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

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

rapid measurement of strontium in speleothems using core scanning micro x ray fluorescence abstract speleothem trace element ratios such as mg ca and sr ca are increasingly used in speleothem paleoclimatology as a supplement to stable oxygen and carbon isotope ratios as proxies for past variability in the hydrologic system using multiple proxies together allows for a better understanding of both the local and distal hydrologic changes recorded in speleothem chemistry and therefore of changes in past rainfall despite the potential benefits trace element analysis of speleothems has yet to become widespread which is likely due to the significant time and costs required by traditional trace element analytical techniques in this study we present an in depth investigation into a rapid relatively non destructive and competitively priced technique for measuring sr ca in speleothems core scanning micro x ray fluorescence cs xrf we show that cs xrf reliably and precisely records sr concentration in speleothems ratioed to near stoichiometric ca the sr ca ratio accounts for variations in beam strength and machine settings producing a more reliable reported measurement for both intra and inter run comparisons cs xrf compares favorably with more conventional trace element procedures such as quadrupole icp ms and icp aes giving confidence in the ability of cs xrf to produce paleoclimatologically significant sr ca results we also identify secondary issues relating to speleothem crystallinity the dominance of ca spectral peaks and comparatively lower energy x rays that can interfere with precise cs xrf analyses if these can be overcome then cs xrf may provide an even more useful method of trace element analysis in speleothem studies

reconstruction of holocene coupling between the south american monsoon system and local moisture variability from speleothem δ18o and 87sr 86sr records abstract investigating controls on past variability of south american hydroclimate is critical to assessing its response to future warming scenarios 18o records from south america offer insight into past variability of the south american monsoon system sams the controls however on precipitation 18o values can be decoupled from precipitation amount at a given site and thereby limit local moisture condition reconstructions here we use a principal components analysis to assess the coherence of speleothem and lake core holocene 18o records in tropical and subtropical south america to evaluate the extent to which 18o variability reflects changes in sams intensity at different sites across the region the main mode of variability across holocene 18o records pc1 closely tracks austral summertime insolation consistent with existing work sites towards the periphery of the continent are heavily weighted on pc1 whereas interior sites as not further 18o variability at interior sites bear little similarity to each other and implicate controls beyond regional monsoon intensity on these 18o records further we develop speleothem 87sr 86sr records spanning the holocene from tamboril cave brazilian highlands paraiso cave eastern amazon basin jaragua cave mato grosso do sul plateau and botuvera cave atlantic coastal plain to investigate coupling between reconstructed monsoon variability reflected by pc1 and local moisture conditions interpreted from 87sr 86sr records we interpret speleothem 87sr 86sr variability as a proxy of local moisture conditions reflecting the degree of water rock interaction with the cave host rock as driven by variations in water residence time speleothem 87sr 86sr records from all the sites except botuvera cave do not co vary with pc1 suggesting that local moisture conditions do not necessarily follow variations in regional monsoon intensity at these interior sites these speleothem 87sr 86sr records generally suggest dry mid holocene conditions relative to the early and late holocene consistent with interpretations of other paleo moisture records in the region but timing of wet dry transitions varies between sites these results highlight that controls in addition to sams variability might influence 18o variability further our results suggest spatially variable local moisture conditions at interior sites that do not uniformly respond to regional monsoon intensity and stress the need for 18o independent reconstructions of moisture conditions

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

sr isotope analysis of speleothems by la mc icp ms high temporal resolution and fast data acquisition abstract speleothems are well established climate archives a wide array of geochemical proxies including stable isotopes and trace elements are present within speleothems to reconstruct past climate variability however each proxy is influenced by multiple factors often hampering robust interpretation sr isotope ratios 87 sr 86 sr can provide useful information about water residence time and water mixing in the host rock as they are not fractionated during calcite precipitation laser ablation multi collector inductively coupled plasma mass spectrometry la mc icp ms has rarely been used for determination of sr isotope signatures in speleothems as speleothems often do not possess appropriately high concentrations of sr to facilitate this analysis yet the advantages of this approach include rapid data acquisition higher spatial resolution larger sample throughput and the absence of chemical treatment prior to analysis we present la mc icp ms sr isotope data from two speleothems from morocco grotte de piste and india mawmluh cave and we compare linescan and spot analysis ablation techniques along speleothem growth axes the analytical uncertainty of our la mc icp ms sr data is comparable to studies conducted on other carbonate materials the results of both ablation techniques are reproducible within analytical error implying that this technique yields robust results when applied to speleothems in addition several comparative measurements of different carbonate reference materials i e macs 3 jct 1 jcp 1 including tests with standard bracketing and comparison of the 87 sr 86 sr ratios with a nanosecond laser ablation system and a state of the art femtosecond laser ablation system highlight the robustness of the method

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

evidence of warm and humid interstadials in central europe during early mis 3 revealed by a multi proxy speleothem record abstract marine isotope stage 3 mis 3 57 27 ka was characterised by numerous rapid climate oscillations i e dansgaard oeschger d o events which are reflected in various climate archives so far mis 3 speleothem records from central europe have mainly been restricted to caves located beneath temperate alpine glaciers or close to the atlantic ocean thus mis 3 seemed to be too cold and dry to enable speleothem growth north of the alps in central europe here we present a new speleothem record from bunker cave germany which shows two distinct growth phases from 52 0 0 8 0 5 to 50 9 0 6 1 3 ka and 47 3 1 0 0 6 to 42 8 0 9 ka rejecting this hypothesis these two growth phases potentially correspond to the two warmest and most humid phases in central europe during mis 3 which is confirmed by pollen data from the nearby eifel the hiatus separating the two phases is associated with heinrich stadial 5 hs 5 although the growth stop precedes the onset of hs 5 the first growth phase is characterised by a fast growth rate and mg concentrations and sr isotope data suggest high infiltration and the presence of soil cover above the cave the second growth phase was characterised by drier but still favourable conditions for speleothem growth during this phase the 13c values show a significant decrease associated with d o event 12 the timing of this shift is in agreement with other mis 3 speleothem data from europe and greenland ice core data

