travertines associated with the alhama jaraba thermal waters ne spain genesis and geochemistry abstract freshwater carbonates are interesting archives in palaeoenvironmental reconstructions however more studies of those systems are needed to fully understand past environments in this work the actively forming travertines of the alhama jaraba thermal system were studied for the first time in order to evaluate the relationship between the geochemical and mineralogical composition and the environmental conditions during their formation with that aim a combination of petrographical mineralogical geochemical and stable isotope analyses were carried out these carbonates provide a natural laboratory for the study of the effect of different variables natural and anthropogenic on carbonate precipitation the results showed that there is a close relationship between the mineralogy of the solid precipitates and the formation temperature and only the samples formed from overheated waters 40 60 c show significant concentrations of aragonite aragonite bearing samples show higher concentrations in sr ba and u while calcitic solids are enriched in mg these differences could be attributed to mineralogy temperature or different precipitation rates the geochemical evaluation of the chemistry of both the solids and their parental waters suggests that differences in the rate of co 2 degassing and in some cases evaporation are the primary environmental controls on isotopic compositions in addition the results show that if strong evaporation and co 2 degassing are involved calcite precipitation occurs under conditions of isotopic disequilibrium with its parental water the results of our study are useful to interpret old depositional environments and palaeotemperatures

sedimentology and geochemistry of a human induced tufa deposit implications for palaeoclimatic research geochemical variations across laminated tufas and travertines may reflect the growth style of the carbonate build up and not just climate related changes this work presents the study of a carbonate deposit formed on a ravine wall in gran canaria island spain from a broken pipe system used for irrigation of banana plantations the deposit is a few tens of metres long and has a stepped morphology formed by successive cascade barriers and pools the main facies are framestones of coated stems laminated bindstones phytoclastic wackestones and silty mudstones all of which display micritic or coarse crystalline textures lamination from a framestone with coarse crystalline texture was studied from a petrological sedimentological and geochemical perspective and water palaeotemperatures were calculated lamination displaying five orders of magnitude from daily to annual or higher was controlled by the discontinuous supply of water lamination consists of crystalline laminae discontinuity couplets at all observed scales estimated mean precipitation rates are 0 7 mm year 1 but discontinuity of sedimentation at all lamination orders may have involved greater precipitation rates whereas elemental geochemistry suggests variable conditions not far from chemical equilibrium stable isotopes suggest that calcite precipitated under disequilibrium conditions however the small dimensions of the deposit and the relatively high flow velocities allowed lack of 13c and 18o isotope fractionation in co2 nor in calcite leading to independent temperature calculations both with mean values of 25 c isotopic trends found throughout lamination cannot be explained by strong changes in water temperature nor in 13cdic or 18ow the correction made to eliminate these isotopic trends yielded narrower temperature ranges this paper discusses the accuracy of temperature estimations despite the difficulties coming from disequilibrium and how isotopic trends through time could be explained by the growth of the deposit and not by climate related changes

climate and vegetation history of the midcontinent from 75 to 25 ka a speleothem record from crevice cave missouri usa four missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago ka the thorium 230 dated records reveal that between 75 and 55 ka the midcontinental climate oscillated on millennial time scales between cold and warm and vegetation alternated among forest savanna and prairie temperatures were highest and prairie vegetation peaked between 59 and 55 ka climate cooled and forest replaced grassland at 55 ka when global ice sheets began to build during the early part of marine oxygen isotope stage 3

carbon and oxygen isotope study of the active water carbonate system in a karstic mediterranean cave implications for paleoclimate research in semiarid regions abstract in a semiarid climatic zone such as the eastern mediterranean region annual rainfall variations and fractionation processes in the epikarst zone exert a profound influence on the isotopic compositions of waters seeping into a cave consequently the isotopic compositions of speleothems depositing from cave waters may show complex variations that need to be understood if they are to be exploited for paleoclimate studies this is confirmed by a four year study of the active carbonate water system in the soreq cave israel the 18o smow values of cave waters range from 6 3 to 3 5 the highest 18o values occur at the end of the dry season in waters dripping from stalactites and reflect evaporation processes in the epikarst zone whereas the lowest values occur in rapidly dripping fast drip waters at the peak of the rainy seasons however even fast drip waters are about 1 5 heavier than the rainfall above the cave which is taken to reflect the mixing of fresh with residual evaporated water in the epikarst zone 13c pdb values of dissolved inorganic carbon dic vary from 15 6 to 5 4 with fast drip waters having lower 13c values mostly 15 6 to 12 and higher dic concentrations relative to pool and stalactite drip water the low 13c values of fast drip waters and their supersaturation with respect to calcium carbonate indicates that the seepage waters have dissolved both soil co2 derived from overlying c3 type vegetation and marine dolomite host rock the 18o pdb values of various types of present day low magnesium calcite lmc speleothems range from 6 5 to 4 3 and 13c values from 13 to 5 5 and are not correlated with speleothem type an analysis of 18o values of present day calcite rafts and pool waters shows that they form in oxygen isotope equilibrium similarly the measured ranges of 13c and 18o values for all types of present day speleothems are consistent with equilibrium deposition at cave temperatures the 13c 18o range of contemporary lmc thus reflects the variations in temperatures and isotopic compositions of the presentday cave waters the 10 variation in the 13c values in waters can be modeled by a simple rayleigh calculation of the carbon isotope fractionation accompanying co2 degassing and carbonate precipitation these variations may obscure the differences in the carbon isotopic composition of speleothems that could arise when vegetation cover changes from c3 to c4 type plants this consideration emphasizes that it is necessary to characterize the full range of 13c values associated with contemporaneous speleothems in order to clarify the effects of degassing from those due to differing vegetation types isotopic studies of a number of different types of fossil lmc speleothems show many of them to exhibit isotopic trends that are similar to those of present day lmc but others show both higher and lower 18o ranges in particular the higher 18o range has been shown by independent age measurements to be associated with a period of drier conditions the results of the study thus indicate that it is necessary to work on a well calibrated cave system in semiarid climates and that the fossil speleothem record should be obtained from different types of contemporaneous deposit in order to fully characterize the 18o 13c range representative of any given climatic period

