trace element variations and dating of a late pleistocene tasmanian speleothem abstract a calcitic stalagmite from lynds cave a limestone cave near mole creek in northern tasmania australia has been dated and shows continuous deposition at a uniform rate from 15 0 to 11 7 ka b p ionium dates or 12 6 8 8 ka b p radiocarbon dates the age difference obtained by comparing the two dating methods is highly significant and strongly supports recent work by bard et al 1990 on barbados corals the speleothem was found to be unsuitable for palaeotemperature estimation by oxygen isotope analysis but the time of deposition is known to have been one rapidly rising temperatures trace element composition was determined by neutron activation analysis naa for fifteen samples spaced along the stalagmite core all elements present in measurable quantities showed significant temporal variation in concentrations which are in part believed to be due to environmental change a significant positive trend in mg sr content and a negative trend in br content appear to be temperature related the halide content is shown to be of terrestrial origin

chemical diagenesis of carbonates in thin sections ion microprobe as a trace element tool abstract ion microprobe is a potential tool for determination of trace element concentrations directly in thin sections such an approach enables direct correlation of chemistry with microtextural features we demonstrate the utility of this instrument for sr mn fe and mg in calcites and dolomites at this stage the sensitivity is 10 ppm and the reproducibility is usually better than 15 relative percent the analyzed spots are 20 we believe that with more homogeneous standards at low concentrtion levels the technique is potentially capable of sensitivity in the ppb ppm ranges fe may prove an exeption from this prediction the technique may also prove suitable for determination of na ion microprobe can serve as a valuable tool for diagenetic and petrological studies of carbonates at this stage its major disadvantage is the poor optical resolution in transmitted light

cenozoic dolomites of carbonate islands their attributes and origin abstract dolomites found on and below carbonate islands atolls and oceanic platforms provide useful insights into the origin of dolomite insights that may not be attainable from the study of more ancient cratonic dolomites for this reason they have been the subject of study for decades a critical mass of case studies now exist and some significant conclusions can be drawn from the cumulative data in most cases the association with an island is causal and not genetic nevertheless these dolomite occurrences are referred to herein as island dolomites one type of dolomite on carbonate islands is penecontemporaneous dolomite a phase that forms while the host sediment is in its original depositional setting island examples are holocene in age occur in holocene sediments and originate as a direct precipitate from either normal or evaporated seawater these are microcrystalline poorly ordered ca rich 18o enriched and geochemically unstable phases that are susceptible to recrystallization in the setting in which they formed post depositional dolomite is the other type of dolomite associated with carbonate islands this type of dolomite replaces older precursors and forms as cement distinctive characteristics include a dominance of fabric preserving texture pore lining cement rims that may exhibit micron scale banding with low mg calcite and formation in association with precursor dissolution sr isotopic dating indicates that all examples are neogene or quaternary in age those formed during the middle miocene through pliocene are massive laterally continuous and often multigenerational in contrast younger examples tend to be localized partial replacements of a single generation sr isotope ages also suggest global synchroneity in many dolomitization events which suggests a connection between dolomitization global eustacy and or global climatic factors geochemical attributes of post depositional island dolomites are ca enrichment positive 18o and 13c low sr contents 150 300 ppm and low fe global similarity in petrography and geochemistry of replacive island dolomites argues for a similar origin inferred origins however depend primarily on how 18o and sr data are interpreted values for 18o and dsr must be assumed due to uncertainties in oxygen isotope fractionation and sr partitioning there is no consensus or uniformity in those assumptions thus interpretations can vary and be biased to a desired result covariant trends in 13c and 18o some negative 13c values and high sr all favor a mixing zone origin but examples with these attributes are few lack of covariance in the isotopes mean 18o of 2 0 to 3 5 and low sr future studies should standardize the type of data collected and the analytical techniques employed multiple geochemical attributes should be measured on microsampled components and quantitative modeling should be employed in order to constraint interpretations as much as possible also needed are a better understanding of the kinetic processes that form these dolomites more careful assessment of their recrystallization status and an improved understanding of dsr and 18o at low temperature

