 and light elements at id21 with 1 3 m resolution has been combined with data from ion microprobe analyses to reveal chemical variability across the visible layers of these annual laminae a series of elements display a symmetrical peak centered around the thin dark layer at the top of each lamina the peak concentration is ordered y zn cu and pb p and br this hierarchy is thought to reflect the selectivity of transport of these elements possibly by organic colloids flushed from the soil zone during autumn infiltration ion microprobe analysis indicates na and f also increase as does h the latter reflecting increased microporosity sr displays a trough around the dark and thin autumn layer implying that its incorporation may be limited by competition with other elements mg and s show a different pattern of annual variation and fe displays none the trace metals br and y display peak abundance in the early 20th century which appears to reflect a period of tree felling rather than a climatic anomaly the results demonstrate the power of the high spatial resolution and low detection limits of the synchrotron technique and its ability to produce quantitative maps that allow distinction of layered structure from that of isolated particles or irregular inhomogeneities

factors governing cellular convection in orographic precipitation the development of shallow cellular convection in warm orographic clouds is investigated through idealized numerical simulations of moist flow over topography using a cloud resolving numerical model buoyant instability a necessary element for moist convection is found to be diagnosed most accurately through analysis of

seasonal variations in sr mg and p in modern speleothems grotta di ernesto italy sub annual variations in trace element chemistry and luminescence have recently been demonstrated from speleothems and offer the potential of high resolution palaeoclimatic proxies however no studies have yet examined microscopic trace element variations in relation to modern cave conditions in this study the spatial variations in trace element sr mg and p concentrations in speleothems a stalagmite and a soda straw stalactite from the alpine ernesto cave temperature 6 6 0 1 c in a forested catchment in ne italy have been studied using secondary ion mass spectrometry sims and compared with environmental parameters and waters in the modern cave an annual lamination exists in the stalagmite and soda straw stalactite in the form of clear calcite with narrow visible layers which are uv fluorescent and interpreted to contain soil derived humic fulvic acids washed into the cave during autumn rains microanalyses were undertaken of seven annual laminae probably deposited during the 1960s in the stalagmite and seven laminae in the 1990s for the stalactite the analysis results show that sr consistently has a trough and p a peak centred on the inclusion rich layer mg shows mainly a negative covariation with sr in laminae formed in the 1990s but a positive covariation in the stalagmite formed in 1960s the spatial scale of the main geochemical variations is the same as that of annual laminae of inclusion poor and inclusion rich couplets mass balance arguments are used to show that the p is inorganic in form and presumably occurs as individual phosphate ions within the calcite most drip waters show limited chemical variations but a summer peak in trace elements in 1995 and a decrease in mg ca in the following winter are notable more pronounced covariations in mg ca and sr ca are shown by a site with highly variable drip rates where ratios increase at slow drip rates the strongest seasonal variations are found in pool waters where ratios increase reflecting significant ca removal from the water into the calcite during the winter in response to seasonal pco2 variations in cave air thus the cave waters compositions tend to reflect climate conditions such that mg ca and sr ca are tentatively interpreted to be higher when climate conditions are dry combining results from the speleothems and cave water along with the behaviour of each trace species mg ca variations in the speleothems are considered to reflect their variation in the cave waters whereas sr incorporation is also dependent on precipitation rate in this case mainly controlled by temporal variations in pco2 in the cave and conceivably also by inhibitors such as phosphate p adsorption a fraction of which is subsequently incorporated within calcite depends on aqueous phosphate concentration and water flux both of which should increase during the autumn therefore multiple trace element profiles in speleothems reflect multiple aspects of environment seasonality and conditions and hence a calibration against weather records is desirable to establish their palaeoclimatological meaning the strong annual variation of trace elements and particularly p can provide chronological markers for high resolution studies of other climate proxies such as stable isotopes

annual trace element variations in a holocene speleothem high resolution secondary ionization mass spectrometry sims analysis along the growth axis of a holocene speleothem from northern scotland reveals high frequency oscillations and longer term trends in mg ca sr ca and ba ca at the scale of the high frequency oscillations mg ca and sr ca display a well defined anticorrelation while sr ca and ba ca are positively correlated imaging of elemental ratios in two dimensions reveals that the high frequency signal is well preserved and laterally continuous across the sample tims 230th ages and annual ultraviolet luminescence banding provide chronological control and demonstrate that the high frequency cyclicity is annual trace element variations in speleothem calcite are a reflection of hydrochemical processes in the unsaturated zone overlying the cave supply effects and partitioning at the water calcite interface mg partitioning between water and calcite is temperature dependent calculations suggest that the annual mg ca oscillations may be caused by seasonal temperature changes however the longer timescale variations in mg ca are too great to be explained by this mechanism seasonal variations in water residence time in the unsaturated zone which reflect effective precipitation provide a more probable explanation for the observed annual oscillations and also explain the inverse relationship between mg ca and sr ca this record suggests that trace elements in speleothems have the potential to provide the high resolution insights into interannual palaeoclimatic variability required for assessment of general circulation models

calcite fabrics growth mechanisms and environments of formation in speleothems from the italian alps and southwestern ireland five fabrics were identified in alpine and irish caves on the basis of morphological and microstructural characteristics and re lated to growth mechanisms and growth environment columnar and fibrous fabrics grow when speleothems are continuously wet and from fluids at near equilibrium conditions low supersaturation sicc 0 35 through the screw dislocation mechanism the highly defective microcrystalline fabrics form at the same supersaturation range as co lumnar fabric but under variable discharge and the presence of growth inhibitors dendritic fabrics which have the highest density of crystal defects develop in disequilibrium conditions high supersaturation un der periodic very low flow regime periods that result in prolonged out gassing cave calcareous tufa forms in disequilibrium conditions only the calcite crystals of fabrics formed at low supersaturation seem to precipitate near isotopic equilibrium conditions

trace elements in speleothems as recorders of environmental change speleothems are now established as important palaeoenvironmental archives and contain a number of suitable proxies although trace elements have been much less widely used than oxygen and carbon isotopes the complexity of the cave environment helps to explain this since the fluids from which speleothems form vary greatly in composition in space even within a cave chamber seasonally and over longer periods understanding the forcing factors for this variability is the key to decoding the significance of the trace element records a variety of techniques are available for trace element work and it is important to understand the strengths and limitations of each and also to seek an understanding e g by micro imaging techniques of whether the elements are associated with inclusions in the caco3 or are isolated within the crystal lattice for some elements there is a more or less predictable relationship between element ratios to ca in the water and in the calcite individual trace elements may be derived from atmospheric deposition superficial deposits or bedrock and can be recycled in soil processes before being transferred to the cave some components show an instantaneous response to water infiltration whereas others are only leached by slow flowing seepage waters changing in the proportion of water from fracture fed and seepage flow aquifer compartments is an important factor in influencing trace element supply high flows lead to higher fluxes of soil derived colloidally transported elements conversely under relatively dry conditions degassing of co2 results in prior calcite precipitation upflow of the site of speleothem deposition and leads to higher ratios of sr ca and mg ca some trace element variations in speleothems over time are induced during crystal growth whereby faster growth leads to a greater departure from equilibrium element partitioning despite the demonstrated temperature dependence of mg partitioning into calcite attempts at deriving palaeotemperature records from speleothems have been so far confounded by variations in solution mg ca and or crystallographic effects a number of case studies have effectively used trace elements such as speleothem mg as records of palaeo aridity using supporting arguments from modern monitoring or covariations with other parameters such as stable isotopes sr and u isotopes can also be indicators of palaeohydrology although sr isotope variations can also reflect varying aeolian input considerable progress has been made in decoding the meaning of annual trace element variations using criteria for understanding dripwater hydrology and ph this should lead in the future to more specific interpretations of how seasonality evolves through time