intra annual perturbations of stable isotopes in tufas effects of hydrological processes abstract tufas which are freshwater carbonates are potential archives of terrestrial paleoclimate time series of stable isotopic compositions commonly show regular seasonal patterns controlled by temperature dependent processes and some perturbation intrinsic to the locality we examined three tufa depositing sites in southwestern japan with similar temperate climates to understand the origin of local characteristics in the isotopic records seasonal change in the oxygen isotope is principally reflected by temperature dependent fractionation between water and calcite but was perturbed after heavy rainfalls overwhelming the stability of the 18o value of the groundwater at one site isotopic mass balance indicates an undersaturated and relatively small aquifer at this locality water 18o values at the other two sites were stable reflecting a regular seasonal change in the 18o value of tufa perturbation of the 13c values in tufa is largely due to co2 degassing from the stream which significantly increases the 13c values of dissolved inorganic carbon dic at a site with remarkably high pco2 in springwater and a sensitive response of flow rate to rainfall the amount of co2 degassing changed distinctly with flow rate in contrast the other two sites having low pco2 springwater reflect a regular seasonal pattern of 13c in dic and tufa specimens

interaction between the enso and the asian monsoon in a coral record of tropical climate the oxygen isotopic composition of a banded coral from the western equatorial indian ocean provides a 150 year long history of the relation between the el nino southern oscillation enso phenomenon and the asian monsoon interannual cycles in the coral time series were found to correlate with pacific coral and instrumental climate records suggesting a consistent linkage across ocean basins despite the changing frequency and amplitude of the enso however decadal variability that is characteristic of the monsoon system also dominates the coral record which implies important interactions between tropical and midlatitude climate variability one prominent manifestation of this interaction is the strong amplitude modulation of the quasi biennial cycle

equilibrium vs kinetic fractionation of oxygen isotopes in two low temperature travertine depositing systems with differing hydrodynamic conditions at baishuitai yunnan sw china abstract in order to understand the behavior of oxygen isotopic fractionation and obtain more reliable paleoclimatic data from surficial travertine deposits the hydrochemistry carbonate precipitation rates and the temporal and spatial variations in 18 o values of the modern travertine in two low temperature travertine depositing systems canal and pool with differing hydrodynamic conditions at baishuitai yunnan sw china were investigated during the warm rainy season may 24 to november 2 in 2010 it was found that the oxygen isotopic composition of travertine in the two systems showed distinct controlling mechanisms mainly due to different carbonate precipitation rates and water residence times for the canal system with fast flow large deviations between the calculated and measured temperatures indicated that travertine precipitated out of isotopic equilibrium this was due to rapid carbonate precipitation with intense co 2 degassing 18 o travertine values and water temperature increased downstream 1 and 4 c respectively while 18 o water values remained relatively stable it was shown that the 18 o values of travertine in the canal system recorded the 18 o values of dissolved carbonates hco 3 which also increased along the canal controlled by rayleigh distillation effects in contrast in the pools system with slow flow oxygen isotopic equilibrium between dissolved carbonates hco 3 and h 2 o was achieved and the 18 o travertine values did not display spatial variations calculated water temperatures using the equilibrium fractionation factors of coplen 2007 were identical to the measured ones which indicates that travertine in such pools system is suitable for the reconstruction of paleo precipitating temperatures finally by comparing these two systems we have obtained a simple criterion to determine the suitability of travertine to estimate temperatures the 18 o value of baco 3 precipitated from water samples is compared with the theoretical 18 o value of dissolved carbonate calculated using water temperature and 18 o water to check if the oxygen isotopes of the dissolved carbonate are in equilibrium with the water

