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

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

thermal history of australian passive margin cover sequences accreted to timor during late neogene arc continent collision indonesia abstract paleotemperature indicators and apatite fission track analysis of australian continental margin cover sequences accreted to the active banda arc continent collision indicate little to no heating during rapid late neogene uplift and exhumation thermal maturation patterns of vitrinite reflectance conodont alteration and illite crystallinity show that peak paleotemperatures ppt increase with stratigraphic and structural burial the highest ppt is found in the northern hinterland of the accretionary wedge which was beneath progressively thicker parts of the upper plate towards the north major discontinuities in the pattern of ppt are associated with the position of major thrust ramps such as those forming the ramelau kekneno arch rka ppt for upper triassic to neogene strata south of the rka are 60 80 c which are similar to and in many cases lower than correlative and age equivalent units drilled on the nw australian shelf permian to lower triassic sedimentary strata thrust over younger units within and north of the rka have ppt of 100 220 c thrust sheets accreted beneath the upper plate have ppt approximately 90 c higher than those frontally accreted metamorphism of the northernmost units of these sequences yield ppt of 300 c thrust stacking yields an inverted thermal profile of ppt decreasing discontinuously downward and to the south towards the foreland the timing of ppt is constrained by apatite fission track ages from mostly triassic continental margin cover sequences ages of upper triassic units are primarily coeval with deposition and show little evidence of thermal annealing whereas those of lower triassic units are almost completely annealed and range from 1 8 0 5 19 2 9 7 ma the clustering of apatite fission track ages into two distinct groups indicates that the upper boundary of the partial annealing zone has remained for some time at a triassic stratigraphic interval in the slope and rise of the nw australian continental margin the position of this zone on the present shelf is higher in the stratigraphic column due to the greater thickness of post breakup shelf facies units thrust stacking of rise slope and shelf units produces an inverted vertical profile of increasing apatite fission track age with depth lack of any long confined track lengths in apatite from all of the units requires rapid and recent exhumation of the thrust stack which is coincident with rapid phases of pliocene pleistocene exhumation documented throughout timor these data preclude pre late miocene tectonic burial or pre pliocene exhumation of the nw australian continental margin

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

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

uncertainty quantification of structural and geotechnical parameter by geostatistical simulations applied to a stability analysis case study with limited exploration data abstract there are many uncertain factors impacting stability analyses of rock structures quantification of these factors significantly impact the engineering decision making process some of these factors are spatially distributed within the geological domain and the quantification of the spatial uncertainty is beneficial for stability analysis of the structure this paper proposes an integrated methodology for a stability analysis of rock structure by incorporating spatially varying factors this research models two key factors one categorical structural parameter fault zones and one continuous geotechnical parameter rock quality designation rqd two geostatistical simulation algorithms i e sequential indicator simulation and sequential gaussian simulation are applied to quantify the spatial uncertainty by generating multiple equiprobable simulation maps of fault zones and rqd values a slope stability analysis is performed by modeling the spatially varying fault zones and rqd the proposed method is validated using a synthetic data set the results from the synthetic data show the stability value of the synthetic data closely match with stability value calculated from simulated data finally the proposed method is applied to a slope stability analysis for an open pit mine design where limited exploration data is available geostatistically simulated rqd maps from the case study mine are analyzed to determine a safe slope angle of 44 for the open pit mining operation the proposed method can be applied for quantifying other geotechnical risk and integrated within any stability analysis framework

an intensity ratio calibration method for the accurate determination of mg ca and sr ca of marine carbonates by icp aes an inductively coupled plasma atomic emission spectroscopy icp aes method for the accurate and precise simultaneous measurement of the mg ca and sr ca content of carbonates was established while a precision of 0 3 1 standard deviation sd is easily obtainable for both mg ca and sr ca analysis a ca matrix effect complicates achieving similar levels of accuracy with conventional calibration procedures an alternative ratio calibration procedure is proposed which overcomes the ca matrix effects and ensures the accuracy of the mg ca and sr ca analysis of marine carbonates to 0 3 almost an order of magnitude better than conventional calibration methods the longer term precision is 0 1 if the batch run average values are corrected for longer term drift the method is suitable for analysis of foraminiferal calcite and coral aragonite and can easily be adjusted for the analysis of other carbonates or microsamples