speleothems and climate a special issue of the holocene speleothems cave dripstones are formed as a part of the meteoric water cycle and therefore vari ations in their growth rate and composition reflect environmental changes on the land surface above the cave since they are continental deposits and possess a remarkably accurate dating potential using tims u series techniques speleothems are important palaeoclimatic archives for the terrestrial environment complementing the marine and ice core records the climatic proxies that can be deciphered from speleothems are growth rate stable isotope composition d18o d13c organic humic matter and trace element composition as well as luminescent laminae which may display annual rhythms the nine papers in this special issue oftheholocene present the latest results in palaeoclimatic analysis from speleothems

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

late cainozoic ostracod faunas and paleoenvironmental changes at odp site 1148 south china sea ostracod faunas from odp site 1148 in the south china sea have been analyzed quantitatively in order to understand paleoenvironmental changes in the late cainozoic deep water more than 2000 core samples were taken from the oligocene to quaternary section of which 725 contained ostracods and yielded at least 100 species krithe dominates the faunas throughout the oligocene quaternary sequences indicating that deep sea conditions had existed since the earliest oligocene ca 34 5 ma this suggests that the spreading of the south china sea basin predates the oligocene three distinct ostracod assemblages have been recognized and their respective faunal turnover reflects a change in paleodepth from the upper bathyal 2500 m since the late middle miocene 14 ma to the present intervals when ostracods become very rare are at 28 5 27 20 18 2 and 13 2 8 ma the earliest of these intervals was probably related to the high surface productivity and the depletion of oxygen content in bottom water while intervals were the product of enhanced carbonate dissolution measures of evolutionary activity origination extinction and diversity have been applied to detecting the environmental change and their relationship to global events five peaks of evolutionary activity occurred in the oligocene p18 p21a and p22 and in the earlier mid miocene n8 and late pliocene quaternary n21 n22 respectively the peaks in p18 and p21a are the possible response respectively to the global cooling events oi 1 and oi 2 which occurred in the early oligocene the marked increase in extinction origination and diversity was synchronous with the major enrichment in benthic 18o in the late pliocene n21 suggesting a reaction of the ostracod faunas to the rapid cooling of the bottom water and the initiation of the north hemispheric glaciation during the period of 3 2 5 ma

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

seasonal dripwater mg ca and sr ca variations driven by cave ventilation implications for and modeling of speleothem paleoclimate records a 4 year study in a central texas cave quantifies multiple mechanisms that control dripwater composition and how these mechanisms vary at different drip sites we monitored cave air compositions in situ calcite growth dripwater composition and drip rate every 4 6 weeks three groups of drip sites are delineated groups 1 3 based on geochemical variations in dripwater composition quantitative modeling of mineral solution reactions within the host carbonate rock and cave environments is used to identify mechanisms that can account for variations in dripwater compositions the covariation of mg ca and sr ca and sr isotopes is key in delineating whether mg ca and sr ca variations are dictated by water rock interaction i e calcite or dolomite recrystallization or prior calcite precipitation pcp group 1 dripwater compositions reflects a narrow range of the extent of water rock interaction followed by varying amounts of prior calcite precipitation pcp group 2 dripwater compositions are controlled by varying amounts of water rock interaction with little to no pcp influence group 3 dripwater compositions are dictated by variable extents of both water rock interaction and pcp group 1 drip sites show seasonal variations in dripwater mg ca and sr ca whereas the other drip sites do not in contrast to the findings of most previous dripwater mg ca sr ca studies these seasonal variations at group 1 drip sites are independent of changes in water flux i e rainfall and or drip rate and instead significantly correlate with changes in cave air co2 concentrations these results are consistent with lower cave air co2 related to cool season ventilation of the cave atmosphere enhancing calcite precipitation and leading to dripwater geochemical evolution via pcp group 1 dripwater mg ca and sr ca seasonality and evidence for pcp as a mechanism that can account for that seasonality have two implications for many other regions where seasonal ventilation of caves is likely 1 speleothem trace element records may provide seasonal signals and 2 such records may be biased toward recording climate conditions during the season when calcite is depositing additionally we use our results to construct a forward model that illustrates the types of speleothem mg ca and sr ca variations that would result from varying controls on dripwater compositions the model provides a basis for interpreting paleodripwater controls from high frequency mg ca and sr ca variations for speleothems from caves at which long term monitoring studies are not feasible 2011 elsevier ltd all rights reserved

controls on trace element sr mg compositions of carbonate cave waters implications for speleothem climatic records abstract at two caves clamouse s france and ernesto ne italy cave drip and pool waters were collected and sampled at intervals over a 2 3 year period mg ca and sr ca concentration ratios corrected for marine aerosols are compared with those of bedrocks and in some cases aqueous leachates of soils and weathered bedrocks cave waters do not lie along mixing lines between calcite and dolomite of bedrock carbonate but typically show enhanced and covarying mg ca and sr ca four factors are considered as controlling processes 1 the much faster dissolution rate of calcite than dolomite allows for the possibility of increase of mg ca if water rock contact times are increased during drier conditions a theoretical model is shown to be comparable to experimental leachates 2 prior calcite precipitation along a flow path is a powerful mechanism for generating enhanced and covarying mg ca and sr ca ratios this mechanism requires the solution to lose co 2 into pores or caverns 3 incongruent dolomite dissolution has only limited potential and is best regarded as two separate processes of dolomite dissolution and calcite precipitation 4 selective leaching of mg and sr with respect to ca is shown to be important in leachates from ernesto where it appears to be a phenomenon of calcite dissolution in general selective leaching can occur whenever ca is sequestered into precipitates due to freezing or drying of soils or if there is derivation of excess sr and mg from non carbonate species the ernesto cave has abundant water supply which in the main chamber is derived from a reservoir with year round constant p co 2 of around 10 2 4 and no evidence of calcite precipitation in the karst above the cave two distinct but overlying trends of enhanced and covarying mg ca and sr ca away from the locus of bedrock compositions are due to calcite precipitation within the cave and at a variable drip site due to enhanced selective leaching at slow drip rates mg enhancement in the first chamber is due to a more dolomitic bedrock and longer residence times the clamouse site has a less abundant water supply and presents geochemical evidence of prior calcite precipitation both in the cave and in overlying porous dolomite dedolomitized limestone bedrock initial p co 2 values as high as 10 1 are inferred experimental incubations of clamouse soils which generated enhanced p co 2 and precipitated caco 3 had compositions similar to the karst waters calcite precipitation is inferred to be enhanced in drier conditions hydrological controls on cave water chemistry imply that the trace element chemistry of speleothems may be interpretable in palaeohydrological terms drier conditions tends to promote not only longer mean residence times enhancing dolomite dissolution and hence mg ca but also enhances degassing and calcite precipitation leading to increased mg ca and sr ca