constraints on pleistocene pluvial climates through stable isotope analysis of fossil spring tufas and associated gastropods kharga oasis egypt abstract stable isotope analyses of fossil spring carbonates tufas and freshwater gastropods melanoides tuberculata from the currently hyperarid western desert of egypt indicate that this region received enough precipitation to support a small perennial lake during the height of the oxygen isotope stage 6 5e pluvial event and a substantial volume of spring discharge during prior pluvial phases tufa and gastropod oxygen isotope ratios are generally low relative to modern precipitation in the region confirming that the majority of pleistocene pluvial precipitation came from an atlantic source as determined by previous workers mean tufa 13c 2 pdb suggests a significant proportion of c4 vegetation in the recharge area of the tufa depositing springs while the paucity of tufas with 13c greater than 0 suggests that equilibrium between spring water and atmospheric co2 represented an endpoint for the evolution of spring water carbon though spring carbonate deposition requires a substantial increase in humidity in central egypt relative to modern conditions high variation in tufa 18o up to 4 within individual stratigraphic units as well as positive covariance between tufa carbon and oxygen isotope ratios reflect significant effects of evaporation on spring water during tufa formation similarity in 18o and 13c values of tufas from different stratigraphic units indicates that climatic conditions did not vary significantly among pluvial phases recorded by spring carbonate deposition the lack of substantial carbonate formation at tufa localities during the holocene pluvial phase however suggests that tufa deposition represents substantially wetter conditions than have existed during holocene time

effect of in stream physicochemical processes on the seasonal variations in δ13c and δ18o values in laminated travertine deposits in a mountain stream channel abstract travertines are potential archives of continental paleoclimate records of stable carbon and oxygen isotopic composition 13 c and 18 o in laminated travertine deposits from endogene spring waters show regular cyclic patterns which may be due to seasonal change in climate determinants such as temperature and rainfall in this study 13 c and 18 o measurements of three travertine specimens that grew naturally over the eight years 2004 2011 at upstream middle and downstream sites in a canal at baishuitai sw china are presented they exhibit clear seasonal variations that generally correlate with biannual laminations specifically 13 c and 18 o values show significant positive correlation with each other for the three travertine specimens with the correlation coefficients increasing downstream along the canal to reveal the factors governing the seasonal and spatial variations in 13 c and 18 o values newly formed travertines precipitated on plexiglas substrates are also examined both 13 c and 18 o of the substrate travertines are low in the summer rainy season and high in the winter dry season showing a great consistency with the patterns in the natural travertines spatially isotope values increase downstream in both seasons with higher increase rates in winter that are related to removal of larger fractions of dissolved inorganic carbon dic from the solution and stronger kinetic isotopic fractionation in winter due to in stream physicochemical processes including caco 3 precipitation and the associated degassing of co 2 seasonal changes in 13 c and 18 o in the travertines are amplified by two times between the upstream and downstream sites this is opposite to trends for epigene meteogene tufas whose seasonal changes in stable isotope compositions are reduced downstream we suggest in stream physicochemical processes are a potential reason for underestimation of annual temperature ranges that are inferred from epigene tufa 18 o data

origin of annual laminations in tufa deposits southwest japan abstract laminated tufas and a tufa depositing stream in sw japan shirokawa ehime prefecture were studied monthly over a 3 yr period a series of samples from the tufa clearly reveals the pattern of annual laminations the annual layering pattern was primarily controlled by changes in the rate of calcite precipitation as calculated from water chemistry the concentration of dissolved caco 3 which correlates with the precipitation rate was high in summer autumn and low in winter spring owing to changes in the partial pressure of co 2 in underground air regular seasonal changes in underground pco 2 probably resulted from two temperature dependent processes the diffusion of soil co 2 and the ventilation of underground air these changes in addition to water temperature changes altered the precipitation rate which has a clear seasonal pattern especially in the lower stream the seasonal precipitation rate was high in summer autumn and low in winter spring which is consistent with the seasonal lamination pattern seen in the tufas the textures of collected samples show that the laminations consist of densely calcified summer autumn june october laminae and lightly calcified winter spring november may laminae we infer that the increased precipitation rate stimulated thick calcite encrustation on cyanobacterial filaments to produce the dense textures this interpretation is supported by the lowered organic inorganic carbon production ratio in summer autumn seasonal variations in cyanobacterial assemblages are present but do not reflect the seasonal lamination pattern because the relevant processes are temperature dependent the seasonal lamination pattern at shirokawa is thought to generally apply to other laminated tufas deposited in temperate climates however a reversed pattern can result from local and climatic circumstances dense laminae were deposited in winter near the source of the spring at shirokawa because calcite precipitation was high owing to low underground pco 2 in winter reversed patterns reported from northwestern europe were probably influenced by seasonal rainfall which is reflected in hydrological conditions

controlling factors and implications for travertine and tufa deposition in a volcanic setting abstract this work studies a fossil system of perched and fluvial travertines passing distally to fluvial tufas within a volcanic ravine sedimentology petrology and geochemistry of fossil aragonitic calcitic travertines and downstream calcitic tufas from the azuaje volcanic ravine were studied these spring related carbonates seem to be formed after the mid holocene climate change the transition from a monsoon dominated humid climate to an arid semiarid climate controlled by trade winds the main travertine facies include rafts dendrites shrubs ooids oncoids and stromatolites among others whereas tufas are characterised by phytoclasts oncoids coated stems intraclasts and stromatolites facies observed can be i microbial influenced when the microbial growth rate is greater than the precipitation rate and flow energy is not above the threshold value tolerated by microbes or ii inorganic dominated if the precipitation rate exceeds that of the microbial growth rate and or flow energy is above the threshold tolerated by microbes travertine facies vary from mostly inorganic to microbially dominated whereas tufa facies are mostly microbially influenced observed changes of facies in both travertines and tufas were interpreted as due to changes in environmental conditions from a less to more evaporative b less saturated to oversaturated and c high to low energy changes in textures mineralogy geochemistry and stable isotope composition downstream from travertine to tufa suggest a decrease in the caco3 precipitation rate and an increase in microbial influence from travertines proximal part of the system to distal tufas our study case illustrates the wide variety of facies and processes operating in spring related travertine and tufa deposits the details of arrangement mineralogy facies and geochemistry of the deposits were mostly controlled by climate and hydrogeology although the volcanic setting provided suitable conditions for spring carbonate deposition