a new tool for palaeoclimate reconstruction noble gas temperatures from fluid inclusions in speleothems abstract the aim of our research is to apply the absolute palaeothermometer provided by dissolved noble gases in water to the reliably dated high resolution archive of speleothems here we report on methods used to extract and quantify water and noble gases from fluid inclusions in speleothems and the first successful derivation of noble gas temperatures ngts from this archive the water amount was determined manometrically whereas the low noble gas amounts were measured by mass spectrometry applying rigorous blank control gas was extracted by crushing either in a steel cylinder or in a copper tube with little heating which both yielded acceptably low blanks extraction in the steel cylinder is more efficient as a finer grain size distribution can be achieved a major problem is the often high contribution of noble gases from air inclusions masking the temperature information present in the noble gases dissolved in water filled inclusions however ngts with an uncertainty in the range of 1 c can be derived from suitable stalagmites with low air water ratios in the inclusions such favourable conditions were found to be present in stalagmites of milky white appearance suitable samples were collected from the stalagmites bu u bu 1 and a soda straw from the bunker cave in north west germany inverse modeling of measured ne ar kr and xe concentrations leads to a mean temperature of 2 9 0 7 c for all bu u sub samples with an age between 10 800 and 11 700 years and of 7 1 0 8 c for a 1300 years old sample from bu 1 compared to the modern mean annual air temperature at the investigated site of about 9 5 c the calculated temperatures appear rather low but not unreasonable as the ages correspond to comparatively cool periods around the younger dryas preboreal transition and the early middle ages respectively moreover the indicated temperature difference of about 4 c between the early and late holocene periods is in agreement with expectations

processes controlling colloid composition in a fractured and karstic aquifer in eastern tennessee usa abstract groundwater was sampled from a number of wells along recharge pathways between fractured shale and karstic formations to evaluate the chemical and hydrologic mechanisms controlling the nature and abundance of groundwater colloids the colloids recovered using low flow rate purging and sampling exhibited a composition and abundance consistent with lithology flow paths and effects of hydrology and aqueous chemistry on colloid mobilization and stability in general the larger size colloids and ca containing colloids were more abundant in the karstic lithologies while na containing colloids were more important in the shales the composition of the colloids reflected recharge pathways from the fractured shale and dolomite formations on the ridges into the limestone in the valley floor the mg colloids in the limestone reflect the possible contributions from the dolamite while the na k and si reflect possible contributions from the shale however it was not possible to use the colloid composition as a signature to demonstrate colloid transport from one lithology to another mixing of recharge water from the shale with groundwater within the limestone formation and precipitation dissolution reactions could account for the colloids present in the limestone without invoking transport of specific shale derived colloids into the limestone formation the abundance of colloids in groundwater appears to be controlled by both chemical factors affecting colloid stability as well as physical factors related to hydrology storm driven recharge and water velocities in general colloids were more abundant in wells with low ionic strength such as shallow wells in water table aquifers near sources of recharge at the top of the ridges increases in cation concentrations due to dissolution reactions along flow paths were associated with decreases in colloid abundance however in spite of elevated ionic strength colloid concentrations tended to be unexpectedly high in karstic wells that were completed in cavities or water bearing fractures the higher levels of colloids appear to be related to storm driven changes in chemistry or flow rates that causes resuspension of colloids settled within cavities and fractures

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

partitioning of strontium between calcite and fluid the sr ca ratio of biogenic carbonate is widely used as a proxy for paleotemperature this application is supported by empirical calibrations of sr ca as a function of temperature but it is also known that sr uptake in calcite gauged by kdsr is affected by other variables including bulk precipitation rate kdsr increases with increasing precipitation rate there are no data from controlled experiments specifically addressing the effect of radial growth rate of individual crystals on kdsr for this reason we conducted two series of experiments to explore sr partitioning at varying growth rates 1 growth from a cacl2 nh4cl srcl2 solution by diffusion of co2 from an ammonium carbonate source drift experiments and 2 drip precipitation of calcite on a substrate using a steady flow of cacl2 srcl2 and na2co3 solutions mixed just before passage through a tube and dripped onto a glass slide precoated with calcite cave type experiments the growth rates of individual crystals were determined by periodic monitoring of crystal size through time or roughly by comparison of the final size with the duration of the experiment electron microprobe analyses across sectioned crystals grown in the drift experiments show that the concentration of sr is high in the center where radial growth rates are highest and decreases systematically toward the edge the center to edge drop in sr concentration is a consequence of the slowing radial growth rate as individual crystals become larger in general high crystal growth rate v enhances sr uptake in calcite due to a type of kinetic disequilibrium we refer to as growth entrapment the apparent kdsr ranges from 0 12 to 0 35 as v increases from 0 01 nm s to 1 m s at 25 c