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

environmental controls on the petrology of a late holocene speleothem from botswana with annual layers of aragonite and calcite abstract a carbonate stalagmite from drotsky s cave in northwestern botswana consists of alternating layers of calcite and aragonite layer counts and radiocarbon ages indicate that the calcite aragonite pairs are annual layers representing about 1500 years of deposition the annual layering probably resulted from highly seasonal rainfall comparison of the uppermost layers of the speleothem with meteorological records shows that precipitation of caco3 in drotsky s cave was controlled by climate thickness of calcite layers correlates with rainfall suggesting that calcite precipitation was largely dependent on the quantity of water supplied to the speleothem by contrast thickness of aragonite layers correlates with temperature although variation in temperature cannot explain greater aragonite abundance on the sides of the speleothem compared to its center mg ca ratios in calcite layers increase upward to the bases of overlying aragonite layers and analyses of cave waters suggest that fluid mg ca ratios reach levels sufficient to cause aragonite precipitation increasing evaporation which caused greater ionic strength and supersaturation resultant increasing mg ca ratios in the fluid and perhaps increasing temperature probably combined to cause aragonite precipitation detailed petrographic analysis suggests that each annual cycle of caco3 precipitation began with relatively intense fluid flow sometimes sufficient to dissolve some of the underlying aragonite before precipitation of calcite calcite precipitation under a thick fluid layer allowed euhedral crystals to form at first but thinning of the fluid to a film allowed only flatly terminated calcite crystals by season s end as fluid flow diminished increasing evaporation increasing mg ca ratios in the fluid and perhaps increasing temperature combined to cause aragonite precipitation to begin particularly on the sides of the speleothem in some years fluid flow diminished to the point that dust accumulated on aragonite surfaces before the onset of the next year s precipitation p

temperature driven seasonal calcite growth and drip water trace element variations in a well ventilated texas cave implications for speleothem paleoclimate studies abstract a two year cave monitoring study at westcave preserve in central texas provides insight into the controls on the rate of calcite growth and drip water mg ca sr ca and ba ca variations the cave is shallow and has a large ratio of its opening area to its volume which results in year round ventilation of the cave unlike larger and deeper caves in the region that ventilate seasonally cave air temperature and co2 concentrations at westcave are near atmospheric throughout the year and calcite growth is continuous changes in the rate of calcite growth positively correlate with seasonal temperature variations at all six drip sites studied r2 0 12 0 76 mean r2 0 47 average monthly surface air temperature is positively correlated with drip water sr ca at five of six drip sites studied r2 0 21 0 80 mean r2 0 44 and ba ca at all six sites r2 0 41 0 85 mean r2 0 57 whereas this correspondence is only seen in one of six drip sites for mg ca applying geochemical modeling of mineral solution reactions to the sr ca and ba ca time series at westcave indicates that the evolution of drip water sr ca and ba ca can be accounted for by two mechanisms 1 prior calcite precipitation and or incongruent calcite dissolution pcp icd which dominate drip water evolution at one site and 2 a combination of pcp icd and water rock interaction wri at the other five drip sites the results suggest a possible seasonality in the operation of the mechanisms of drip water evolution whereby pcp icd plays a larger role than wri during the warmer months of the year understanding drip water seasonal sr ca and ba ca variations has implications for paleoclimate studies using speleothems it is important to first determine if seasonal geochemical variations in drip waters can be identified one can then determine if these variations are preserved as geochemical laminae in speleothems which may then provide seasonal temperature variations and thus seasonal age constraints for speleothems determining the proportional contributions of the mineral solution reactions that drive drip water trace element variations for different drip sites as well as the extent to which trace element concentrations vary seasonally will help inform speleothem sample selection and interpretation of geochemical data for paleoclimate study our results indicate that speleothems near the well ventilated entrances of many larger and deeper caves may warrant further consideration for paleoclimate studies

application of the trace element and isotope geochemistry of strontium to studies of carbonate diagenesis carbonate rocks and natural waters exhibit a wide range in the concentration and isotopic composition of strontium this wide range and the quantifiable covariation of these parameters can provide diagnostic tools for understanding processes of fluid rock interaction careful consideration of the uncertainties associated with trace element partitioning sample heterogeneity and fluid rock interaction mechanisms is required to advance the application of the trace element and isotope geochemistry of strontium to studies of diagenesis goundwater evolution ancient seawater chemistry and isotope stratigraphy a principal uncertainty involved in the application of sr concentration variations to carbonate systems is the large range of experimental and empirical results for trace element partitioning of sr between mineral and solution this variation may be a function of precipitation rate mineral stoichiometry crystal growth mechanism fluid composition and temperature calcite and dolomite in ancient limestones commonly have significantly lower sr concentrations 20 70 p p m than would be expected from published trace element distribution coefficient values and sr ca ratios of most modern sedimentary pore waters this discrepancy probably reflects the uncertainties associated with determining distribution coefficient values as techniques improve for the analytical measurement and theoretical modelling of sr concentration and isotopic variations the petrological analysis of carbonate samples becomes increasingly important the presence of even small percentages of non carbonate phases with high rb concentrations and high 87 sr86 sr values such as clay minerals can have significant effects on the measured 87 sr 86 sr values of carbonate rocks due to the decay of 87rb to 87 sr for example a permian marine limestone with 50 p p m sr and 1 p p m rb will have a present day 87 sr 86 sr value that is 2 10 4 higher than its original value this difference is an order of magnitude greater than the analytical uncertainty and illustrates the importance of assessing the need for and accuracy of such corrections a quantitative evaluation of the effects of water rock interaction on sr concentrations and isotope compositions in carbonates strengthens the application of these geochemical tracers geochemical modelling that combines the use of trace elements and isotopes can be used to distinguish between different mechanisms of water rock interaction including diffusive and advective transport of diagenetic constituents in meteoric pore fluids during the recrystallization of carbonate minerals quantitative modelling may also be used to construct diagnostic fluid rock interaction trends that are independent of distribution coefficient values and to distinguish between mixing of mineral end members and fluid rock interaction