continuous 60 year stable isotopic and earth alkali element records in a modern laminated tufa jaruga river krka croatia implications for climate reconstruction abstract a continuous 60 year record 1938 1998 of stable isotope compositions of carbon and oxygen as well as trace metal mg sr ba concentrations in a laminated calcite crust precipitated in a short artificial tunnel on a non equilibrium groundwater fed karstic river is presented chemical and isotopic records have been compared to hydrometeorological data available for the last 48 years an attempt is made to relate isotopic and geochemical variations in the crust to environmental parameters such as temperature precipitation and changes in vegetation cover as well as to postdepositional recrystallisation of the older crust material isotopic composition of the crust is largely influenced by non equilibrium precipitation which favours the incorporation of isotopically depleted c and o into the carbonate furthermore because of the complicated hydrological situation there is no observable correlation between the stable oxygen isotope composition of water and temperature the result is that the 18 o isotopic thermometers overestimate the measured precipitation temperatures temperatures calculated from mg ca ratios of water and the carbonate match the 18 o palaeotemperatures within 2 4 c in the older part of the crust precipitated before the onset of industrial pollution of the river it was demonstrated that the application of mg palaeothermometry in natural systems where the mg ca ratio of water is influenced not only by temperature but also by other environmental parameters such as precipitation surface runoff groundwater retention time and anthropogenic influences is subject to a large uncertainty up to 10 c

wet dry seasonal and spatial variations in the δ13c and δ18o values of the modern endogenic travertine at baishuitai yunnan sw china and their paleoclimatic and paleoenvironmental implications abstract seasonal and spatial variations in the 13 c and 18 o values of the modern endogenic thermogene travertine deposited in a calcite depositing canal at baishuitai yunnan sw china were examined to understand their potential for paleoclimatic and paleoenvironmental implications the sampling sites were set in the upstream middle reach and downstream of the canal and the modern endogenic travertine samples were collected semimonthly to measure their 13 c and 18 o values it was found that both 13 c and 18 o values of the endogenic travertine were low in the warm rainy season and high in the cold dry season and correlated with each other the low 18 o values in warm rainy season were mainly related to the higher water temperature and the lower 18 o values of rainwater and the low 13 c values are caused by the dilution effect of overland flow with low 13 c values in the warm rainy season and the reduced co 2 degassing of canal water caused by the dilution effect of the overland flow the linear negative correlation between the travertine 18 o or 13 c values and rainfall amount may be used for paleo rainfall reconstruction if one knows the 18 o or 13 c values of the fossil endogenic travertine at baishuitai though the reconstruction was not straightforward it was also found that there was a progressive downstream increase of the 18 o and 13 c values of the travertine along the canal the former being mainly due to the preferential evaporation of h 2 16 o to the atmosphere and the latter to the preferential release of 12 co 2 to the atmosphere during co 2 degassing however the downstream increase of the travertine 18 o and 13 c values was less intensive in rainy season because of the reduced evaporation and co 2 degassing during the rainy season to conclude the downstream travertine sites could be more favorable for the paleo rainfall reconstruction while the upstream travertine sites are more favorable for the paleo temperature reconstruction so this study demonstrates that endogenic travertine like epigenic meteogene tufa could also be a good candidate for high resolution paleoclimatic and paleoenvironmental reconstruction

thickness and stable isotopic characteristics of modern seasonal climate controlled sub annual travertine laminas in a travertine depositing stream at baishuitai sw china implications for paleoclimate reconstruction a continuous high resolution monthly record of stable isotopes 13c and 18o in a well laminated freshwater travertine deposited at baishuitai sw china from may 1998 to november 2001 was presented the travertine exhibits clear annual bands with coupled brown white color laminations throughout field investigation it was found that the thin 1 5 2 2 mm brown porous lamina was formed in the monsoonal rainy season from april to september whereas the thick 5 8 mm dense white lamina was formed in the dry season from october to march the comparisons of lamina thickness and stable isotope signals in the travertine with the meteorological records allow us to constrain the relevant geochemical processes in the travertine formation under different climate conditions and to relate climate variables to their physicochemical proxies in the travertine record sympathetic variations in lamina thickness 13c and 18o along the sampled profile reflect changes in hydrogeochemistry showing that thin lamina and low 13c and 18o values occur in warm and rainy seasons the decreased amount of calcite precipitation and low 13c values during the warm and rainy seasons is caused by dilution of overland flow after rainfall the low 18o values are believed to be related to the rainfall amount effect in subtropical monsoonal regions this process is thought to be markedly subdued whenever the amount of rainfall is lower than a given threshold accordingly distinct minima in lamina thickness 13c and 18o are interpreted to reflect events with above average rainfall possibly heavy floods and vice versa this study demonstrates the potential of freshwater travertine to provide valuable information on seasonal or even monthly rainfall variations