determination of multiple element calcium ratios in foraminiferal calcite by quadrupole icp ms a method has been developed for rapid and precise simultaneous determination of nine element ca ratios in foraminiferal tests directly from intensity ratios using external matrix matched standards on a quadrupole inductively coupled plasma mass spectrometer icp ms all quantification isotopes are determined in pulse mode to avoid cross calibration small argide 40ar26mg interferences on 66zn are corrected by using two additional mg and zn standards a stable signal conducive for high precision measurements is obtained by cone conditioning variable calcium concentration has negligible effect on li al mn and sr but ca concentrations for standards and samples need to be constrained at a similar level for precise measurements of zn cd and u aliquots of samples are first analyzed for ca concentrations on an inductively coupled plasma atomic emission spectrometer icp aes and the remaining solutions are diluted to ca concentration of 100 ppm for ratio measurements to assure data quality the long term reproducibility of the method yielded precisions of li ca 2 4 b ca 4 2 mg ca 1 4 al ca 14 mn ca 0 9 zn ca 2 8 1 2 7 8 mol mol and 5 1 0 5 1 2 mol mol sr ca 0 9 cd ca 2 4 0 07 0 24 mol mol and 4 8 0 01 0 07 mol mol and u ca 2 5 for foraminiferal samples as small as 60 g

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

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

comparative study of a stalagmite sample by stratigraphy laser induced fluorescence spectroscopy epr spectrometry and reflectance imaging abstract in the last few years it has been shown that multi proxy data are recorded in speleothems and that these secondary deposits can be used to retrieve records of environmental evolution in extra glacial continental conditions the goal of many current research is to obtain a better understanding of the processes leading to the growth of these chemical sediments and to relate them to changes in environmental conditions in the present research the multi proxy study of a well laminated speleothem sample points out the interest of reflectance trend measurement as a water excess indicator results from stratigraphy laser induced fluorescence spectroscopy epr spectrometry and reflectance imaging have been combined in order to get a better understanding of the environmental conditions pertaining during speleothem growth several parameters have been measured i mn 2 concentration evolution shown to be linked to soil processes ii linewidth h of the low field mn 2 epr line linked to crystalline properties of the speleothem iii intensities of the laser excited fluorescence linked to organic matter content of calcite and reflectance linked to calcite porosity iv wavelength peak of the intensity maximum of laser excited fluorescence bands linked to the size of trapped organic molecules other data resulting from statistical treatment of the annual fluorescence cycles have also been used significant correlations demonstrate the covariation of peak and calcite reflectance with the hydrological regime of the cave in the well drained soils of a karstic area mn 2 and peak appear to be accurate proxies for soil moisture evolution directly linked to the water excess these results are confirmed by the comparison with historical knowledge of environmental changes of the surrounding plateau

high resolution temporal record of holocene ground water chemistry tracing links between climate and hydrology strontium isotope analysis of precisely dated calcite growth layers in holocene speleothems from barbados west indies reveals high resolution temporal variations in ground water composition and may provide a new approach to documenting the links between climate variability andfluctuations in the hydrologic cycle such as recharge rates andflow paths the speleothems grew in a cave that developed in a fresh water aquifer in upliftedpleistocenereeflimestones threeperiodsofground watersrisotopeevolutionare observed 87 sr 86 srvaluesdecreasedfrom6to4ka increasedfrom4to1ka anddecreased again after 1 ka the sr isotope oscillations appear to record periodic variations in the relative sr fluxes to ground water from exchangeable soil sites vs carbonate mineral reactions asreflectedin 87 sr 86 srvaluesofmodernbarbadosgroundwaters ahydrologic model that explains changes in ground waterflow routes in karst aquifers as a function of amountofrainfallrechargecanaccountforthespeleothemsrisotoperecord independent holoceneclimaterecordsthatindicateamajorperiodofaridityataround1 3 1 1kainthe american tropics correspond with periodic variations in rainfall on barbados that are predicted by this hydrologic model

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

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

mg isotopic composition of carbonate insight from speleothem formation simultaneous high precision measurement of 24 mg 25 mg and 26 mg isotopic compositions were made by multiple collector inductively coupled mass spectrometry mc icp ms relative to the international standard srm980 data are presented on low mg calcite speleothems and their associated host rocks and waters from four caves one in the french alps and three in israel covering various climate conditions in addition data are presented on three dolostones and three limestones from the himalaya the overall variation is 4 13x and 2 14x in n 26 mg and n 25 mg respectively this is 35 times the uncertainty of the measurements and clearly demonstrates that the terrestrial isotopic composition of mg is not unique each speleothem shows a characteristic range of n 26 mg values that are attributed to the isotopic composition of the local water differences between the isotopic composition of mg in the water dripping from stalactites and that of the modern speleothem are interpreted as being due to mg isotopic fractionation during carbonate precipitation in the temperature range of 4 18 c the low mg calcite is enriched in light isotopes by 1 35x amu and the dependence on temperature has been found to be less than 0 02x amu c despite various geological settings the n 26 mg of the studied dolostones is 2 0 1 2x higher than the n 26 mg of the limestones all together these results suggest a strong mineralogical control and a weak temperature effect on the mg isotopic composition of carbonate a 2002 elsevier science b v all rights reserved

arc parallel extrusion of the timor sector of the banda arc continent collision structural studies of synorogenic basins in timor using field and remote sensing techniques provide new structural and geomorphic evidence for syn collisional extension in the converging plate boun