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

middle and late pleistocene paleoscape modeling along the southern coast of south africa abstract changing climates environment and sea levels during the middle and late pleistocene must have had significant impacts on early modern humans and their behavior however many important archaeological sites occur along the current coastline of south africa where the gradual slope of the offshore agulhas bank meant that small changes to sea level height potentially caused significant shifts in coastline position the geographic context of these currently coastal sites would have been transformed by sea level shifts from coastal to near coastal to fully terrestrial to understand human adaptations as reflected in the archaeological deposits of these now coastal sites we need to accurately model coastline position through time here we introduce a paleoscape model as a conceptual tool to ground the records for human behavioral evolution within a dynamic model of paleoenvironmental changes using integrated bathymetric datasets gis and a relative sea level curve we estimate the position of the coastline at 1 5 ka increments over the last 420 000 years we compare these model predictions to strontium isotope ratios from speleothems as an independent test and then compare the coastline predictions to evidence for shellfish exploitation through time both tests suggest our model is relatively robust we then widen our paleoscape model to most of the cape region and compare the predictions of this broadened model to evidence from blombos cave

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

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

palaeohydrological significance of late quaternary strontium isotope ratios in a tropical lake ostracods preserved in late quaternary sediments of wallywash great pond a fresh coastal lake in sw jamaica record temporal variations in the strontium isotope composition of lake water oxygen isotope and sr ca ratios in ostracods reveal temporal variations in the lake s hydrology related to effective precipitation and in its salinity related to varying marine saline groundwater input from changes in relative sea level evaluation of isotopic and trace element data indicates that the stratigraphic variations in 87sr 86sr ratios during the late quaternary are best explained by climatically controlled hydrological changes during wetter periods the lake s sr budget was dominated by springwater input with relatively low 87sr 86sr ratio whereas during drier times reduced springflow possibly coupled with input of more radiogenic sr from other sources such as sea spray aerosols and perhaps saharan dust led to an increase in the sr isotope ratio of the lake water despite proximity of the lake to the sea and evidence for slight intrusion of marine saline groundwater in the past however the extent of marine input appears to have had limited influence on the lake s sr isotope ratios whereas the 87sr 86sr ratios cannot be used as a palaeosalinity proxy in this particular lake they do provide valuable information about the mechanisms underlying hydrological change

aeolian contribution to strontium and strontium isotope variations in a tasmanian speleothem abstract a speleothem from south central tasmania shows marked secular variations in its strontium content the element exhibits a striking bimodal distribution pattern with abrupt changes between two modal groups that is believed to be due to rapid changes in the direction of the dominant strong winds strontium isotope compositions in the speleothem range from 0 70865 to 0 70898 indicating derivation of sr from at least two distinct sources the first a persistent one from the overlying limestone the second a higher 87 sr 86 sr component probably representing input from terrestrial dust the speleothem record is unusual because it indicates a greater input of radiogenic sr dust flux during interstadial times than under full glacial conditions if an aeolian origin of some of the strontium contained in speleothems at other inland cave sites around the world can be confirmed variations in strontium isotope composition will provide high resolution records of how terrestrial dust flux has varied during the quaternary in near coastal sites significant amounts of strontium may be derived from seasalt and in those areas temporal variation of the element in speleothems may reflect at least in part changing distance from the coast due to changes in sealevel

dust impure calcite and phytoliths modeled alternative sources of chemical weathering solutes in shallow groundwater abstract in highly reactive carbonate terrains that constitute more than one fifth of critical zone landscapes quantifying bedrock weathering processes may require understanding the realities of carbonate mineral impurity on solubility biotically produced minerals as an integral part of leaky biogeochemical cycles and dust deposited minerals as important high surface area first contact solute sources the potential impact of these processes has not been thoroughly investigated as groundwater solutes are mostly thought to be sourced from chemical reactions with soil and bedrock although dust is often viewed as an important delivery mechanism of nutrients to other ecosystems including those in mountain and tropical settings we present results of computer and hand calculated manual inverse modeling of two years of stream water chemistry spanning a dry and a wet year for a groundwater fed headwater stream at the konza tallgrass prairie long term ecological research site in northeastern kansas weathering of the limestone and shale bedrock at the site provide a possible source of solutes to the groundwater fed stream but our modeling suggests an alternate source considering the pathway of groundwater recharge likely encounters highly reactive phases before encountering bedrock we used the mineralogy and geochemistry of local dust collected previously estimates of a possible chemical composition of phytolith containing potassium and an impure calcite representing measured limestone bedrock chemistry to show that chemical reactions with the current dust flux are adequate to account for the groundwater chemistry average annual amounts were about 1 380 kg ha 1 yr 1 dust dissolved 2 80 kg ha 1 yr 1 bedrock carbonate dissolved and 3 320 kg ha 1 yr 1 phytoliths precipitated small amounts of cation exchange were also required to balance the models there were only small differences between the computer and manual inverse models both methods resulted in up to 4 6 times more mass of dust dissolved than bedrock we suggest that dust weathering may be a process that occurs widely considering the ubiquitous dust flux in continental regions significance of research solutes in groundwater and in streams fed by groundwater are thought to be mostly derived from aquifer bedrock and soil water recharging the aquifer this paradigm may fail for landscapes that have been subaerially exposed for 10 s to 100 s of millions of years in terrains where relatively rapid dissolution of minerals dominates such as carbonate mineral dominated rocks like limestone here we test whether dust having high surface area and being the first inorganic solid encountered by meteoric precipitation could provide enough solutes water to reduce the amount of bedrock that dissolves extending the timeframe of landscape evolution we found through inverse modeling with phreeqc that dust can provide 4 6 times as much mass to stream water in merokarst than calcite and that the mass of dust dissolved was the same order of magnitude as local dust deposition these results give permissive evidence that dust is important to understanding groundwater chemistry

high resolution stratigraphy with strontium isotopes the isotopic ratio of strontium 87 to strontium 86 shows no detectable variation in present day ocean water but changes slowly over millions of years the strontium contained in carbonate shells of marine organisms records the ratio of strontium 87 to strontium 86 of the oceans at the time that the shells form sedimentary rocks composed of accumulated fossil carbonate shells can be dated and correlated with the use of high precision measurements of the ratio of strontium 87 to strontium 86 with a resolution that is similar to that of other techniques used in age correlation this method may prove valuable for many geological paleontological paleooceanographic and geochemical problems