oxygen isotopic fractionation between drip water and speleothem calcite a 10 year monitoring study central texas usa abstract speleothem 18o values can serve as a paleoclimate proxy yielding information about past temperature and rainfall an accurate determination of the equilibrium calcite water oxygen isotopic fractionation factor and an assessment of kinetic isotopic fractionation are required for interpretation of speleothem 18o data in this study 18o values were measured for calcite deposited on artificial substrates at four sites in two central texas caves monitored for over 10 years the results are used to evaluate the equilibrium isotopic fractionation factor and the impact of climatic and hydrologic conditions on kinetic isotopic fractionation the 18o values of calcite from the four sites ranged from 24 8 to 26 7 v smow and associated drip water values ranged from 4 6 to 3 9 a comparison of predicted equilibrium calcite 18o values calculated using a commonly used isotopic fractionation factor with measured values indicates that 94 of the calcite samples are not in oxygen isotopic equilibrium with respect to their associated drip water the departure from oxygen isotopic equilibrium expressed as 18occ e ranges from 0 7 to 1 4 three of the four drip sites yield similar linear relationships between 18occ e and water temperature tw and can be collectively expressed as 18occ e 0 3tw 4 7 r2 0 56 n 93 therefore calcite deposited during time periods of lower tw lower cave air co2 concentration and faster calcite deposition rates have 18o values closer to equilibrium this contradicts conceptual models which predict that a faster calcite deposition rate leads to a larger departure of calcite 18o from equilibrium if slower calcite deposition indeed facilitates equilibrium fractionation i e 18occ e 0 then the results of this study support a larger than commonly accepted value for the equilibrium calcite water oxygen isotopic fractionation factor adopting a larger published value for the fractionation factor yields negative 18occ e values of up to 2 4 these negative values cannot be explained by existing kinetic fractionation models alternatively they may reflect the trapping of a calcite surface layer with a lower 18o value than that of calcite in isotopic equilibrium with ambient water the relationship between deposition rates and 18occ e for this study is consistent with the same relationship using data for synthetic calcite from the literature this relationship indicates a 0 8 shift of calcite 18o for every ten fold increase in deposition rate at 5 to 25 c and a ph of 8 3 the significant kinetic fractionation observed in this study warrant consideration in applying measured speleothem calcite 18o values to interpret past climate conditions

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

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

comparison of high resolution sub annual records of trace elements in a modern 1911 1992 speleothem with instrumental climate data from southwest australia high spatial resolution measurements of mg p u sr ba and na using 193 nm excimer laser ablation inductively coupled plasma mass spectrometry has revealed clearly resolvable annual cycles in a modern speleothem from southwestern australia the age of this stalagmite is established by the dates of emplacement and removal of the boardwalk where it grew 1911 1992 this chronological constraint allows for the first confident comparison between the instrumental climate record and speleothem trace element content eleven laser ablation transects across a 0 5 mm wide section of the speleothem growth axis were measured cycles that could be matched between adjacent transects were stacked into a master record to minimise variability between tracks and permit greater confidence in comparing the trace elements to the instrumental climate record p and u positively and mg inversely mimic the sudden 20 decrease in annual rainfall experienced by this region since 1965 we argue that p from seasonal vegetation decay is transported to the speleothem before it is mineralised in the soil owing to the low p retention capacity of southwest australian soils both vegetation activity and the transport of vegetation derived hpo42 are sensitive to rainfall groundwater p concentration may also influence the transport of u through the strong affinity between phosphate and uranyl ions mg appears to be sensitive to groundwater residence time as this affects drip water mg ca composition by preferential loss of ca during drier episodes when calcite precipitates before reaching the stalagmite the effects of groundwater residence time may also be important for sr on inter annual scales however the behaviour of sr on the annual cycle is opposite to mg but compatible with ba and na which are shown to depend on speleothem growth rate

annual growth banding in a cave stalagmite the presence of microscopic luminescence banding in cave calcite deposits speleothems has recently been reported1 3 the luminescence seems to be caused by excitation of humic and fulvic acids derived from the overlying soil and subsequently incorporated into the calcite3 4 we have tested whether such luminescence corresponds to annual growth layers using high precision thermal ionization mass spectrometric 238u 234u 230 th ages from banded sections of a holocene stalagmite we report here that the timespans yielded by counting bands on the assumption that they are annual agree within error limits with those obtained by our uranium thorium dating this demonstration that the banding is annual should make banded speleothems valuable resources for providing high resolution records of past climate in which precipitation can be estimated from growth rates5 6 and temperatures from stable isotope measurements7 and solar terrestrial correlations as the luminescence intensity can be related to the solar sunspot cycle1 3

seasonal trace element and stable isotope variations in a chinese speleothem the potential for high resolution paleomonsoon reconstruction abstract we report the presence of clear annual cycles in trace element mg ca sr ca ba ca and u ca and stable isotope 18o and 13c composition in an annually banded stalagmite from heshang cave hubei province china 30 44 n 110 42 e through a combination of micromilling and in situ analysis la mc icpms we measured geochemical variations across 16 annual growth bands to assess their potential as seasonal resolution paleomonsoon proxies to facilitate comparison with modern climatic and environmental data we created composite annual cycles for each proxy by stacking 6 well defined years speleothem 18o variations 10 8 to 8 5 are controlled by seasonal variations in temperature and drip water 18o which lead to maximum values during may around the time of summer monsoon onset this provides a chronological marker which can be used to constrain the timing of the other geochemical cycles the composite cycles reveal a strong positive correlation between mg ca sr ca ba ca and 13c values in the micromilled section r2 0 65 0 98 with minimum values occurring around may maximum u ca values occur at the same time we present simple models which show that these correlations as well as the observed ranges of mg ca 14 1 to 22 4 mmol mol sr ca 0 2 to 0 4 mmol mol and 13c 12 5 to 10 7 may be fully explained by progressive co2 degassing and calcite precipitation from an initially saturated solution using realistic initial conditions for heshang cave t 18 c mg casolution 0 84 mol mol sr casolution 0 69 mmol mol 13ctdic 16 75 we find that the observed relationships can be produced by using dmg 0 016 and dsr 0 30 within the range of expected values the model suggests that the fraction of ca removed from the solution ranges from 0 to 30 to produce the observed seasonal cycles this variation may be due to two related processes which occur during drier periods 1 increased prior precipitation of calcite in the epikarst or on the cave ceiling and or 2 a greater degree of co2 degassing and calcite precipitation on stalagmite surfaces when drip rates are lower both mechanisms would have the effect of enriching speleothem mg ca sr ca ba ca and 13c values during drier periods past variations in heshang carbonate chemistry may therefore be useful as seasonal resolution proxies for past rainfall

effects of orography on the generation and propagation of mesoscale convective systems in a two dimensional conditionally unstable flow abstract effects of orography cold air outflow and gravity waves on the generation and propagation of convective systems in a conditionally unstable airstream over a mesoscale mountain are studied using a two dimensional cloud model based on the propagation of convective systems three regimes are identified i an upstream propagating convective system ii a quasi stationary convective system and iii quasi stationary and downstream propagating systems in regime i low moist froude number fw the convective cells are generated by upstream deceleration associated with orographic forcing by gravity waves associated with convective cells over the upslope area at earlier stages and by the upstream propagating density current at later stages when the density current is fully developed in this flow regime quasi continuous and heavy rainfall is produced over the upslope and plain areas as individual convective cells develop farther upstream at the head of the density current and then propagate d