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

the hydrochemical response of cave drip waters to sub annual and inter annual climate variability wombeyan caves se australia abstract a thorough understanding of cave seepage waters is necessary to interpret geochemical variations in speleothem calcite in terms of changing surface climatic conditions at a particular site here we present the hydrochemistry of ten cave drip waters from a karst system in se australia based on up to 5 5 years of monitoring discharge was continuously measured at six sites and manually at the other sites dripwater samples were analysed for ph electrical conductivity cations and anions at all sites at monthly or more frequent intervals each drip possesses a unique chemistry and not all drip waters responded to antecedent short term hydrological variations for example the hydrochemical behaviour of three adjacent drips at a bedrock depth of 45 m was completely different to that of shallower sites and was apparently un related to surface hydrology throughout the investigation based on modelled calcite precipitation vectors prior calcite precipitation was demonstrated at several sites but can only be linked directly to changes in surface recharge at the shallowest sites at extremely low flow shallow drip waters accessed a high mg sr and ba source thought to be the overlying soil high frequency sample collection allows for the calculation of predicted mg ca calcite and sr ca calcite values highlighting that the sites with the greatest potential to record high resolution palaeohydrological records are those situated at shallow depth longer temporal resolution palaeohydrological records may be recorded at deeper sites but longer term monitoring is required to identify probable time scales inherent system non linearities dissolution of secondary calcite in pore spaces of the aquifer changes in the source of trace elements and the presence of multiple reservoirs confirm the need for the use of multiple speleothems and a multi proxy approach to gain accurate palaeohydrological records from this site

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

u th isotope systematics from the soreq cave israel and climatic correlations precise 230 th 234 u ages were obtained on thirty one growth laminae in speleothem samples which are self consistent with the detailed layer stratigraphy samples with low 232 th 238 u ratios give ages with analytical uncertainties of 40 years at 2 ky and 1000 years at 90 ky some growth zones with high but variable 232 th 238 u were dated by intermal isochrons this permits the determination of the initial 230 th 232 th assuming equilibrium of 232 th and 238 u series in the source of the high 232 th component this shows initial 230 th 232 th in activity units of from 1 3 to 2 9 the calculated atomic ratios of 232 th 238 u for the high 232 th component range from 1 08 to 2 4 which is well below the average crustal value speleothem materials with high 232 th 238 u are found to exhibit clear correlations of 232 th with si al and fe while 238 u correlates with sr and ba analyses of soreq cave drip waters show that the particulates in the waters have high 232 th concentrations and a 232 th 238 u ratio much lower than that found in the high 232 th component in speleothems but with 230 th 232 th 1 0 to 2 4 we infer that the trapped high th component in speleothems is from particulate matter in water with a large concentration of adsorbed u and not simply from detrital material the speleothems have only small234u excess the initial 234 u 238 u 0 show a range of 1 02 to 1 14 that was found to correlate with age over the past 25 ky the youngest samples have values in the same range as the modern drip waters there appears to be a correlation of 234 u 238 u 0 with the 18 o values there is a drop of 18 o in the time interval 20 to 15 ky which then remains relatively constant to recent times as the high 18 o values have been related to rainfall and associated climatic conditions we suggest that the 234 u 238 u in the speleothem reflects the effects of rainfall and soil weathering conditions on drip water composition and may provide a proxy for climate change

planktonic foraminiferal cd ca paleonutrients or paleotemperature records of cd ca in planktonic foraminiferal calcite of globigerinoides bulloides in cores from the subantarctic region of the southern ocean show large glacial interglacial variations with lower cd ca by 0 06 0 10 mol mol 1 at glacial times interpretation of these records in terms of lower dissolved phosphate and inferred higher glacial nutrient utilization has significant implications for glacial atmospheric carbon dioxide pco2 draw down however box core top data for g bulloides in the north atlantic suggest that the incorporation of cd into planktonic foraminifera relative to seawater dcd is temperature sensitive dcd 0 637 exp 0 15t when the subantarctic planktonic cd ca records are corrected for this temperature dependence they show little or no glacial interglacial diferences if as seems likely this observation can be interpreted to indicate a minimal change 0 5 mol kg 1 in surface water phosphate concentrations then the explanation for lowered glacial pco2 must be looked for elsewhere