tracing ground water evolution in a limestone aquifer using sr isotopes effects of multiple sources of dissolved ions and mineral solution reactions uplifted pleistocene coral reef terraces on barbados west indies constitute an aquifer that is built on low permeability tertiary pelagic rocks that overlie the barbados accretionary prism the downdip segments of the aquifer are composed of younger reef limestones that contain more aragonite and have higher 87sr 86sr and sr ca ratios than the updip parts of the aquifer ground waters and host limestones display similar stratigraphic trends in 87sr 86sr and sr ca the ground waters have lower 87sr 86sr values however indicating that they acquire a significant fraction of their dissolved sr through interaction with components of tertiary rocks which compose the underlying aquitard and parts of overlying soils geochemical modeling results indicate that ground water evolution is controlled by 1 variations in the age and composition of the aquifer and aquitard rocks and 2 the relative roles of calcite dissolution calcite recrystallization and the transformation of aragonite to calcite sr isotopes can provide unique information for tracing ground water evolution which requires consideration of the multiple components and processes that make up even relatively simple limestone aquifer systems

neodymium and strontium isotopic constraints on soil sources in barbados west indies abstract neodymium and strontium isotopic compositions and sm nd ratios are used to constrain the sources of silicate rich soils developed on uplifted pleistocene coral reef limestones on barbados west indies the geographic and geologic setting of barbados facilitates the application of these tracers to the evaluation of the following soil sources 1 pleistocene reef limestone regolith 2 tertiary carbonate rocks sandstones and mudstones that are exposed in northeastern barbados 3 volcanic ash erupted from the lesser antilles arc 4 saharan dust transported by trade winds and 5 fertilizer the soils have nd values that range from 6 6 to 1 9 87 sr 86 sr values of 0 70890 to 0 71067 and sm nd ratios of 0 223 0 260 the pleistocene limestone component is the most significant source of sr in the soils and a negligible source of nd comparison of sm and nd concentrations and neodymium isotopic compositions of soil samples that are weathered to varying extents indicates that sm and nd are relatively unfractionated and retained in the soils during weathering nd and sm nd variations in the soils therefore primarily reflect the compositions and proportions of the silicate sources mass balance calculations based on sm nd systematics require that the silicate soil components contain between 30 85 volcanic ash with the remaining silicate fraction comprised of old continentally derived sediment in contrast to sm and nd sr is mobilized and removed from the soils during weathering strontium from volcanic and carbonate sources is preferentially removed relative to continental silicate sources the strontium isotopic compositions of the soils therefore reflect the combined effects of the degree of weathering and the compositions and proportions of the soil sources mass balance calculations indicate that at least 35 60 of the initial sr in the soils has been removed by weathering these results illustrate 1 the utility of radiogenic isotopes in identifying and quantifying soil sources and weathering processes 2 the compositional influence of numerous sources on soils even those developed in a relatively isolated area such as barbados and 3 the domination of barbados soil sm nd systematics by nonregolith eolian components

effects of sea level rise and climatic changes on mangroves from southwestern littoral of puerto rico during the middle and late holocene abstract we evaluated the response to sea level rise and climatic changes of the northeastern caribbean by establishing a palaeoenvironmental reconstruction of the flamenco lagoon located in the coastal side of the guanica dry forest a mab unesco reserve in the semi arid southwestern coast of puerto rico 17 57 10 31 n 66 50 39 30 w the reconstruction was based on pollen records sediments analysis 13 c 15 n c n data and ams 14 c dating of one sediment core the geology of the area is rocky calcareous karst with rocky outcrops and canyons with intermittent streams that move water during periods of high run off conditions the present lagoon is surrounded by rocky outcrops where dry forest vegetation is present on the terrestrial sides and sand dunes on the coastal side we propose that the studied lagoon developed after the stabilization of sea level rise in the region following three main stages 1 before 5400 cal yr bp sediments were accumulated according to small channels dynamics and trees shrubs and herbs were present the sedimentary organic matter was mainly sourced from terrestrial c 3 and c 4 plants 2 between 5400 and 4400 cal yr bp tidal flats were established and mangroves mainly represented by rhizophora trees migrated landward with sea level rise and established in the area and the sedimentary organic matter was sourced from terrestrial c 3 plants 3 around 4400 cal yr bp sea level was near the stabilization the endorheic minibasin was closed when a coastal sand dune was established as a result of drier climatic conditions mangroves were eliminated from the system as a result of the closure of the area by sand dunes and increased salinity in water due to high evaporative demand of the climate the pollen dominance of herbaceous and shrubby vegetation prevails until present throughout the lagoon development sedimentary organic matter was sourced from c 3 and c 4 plants as well as phytoplankton organic matter the closure of the lagoon and the drier conditions prevalent in the region during the late holocene which lasts until the present day and increased the contribution of salinity tolerant phytoplankton that characterizes the current conditions of the flamenco lagoon

assessing response of local moisture conditions in central brazil to variability in regional monsoon intensity using speleothem 87 sr 86 sr values abstract delineating the controls on hydroclimate throughout brazil is essential to assessing potential impact of global climate change on water resources and biogeography an increasing number of monsoon reconstructions from 18 o records provide insight into variations in regional monsoon intensity over the last millennium the strength however of 18 o as a proxy of regional climate limits its ability to reflect local conditions highlighting the need for comparable reconstructions of local moisture conditions here speleothem 87 sr 86 sr values are developed as a paleo moisture proxy in central brazil to complement existing 18 o based reconstructions of regional monsoon intensity speleothem 87 sr 86 sr values are resolved using laser ablation and conventional solution mass spectrometry at high resolution relative to existing non 18 o based paleo moisture reconstructions to allow comparisons of centennial variability in paleo monsoon intensity and paleo moisture conditions variations in speleothem 87 sr 86 sr values from tamboril cave are interpreted to reflect varying extents of water interaction with the carbonate host rock with more interaction resulting in greater evolution of water isotope values from those initially acquired from the soil to those of the carbonate bedrock increasing speleothem 87 sr 86 sr values over the last millennium suggest progressively less interaction with the carbonate host rock likely resulting from higher infiltration rates expected under wetter conditions increasingly wetter conditions over the last millennium are consistent with an overall trend of increasing monsoon intensity decreasing 18 o values preserved in many existing 18 o records from the region such a trend however is absent in 18 o records from our site central brazil and cristal cave southeast brazil suggesting the existence of divergent relevant to 18 o precip shifts in the climate patterns within and outside the core monsoon region

