silicon isotope fractionation during silica precipitation from hot spring waters evidence from the geysir geothermal field iceland this study aims to explore the extent and controls of silicon isotope fractionation in hot spring systems of the geysir geothermal area iceland a setting where sinter deposits are actively formed the 30si values of dissolved silica measured in the spring water and sampling sites along outflowing streams covering a temperature range between 20 and 100 c were relatively constant around 0 2 whereas the 30si signatures of associated opaline sinters from the streambeds were between 0 1 and 4 0 becoming progressively more negative in the downstream parts of the aprons here the deposited sinters represent some of the most 30si depleted abiotically produced terrestrial materials documented to date compared to the data reported for icelandic basalts considered to be the source of the silicon the 30si values of the fluids and sinter deposits are higher and lower respectively the resulting values for apparent solid water isotope fractionation 30sisolid water decreased with decreasing temperature from ca 0 7 at 80 c to 3 7 at 20 c locally down to 4 4 this temperature relationship was reproducible in each of the investigated hot spring systems and is qualitatively consistent with recent findings in laboratory experiments on kinetic fractionation for a flowing fluid however the apparent fractionation magnitudes observed in the field are ca 2 more negative and thus significantly larger we infer that solid water silicon isotope fractionation during deposition of amorphous silica from a flowing fluid correlates inversely with temperature but is essentially a function of the precipitation rate such that the fractionation factor decreases with increasing rate as an important corollary the effective fractionation behavior during precipitation of silica from saturated solutions is a system dependent feature which should be taken into account when using silicon isotopes for paleo environmental reconstructions

stratigraphic correlation of the neogene basins in southwestern anatolia regional palaeogeographical palaeoclimatic and tectonic implications abstract the extensional intramontane grabens that formed in southwestern anatolia in the late cenozoic bear the unique tectono sedimentary palaeontological and palynological record of a region that underwent rapid transition from the last compressional pulses of the alpine orogeny to the tectonic phase of orogen collapse and the onset of neotectonic regime the change in tectonic regime was accompanied by regional climatic changes recorded by the sedimentary environments of the basins and evidenced by palaeontological and palynological data the late early to mid middle miocene was characterized by a warm and humid subtropical climate with densely forested wetlands the late middle to late miocene witnessed a change to arid climatic conditions with grass dominated steppe ecosystems the pliocene climate was warm and humid with savannah type open habitats in terms of their stratigraphic development the southwestern anatolian basins form two distinct groups one group is represented by the denizli soke and yatagan basins which commenced their development in the early burdigalian and underwent similar phases of environmental change 1 the burdigalian phase of alluvial environment and redbed deposition 2 the late burdigalian langhian phase of alluvial sedimentation accompanied by the formation of terminal lakes 3 the serravallian middle tortonian phase of the formation of shallow perennial lakes 4 the middle tortonian messinian phase of lake expansion and deepening followed by shrinking and shallowing 5 the pliocene phase of lake expansion and deepening and 6 the erosional quaternary phase of two stage alluvial sedimentation separated by a high relief erosional unconformity the other younger group of tectonic grabens is represented by the karacasu bozdogan cameli and esen basins which commenced their development in the earliest tortonian and underwent common environmental changes 1 the tortonian phase of alluvial environment and redbed deposition coeval with the phase of lake drying in the denizli soke and yatagan basins 2 the messinian phase of the formation of terminal lakes coeval with the re establishment of shallow lakes in the three other basins 3 the zanclean phase of shallow perennial lakes coeval with the expansion and deepening of lakes in the other basins 4 the piacenzian phase of deep lacustrine environments 5 the gelasian phase of shallow lacustrine environments and 6 the erosional quaternary phase of two stage alluvial sedimentation similar as in the other basins in spite of the time offset in their development the two basin groups have been strongly modulated by climate and hence show correlative responses to regional climatic changes despite the time offset in their tectonic development the two basin groups showed correlative environmental changes imposed by regional climatic conditions the basins were environmentally unified by the quaternary alluvial phase of their development in the late cenozoic anatolia was at the crossroads of fauna migration routes between africa asia and europe and the palaeontological data from the southwestern anatolian basins shed more light on this phenomenon the study as a whole contributes to a better understanding of the late cenozoic environmental climatical and biogeographical changes in the eastern mediterranean