stable isotope data as constraints on models for the origin of coralloid and massive speleothems the interplay of substrate water supply degassing and evaporation abstract many speleothems can be assigned to one of two morphological groups massive speleothems which consist of compact bulks of material and coralloids which are domal to digitate in form faster growth on protrusions of the substrate occurs in the typical growth layers of coralloids where those layers are termed coralloid accretions but it is not observed in the typical layers of massive speleothems which in contrast tend to smoothen the speleothem surface and can therefore be defined as smoothing accretions the different growth rates on different areas of the substrate are explainable by various mechanisms of caco3 deposition e g differential aerosol deposition differential co2 and or h2o loss from a capillary film of solution deposition in subaqueous environments to identify the causes of formation of coralloids rather than massive speleothems this article provides data about 13c and 18o at coeval points of both smoothing and coralloid accretions examining the relationship between isotopic composition and the substrate morphology in subaerial speleothems data show enrichment in heavy isotopes both along the direction of water flow and toward the protrusions the first effect is due to h2o evaporation and co2 degassing during a gravity driven flow of water gravity stage and is observed in smoothing accretions the second effect is due to evaporation and degassing during water movement by capillary action from recesses to prominences capillary stage and is observed in subaerial coralloids both effects coexist in smoothing accretions interspersed among coralloid ones intermediate stage thus this study supports the origin of subaerial coralloids from dominantly capillary water and disproves their origin by deposition of aerosol from the cave air on the other hand subaqueous coralloids seem to form by a differential mass transfer from a still bulk of water toward different zones of the substrate along diffusion flux vectors of nutrients perpendicular to the iso depleted surfaces finally this isotopic method has proved useful to investigate the controls on speleothem morphology and to obtain additional insights on the evolution of aqueous solutions inside caves

direct measurements of deglacial monsoon strength in a chinese stalagmite chinese speleothems cave deposits preserve a remarkable paleoclimate record in their oxygen isotope ratios 18 o the precise interpretation of this record has been the subject of stimulating discussion most studies link the 18 o variability in chinese speleothems to regional summer monsoon rainfall and or rainfall integrated between tropical sources and cave sites discussion has centered on mechanisms behind this link as well as the location and seasonality of hypothesized rainfall changes until now these hypotheses were not directly tested in speleothems because conventional drill sampling techniques are insufficient for measuring speleothem 18 o at seasonal resolution here we use an ion microprobe to analyze seasonal 18 o variability in an annually banded stalagmite from kulishu cave northeastern china that grew during the last deglaciation the new seasonal resolution data show that the stalagmite 18 o values record two aspects of regional monsoon dynamics 1 changes in the isotopic fractionation of water vapor sourced from both the indian and pacific oceans and 2 the annual proportion of summer monsoon rainfall which was systematically greater during the holocene and bolling allerod than during the younger dryas both relate to regional rainfall the isotopic fractionation changes also relate to rainfall integrated from tropical sources

recrystallization induced oxygen isotope changes in inclusion hosted water of speleothems paleoclimatological implications abstract the issue of diagenetic alteration of carbonate deposits in caves speleothems has gained increasing importance in recent years as this process has serious consequences for speleothem based paleoclimate studies in this study stable hydrogen and oxygen isotope data of water trapped in fluid inclusions were collected for recently forming stalagmites and flowstones in order to determine how dripwater compositions are reflected and preserved in the inclusion water compositions hydrogen isotope compositions were found to reflect dripwater values whereas the oxygen isotope data were increasingly shifted from the local dripwater compositions with the time elapsed after deposition the 18 o data are correlated with x ray diffraction full width at half maximum values related to crystal domain size and lattice strain suggesting that the oxygen isotope shift is related to recrystallization of calcite transmission electron microscope analyses detected the presence of nanocrystalline 200 nm may have induced re equilibration between the carbonate and the trapped inclusion water the ostwald ripening process provides an explanation for unexpectedly low oxygen isotope compositions in the inclusion water the detected diagenetic alteration and its isotopic effects should be taken into consideration during sampling strategies and data evaluation as speleothems containing nanocrystalline calcite during their deposition are prone to late stage oxygen isotope water carbonate re equilibration which may shift the oxygen isotope composition of the inclusion water to more depleted values while the hydrogen isotope composition remains intact

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

radiocarbon evidence for decomposition of aged organic matter in the vadose zone as the main source of speleothem carbon 2015 elsevier ltd several recent studies have used records of the radiocarbon 14c bomb peak in speleothems to inversely model the soil a 14co 2 and the age distribution of soil organic material som above caves in part to investigate the potential of speleothems as sensitive records of past som dynamics the results of these modeling studies have suggested that soil co 2 at karst sites is derived primarily from the decomposition of som with turnover times on the order of decades to centuries this result is in stark contrast with observations of soil a 14co 2 at non karst sites which indicate that soil co 2 is derived primarily from root respiration and decomposition of som with much shorter turnover times this discrepancy suggests that som in karst settings may have a very different age distribution than sites that have been studied previously and or that soil co 2 is not the main source of speleothem carbon to help resolve this discrepancy we present an improved inverse model which we use to estimate the age of co 2 above several caves we also present results from a detailed case study of soil carbon dynamics at heshang cave china this work demonstrates that som in karst sites may be much older than som in non karst soils that have been studied previously but that co 2 produced in the shallow soil zone is unlikely to be the main source of speleothem carbon a review of the literature suggests that the most likely explanation for the aforementioned discrepancy is that decomposition of down washed som in the vadose zone is the dominant source of speleothem carbon

millennial scale climate variability during the last interglacial recorded in a speleothem from south western france abstract a stalagmite bdinf recovered from an archaeological cave bourgeois delaunay la chaise de vouthon in sw france provides a rare high resolution precisely dated continental palaeoclimate record covering the warmest part of the last interglacial 128 1 121 1 ka the growth interval spans the pluvial period recorded in soreq and peqiin cave speleothems during sapropel event s5 suggesting that the eastern mediterranean and western europe experienced relatively wet conditions simultaneously during this part of the last interglacial stable oxygen and carbon isotope ratios from bdinf show prominent millennial scale variations which are interpreted respectively in terms of changes in the amount of rainfall reaching the cave and soil biological activity the timing of the oxygen isotope changes agrees with similar excursions recorded in speleothems from corchia cave italy where close coupling between rainfall amount and regional sea surface temperatures has been demonstrated three warmer wetter periods are interspersed with four cooler drier periods the first warmer wetter period is the most prominent as is the case at corchia and coincides with the sst optimum off western europe this is followed by a prominent cooler drier excursion centred on 126 ka which can be linked to a period of increased loess deposition recorded in annually laminated lake sediments from eifel germany although there is already ample evidence for last interglacial climate instability we show for the first time that specific climatic events occurred more or less synchronously between southwestern europe central mediterranean italy and northern europe germany

the mesoscale and microscale structure and organization of clouds and precipitation in midlatitude cyclones ix some effects of orography on rainbands abstract the effects of orography on the mesoscale structures and precipitation processes in warm frontal warm sector wide cold frontal narrow cold frontal and post frontal rainbands in four pacific cyclones are described the rainbands were tracked with a doppler radar as they approached the washington coast and then for 150 km inland as they passed over topographic features ranging from modest hills to mountain ranges the rainbands were affected in a variety of ways by orography ranging from dissipation to formation and precipitation from the bands was enhanced and reduced in different situations these effects are discussed with respect to the large scale flow mesoscale air motions and precipitation growth mechanisms