combined records from a stalagmite from barbados and from lake sediments in haiti reveal variable seasonality in the caribbean between 6 7 and 3 ka bp abstract the growth of a well dated stalagmite from barbados records high infiltration rates into the karst aquifer and hence increased rainfall intensity between 6 7 and 3 ka bp in agreement with records from lake miragoane haiti hodell et al 1991 reconstruction of the caribbean climate change over the past 10 500 years nature 352 790 793 mainly reflecting the insolation maximum of the northern hemisphere both the lake record and the stable isotope record of the stalagmite reveal additional centennial variability of recharge high oxygen isotope values in stalagmite calcite corresponding to reduced recharge are synchronous with periods of lower stable isotope values recorded in lake miragoane ostracods previously attributed to enhanced precipitation accordingly periods of increased recharge in barbados correspond to 18o enriched isotope values of ostracods which were attributed to higher evaporation precipitation ratios in the lakes we ascribe this apparent discrepancy to changes in seasonality i e winter periods of reduced temperature and relative humidity following summer months of increased precipitation at present such climate conditions occur during periods of enhanced northern atlantic oscillation nao if enhanced seasonality is a consequence of a nao situation the apparent discrepancy of high isotope values in lakes previously attributed to droughts can be reconciled with lower winter temperatures in the lakes further the correlation of solar intensity derived from 14c and 10be with the isotopic signals recorded in the lacustrine sediments suggests a solar forcing of the nao during the mid holocene

tectonic relationships between forearc basin strata and the accretionary complex at bath barbados the island of barbados exposes the crestal zone of the accretionary prism of the lesser antilles forearc tertiary rocks at bath barbados include four lithic suites 1 inter bedded volcanogenic and mainly calcareous pelagic rocks the oceanic beds 2 radiolarite 3 siliceous hemipelagic rocks and 4 melange suites 1 3 are in structurally discrete groups of fault packets melange occurs in apparently diapiric crosscutting bodies the oceanic beds occupy a pre pleistocene nappe complex that underlies much of barbados radiolarite and hemipelagic rocks belong to a thick accretionary basal complex and constitute the relative autochthon to the oceanic nappes fault rocks of the sub oceanic fault zone developed during emplacement of the oceanic nappes the lower portion of the tectonic stack is deformed in a major south verging fold couple with wavelength of 250 m lower early emplaced oceanic nappes are restricted to the core of the major synform and are increasingly deformed with depth structures suggest easterly transport of oceanic nappes and upward younging of nappe emplacement indicating that the deformation of oceanic beds propagated westward the oceanic nappes provided a seal to rising fluids transport of nappes may have been facilitated by elevated fluid pressure beneath their sole thrust pre and post nappe folds record north south shortening about shallow west plunging axes consistent with folded accretionary strata elsewhere on barbados deformation occurred under shallow nonmetamorphic conditions the oceanic beds are interpreted as being trapped outer forearc basin strata that have been tectonically shouldered by the arcward migrating prism flank or crest the hemipelagic and radiolarite suites may be offscraped abyssal plain and trench wedge accumulations paleogene lower miocene oceanic strata were deposited at depths between 2 0 and 4 8 km middle miocene oceanic beds accumulated at shallower depths 1 1 5 km thus early miocene was the probable time of inception of major uplift and arcward shouldering in the crestal zone of the accretionary prism accretion of the basal complex of barbados probably occurred in late eocene time

paleoclimate implications of mass spectrometric dating of a british flowstone the timing of growth phases in a cave flowstone from yorkshire england has been precisely dated by thermal ionization mass spectrometric 238u 234u 230th dating six growth periods of both short duration and fast growth rate are separated by nondepositional hiatuses the ages of these phases were determined to be 128 8 2 7 103 1 1 8 84 7 1 2 57 9 1 5 49 6 1 3 and 36 9 0 8 ka there is a remarkably good correlation between the periods of active speleothem growth and the timing of solar insolation maxima derived from orbital parameters which has not previously been reported speleothem growth theory and evidence from other terrestrial paleoclimate records suggest that episodic rapid growth phases at the insolation maxima are most likely to be caused by changes in either precipitation intensity or volume which caused switching in the routing of water flow in the unsaturated zone above the cave such a result provides new evidence of the importance of variations in solar insolation for terrestrial paleoclimate and offers the potential for derivation of a paleowetness index from speleothem growth

the sahara east mediterranean dust and climate connection revealed by strontium and uranium isotopes in a jerusalem speleothem this paper explores the potential of sr and u isotope systems in speleothems as tracers of eolian dust transport and hydrological conditions the study focuses on a speleothem from jerusalem spanning the past 220 kyr this speleothem provides a precisely dated record of dust flux from the sahara to the east mediterranean enhanced dust flux and terra rossa soil development are reflected by elevated 87sr 86sr ratios in the speleothem 0 7082 0 7086 while lower 87sr 86sr ratios 0 7078 indicate higher contribution of the local bedrock due to low dust flux and low soil accumulation the strontium isotope system in the speleothem is a robust monitor of the sahara monsoon modulated climate since dust uptake is related to development or reduction in vegetation cover of sahara soil the 234u 238u activity ratios in the speleothem range between 1 12 and 1 0 the high activity values may indicate selective removal of 234u from the soil while the low values converge to the bedrock the migration of 234u to the cave reflects mainly the regional hydrological conditions that are modulated by the north atlantic mediterranean climate system thus the speleothem provides a combined record of the monsoon north atlantic climatic systems long term stability in glacial 87sr 86sr ratios 0 7083 0 0001 over the past 220 kyr suggests an overall similarity in eolian dust sources and uniformity in the synoptic conditions that dominate the dust storm tracks during glacial periods

ree3 and mn2 activated cathodoluminescence in lateglacial and holocene stalagmites of central europe evidence for climatic processes combined visual cathodoluminescence cl and spectral analyses of cl reveals periodic enrichments of rare earth elements ree3 and manganese mn2 within the laminations of eight calcitic lateglacial to postglacial stalagmites in the annual layers the enrichment of trace elements can be correlated with the autumn winter laminae which are strongly pigmented and rich in organic carbon during the holocene they occur especially in the atlantic stage and in subrecent recent times the enrichment of ree3 and mn reflects times of more intense weathering which presumably prevailed during the atlantic warm and humid climate in subrecent recent times especially the last 100 years these enrichments may have been at least partially anthropogenically induced