the origin and growth of a recently active fissure ridge travertine over a seismic fault tivoli italy abstract an enigmatic c 2 km long and 15 m high travertine ridge the colle fiorito ridge occurs in the northwestern sector of the tivoli travertine plateau central italy the main questions addressed in this paper concern the origin and mode of growth of this prominent ridge the presence of active structures beneath the studied ridge is inferred by recent and past earthquakes located at shallow depths immediately beneath colle fiorito to understand the surficial structure of the colle fiorito ridge and the travertine depositional environment we constructed a 10 m resolution dem analyzed recent and past aerial photographs and conducted field surveys and meso to micro scale sedimentological analyses to understand the ridge subsurface structure we studied a set of 32 stratigraphic well logs available from previous works and from the local decorative stone industry and realized a 2d electrical resistivity tomography ert across the ridge results show a gentle antiformal structure affected by subvertical zones of strata discontinuity the colle fiorito structure is interpreted as a previously unknown fissure ridge travertine grown at the edge of the tivoli travertine plateau perhaps when the volumetric deposition rate reached its climax in the plateau for the abundance of fluid discharge and the rise of the water table such a fluid pressure may have activated the faults and fractures beneath colle fiorito thus opening new pathways for the ascension of geothermal fluids toward the surface

calibration of the calcite water oxygen isotope geothermometer at devils hole nevada a natural laboratory abstract the 18 o of ground water 13 54 0 05 and inorganically precipitated holocene vein calcite 14 56 0 03 from devils hole cave 2 in southcentral nevada yield an oxygen isotopic fractionation factor between calcite and water at 33 7 c of 1 02849 0 00013 1000 ln calcite water 28 09 0 13 using the commonly accepted value of calcite water t of 0 00020 k 1 this corresponds to a 1000 ln calcite water value at 25 c of 29 80 which differs substantially from the current accepted value of 28 3 use of previously published oxygen isotopic fractionation factors would yield a calcite precipitation temperature in devils hole that is 8 c lower than the measured ground water temperature alternatively previously published fractionation factors would yield a 18 o of water from which the calcite precipitated that is too negative by 1 5 using a temperature of 33 7 c several lines of evidence indicate that the geochemical environment of devils hole has been remarkably constant for at least 10 ka accordingly a re evaluation of calcite water oxygen isotopic fractionation factor may be in order assuming the devils hole oxygen isotopic value of calcite water represents thermodynamic equilibrium many marine carbonates are precipitated with a 18 o value that is too low apparently due to a kinetic isotopic fractionation that preferentially enriches 16 o in the solid carbonate over 18 o feigning oxygen isotopic equilibrium

freshwater carbonates within a late triassic siliciclastic fluvial system in a gondwana rift basin the maleri formation india abstract spring related carbonates are valuable repositories for information on physical and biotic environments of the past however for mesozoic and earlier records their use is limited due to their low preservation potential and difficulties in accurate identification of the carbonate type this study aims to characterise the source of carbonate clasts preserved as thin beds of cross bedded grainstones in late triassic siliciclastic fluvial deposits the maleri formation pranhita godavari rift basin india the microfabric and stable isotopic compositions of the grainstones and thin and discontinuous beds of impure limestones of this formation are presented here these features help in identifying the freshwater carbonate precipitating environments that existed in an ancient continental rift basin though such deposits are not primarily preserved in this case the microfabric of the carbonate grains provides evidence for carbonate precipitation in aquatic environment related to karstic springs taking together the microfabric stable isotopic compositions as well as the associated geological and palaeontological information it could be shown that the calcium carbonate precipitation took place in palustrine pools related to tufa like spring systems and in alluvial swamps under a pluvial climatic setting this research thus demonstrates that carbonate grains derived from spring related carbonate deposits formed mainly near the margins of rift basins can be incorporated into nearby siliciclastics if interpreted correctly they can be used in reconstructing ancient karstic carbonate environments even when in situ primary record is not preserved therefore making it possible to access the information stored in freshwater carbonates