a 53 year seasonally resolved oxygen and carbon isotope record from a modern gibraltar speleothem reconstructed drip water and relationship to local precipitation abstract the response of a climate proxy against measured temperature rainfall and atmospheric circulation patterns at sub annual resolution is the ultimate test of proxy fidelity but very few data exist showing the level of correspondence between speleothem climate proxies and the instrumental climate record cave sites on the gibraltar peninsula provide a unique opportunity to calibrate speleothem climate proxies with the longest known available precipitation isotopes and instrumental records an actively growing speleothem sampled from new st michaels cave in 2004 is composed of paired laminae consisting of light columnar calcite and a darker microsparitic calcite stable isotope analysis of samples micromilled in 100 m steps at the equivalent of bi monthly intervals reveals fabric correlated annual cycles in carbon isotopes oxygen isotopes and trace elements responding to seasonal changes in cave microclimate hydrology and ventilation patterns calcite 13 c values reach a minimum in the light columnar fabric and evidence from trace element behaviour and cave monitoring indicates that this grows under cave winter conditions of highest p co 2 whereas the dark microsparitic calcite characterised by elevated 13 c and 18 o values grows under low summer p co 2 conditions drip water 13 c dic reaches a minimum in march april at which time the attenuated 18 o signal becomes most representative of winter precipitation an age model based on cycle counting and the position of the 14 c bomb carbon spike yields a precisely dated winter oxygen isotope proxy of cave seepage water for comparison with the gnip and instrumental climate record for gibraltar the 18 o characteristics of calcite deposited from drip water representing winter precipitation for each year can be derived from the seasonally resolved record and allows reconstruction of the 18 o drip water representing winter precipitation for each year from 1951 2004 these data show an encouraging level of correspondence r 2 0 47 with the 18 o of rainfall falling each year between october and march and on a decadal scale the 18 o of reconstructed winter drip water mirrors secular change in mean winter temperatures

seasonal climate signals 1990 2008 in a modern soreq cave stalagmite as revealed by high resolution geochemical analysis article high resolution isotopic and geochemical analyses in a modern 1990 2008 soreq cave stalagmite are com pared to instrumental records of rainfall and dripwater from the cave with the aim of determining how seasonal resolutionclimateinformationistransmittedtospeleothemgeochemistry insitu micron scaleanalysis of oxygen isotope ratios 18 o and trace elements by ion microprobe in combination with a continuous linear traverse of trace element concentrations by laser ablation icp ms la icp ms allow the definition of geochem ical pathways within the cave fluorescent banding imaged by confocal laser fluorescent microscopy clfm as well as

age determination of recent cave deposits using excess 210pb a new technique cave deposits have been widely used as proxy recorders in deciphering palaeoclimate during the last glacial interglacial maxima 120 ka harmon et al 1975 atkinson et al 1978 goede and harmon 1983 ayliffe and veeh 1989 palaeoclimatic studies of cave deposits for the past 1 1000 yr time scale require a precise dating technique that until now has been lacking due to the multiple sources of carbon in speleothems 14c dates obtained for recently deposited calcite are highly variable and thus 14c dating techniques are not suitable to obtain speleothem ages for the past 1 1000 years here we show for the first time that speleothems contain high concentrations of excess 210pb and that this 210pb excess can be successfully employed to obtain growth rates of speleothems deposited during the last 100 years of two specimens analyzed a tubular soda straw stalactite yielded a longitudinal growth rate of 1 1 mm yr while a normal icicle shaped stalactite had a lateral growth rate of 0 028 mm yr the mass growth rates of these two speleothems 149 and 78 mg yr respectively are comparable within a factor of two studies of fine scale variations in the isotopic composition of recent speleothems will help to corroborate the validity of palaeoclimate records obtained using longer lived isotopes and extending back into pleistocene

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

evidence of rainfall variations in southern brazil from trace element ratios mg ca and sr ca in a late pleistocene stalagmite trace element ratios in the bt2 stalagmite from botuveracave southern brazil are explored as a proxy for changes in the local rainfall recharge during the last 116 ky bp mg ca and sr ca ratios measured with an electron microprobe are signif icantly positively correlated with one another throughout the entire record and vary in a way that is very consistent with variations of d 18 o in the same speleothem during the last glacial period we suggest that prior calcite precipitation in the vadose zone of the cave system is the main factor affecting the incorporation of mg and sr into calcite of the stalagmite this interpretation is supported by trace element correlation patterns and by results from a hydrochemistry study performed in a cave located in the same region and in a similar environmental setting therefore we conclude that higher lower mg ca and sr ca values are associated with lower higher levels of recharge into the karstic aquifer as such conditions lead to an increase decrease in the volume of calcite precipitated in the unsaturated zone above the cave during dry wet climate periods trace element variations point to generally dryer wetter conditions during lower high phases of summer insolation in the southern hemisphere these periods coincide with decreased increased activity of the south american summer monsoon as revealed by d 18 o stalagmite records in addition trace element variations show that rather wet conditions persisted through out most of the last glacial period from approximately 70 to 17 ky bp we suggest that during this period the glacial boundary conditions especially ice volume buildup in the northern hemisphere played an important role for monsoon rainfall inten sification in the region 2007 elsevier ltd all rights reserved

applications of stalagmite laminae to paleoclimate reconstructions comparison with dendrochronology climatology abstract laminated stalagmites observed in either ultra violet or visible light or recognized via trace elements are now widely recognized as a common deposition form annually laminated stalagmites should be expected in caves which have an overlying climate that has a strong seasonality similar climate zones to where trees grow with distinct annual rings continuous laminated stalagmite chronologies up to several thousand years should be expected where some mixing of stored water occurs such stalagmites can be used to reconstruct climate particularly through variations in lamina width such climate records would be relatively damped by mixing of event water with stored groundwater constraining the amount of high frequency climate signals contained in the stalagmite but relatively long continuous lamina sequences permit the preservation of low frequency centennial scale climate signals this contrasts with numerous tree ring climate records which are frequently limited in preserving multi centennial trends due to the necessary removal of age related noise from relatively short tree segments laminated stalagmites and tree rings should therefore to some degree provide complementary climate information appropriate methods for compiling stalagmite layer chronologies and climatologies are presented

temperature control on the incorporation of magnesium strontium fluorine and cadmium into benthic foraminiferal shells from little bahama bank prospects for thermocline paleoceanography surface sediments from little bahama bank lbb intersecting the subtropical thermocline were used to assess the influence of temperature on the incorporation of mg sr f and cd into shells of benthic foraminifera samples were obtained from twelve cores along the southern slope of lbb covering a temperature range of 18 4 5 c between 301 and 1585 m we studied the composition of ten calcitic and one aragonitic species which are often used in paleochemical reconstructions mg ca ratios decrease with increasing water depth in all benthic species both with calcitic and aragonitic mineralogy showing a strong correlation with water temperature similar decrease is seen in sr ca but with no correlation with temperature none of the benthic species studied here exhibits a depth or temperature related change in f ca similar trends are observed when using an ocean wide dataset which includes shallow and deep core tops 300 5000 m we suggest that temperature is the primary control on the mg content of benthic foraminifera based on inorganic precipitation experiments and thermodynamic considerations presented here a 30 40 decrease in the mg distribution coefficient in calcite may be expected as a result of a temperature change from 25 c to 5 c which is about half the observed change in lbb a calibration curve applied to c pachyderma data from core tops along the slope of little bahama bank suggests that water temperature may be inferred from mg ca ratios with an uncertainty of about 0 8 c therefore the mg content of benthic foraminifera may provide a new independent temperature proxy for studying shallow waters paleoceanography the linear decrease in sr ca with increasing depth is not correlated with temperature the trend is constant from the ocean surface down to 5 km suggesting that pressure related effects on the calcification process are a more likely explanation than post depositional dissolution mg ca ratios in aragonitic shells of h elegans covary with temperature in accord with recent observations from corals in contrast the sr and f chemistry of h elegans is very different than that of corals and inorganically precipitated aragonites the disparities between the elemental composition of biogenic and inorganic phases and the large intergeneric and interspecific differences observed both in planktonic and benthic foraminifera implicate temperature related physiological processes in regulating the coprecipitation of elements in foraminiferal shells our work demonstrates that cd ca ratios of shallow calcitic species reflect the vertical distribution of nutrients no significant influence of temperature on the partitioning of cd into the shells was found our data extend the previous deep water calibration boyle 1992 thereby allowing for the reconstruction of the nutrient chemistry of shallow thermocline waters