a high resolution record of holocene climate change in speleothem calcite from cold water cave northeast iowa high precision uranium thorium mass spectrometric chronology and 18o 13c isotopic analysis of speleothem calcite from cold water cave in northeast iowa have been used to chart mid holocene climate change significant shifts in 18o and 13c isotopic values coincide with well documented holocene vegetation changes temperature estimates based on 18o 16o ratios suggest that the climate warmed rapidly by about 3 c at 5900 years before present and then cooled by 4 c at 3600 years before present initiation of a gradual increase in 13c at 5900 years before present suggests that turnover of the forest soil biomass was slow and that equilibrium with prairie vegetation was not attained by 3600 years before present

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

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

quaternary climatic instability in south east australia from a multi proxy speleothem record milankovitch scale quaternary climatic oscillations within south east australia are known to be characterized by relatively arid glacial and wet interglacial stages however terrestrial proxy records of environmental change are scarce based largely on river terraces dune sediments and pollen sequences here we present a speleothem based palaeoclimate record from yarrangobilly caves south east australia the oxygen isotopic composition of calcite 18ocalcite is taken to represent rainfall amount and used as an aridity index high resolution trace element profiles and uv fluorescence support interpretations based on 18ocalcite allowing further designation of key phases of speleothem growth into periods of relative aridity and moisture excess a hiatus of approximately 37 ka duration divides the record into two key phases of growth which can be mapped onto marine isotope stages 5c a and 3 respectively increasing aridity in the latter half of mis 5 led to cessation of speleothem growth for the duration of mis 4 growth recommences during mis 3 associated with greater moisture availability enhanced vegetation and augmented biogeochemical cycling this speleothem record provides a unique context of terrestrial environmental change and depicts hydrological conditions which fluctuate markedly over the 70 ka period covering the time of megafauna extinction and human arrival on the continent

ion microprobe analysis of oxygen isotope ratios in granulite facies magnetites diffusive exchange as a guide to cooling history ion microprobe analysis of magnetites from the adirondack mountains ny yields oxygen isotope ratios with spatial resolution of 2 8 m and precision in the range of 1 1 sigma these analyses represent 11 orders of magnitude reduction in sample size compared to conventional analyses on this material and they are the first report of routinely reproducible precision in the 1 per mil range for analysis of 18o at this scale high precision micro analyses of this sort will permit wide ranging new applications in stable isotope geochemistry the analyzed magnetites form nearly spherical grains in a calcite matrix with diopside and monticellite textures are characteristic of granulite facies marbles and show no evidence for retrograde recrystallization of magnetite magnetites are near to fe3o4 in composition and optically and chemically homogeneous a combination of ion probe plus conventional brf5 analysis shows that individual grains are homogeneous with 18o 8 9 1 smow from the core to near the rim of 0 1 1 2 mm diameter grains depth profiling into crystal growth faces of magnetites shows that rims are 9 depleted in 18o these low 18o values increase in smooth gradients across the outer 10 m of magnetite rims in contact with calcite these are the sharpest intracrystalline gradients measured to date in geological materials this discovery is confirmed by bulk analysis of 150 350 m diameter magnetites which average 1 2 lower in 18o than coarse magnetites due to low 18o rims conventional analysis of coexisting calcite yields 18o 18 19 suggesting that bulk 18o cc mt 9 3 and yielding an apparent equilibration temperature of 525 c over 200 c below the temperature of regional metamorphism consideration of experimental diffusion data and grain size distribution for magnetite and calcite suggests two contrasting cooling histories the data for oxygen in calcite under hydrothermal conditions at high p h2o indicates that diffusion is faster in magnetite and modelling of the low 18o rims on magnetite would suggest that the adirondacks experienced slow cooling after grenville metamorphism followed by a brief period of rapid cooling possibly related to uplift conversely the data for calcite at low p h2o show slower oxygen diffusion than in magnetite modelling based on these data is consistent with geochronology that shows slow cooling through the blocking temperature of both minerals suggesting that the low 18o rims form by exchange with late low temperature fluids similar to those that infiltrated the rock to serpentinize monticellite and which infiltrated adjacent anorthosite to form late calcite veinlets in either case the ion microprobe results indicate that two distinct events are recorded in the post metamorphic exchange history of these magnetites recognition of these events is only possible through microanalysis and has important implications for geothermometry