stable isotope characterisation of recent aragonite travertine deposits associated with the fitero thermal waters spain the travertines of the fitero thermal springs with more than 98 of aragonite in most of the samples are studied in this paper the main objective is to improve the general understanding of aragonite precipitation since the deposits of almost pure aragonite are very scarce this study presents a complete mineralogical and isotopic characterisation including the evaluation of the 18o and 13c fractionation during precipitation as valuable information for paleoclimate and paleoenvironmental studies samples of a laminated travertine deposit constituted by almost pure aragonite were taken from a pipe discharging water at 40 c waters suffered an important co2 outgassing as suggested by the geochemical calculations and the 13c values of travertines and waters this outgassing triggers the oversaturation and precipitation of carbonate phases temperature seems to be the main factor controlling the precipitation of aragonite or calcite as checked by studying another travertine sample with higher calcite content various 18o isotope fractionation equations for aragonite and calcite were used the results indicate that precipitation took place close to equilibrium according to some of these equations the fact that the equilibrium is maintained in a natural system with an important co2 loss is surprising however it can be explained by an hco3 water oxygen isotopic equilibrium and a direct transfer of the hco3 isotope signal to the carbonate without fractionation due to the fast co2 loss and precipitation finally considering other natural aragonite samples a fractionation equation is defined for natural aragonite in the temperature range between 23 and 80 c

oxygen isotope fractionation in travertine depositing pools at baishuitai yunnan sw china effects of deposition rates abstract travertine 18o values can be used to reconstruct paleo temperatures if the oxygen isotope fractionation factors between travertine and water are accurately understood for this purpose the 18o values of pool travertine and its parent water and the deposition rates of the calcite were investigated at baishuitai yunnan sw china over the course of the full hydrological year april 23 2006 april 25 2007 the results show that the travertine water isotope fractionation factors are close to the commonly accepted equilibrium line of kim and o neil 1997 this differs from the results obtained by yan et al 2012 who found that the oxygen isotope fractionation factors in the travertine depositing pools were close to the line suggested as equilibrium relationship by coplen 2007 the average calcite deposition rate 2 30 mg cm 2 d 1 in the present study is six times larger than that 0 38 mg cm 2 d 1 in yan et al 2012 if slower calcite precipitation leads to equilibrium oxygen isotopic fractionation then the results of this study support the results of coplen 2007 that indicate that the equilibrium fractionation factor may be greater than the commonly accepted one derived by kim and o neil 1997 the relationship between oxygen isotope fractionation factor and calcite deposition rate in our study also agrees with the results of dietzel et al 2009 who found that the kinetic isotope effect favors preferential incorporation of 16o in solid calcite as the calcite deposition rate increases there was a threshold for calcite precipitation rate control on oxygen isotopic equilibrium in our case of travertine depositing pools when the calcite deposition rate was lower than 0 38 mg cm 2 d 1 oxygen isotopic equilibrium between calcite and water was attained therefore calcite deposition rate is a potentially important consideration when using 18o in natural carbonates as a proxy for terrestrial and ocean temperature

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

response of dissolved inorganic carbon dic and δ13cdic to changes in climate and land cover in sw china karst catchments abstract monthly hydrochemical data and 13c of dissolved inorganic carbon dic in karst water samples from september 2007 to october 2012 were obtained to reveal the controlling mechanisms on dic geochemistry and 13cdic under different conditions of climate and land cover in three karst catchments banzhai dengzhanhe and chenqi in guizhou province sw china dic of karst water at the banzhai site comes mainly from carbonate dissolution under open system conditions with soil co2 produced by root respiration and organic carbon decomposition with lowest 13c values under its dense virgin forest coverage weaker carbonate bedrock dissolution due to sparse and thin soil cover results in lower 13cdic pco2 dic and ec and lower cation and anion concentrations at the chenqi site larger soil co2 input from a thick layer of soil results in high pco2 and dic and low ph sic and 13cdic in the karst water at the dengzhanhe site a lesser soil co2 input due to stronger karst rock desertification and strong gypsum dissolution contribute to higher 13cdic high ec and high cation and anion concentrations soil co2 inputs controlled by biological activity and available soil moisture carbonate bedrock dissolution dilution and degassing effects vary seasonally following rainfall and temperature changes consequently there are seasonal cycles in hydrochemistry and 13cdic of the karst water with high pco2 and low ph ec sic and 13cdic values in the warm and rainy seasons and vice versa during the cold and dry seasons a strongly positive shift 3 in 13cdic occurred in the drought year 2011 indicating that 13cdic in groundwater systems can be an effective indicator of environmental and or climate changes