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

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

radiogenic isotopes systematics and applications to earth surface processes and chemical stratigraphy radiogenic isotopes have wide application to chemical stratigraphy geochronology provenance studies and studies of temporal changes in earth surface processes this paper briefly reviews the principles of radiogenic isotope geochemistry and the distribution of a number of elements of interest in the environment and then uses this information to explore the range of applications to chemical stratigraphy and other fundamental subjects of sedimentary geology many of these applications center on the reconstruction of secular variations in paleoseawater isotope signals these seawater isotope curves can be used for stratigraphic correlation and to assess changes through earth history in processes such as tectonic uplift climate change biogeochemical cycling ocean circulation crustal growth and surface water evolution understanding the modern biogeochemical cycle of the element isotope system of interest is essential for gaining the maximum information regarding the operation of ancient cycles the main sources of uncertainty for reconstructing seawater isotope curves involve diagenetic alteration sample impurities and errors in age assignments rigorous sample selection criteria and pretreatment methods are keys to reconstructing the most accurate seawater isotope curves applications are discussed for the rb sr sm nd la ce lu hf re os u th pb k ar and cosmogenic isotope systems d 2003 elsevier b v all rights reserved

prior calcite precipitation and source mixing process influence sr ca ba ca and 87sr 86sr of a stalagmite developed in southwestern japan during 18 0 4 5ka abstract we measured sr ca ba ca 87 sr 86 sr ratios 18 o and 13 c values in a stalagmite which developed 18 0 4 5 thousand years ago ka in southwestern japan dripwater and two major bedrocks limestone and andesite in the locality were also studied the 87 sr 86 sr ratios of the stalagmite are relatively homogeneous 0 706852 0 706921 suggesting a steady source mixing ratio of 40 from high 87 sr 86 sr limestone and 60 from low 87 sr 86 sr andesite the stalagmite sr ca and ba ca ratios were higher than the ratio expected from the dissolved fraction of limestone and andesite the covariance among sr ca ba ca and 13 c profiles suggests a significant role of prior calcite precipitation pcp i e carbonate precipitation from infiltrating water before the water drips on a stalagmite the relationships among stalagmite sr ca ba ca ratios and 13 c values are consistent with the rayleigh type fractionation model supporting that pcp results in successive enrichment of sr ba and 13 c in the aqueous phase and the resulting stalagmite the degree of pcp calculated for the stalagmite is highly variable from 0 to 85 and generally decreased from the last glacial period to the middle holocene the large degree of pcp observed during 18 15 ka implies a relatively dry climate during this period which is consistent with weak monsoon intensity inferred by the 18 o values the 87 sr 86 sr ratios of the stalagmite show a slight decrease through the entire period the increase in the andesite derived fraction with relatively high 87 sr 86 sr may result from accelerated silicate weathering in the epikarst with increasing temperature humidity and soil p co 2

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

time series δ26mg analysis in speleothem calcite kinetic versus equilibrium fractionation comparison with other proxies and implications for palaeoclimate research abstract magnesium isotope time series mc icp ms analyses from a pleistocene speleothem collected in a limestone cave in nw africa morocco are reported and discussed in a process oriented context in addition high resolution c o and sr isotope data and mg and sr element abundances were compiled from the same stalagmite sub samples were collected along the stalagmite growth axis and a second data set was drilled perpendicularly within one growth interval hendy test the analytical results show clearly co variant systematic and cyclical fluctuations for all proxies collected along the growth axis and with respect to the analytical error invariant data within one growth increment magnesium isotope ratios 26 mg fluctuate between 4 39 0 02 2 and 4 17 0 05 2 and are within the range of published results of speleothem calcite from limestone caves the difference of 0 22 is significantly beyond the error of the external reproducibility of 0 03 2 for 26 mg considering the analytical error neither a purely kinetic nor an equilibrium fractionation process explains the observed isotope pattern for the time being it is suggested that two external factors drive the speleothem mg isotope cyclicity 1 climate driven arid versus humid variances in the precipitation rate of a carbonate phase from meteoric water within the karstic system prior to entering the cave system and 2 changing rates of silicate aeolian material versus carbonate weathering both of these processes fractionate the mg isotopic composition of runoff seepage water there is evidence that the magnesium isotope system applied to speleothem archives bears significant information concerning continental climatic variability in arid zones and deserves further research

leaf wax biomarkers in transit record river catchment composition rivers carry organic molecules derived from terrestrial vegetation to sedimentary deposits in lakes and oceans storing information about past climate and erosion as well as representing a component of the carbon cycle it is anticipated that sourcing of organic matter may not be uniform across catchments with substantial environmental variability in topography vegetation zones and climate here we analyze plant leaf wax biomarkers in transit in the madre de dios river peru which drains a forested catchment across 4 5 km of elevation from the tropical montane forests of the andes down into the rainforests of amazonia we find that the hydrogen isotopic composition of leaf wax molecules specifically the c28 n alkanoic acid carried by this tropical mountain river largely records the elevation gradient defined by the isotopic composition of precipitation and this supports the general interpretation of these biomarkers as proxy recorders of catchment conditions however we also find that leaf wax isotopic composition varies with river flow regime over storm and seasonal timescales which could in some cases be quantitatively significant relative to changes in the isotopic composition of precipitation in the past our results inform on the sourcing and transport of material by a major tributary of the amazon river and contribute to the spatial interpretation of sedimentary records of past climate using the leaf wax proxy

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

application of sr isotopes in secondary silicate minerals to paleogroundwater hydrology an example from k metasomatized rocks in the western u s abstract strontium isotope analyses of secondary silicate minerals represent a largely unexploited method of investigating paleogroundwater hydrology guided by cathodoluminescent imaging we obtained sr isotopic data from physical microsamples of primary and secondary silicate minerals in a k metasomatized mid tertiary ash flow tuff at socorro new mexico the intent was to test the utility of silicate sr isotopic data in paleohydrologic studies and to assess models for the basin scale paleogroundwater flow responsible for the k metasomatism in the socorro area secondary adularia in the upper lemitar tuff from a location at the southwestern extent of k metasomatized rocks contain sr with significantly higher 87 sr 86 sr ratios 0 720 than igneous feldspars 0 709 at the approximate time of the late cenozoic metasomatism 6 ma estimates of saline brine 87 sr 86 sr ratios obtained from late cenozoic evaporites in the region are much lower 0 712 than the adularia values and suggest that such brines were not responsible for the k metasomatism in this area groundwaters that had passed through high 87 sr 86 sr precambrian rocks prior to entering the tuffs are more likely k metasomatizing fluids but isotopic data from altered upper lemitar tuff from throughout the socorro area are required to fully test this possibility