geomagnetic palaeosecular variation 0 13 000 yr bp as recorded in sediments from three maar lakes from the west eifel germany summary geomagnetic palaeosecular variation psv profiles have been obtained from 12 cores raised from three maar lakes in the west eifel germany age control is provided by varve chronology analysis of mean inclinations suggests that a post depositional remanent magnetization pdrm was acquired in all three lakes a lock in time of 150 yr corresponding to an average lock in depth of 24 cm has been determined from a comparison with archaeomagnetic sv data stacked psv results demonstrate directional geomagnetic field behaviour through the late and post glacial in central europe and show good agreement with the holocene british master curve turner thompson 1982 psv results suggest that westward drift of the non dipole field was not persistent over the last 13 000 yr spectral analyses yield declination variations with durations of about 1800 yr in the younger holocene 0 5000 yr bp and 4300 yr between 5000 and 13 000 yr bp the inclination exhibits swings of 1000 yr duration in the younger holocene and about 2000 yr in the older part moreover inclination spectra suggest the presence of one inclination variation with a very long duration approaching the length of the time span investigated 8600 yr

high resolution records of rainfall events from clay bands in tufa individual rainfall events are recorded as thin clay bands in annually laminated freshwater carbonate tufa runoff from rainfall events entrains clay that then adheres to the tufa surface a specimen collected from southwest japan exhibits 100 clay bands formed during a 15 yr period from 1988 to 2002 the chronology of the clay bands was determined by using the temperature dependent cycle of oxygen isotope ratios in the carbonate and the clay content was quantified by electron probe microanalysis si x ray strength the obtained si x ray strength curve and actual rainfall record follow a nearly identical pattern the clay content of each band correlates with rainfall amount rainfall of 50 mm week produced sufficient amounts of suspended cave clay to produce clay bands in the tufa because the clay bands survive postdepositional alteration this new method can be applied to ancient tufa deposits and has great potential as a high resolution rainfall record for use in climate studies

laminated carbonate deposits in roman aqueducts origin processes and implications carbonate deposits in roman aqueducts of patara and aspendos southern turkey were studied to analyse the nature of their regular layering optical microscopy and electron backscattered diffraction results show an alternation of dense coarsely crystalline translucent laminae composed of bundles and fans of elongate calcite crystals with their c axes parallel to the long axis and porous fine grained laminae with crystals at near random orientation the 18o and 13c data show a strong cyclicity and anti correlation whereby high and low 18o values correspond to dense columnar and porous fine grained laminae respectively geochemical analyses show similar cyclic changes in carbonate composition electron microprobe and laser ablation inductively coupled mass spectrometry analyses show that porous fine grained laminae are enriched in elements associated with detrital material fe mg k al and si whereas the dense columnar laminae are nearly pure calcite the gradient in major and trace element distribution regular changes in crystal type and in oxygen and carbon isotope composition from porous fine grained to dense columnar laminae reflect changes in water chemistry discharge temperature and biological activity because of the strong bimodal cyclicity of the mediterranean climate in southern turkey the observed laminae can be attributed to calcite deposition during the dry porous fine grained and wet season dense columnar respectively this observation implies that with proper geochemical and microstructural control lamination in carbonate deposits in roman aqueducts can be used for relative dating of aqueduct construction and maintenance and to obtain data on external factors that influenced the aqueducts such as palaeoclimate and natural hazards carbonate deposits in roman aqueducts show properties of both flowstone speleothems and riverine fresh water tufa as many aqueducts of nearly identical channel geometry are present in different climate zones and with different source water characteristics they can be used as natural experiment setups to test and improve existing models of how laminated fresh water carbonates record climate on time scales ranging from seasonal to millennial

the hekla 3 volcanic eruption recorded in a scottish speleothem recent research has demonstrated the presence of annual luminescent growth banding in a stalagmite from sutherland n w scotland baker smart edwards and richards 1993 the banding record of this sample contains a short duration increase in annual band width indicating a doubling of growth rate for a period of four years predicted growth rates derived from calcite precipitation kinetics are compared with observed growth rate variability to demonstrate that such a doubling of growth rate would not be expected within the probable range of normal climate variation the growth rate peak is dated to 1135 130 bc by thermal ionization mass spectrometric 238u 234 u 230th dating not inconsistent with the timing of the hekla 3 volcanic eruption this event may explain the observed variation in growth rate and provide a new source of evidence for interpretation of the effects of large explosive eruptions