paleoenvironmental evolution of the late pliocene early pleistocene fluvio deltaic sequence of the denizli basin sw turkey abstract the late pliocene early pleistocene tosunlar succession denizli basin southwestern turkey represents fluvial dominated delta environments at the margins of a brackish long lived lake two main facies associations are documented i a delta front facies association with a distal df1 and proximal df2 deposits and ii a delta plain facies association that contains distributary channel dp1 and interdistributary swamp dp2 deposits the stable isotopic analysis of the mollusc faunas exhibit a narrow range of values 4 68 18 o 13 c 18 o 13 c correlation r 0 16 may indicate hydrologically open lake and significant diagenetic alteration the mollusc faunas and their stable isotope ratios show a biogeographically isolated brackish lake system under semiarid climatic conditions under special environmental conditions the endemic faunal composition remained constant which is very unusual for a semi isolated long lived lake setting

travertine deposits deep thermal metamorphism and tectonic activity in the longmenshan tectonic region southwestern china abstract recently a series of high magnitude earthquakes including the 2008 wenchuan earthquake m 8 0 have occurred in the longmenshan tectonic region of southwestern china many researchers are currently examining the geological aspects of the activity but little attention has been given to the huge travertine deposits along large fault zones carbon isotopes were measured in 106 samples and the results indicate that the travertine originated from 13 c enriched co 2 sourced from deep reservoirs and can be characterized by notable positive 13 c values co 2 is thought to have originated from isotopic equilibrium fractionation under thermal metamorphism temperature conditions within 350 850 c the re equilibrium fractionation between the deep co 2 and the dissolved carbonate composition during travertine formation is due to the declining temperature of thermo genetic co 2 which in turn leads to higher 13 c carb values based on oil drilling data and geochemical thermometry modeling the depth of the 13 c enriched co 2 source is inferred to be below 4643 m which coincides with the measured focal depth of the wenchuan earthquake and subsequent aftershocks the variation of tectonic activity intensity and the quantity of co 2 from deep formations are mainly responsible for the 13 c fluctuations observed in the travertine the 13 c values in travertine deposits have increased dramatically which implies the rapid upwelling of the co 2 bearing fluid the enhancement of thermal metamorphism and the continuous increase of the internal pressure in deep reservoirs these findings may contribute to a better understanding of the deep seismic activity and high frequency aftershocks in the longmenshan region

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

stable isotope geochemical study of pamukkale travertines new evidences of low temperature non equilibrium calcite water fractionation abstract in this paper we present the first detailed geochemical study of the world famous actively forming pamukkale and karahayit travertines denizli basin sw turkey and associated thermal waters sampling was performed along downstream sections through different depositional environments vent artificial channel and lake terrace pools and cascades of proximal slope marshy environment of distal slope 13 c travertine values show significant increase from 6 1 to 11 7 pdb with increasing distance from the spring orifice whereas the 18 o travertine values show only slight increase downstream from 10 7 to 9 1 pdb mainly the co 2 outgassing caused the positive downstream shift 6 in the 13 c travertine values the high 13 c values of pamukkale travertines located closest to the spring orifice not affected by secondary processes suggest the contribution of co 2 liberated by thermometamorphic decarbonation besides magmatic sources based on the gradual downstream increase of the concentration of the conservative na k cl evaporation was estimated to be 2 5 which coincides with the moderate effect of evaporation on the water isotope composition stable isotopic compositions of the pamukkale thermal water springs show of meteoric origin and indicate a local meteoric water line of denizli basin to be between the global meteoric water line craig 1961 and western anatolian meteoric water line imsek 2003 detailed evaluation of several major and trace element contents measured in the water and in the precipitated travertine along the pamukkale mm section revealed which elements are precipitated in the carbonate or concentrated in the detrital minerals former studies on the hungarian egerszalok travertine kele et al 2008a b 2009 had shown that the isotopic equilibrium is rarely maintained under natural conditions during calcite precipitation in the temperature range between 41 and 67 c in this paper besides the detailed geochemical analyses along downstream sections we present new evidences of non equilibrium calcite water fractionation in lower temperature range 13 3 to 51 3 c our measurements and calculations on natural hot water travertine precipitations at pamukkale and egerszalok revealed that the 18 o travertine is equal with the 18 o hco3 at the orifice of the thermal springs which means that practically there is no oxygen isotope fractionation between these two phases high rate of co 2 degassing with rapid precipitation of carbonate could be responsible for this as it was theoretically supposed by o neil et al 1969 thus for the determination of the deposition temperature of a fossil travertine deposit we propose to use the water bicarbonate oxygen isotope equilibrium fractionation instead of the water travertine fractionation which can result 8 9 c difference in the calculated values our study is the first detailed empirical proof of o neil s hypothesis on a natural carbonate depositing system the presented observations can be used to identify more precisely the deposition temperature of fossil travertines during paleoclimate studies