hydrogeodeformation monitoring prospects of earthquake prediction the regional hydrogeodeformatics the new discipline dealing with regional deformation processes and based on hydrogeodeformation hgd monitoring meth odology was introduced in russia in the early 1980s during the last 30 years the theoretical principles and hgd methodology were further developed and modified in russia and some other countries the hgd field is a combination of short lived 3d deformation structures which are formed within the lithosphere and have a lifetime ranging from several days to several months monitoring of the hgd field within the study area provides a compre hensive picture of deformation changes and transforma tions occurring in real time some important hgd field features and parameters were described and discussed a combined analysis of these parameters and seismic infor mation was applied to the southwestern part of british columbia canada the results indicated that british columbia was the area highly sensitive to global defor mations and as such should be included in the interna tional hgd monitoring network prior to establishing such a network the existing provincial groundwater monitoring network in british columbia could be utilized for hgd monitoring and predicting strong earthquakes in the prov ince and the neighboring areas

structure of the 8200 year cold event revealed by a speleothem trace element record abrupt first order shifts in strontium and phosphorus concentrations in stalagmite calcite deposited in western ireland during the 8200 year event the major cooling episode 8200 years before the present are interpreted as responses to a drier climate lasting about 37 years both shifts are centered on 8330 80 years before the present coinciding with a large oxygen isotope anomaly and a change in the calcite petrography in this very high resolution monthly record antipathetic second order oscillations in phosphorus and strontium reveal decreased growth rates and increased rainfall seasonality growth rate variations within the event reveal a two pronged structure consistent with recent model simulations

wet dry seasonal variations of hydrochemistry and carbonate precipitation rates in a travertine depositing canal at baishuitai yunnan sw china implications for the formation of biannual laminae in travertine and for climatic reconstruction travertine or tufa is a chemical sedimentary deposit that is precipitated from springfed stream water supersaturated with calcite due to co2 degassing liu et al 1995 pentecost 1995 ford and pedley 1996 these deposits have biannual laminations which could provide valuable paleoclimatic and paleoenvironmental information with high resolution liu et al 2006 kano et al 2007 brasier et al 2009 lojen et al 2009

temperatures at the last interglacial simulated by a coupled ocean atmosphere climate model the last interglacial eemian 125 000 years ago has generally been considered the warmest time period in the last 200 000 years and thus sometimes been used as a reference for greenhouse projections herein we report results from a coupled ocean atmosphere climate model of the surface temperature response to changes in the radiative forcing at the last interglacial although the model generates the expected summer warming in the northern hemisphere winter cooling of a comparable magnitude occurs over north africa and tropical asia the global annual mean temperature for the eemian run is 0 3 degrees c cooler than the control run validation of simulated sea surface temperatures ssts against reconstructed ssts supports this conclusion and also the assumption that the flux correction fitted for the present state operates satisfactorily for modest perturbations our results imply that contrary to conventional expectations eemian global temperatures may already have been reached by the mid 20th century

centennial scale holocene climate variability revealed by a high resolution speleothem δ18o record from sw ireland evaluating the significance of holocene submillennial 18 o variability in the greenland ice cores is crucial for understanding how natural climate oscillations may modulate future anthropogenic warming a high resolution oxygen isotope record from a speleothem in southwestern ireland provides evidence for centennial scale 18 o variations that correlate with subtle 18 o changes in the greenland ice cores indicating regionally coherent variability in the early holocene evidence for previously undetected early holocene cooling events is presented but mid to late holocene ice rafting in the north atlantic appears to have had little impact on 18 o at this ocean margin site

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

hydrochemical and isotope characteristics of spring water and travertine in the baishuitai area sw china and their meaning for paleoenvironmental reconstruction a method of combining hydrochemical data logging and in situ titrating with measurement of stable carbon and oxygen isotopes was used to reveal the hydrochemical and isotopic characteristics in the baishuitai travertine scenic area of sw china it was found that the travertine forming springs have a very high concentration of calcium and bicarbonate and accordingly very high co2 partial pressures which are not likely to be produced by biological activity in soil alone further analysis of the stable carbon isotopes of the springs shows that the high pressure of co2 is mainly related to an endogenic co2 source that means the baishuitai travertine is endogenic in origin this is contrast to the commonly accepted saying that the travertine deposition in this study simply is a product of warm and humid conditions in a karst ecological environment rapid co2 degassing from the water is triggered by the much higher partial pressures in water than that of the surrounding air consequently as the waters flow downstream of the spring the ph increases the waters become supersaturated with respect to calcite and travertine is deposited the preferential release of 12co2 to the atmosphere results in a progressive increase of travertine 13c downstream this is concluded with a preliminary discussion of variation in travertine forming water temperatures according to differences in stable oxygen isotopic compositions of the travertine formed in different epochs at baishuitai it was found that the change in water temperature is as high as 13 c i e from 23 c at about 2500 years b p to 10 c at present this may mainly reflect that the effect of geothermal source on water temperature is decreasing the problems involved in paleoenvironmental reconstruction with endogene travertine are also discussed they are the impacts of dead carbon in radiocarbon dating and the enrichment in 13c of travertine by endogenic co2 and degassing of co2 from water which has to be considered in paleovegetation reconstruction when using 13c data of the endogene carbonate deposits