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

caribbean hydroclimate and vegetation history across the last glacial period abstract we present a new speleothem trace element and stable isotope record which extends previous paleoclimate evidence from cuban speleothems to the last 96 ka multiple proxies were used to reconstruct caribbean hydroclimate and vegetation variability on orbital to millennial timescales in particular our proxies indicate a shift to more abundant c4 compared to c3 vegetation and or reduced soil activity during the last glacial maximum our results confirm the close link of caribbean precipitation to north atlantic climate variability insolation and the strength of the amoc the associated variations in caribbean ssts and the shift of the itcz led to substantial changes of the hydrological cycle during heinrich stadials and the younger dryas climatic conditions in cuba were comparably cool and or dry in contrast warm dansgaard oeschger cycles were accompanied by wetter conditions this is in agreement with previous evidence for the holocene when north atlantic cold warm events coincided with drier wetter conditions in cuba however our record suggests that this connection was less dominant during mis 4 to 2 displayed by a weaker response of cuban precipitation proxies to north atlantic climatic shifts than during mis 5 in particular we hypothesize that this weaker connection was mediated by the southerly shifted itcz inducing a weakening of the northern branch of the caribbean low level jet which usually transports moisture into the northern caribbean this is strikingly evident during the deglacial when driest and or coolest conditions prevailed in western cuba from hs 1 into the younger dryas including the bolling allerod interstadial

the large scale climate in response to the retreat of the west antarctic ice sheet abstractbased upon coupled climate simulations driven by present day conditions and conditions resembling the marine isotope stage 31 this simulation is called wice exp insofar as the west antarctic ice sheet wais configuration is concerned it is demonstrated that changes in the wais orography lead to noticeable changes in the oceanic and atmospheric circulations compared with the present day climate wice exp is characterized by warmer conditions in the southern hemisphere sh by up to 5 c in the polar oceans and up to 2 c in the northern hemisphere nh these changes feed back on the atmospheric circulation weakening strengthening the extratropical westerlies in the sh northern atlantic calculations of the southern annular mode sam show that modification of the wais induces warmer conditions and a northward shift of the westerly flow in particular there is a clear weakening of the polar jet these changes lead to modification of the rate of deep water formation reducing the magnitude

continuous early last glacial palaeoenvironmental record from a tasmanian speleothem based on stable isotope and minor element variations a columnar stalagmite from a limestone cave in the florentine valley tasmania has been dated by three 230th 234u age determinations continuous profiles of 170 18o and 13c values as well as magnesium and strontium concentrations are presented 18o values indicate temperatures lower than today with a gradual temperature decline in the basal part of the profile punctuated by two short cooling events and culminating in a double temperature minimum between 70 and 60 ka the profile shows marked similarities with the gisp ice core record from greenland which shows two short intense stadials centred on 74 and 70 ka preceding the last glacial temperature minimum they have been correlated with heinrich events in north atlantic marine cores which in turn have been attributed to periodic massive discharges of icebergs into the north atlantic the tasmanian speleothem record suggests that these events may also have affected climates in the southern hemisphere the 13c variations also appear to indicate periodic environmental change minor element variations were found to be significantly correlated with isotopic changes strontium concentrations show a bimodal distribution indicating control by a switching mechanism tentatively attributed to variations in calcitic dust supply to the ground surface above the site