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

87sr 86sr and sr ca in speleothems for paleoclimate reconstruction in central china between 70 and 280 kyr ago limestone cave deposits speleothems provide archives for past changes in regional climates over a range of timescales while 18o and 13c in speleothem calcite have been commonly used for reconstruction of paleoclimates we report here further efforts in the use of 87sr 86sr and sr ca signals in speleothem calcite to deduce paleomonsoon variability near the loess plateau of central china a two end member mass balance model of concentration and isotopic composition of strontium in a cave system is used to estimate variation of the 87sr 86sr ratio in sediments overlying a limestone cave we show that this ratio reflects climate driven variations in the provenance and the extent of chemical weathering of the epikarstic sediments the measurements of 87sr 86sr made on a well dated stalagmite sfl from buddha cave 33o40n 109o05 e show ratios of 0 71092 to 0 71133 0 00001 as 2 during relatively cold periods e g marine isotope stage mis 5b 5d and 8 lower than ratios of 0 71133 to 0 71194 during relatively warm periods e g mis 5a 5c 5e and 7 as changes in the sr ca ratio may affect speleothem 87sr 86sr we show that the direct use of speleothem 87sr 86sr is less ideal than our modeled 87sr 86sr for the exogenic sr source above the cave as a paleomonsoon proxy using the 18o 13c sr ca and 87sr 86sr records of the stalagmite we reconstruct the variability of the east asian monsoon for the time period between 70 and 280 kyr ago the results show that summer monsoons were more intense during interglacial periods than during glacial periods

the isotopic record of ocean chemistry and diagenesis preserved in non luminescent brachiopods from mississippian carbonate rocks illinois and missouri fossil brachiopod shells are commonly used as a faithful record of the chemical and isotopic composition of the ancient ocean water in which they grew owing to their stable mineralogy and their presence in marine strata throughout phanerozoic time the utility of these fossils for preserving ocean water compositions is evaluated through analyses of multiple specimens that grew in contemporaneous sea water at individual stratigraphic horizons in the mississippian age burlington keokuk formation of mid continent north america significant variations in sr c and o isotopic compositions are observed in contemporaneous non luminescent shells indicating that apparently pristine brachiopod shell material has been altered by post depositional processes of diagenesis the least altered compositions at each horizon are used to estimate secular variations of 87 sr 86 sr in early mississippian ocean water the estimated rates of change of ocean water 87 sr 86 sr are comparable in magnitude to the rapid sr isotopic changes documented for cenozoic ocean water for which high frequency glacial cycles are inferred as a driving mechanism the rigorous assessment of diagenetic effects on the isotopic signatures of marine phases is requisite for the advancement of high resolution reconstructions of paleo ocean chemistry

the timing of high sea levels over the past 200 000 years the 230 th ages and 234 u 238 u ratios were determined for barbados corals that grew during periods of high sea level within the last 200 000 years the similarity of the initial 234 u 238 u ratios of some of the corals to the modern marine value suggests that these samples are pristine and that the marine 234 u 238 u ratio 83 000 and 200 000 years ago was within 2 per mil of the modern value the accuracies of the 230 th ages are evaluated on the basis of the 234 u 238 u values and a model of the behavior of uranium and thorium isotopes during diagenesis for the last three interglacial and two intervening interstadial periods sea level peaked at or after peaks in summer insolation in the northern hemisphere this overall pattern supports the idea that glacial interglacial cycles are caused by changes in earth9s orbital geometry the sea level drop at the end of the penultimate interglacial the last interglacial and a subsequent interstadial period lagged behind the decrease in insolation by 5 000 to 10 000 years

petrography strontium barium and uranium concentrations and strontium and uranium isotope ratios in speleothems as palaeoclimatic proxies soreq cave israel the reconstruction of the palaeoclimate of the eastern mediterranean region for the last 60 ka bp is based on the 18o and 13c variations of speleothems from soreq cave israel climatic conditions during most of the time interval between 60 and 17 ka bp the period equivalent to the last glacial were relatively cold and dry while they were warmer and wetter from 17 ka bp to the present at 17 ka bp there was a major climatic change with a sharp increase in annual rainfall and temperature and a very wet period occurring between 8 5 and 7 0 ka bp during the colder and drier period large detritus free preferentially oriented calcite crystals were deposited from slow moving water as a result of a sharp change in the hydrological regime at 17 ka bp fast moving water started entrainment of the soil and carrying detrital material into the cave and the calcite crystals deposited became small and anhedral coinciding with the petrographic and isotopic changes a sharp drop occurred in the concentration

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

springwater geochemistry at honey creek state natural area central texas implications for surface water and groundwater interaction in a karst aquifer summary a two and a half year study of two adjacent watersheds at the honey creek state natural area hcsna in central texas was undertaken to evaluate spatial and temporal variations in springwater geochemistry geochemical evolution processes and potential effects of brush control on karst watershed hydrology the watersheds are geologically and geomorphologically similar and each has springs discharging into honey creek a tributary to the guadalupe river springwater geochemistry is considered in a regional context of aquifer components including soil water cave dripwater springwater and phreatic groundwater isotopic and trace element variability allows us to identify both vadose and phreatic groundwater contributions to surface water in honey creek spatial and temporal geochemical data for six springs reveal systematic differences between the two watersheds springwater sr isotope values lie between values for the limestone bedrock and soils at hcsna reflecting a balance between these two primary sources of sr sr isotope values for springs within each watershed are consistent with differences between soil compositions at some of the springs consistent temporal variability in springwater geochemistry sr isotopes mg ca and sr ca values appears to reflect changes in climatic and hydrologic parameters rainfall recharge that affect watershed processes springwater geochemistry was unaffected by brush removal at the scale of the hcsna study results of this study build on previous regional studies to provide insight into watershed hydrology and regional hydrologic processes including connections between surface water vadose groundwater and phreatic groundwater