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

influence of temperature on the composition of magnesian calcite overgrowths precipitated from seawater a constant disequilibrium technique was used to determine the composition of magnesian calcite overgrowths precipitated on pure calcite seeds from artificial seawater at 5 25 and 40 c the amount of magnesium incorporated in the overgrowths at a given temperature is independent of the precipitation rate over a wide range of saturation states and is believed to correspond to a composition in true equilibrium with seawater the distribution coefficient of magnesium dmg2 c in the magnesian calcite overgrowths increases almost linearly with temperature being 0 0121 0 0013 at 5 c 0 0172 0 0022 at 25 c and 0 0271 0 0013 at 40 c these values apply only to magnesian calcites precipitated from standard composition seawater since a previous study has shown dmg2 c to be a function of the mg2 ca2 ratio in the parent solution results of this study are compared with values reported previously by other workers and with the compositional distribution of naturally occurring magnesian calcite cements and ooids found in seawater it appears that variations in temperature are not sufficient to account for the compositional variability of naturally occurring inorganic marine magnesian calcite cements

a high resolution absolute dated late pleistocene monsoon record from hulu cave china oxygen isotope records of five stalagmites from hulu cave near nanjing bear a remarkable resemblance to oxygen isotope records from greenland ice cores suggesting that east asian monsoon intensity changed in concert with greenland temperature between 11 000 and 75 000 years before the present yr b p between 11 000 and 30 000 yr b p the timing of changes in the monsoon as established with 230th dates generally agrees with the timing of temperature changes from the greenland ice sheet project two gisp2 core which supports gisp2 s chronology in this interval our record links north atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer east asian monsoon originates

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

magnesium and strontium systematics in tropical speleothems from the western pacific abstract we present bulk average sr and mg data for 13 speleothems from different locations in the western equatorial pacific guam solomon islands and vanuatu these data plot on a single straight line in a graph of ln sr ca vs ln mg ca with a slope of 0 9 a 22 000 year record of sr and mg in one of these samples from guam also plots with the same slope suggesting that the process partitioning mg and sr within the guam speleothem is the same as the one that partitions mg and sr between the different pacific speleothems we rule out temperature growth rate detrital phases and sea spray as likely mechanisms for this correlation we construct mathematical models of limestone diagenesis and show that this cannot explain the slope of the correlation our favoured explanation for the correlation is calcite water interaction in the form of prior calcite precipitation pcp and or incongruent calcite dissolution icd we present a formal mathematical model of pcp and prove that the slope of a graph of ln sr ca and ln mg ca is given by kd sr 1 kd mg 1 a similar equation is derived for icd in a companion paper sinclair 2011 using published values for kdsr and kdmg this slope is calculated to be 0 88 in excellent agreement with our observations because the slope is independent of solution and host limestone composition it can be used to diagnose calcite water interaction in individual cave water studies where host rock composition is unknown or in speleothems for which no field drip water data or host rock geochemistry exists approximately half of published drip and speleothem mg sr studies plot within error of this slope we hypothesize that the overall trend in our pacific speleothem data results from the individual dripwater systems evolving from a roughly similar initial rock composition set by late quaternary reef limestone in the guam speleothem the broad peak in mg and sr centred on the early mid holocene reflects a change in hydrology rainfall with the most likely scenario being that dry conditions prevailed on guam at this time

spatial patterns of holocene glacier advance and retreat in central asia glaciers in the southern himalayas advanced in the early holocene despite an increase in incoming summer solar insolation at the top of the atmosphere these glacier advances are in contrast to the smaller alpine glaciers in the western and northern regions of central asia two different glacier mass balance models are used to reconcile this holocene glacier history with climate by quantifying the change in equilibrium line altitudes ela for simulated changes in holocene climate both ela models clearly show that the lowering of elas in the southern himalayas is largely due to a decrease in summer temperatures and that an increase in monsoonal precipitation accounts for less than 30 of the total ela changes the decrease in summer temperatures is a dynamic response to the changes in solar insolation resulting in both a decrease in incoming shortwave radiation at the surface due to an increase in cloudiness and an increase in evaporative cooling in the western and northern zones of central asia both ela models show a rise in elas in response to a general increase in summer temperatures this increase in temperatures in the more northern regions is a direct radiative response to the increase in summer solar insolation

dripwater organic matter and trace element geochemistry in a semi arid karst environment implications for speleothem paleoclimatology a series of four short term infiltration experiments which revealed hydrochemical responses relevant to semi arid karst environments were carried out above cathedral cave wellington new south wales nsw australia dripwater samples were collected at two sites for trace element and organic matter analysis organic matter was characterised using fluorescence and interpreted using a parafac model three components were isolated that represented unprocessed soil derived humic like and fulvic like material processed humic fulvic like material and tryptophan like fluorescence principal component analysis pca performed on the entire dataset comprising trace element concentrations and parafac scores revealed two dominant components that were identified as soil and limestone bedrock the soil component was assigned based on significant contributions from the parafac scores and additionally included ba cu ni and mg the bedrock component included the expected elements of ca mg and sr as well as si the same elemental behaviour was observed in recent stalagmite growth collected from the site our experiments demonstrate that existing paleoclimate interpretations of speleothem mg and sr developed in regions of positive water balance are not readily applicable to water limited environments we provide a new interpretation of trace element signatures unique to speleothems from water limited karst environments

organic acid fluorescence applications to speleothem palaeoenvironmental reconstruction abstract recent advances in fluorescence spectrophotometry permit the non destructive analysis of speleothems secondary carbonate cave deposits with a view to palaeoenvironmental reconstruction the fluorescence of speleothems is derived from organic acids that have been carried by groundwater from the overlying soil and coprecipitated with the speleothem calcite organic acids are formed as one of the many products of humification and their chemical structures are such that they are particularly suitable for analysis by fluorescence spectrophotometry numerous studies have been carried out that have demonstrated the structure and hence the fluorescence properties of organic acids to be influenced by many factors including extraction method concentration source ph metal and inorganic ion complexing and most importantly in the case of speleothems soil type and climate and vegetation change on the basis of this recent investigations carried out on contemporary historical and quaternary samples have shown it to be possible to obtain palaeoenvironmental information from the fluorescence properties of organic acids in speleothems