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

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

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

evidence of younger dryas and neoglacial cooling in a late quaternary palaeotemperature record from a speleothem in eastern victoria australia a calcitic stalagmite collected from a limestone cave in the buchan area of eastern victoria has been dated by three mass spectrometric uranium series analyses two growth phases are represented the older from 13 4 to 10 6 ka and the younger from 3 2 to 2 1 ka oxygen isotope analysis reveals that temperatures were below present day values at all times but particularly cool conditions are indicated between 12 3 and 11 4 ka and neoglacial conditions occurred at about 3 ka the older cold climate event is clearly synchronous with the younger dryas in europe and this is the first time that strong evidence for this event has been found in australia carbon isotope variations are interpreted as indicating changes in plant productivity on the surface and are most likely controlled by variations in summer rainfall they indicate particularly high levels of plant productivity from 11 5 to 11 0 ka 1996 john wiley sons ltd

mg sr and sr isotope geochemistry of a belgian holocene speleothem implications for paleoclimate reconstructions in this study variations in mg ca sr ca and 87sr 86sr ratios in a holocene belgian speleothem cave secondary carbonate deposit are interpreted in terms of changes in water residence time and changes in weathering processes possibly induced by changes in west european climate a stalagmite from the pere noel cave belgium was dated with the tims u th method and was deposited between 13 and 2 ka bp the 1000 mg ca ratio varies between 4 9 and 26 and displays short term changes but no significant long term trend the 1000 sr ca ratio varies between 0 09 and 0 31 and displays both short term changes and a long term decreasing trend from 12 9 to 3 5 ka in parallel the sr isotopic composition of the speleothem decreases from 0 7090 at 12 9 ka to 0 7088 at 3 5 ka the sr isotope ratio is higher than expected from the overlying limestone 87sr 86sr 0 7081 which implies an external source of radiogenic sr most probably from a silicate phase short term and long term changes in mg ca sr ca as well as long term changes of 87sr 86sr ratios can be explained by changes in the dissolution and precipitation processes of the host limestone these processes are controlled by changes in water residence times linked to changes in the water excess precipitation minus evapo transpiration c 2000 elsevier science b v all rights reserved

climate influence on geochemistry parameters of waters from santana perolas cave system brazil abstract a four year study of water geochemistry and hydrology was performed in a relatively deep cave system overlying bedrock thickness varies from 100 to 300 m as part of two monitoring programs from june 1990 to february 1992 and from march 2000 to march 2002 the ph saturation index for calcite ca and so 4 concentrations and elemental ratios of mg ca and sr ca were measured in surface well and drip waters throughout the system despite local hydrological and geological differences among sampling sites the monitoring revealed significant synchronous intersite variations in these parameters that are related to seasonal changes in rainfall recharge suggesting that element ratios of speleothems formed in deep caves are capable of recording short term climate variations groundwater residence time appears to be the main factor affecting the water composition in the epikarst epikarstic waters are always undersaturated with respect to calcite but both saturation index s i and dissolved solids content increase substantially during drier periods because of longer residence times and longer interaction between meteoric water and limestone by contrast results from cave drips and rimstone pools indicate constant supersaturation for calcite and demonstrate that a major control on trace element ratios of waters in the deep vadose zone is the degree of prior calcite precipitation this mechanism is more effective during drier periods when higher mg ca and sr ca values are observed in all drip and pool sites however variations do occur independently of the general trend of drip discharge which suggest non linear features in cave seepage water geochemistry in addition synchronous variations in so 4 and cl concentration indicate high connectivity between different water flow pathways characterized by similar response to interseasonal changes in vadose water level fluctuations in trace element ratios of cave streams appear to reflect increased contribution of waters flushed from the vadose fissure aquifer during very wet periods by a piston flow mechanism flushing episodes are also responsible for maintaining more positive saturation indices in streams even during periods of high river discharge our results suggest that trace elements are a potential proxy for past rainfall changes but they also reveal different scenarios for interpreting trace elements ratios of speleothems and freshwater tufa deposited in a deep cave systems located in tropical humid areas