δ13c δ18o and deposition rate of tufa in xiangshui river sw china implications for land cover change caused by climate and human impact during the late holocene

calcium isotopic fractionation during travertine deposition under different hydrodynamic conditions examples from baishuitai yunnan sw china abstract revealing the potential of ca isotopes in the research of travertine formation processes is the principal goal of this study to achieve this the hydrochemistry travertine precipitation rates and variations in ca isotopic compositions 44 40 ca of present day endogenic thermogenic travertine in two different hydrodynamic systems canal and pool are studied at baishuitai yunnan sw china in the canal where the travertine precipitation is faster 44 40 ca values of both solution and travertine show a downstream increase with ca isotopic fractionation 44 40 ca caco3 aq equal to 1 6 compared to the canal ca isotopic fractionation between travertine and aqueous ca 2 is smaller 44 40 ca caco3 aq 1 2 in the pools where travertine precipitation rates are lower the spatial variations in 44 40 ca values of solution and travertine are related to the amount of ca removed from the solution when 44 40 ca values of spring water remain stable in addition the results confirm the control of precipitation rates on ca isotopic fractionation between calcite and parent aqueous ca 2 using natural samples the observed negative correlation between 44 40 ca caco3 aq and travertine precipitation rates can be explained by the steady state kinetic surface reaction model proposed by depaolo 2011 with equilibrium and kinetic fractionation factors of eq 1 0000 0 0001 and f 0 9983 0 0002 respectively an important consequence of this study is that ca isotopes in travertine systems are good tools to have access to variations of 44 40 ca aq which are directly linked to the amount of precipitated ca this could then be useful for reconstructing past hydrodynamic conditions when applied to travertine core data

holocene forcing of the indian monsoon recorded in a stalagmite from southern oman a high resolution oxygen isotope record from a thorium uranium dated stalagmite from southern oman reflects variations in the amount of monsoon precipitation for the periods from 10 3 to 2 7 and 1 4 to 0 4 thousand years before the present ky b p between 10 3 and 8 ky b p decadal to centennial variations in monsoon precipitation are in phase with temperature fluctuations recorded in greenland ice cores indicating that early holocene monsoon intensity is largely controlled by glacial boundary conditions after approximately 8 ky b p monsoon precipitation decreases gradually in response to changing northern hemisphere summer solar insolation with decadal to multidecadal variations in monsoon precipitation being linked to solar activity

intrinsic versus extrinsic controls on the development of calcite dendrite bushes shuzhishi spring rehai geothermal area tengchong yunnan province china abstract in the rehai geothermal area located near tengchong there is an old succession of crystalline calcite that formed from a spring that is no longer active the thin bedded succession exposed on the south bank of zaotang river is formed of three dimensional dendrite bushes that are up to 6 cm high and 3 cm in diameter with multiple levels of branching bedding is defined by color which ranges from white to gray to almost black and locally accentuated by differential weathering that highlights the branching motif of the dendrites the succession developed through repeated tripartite growth cycles that involved phase i that was characterized by rapid vertical growth of the dendrite bushes with ever increasing branching phase ii that developed once growth of the dendrites had almost or totally ceased and involved an initial phase of etching that was followed by the precipitation of various secondary minerals sheet calcite trigonal calcite crystals hexagonal calcite crystals hexagonal plates formed of ca and p mn precipitates si mg reticulate coatings opal ct lepispheres on the branches of the calcite dendrites and phase iii that involved deposition of detrital quartz feldspar clay and calcite on top of the dendrite bushes the tripartite growth cycle is attributed primarily to aperiodic cycles in the co 2 content of the spring water that was controlled by subsurface igneous activity rather than climatic controls high co 2 coupled with rapid co 2 degassing triggered growth of the dendrite bushes as co 2 levels waned saturation levels in the spring water decreased and calcite dendrite growth ceased and precipitation of the secondary minerals took place possibly in the microcosms of microbial mats deposition of the detrital sediment was probably related to surface runoff that was triggered by periods of high rainfall critically this study shows that intrinsic factors rather than extrinsic factors e g climate were the prime control on the development of the tripartite growth cycle

climatic significance of seasonal trace element and stable isotope variations in a modern freshwater tufa abstract we present a continuous 14 yr long 1985 to 1999 high resolution record of trace element mg sr ba u and stable isotope 13c 18o variations in a modern freshwater tufa from northwestern queensland australia by utilizing the temperature dependence of the 18o signal an accurate chronology was developed for the sampled profile which allowed a comparison of the chemical records with hydrological and meteorological observations as a consequence it was possible to constrain the relevant geochemical processes relating climate variables such as temperature and precipitation to their chemical proxies in the tufa record temperatures calculated from the mg concentrations of the tufa samples provide close approximations of average annual water temperature variations furthermore we demonstrate that temporal changes in mg ca water can be estimated using an empirically derived equation relating mg ca water to the sr ba ratio measured in the tufa samples by means of this relationship it is theoretically possible to determine the mg ca ratio of paleowaters and hence to derive reliable estimates of former water temperatures from the mg concentrations of fossil tufas from the study area sympathetic variations in sr ba and 13c along the sampled profile record changes in water chemistry which are most probably caused by variable amounts of calcite precipitation within the vadose zone of the karst aquifer this process is thought to be markedly subdued whenever the amount of wet season precipitation exceeds a given threshold accordingly distinct minima in sr ba and 13c are interpreted to reflect years with above average rainfall the pronounced seasonal and annual variability of the u concentration along the profile is thought to primarily record changes in the u flux from the soil to the water table we suggest that during intensive rain events u is transported to the phreatic zone by complexing organic colloids giving rise to conspicuous u maxima in the tufa after above average wet seasons this study demonstrates the potential of freshwater tufas to provide valuable information on seasonal temperature and rainfall variations if tufa deposits turn out to be reasonably resistant to secondary processes combined investigation of speleothems and tufas from the same area could become a promising approach in future research while speleothems offer continuous records of long term paleoenvironmental changes tufas could provide high resolution time windows into selected periods of the past