late pleistocene california droughts during deglaciation and arctic warming abstract recent studies document the synchronous nature of shifts in north atlantic regional climate the intensity of the east asian monsoon and productivity and precipitation in the cariaco basin during the last glacial and deglacial period yet questions remain as to what climate mechanisms influenced continental regions far removed from the north atlantic and beyond the direct influence of the inter tropical convergence zone here we present u series calibrated stable isotopic and trace element time series for a speleothem from moaning cave on the western slope of the central sierra nevada california that documents changes in precipitation that are approximately coeval with greenland temperature changes for the period 16 5 to 8 8 ka from 16 5 to 10 6 ka the moaning cave stalagmite proxies record drier and possibly warmer conditions signified by elevated 18 o 13 c mg sr and ba and more radiogenic 87 sr 86 sr during northern hemisphere warm periods bolling early and late allerod and wetter and possibly colder conditions during northern hemisphere cool periods older dryas inter allerod cold period and younger dryas moaning cave stable isotope records indicate that wet conditions persisted in this area well beyond 11 5 ka suggesting the effects of the younger dryas event may have been longer lived in the western sierra nevada than in greenland however a shifting drip center and corresponding change in seepage water routing may have influenced the trace element records between 10 6 and 9 6 ka linkages between northern high latitude climate and precipitation in the sierra nevada suggested here could indicate that under conditions of continued global warming this drought prone region may experience a reduction in pacific sourced moisture

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

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

paleoenvironmental evidence for first human colonization of the eastern caribbean abstract identifying and dating first human colonization of new places is challenging especially when group sizes were small and material traces of their occupations were ephemeral generating reliable reconstructions of human colonization patterns from intact archaeological sites may be difficult to impossible given post depositional taphonomic processes and in cases of island and coastal locations the inundation of landscapes resulting from post pleistocene sea level rise paleoenvironmental reconstruction is proving to be a more reliable method of identifying small scale human colonization events than archaeological data alone we demonstrate the method through a sediment coring project across the lesser antilles and southern caribbean paleoenvironmental data were collected informing on the timing of multiple island colonization events and land use histories spanning the full range of human occupations in the caribbean from the initial forays into the islands through the arrival and eventual domination of the landscapes and indigenous people by europeans in some areas our data complement archaeological paleoecological and historical findings from the lesser antilles and in others amplify understanding of colonization history here we highlight data relating to the timing and process of initial colonization in the eastern caribbean in particular paleoenvironmental data from trinidad grenada martinique and marie galante guadeloupe provide a basis for revisiting initial colonization models of the caribbean we conclude that archaeological programs addressing human occupations dating to the early to mid holocene especially in dynamic coastal settings should systematically incorporate paleoenvironmental investigations

the eastern mediterranean paleoclimate as a reflection of regional events soreq cave israel the climate of the eastern mediterranean region of the last 60 ky was determined by a high resolution study of the oxygen and carbon isotopic composition 1500 measurement pairs of speleothems from the soreq cave israel with chronology provided by 53 precise 230 th 234 u tims ages the high precision of the speleothem tims ages permits us to determine the timing of regional climatic events in the eastern mediterranean region and to see if they correlate with global events during the period from 60 to 17 ky the 18 o and 13 c values were generally 2 2 5 higher than during the period from 17 ky to present this is consistent with the climatic transition from glacial to interglacial within the 60 to 17 ky period the soreq cave stable isotope profile includes four cold peaks at 46 35 25 and 19 ky and 2 warm peaks at 54 and 36 ky in addition the period 17 ky has two more cold peaks at 16 5 and from 13 2 to 11 4 ky the ages of four of the six cold peaks correlate well with the ages of three heinrich events h1 h2 h5 and with the age of the younger dryas however the other two heinrich events are not reflected in the soreq cave record several other isotope peaks which appear during the last 7 ky are contemporaneous with regional climatic events in the middle east and north africa in addition to the drop in 18 o and 13 c observed between the last glacial and the holocene sharp simultaneous drops in 234 u 238 u 0 ratios sr concentrations and in 87 sr 86 sr are also observed suggesting that the latter are climate related these variations are interpreted in terms of major changes in the temperature the mean annual rainfall and its isotopic composition the isotopic composition of the mediterranean vapor source the soil moisture conditions and in the mixing proportions of sources with different 87 sr 86 sr ratios sea spray dust particles and dolomitic host rock

man and environment in the territory of sagalassos a classical city in sw turkey abstract since 1990 archaeological research by the catholic university of leuven belgium has been carried out at the ancient site of sagalassos a lasun burdur province southwestern turkey at first research focused on the excavation of the city and the study of the immediate vicinity which provided it with raw materials the main objective was to obtain a clear picture of the history and development of the city since 1993 research has also incorporated a study of the territory of the roman city from prehistoric to modern times in order to understand why the site was selected for settlement why it developed into a middle sized town its economy and subsistence how it affected and exploited the environment its decline and what changes have taken place in the district subsequently the focus has now shifted towards obtaining a better understanding of the linkages between human and environment systems so that inter relations between the two can be more readily understood as a result a number of environmental topics concerning the territory of the roman city are presently being studied this territory extended from lake burdur in the west to the aksu canyon in the east from the a lasun da lari in the north to mt kestel in the south interdisciplinary research revealed that for the early neolithic and the roman period there was a slightly warmer climate a richer vegetation and more fertile soils for agricultural practice

last glacial warm events on mount hermon the southern extension of the alpine karst range of the east mediterranean abstract this study focuses on warm last glacial episodes in the southernmost extension of the alpine karst range of the eastern mediterranean levant region through the study speleothems in mizpe shelagim cave located in mt hermon the alpine karst range extends from turkey through syria and lebanon reaching its southern limit in mt hermon at an elevation of more than 2000 m under present day conditions southern mt hermon receives 1000 2000 mm precipitation mostly as snow that originates in the eastern mediterranean sea speleothems deposition in this high altitude region was continuous during interglacials but during the last glacial growth only occurred when average annual temperatures exceeded 3 c as inferred from the study of speleothem fluid inclusions warming episodes occurred at 65 ka 56 ka 54 5 ka 52 5 51 ka 49 ka 42 ka and 36 ka and are coincident with maximum insolation at 65 n the main depositional period from 56 ka to 51 ka coincides with dansgaard oeschger interstadial 15 and 14 and warming in the northeastern basin of the mediterranean sea warming in the southern alpine karst range of the eastern mediterranean was manifested by vegetation development together with significant snow melting that resulted in the drainage of large amount of water to the dead sea rift valley