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

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

microbes in caves agents of calcite corrosion and precipitation abstract diverse biogenic and abiogenic processes produce calcite speleothems from a biogenic perspective cave microbes mediate a wide range of destructive and constructive processes that collectively influence the growth of calcite speleothems and their internal fabrics destructive processes include substrate breakdown by dissolution boring and residue micrite production whereas constructive processes include microbe calcification trapping and binding of detrital particles to substrates and microbial induced calcite precipitation biogenesis can be established from 1 the presence of mineralized microbes 2 fabrics such as stromatolite like structures that can be attributed to microbial activity and or 3 geochemical proxies carbon and oxygen isotopes lipid biomarkers considered indicative of microbe activity such criteria have for example been used to demonstrate microbial involvement in the formation of pool fingers stalactites stalagmites cave pisoliths and moonmilk nevertheless absolute proof of microbial biogenesis in calcitic speleothems is commonly difficult because taphonomic processes and or diagenetic processes commonly mask evidence of microbial activity the assumption that calcitic speleothems are abiogenic which has been tacitly assumed in many studies is dangerous as there is clear evidence that microbes thrive in most caves and can directly and indirectly influence calcite precipitation in many different ways

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

uranium series chronology and environmental applications of speleothems an increasing number of scientists recognize the value of speleothems1 as often extremely well preserved archives of information about past climate vegetation hydrology sea level nuclide migration water rock interaction landscape evolution tectonics and human action well constrained data are required to document past changes reconstruct past patterns and predict future responses of the earth system at a wide range of spatial and temporal scales speleothems are particularly useful in this regard because they can be found in many locations of the globe sampled at high resolution and reliably dated using high precision uranium series techniques speleothems are bodies of mineral material formed in caves as the result of chemical precipitation from groundwater flowing or dripping in a cave most speleothems are composed of calcite formed by slow degassing of co2 from supersaturated groundwater but aragonite and gypsum forms are also common particularly near cave entrances where evaporative effects are important a host of different speleothem types decorate the walls ceilings and floors of caves and their mineralogy and morphology is a function of fluid flow and chemistry of waters feeding a particular location as well as the ambient conditions temperature chemistry light in the air or water filled void subaerial forms include the familiar stalagmites stalactites draperies flowstones subaqueous forms include rimstone pools rafts mammillary calcite wall coatings and dog tooth spar for an extensive review of the types of speleothem that have been observed see hill and forti 1997 speleothems are used in a multitude of ways to explore past environmental conditions perhaps the most fundamental of which is their very presence or absence deposition of speleothems relies on sufficient water supply and soil co2 to enable dissolution and transport of reactants in the vadose zone to underlying caves in arid or glacial times conditions may not have been favorable for speleothem formation

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

the 2002 2003 el nino recorded in australian cave drip waters implications for reconstructing rainfall histories using stalagmites 1 a 30 month study of drip hydrochemistry from kooringa cave eastern australia revealed a clear geochemical response to the 2002 2003 el nino through the drought drip discharge fell to base flow drip ca2 concentrations fell by half and drip mg ca and sr ca increased in a co varying pattern calcite mg ca and sr ca predicted from drip waters displayed a marked increase through and just beyond the period of greatest moisture deficit the results suggest that stalagmites from shallow caves in drought sensitive eastern australia potentially preserve a valuable record of el nino la nina history

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

trace element partition coefficients in the calcite water system and their paleoclimatic significance in cave studies abstract speleothems stalactites stalagmites formed in limestone caves have been found to contain much information on the timing and intensity of past climates from analysis of their u th 13c and 18o contents because the incorporation of certain trace elements e g mg mn and zn in calcite is known to be temperature dependent it may be possible to use variations in trace metal content of fossil speleothems as an alternative paleotem perature indicator using specially developed ion exchange sampling techniques analysis of trace metal content of seepage water and associated fresh calcite deposits in caves in vancouver island and jamaica shows that mg is distributed between phases in a consistent manner within the temperature regimes of the caves 7 and 23 c respectively average values of the distribution coefficient for mg are respectively 0 017 and 0 045 at these temperatures these results indicate that the mg content of calcite varies directly with temperature and in a sufficiently pronounced manner that a 1 c rise in depositional temperature of a speleothem containing 500 ppm mg at 10 c would be seen as an increase of 35ppm mg a readily determinable shift other factors affecting mg content of a speleothem are considered