timing duration and transitions of the last interglacial asian monsoon thorium 230 ages and oxygen isotope ratios of stalagmites from dongge cave china characterize the asian monsoon and low latitude precipitation over the past 160 000 years numerous abrupt changes in 18o 16o values result from changes in tropical and subtropical precipitation driven by insolation and millennial scale circulation shifts the last interglacial monsoon lasted 9 7 1 1 thousand years beginning with an abrupt less than 200 years drop in 18o 16o values 129 3 0 9 thousand years ago and ending with an abrupt less than 300 years rise in 18o 16o values 119 6 0 6 thousand years ago the start coincides with insolation rise and measures of full interglacial conditions indicating that insolation triggered the final rise to full interglacial conditions

travertine distinctive depositional fabrics of carbonates from thermal spring systems the terrestrial limestones forming at the emergence of thermal springs show a variety of unusual depositional facies the specific lithological and petrological features of these deposits have few counterparts in the marine and continental karst related carbonates but they are typical of the epigean limestone that has been quarried since antiquity in the surroundings of tivoli rome under the name of travertine where it is still forming in hydro geothermal fields linked to extensional tectonics the physicochemical hydrodynamic and geological conditions specific to the tivoli thermal spring system imply hypersaturated alkaline sulphate warm to hot waters upwelling from springs fed through open fractures faults in extensional and or volcanic regimes these features together with the hydrodynamic behaviour of the water flows running from the vents control the petrogenetic features of the travertine a well bedded mostly finely laminated porous but quite compact limestone the results of a detailed comparative petrological analysis carried out on the lithofacies of travertine limestones and of those observed during formation within numerous active thermal spring fields provide the elements required for an exhaustive textural classification of the travertine lithofacies which has not yet been described systematically according to the genetic processes and fabrics the thermal deposits that originate from such hypersaturated alkaline sulphate warm to hot waters can be subdivided into abiotic crystalline crusts microbially mediated crusts microbialites and granular deposits mostly represented by small accumulations of lime mudstone some of the granular deposits and the microbialites are only partially comparable with analogous sediments forming on tidal flats sabkhas or other continental sites however the facies association of crystalline crusts and laminar curled microbialites has no counterpart in the marine realm the widespread presence of thermophile bacteria and sulphobacteria and the general absence of autochthonous eukaryote organisms unable to live in poisonous sulphate waters are also undeniable evidence of their thermal origin

contrasts in variations of the carbon and oxygen isotopic composition of travertines formed in pools and a ramp stream at huanglong ravine china implications for paleoclimatic interpretations abstract water samples and modern endogenic thermogene travertine calcite deposited on plexiglass substrates in travertine pools and a ramp stream were collected along the huanglong ravine sichuan sw china at regular 10 day intervals from early may to early november in 2010 including both wet and dry conditions temporal and spatial variations in the 13 c and 18 o values of the modern travertine were examined to understand their potential for paleoclimatic and paleoenvironmental interpretations it was found that 13 c and 18 o of travertine formed in the ramp stream were low in the warm rainy season and high in the cold dry season their positive correlation was mainly due to dilution and rainfall seasonal effects on 13 c and 18 o values respectively i e low 13 c values were caused by dilution by overland flow with depleted 13 c values and reduced co 2 degassing in the warm rainy season while low 18 o values of travertine were because of low 18 o values of water induced by seasonal variation in oxygen isotopic ratios of rainwater meanwhile kinetic effect on oxygen isotopic fractionation during ramp travertine deposition existed and reduced this positive correlation in contrast the 13 c and 18 o values of the pool travertines displayed a converse behavior which was caused mainly by the temperature effect low 18 o values and high 13 c values in the warm rainy season were correlated chiefly with the higher water temperatures therefore the 13 c and 18 o values of the travertine may be used for paleo rainfall or paleotemperature reconstruction respectively this study demonstrates that endogenic travertine like epigenic meteogene tufa may be a suitable candidate for high resolution paleoclimatic and paleoenvironmental reconstructions however since travertines deposited under differing hydrodynamic conditions e g pools with still water contrasted to fast flow streams have different climatic responses it is necessary to check the depositional facies of fossil travertine samples before they can be used for palaeoclimate temperature and or rainfall reconstruction