annual to sub annual resolution of multiple trace element trends in speleothems this study aims to establish evidence for the widespread existence of preserved high resolution trace element variations in speleothems that may have climatic significance ion microprobe analysis of speleothems reveals that annual to sub annual variations in element chemistry exist at five shallow western european cave sites crag cave county kerry and ballynamintra county waterford ireland uamh an tartair sutherland scotland grotte pere noel belgium grotta di ernesto ne italy with widely varying climatic geomorphic and geological settings the variations are not restricted to species mg sr and ba known to substitute directly for ca in the calcite lattice but include h f na and p phosphorus as phosphate displays the greatest variability and may have the most significance as a proxy for the seasonal temperature cycle because of its role as a nutrient element the technique allows estimation of growth rate of speleothems at any interval of interest which is one of several possible uses in palaeoclimatology

hydrologic and climatic implications of stable isotope and minor element analyses of authigenic calcite silts and gastropod shells from a mid pleistocene pluvial lake western desert egypt abstract authigenic calcite silts at wadi midauwara in kharga oasis egypt indicate the prolonged presence of surface water during the marine isotope stage 5e pluvial phase recognized across north africa exposed over an area of 4 25 km 2 these silts record the ponding of water derived from springs along the libyan plateau escarpment and from surface drainage the 18 o values of these lacustrine carbonates 11 3 to 8 0 pdb are too high to reflect equilibrium precipitation with nubian aquifer water or water of an exclusively atlantic origin mg ca and sr ca of the silts have a modest negative covariance with silt 18 o values suggesting that the water may have experienced the shortest residence time in local aquifers when the water 18 o values were highest furthermore intra shell 18 o sr ca and ba ca analyses of the freshwater gastropod melanoides tuberculata are consistent with a perennially fresh water source suggesting that strong evaporative effects expected in a monsoonal climate did not occur or that dry season spring flow was of sufficient magnitude to mute the effects of evaporation the input of a second isotopically heavier water source to aquifers possibly indian ocean monsoonal rain could explain the observed trends in 18 o and minor element ratios

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

multi proxy evidence for human induced deforestation and cultivation from a late holocene stalagmite from middle java indonesia abstract speleothem multi proxy records have proved highly useful in reconstructing past changes in climatic and environmental conditions as well as karst processes and in distinguishing between the numerous potential driving forces that influence these proxies there is lack of such terrestrial proxies from the tropical indo pacific for the first time we present an annual to decadal scale multi proxy record of 377 samples including stable isotopes 18o 13c and trace elements mg ca sr ca from a holocene calcite stalagmite from bribin cave gunung kidul regency middle java indonesia that has grown over the last 4000 years 11 230th dates 18o values average 7 with high frequency variability of up to 1 and hint at relatively stable overall climatic conditions in the tropical indo pacific region during the late holocene the 13c values of stalagmite jb2 are low 13 at the beginning of the record suggesting a c3 dominated rainforest cover strong positive covariation with mg ca and sr ca ratios is a stringent indication of a dominant natural control by prior calcite precipitation and water rock interaction however 13c values increase dramatically by 4 from 1 1 ka to 0 5 ka clear evidence of an anthropogenic influence through deforestation and cultivation

estimating recharge in a tropical karst aquifer unique constraints on seasonal and spatial variations in recharge to the pleistocene limestone aquifer of barbados are obtained from the analysis of oxygen isotopic compositions of groundwater and rainwater conventional methods of estimating recharge are based on groundwater chloride variations coastal groundwater discharge and potential evapotranspiration these methods typically yield estimates of recharge for barbados that range from 9 to 20 of average annual rainfall with significant uncertainties that arise from poorly constrained model input parameters owing to the low relief and tropical climate of barbados variations in rainwater and groundwater 18o values are primarily influenced by the amount of rainfall with negligible temperature or altitude effects composite monthly rainwater 18o values are inversely related to rainfall while groundwater 18o values show little seasonal variability rainwater 18o values are equivalent to groundwater values only at the peak of the wet season by using mass balance the difference between groundwater and weighted mean rainwater 18o values gives recharge values these values are in general agreement with estimates by conventional methods 10 20 and provide unique additional information including the following 1 recharge is restricted to the wettest 1 3 months of the year and 2 there is less recharge at higher elevations the effective shift in 18o values between contemporaneous rainwater and groundwater via recharge is a useful tool for estimating temporal and spatial variability in recharge and must be considered in paleoclimatic studies where climate inferences are based on groundwater 18o values preserved in the geologic record

distinct climate change synchronous with heinrich event one recorded by stable oxygen and carbon isotopic compositions in stalagmites from china abstract uranium series dating of oxygen and carbon isotope records for stalagmite sj3 collected in songjia cave central china shows significant variation in past climate and environment during the period 20 10 ka stalagmite sj3 is located more than 1000 km inland of the coastal hulu cave in east china and more than 700 km north of the dongge cave in southwest china and despite minor differences displays a clear first order similarity with the hulu and dongge records the coldest climatic phase since the last glacial maximum which is associated with the heinrich event 1 in the north atlantic region was clearly recorded in sj3 between 17 6 and 14 5 ka in good agreement in timing duration and extent with the records from hulu and dongge caves and the greenland ice core the results indicate that there have been synchronous and significant climatic changes across monsoonal china and strong teleconnections between the north atlantic and east asia regions during the period 20 10 ka this is much different from the holocene optimum which shows a time shift of more than several thousands years from southeast coastal to inland china it is likely that temperature change at northern high latitudes during glacial periods exerts stronger influence on the asian summer monsoon relative to insolation and appears to be capable of perturbing large scale atmospheric oceanic circulation patterns in the northern hemisphere and thus monsoonal rainfall and paleovegetation in east asia climatic signals in the north atlantic region propagate rapidly to east asia during glacial periods by influencing the winter land sea temperature contrast in the east asian monsoon region