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

cryptic diagenesis and its implications for speleothem geochronologies abstract speleothems are usually considered as one of the most amenable palaeoclimate archives for u series dating a number of studies in recent years however report cases of diagenetic alteration which compromises the use of u series systematics in speleothems resulting in inaccurate u th ages here we present the results of a high resolution u th dating study of a stalagmite cc26 from corchia cave in italy where we document a number of departures from an otherwise well defined age depth model and explore potential causes for these outliers unlike examples illustrated in previous studies cc26 contains no visible evidence of neomorphism and appears at least superficially ideally suited to dating good reproducibility obtained between multi aliquot u th analyses removes any possibility of analytical issues contributing to these outliers furthermore replicate analyses of samples from the same stratigraphic layer yielded ages in stratigraphic sequence implying very localized open system behavior uranium loss is suggested as a causative mechanism on account of the fact that all the outliers are older than their assumed true age a limited number of micro voids were observed under micro ct analyses and it is proposed that these were pathways for u loss uranium loss modelling allows us to constrain the possible timing of diagenetic alteration and indicates that the precursor for the outlier with the largest age discrepancy 309 must have been aragonite this study indicates that visibly unaltered speleothems may still contain small domains that have experienced post depositional alteration such cryptic diagenesis as recorded in this stalagmite has implications for the constancy of accuracy of the u series dating technique and suggests a need for careful examination of speleothems prior to dating particularly in low resolution u th studies

dead carbon in stalagmites carbonate bedrock paleodissolution vs ageing of soil organic matter implications for 13c variations in speleothems twenty one 14c accelerator mass spectrometric analyses were obtained for three holocene stalagmites from the uamh an tartair cave sutherland scotland in order to estimate the past dead carbon proportion dcp results show that the dcp increases from 22 to 38 from 3780 years ago to the present because 13c variation is small within each sample it is concluded that this dcp increase is the product of the ageing of soil organic matter related to peat bog development above the cave that produced older soil co2 and not from a more intense dissolution of the surrounding carbonates which would have led to a 13c increase comparison with samples from other sites in europe shows no intersite correlation between dcp and 13c but a relatively good intersite correlation is observed between dcp and average site temperature thus temperature may be a major factor controlling the production of old soil organic matter co2 and therefore the dead carbon content of seepage water in contrast to the scotland stalagmites two other holocene samples from sites in southern france and belgium exhibit a good correlation between 13c and dcp which can be explained in terms of variations in the intensity of limestone dissolution consequently 13c variations observed in stalagmites are not always due to changes in the vegetation type c3 c4 as has been commonly assumed 13c 12c variations in speleothem calcite may also be controlled by the soil organic matter age and in some cases by the intensity of the limestone dissolution conversely a largely constant speleothem 13c signal as observed for the scotland stalagmites does not necessarily imply that surface climate and vegetation conditions were stable since the dcp variations in this case are clearly related to the peat bog development during stalagmite growth

a high resolution stalagmite record of the holocene east asian monsoon from mt shennongjia central china high resolution oxygen isotope 18o profiles of six stalagmites from sanbao cave in hubei province central china established with 1413 oxygen isotope data and 65 230th ages provide a continuous history of east asian summer monsoon easm intensity for the period from 13 0 2 thousand years before present ky bp relative to ad 1950 the 18o record includes four distinct stages in the evolution of the easm 1 an abrupt transition 11 5 ky bp into the holocene 2 a period of gradual increase in monsoon intensity 11 5 9 5 ky bp 3 the maximum humid period 9 5 6 5 ky bp and 4 a period of gradual decline in monsoon intensity 6 5 0 2 ky bp comparison of sanbao with regional records of comparable resolution reveals that the timing of the beginning and end of the holocene optimum as defined by the minimum in 18 o was similar in the indian and east asian monsoon systems this supports the idea that shifts in the monsoon tied to shifts in the mean position of the inter tropical convergen

palaeoclimate determination from cave calcite deposits calcite deposits formed in limestone caves have been found to be an excellent repository of palaeoclimatic data for terrestrial environments the very presence of a relict deposit indicates non glacial conditions at the time of formation and both 14c and uranium series methods can be used to date the deposit and hence the age of these climatic conditions variations in 13c and 18o content of the calcite in 2h and 18o content of fluid inclusions in trace element concentrations and more recently in pollen assemblages trapped in the calcite are all potentially available as synchronous palaeoclimatic indicators previous work has tended to concentrate mainly on abundance of deposits as a palaeoclimatic indicator for the last 300 000 years this literature is briefly reviewed here together with the theory and methods of analysis of the u series and stable isotopic techniques the combined use of u series ages and 13c and 18o variations in cave calcites illustrates the potential for palaeoclimate determination previously unpublished results of stable isotopic variations in dated calcites from caves in northern england indicate the level of detail of stable isotopic variations and time resolution that can be obtained and the complexity of interpretation that may arise tentative palaeoclimatic signals for the periods 90 125 ka and 170 300 ka are presented more comprehensive studies are needed in future work especially in view of the difficulty in obtaining suitable deposits and the ethics of cave deposits conservation

in situ measurement of seasonal δ18o variations and analysis of isotopic trends in a modern speleothem from southwest australia we present a record of seasonal and inter annual oxygen o and carbon c isotope ratios from an 81 year old stalagmite from moondyne cave southwest australia the growth history of stalagmite mnd s1 is known since it grew on a cave boardwalk that was installed in 1911 and removed in 1992 this stalagmite provides an excellent test of speleothem climate proxies because the regional climate is strongly seasonal wet winter dry summer and has experienced a 200 mm 20 reduction of mean rainfall since the mid 1960s and a 0 8 c temperature rise since 1953 seasonal variations in calcite o were measured in situ by high spatial resolution ion microprobe whilst inter annual variations of o and c were measured by conventional gas source mass spectrometry comparison of the speleothem stable isotopes and instrumental temperature records reveals that o variations are too large to be driven by temperature alone and are in the opposite sense however daily rainfall o measurements show that the mean seasonal range in o of rainfall in southwest australia is large 2 and inversely correlated with rainfall amount a rainfall driver for the speleothem o is confirmed by the detection of seasonal shifts of 0 7 1 5 in speleothem that track rainfall o smoothed by storage in the overlying limestone the seasonal range in speleothem o is larger than any inter annual and decadal variation observed in the record the prominent annual cycles in speleothem o revealed by ion microprobe analysis indicate that subtle changes in the frequency of intense winter rainfall events or possibly also moisture sources could produce significant changes in mean speleothem o the ion microprobe results also raise the possibility that the masses of speleothem calcite deposited in winter and summer could vary as a function of the seasonal drip rate and carbonate saturation state of these waters if this is the case then small changes in the relative masses of calcite deposited in winter and summer could produce significant shifts in mean o and c that have a complex relation to climate this finding should be generally applicable to the interpretation of long term trends in speleothem geochemical records for shallow cave sites where seasonal variations in geochemical tracers are relatively large including most of the sub tropical monsoon belts and mid to high latitudes with distinct rainfall seasons