novel applications of fluid inclusions and isotope geochemistry in unravelling the genesis of fossil travertine systems the denizli basin is a fault bounded neogene quaternary depression located in the western anatolian extensional province western turkey the basin is a unique geological site with abundant active and fossil quaternary travertine and tufa deposits fluid inclusion microthermometry and isotopic analysis were applied to study the genesis of the ballk fossil travertine deposits located in the south eastern part of the basin microthermometry on fluid inclusions indicates that the main travertine precipitating and cementing fluids are characterized by low salinity 07wt nacl equivalent and variable temperatures that cluster at 50 degrees c and ca 100 degrees c fluids of meteoric origin have been heated by migration to the deeper subsurface possibly in a local high geothermal gradient setting a later uncommon cementation phase is related to a fluid with a significantly higher salinity 255 to 260wt bulk the fluid obtained its salinity by interaction with late triassic evaporite layers strontium isotopes indicate that the parent carbonate source rock of the different travertine precipitates is very likely to be the triassic limestone of the lycian nappes carbon isotopes suggest that the parent co2 gas originated from thermal decarbonation of the lycian limestones with minor contributions of magmatic degassing and organic soil co2 oxygen isotopes confirm the meteoric origin of the fluids and indicate disequilibrium precipitation because of evaporation and degassing results were integrated within the available geological data of the denizli basin in a generalized travertine precipitation model which enhanced the understanding of fossil travertine systems the study highlights the novel application of fluid inclusion research in unravelling the genesis of continental carbonates and provides several recommendations for hydrocarbon exploration in travertine bearing sedimentary basins the findings suggest that travertine bodies and their parent carbonate source rocks have the potential to constitute interesting subsurface hydrocarbon reservoirs

comparative study of the pleistocene cakmak quarry denizli basin turkey and modern mammoth hot springs deposits yellowstone national park usa this study compares and contrasts the travertine depositional facies of two of the largest sites of travertine formation located in very different geological contexts i e the modern mammoth hot spring mhs system in the active volcanic complex of yellowstone national park usa and the pleistocene cakmak quarry a well exposed example of the ballik travertines in the extensional denizli basin turkey new 2d to 3d facies maps of both travertine systems combined with microscopy assist in proposing an integrated spring depositional model based on the existing mhs facies model understanding general controls on meter to kilometer scale travertine deposit architecture and its preservation and provide quantitative estimates of facies spatial coverage and slope using gis the comparison resulted in the distinction of eight facies grouped in five downstream facies zones from vent to distal slope notwithstanding the different geological context of both travertine systems observations show that several of the facies are strikingly comparable draping apron and channel facies top slope pond facies crystalline proximal slope facies and distal slope facies whereas other facies do not have a precise exposed equivalent vent facies pavement apron and channel facies extended pond facies and phyto proximal slope facies combining observations of active springs at mhs with the cakmak vertical travertine quarry exposures demonstrates that lateral and vertical facies transitions are a sensitive record of changes in the spring dynamics flow intensity and paths that become well preserved in the geological record and can be recognized as prograding aggrading retrograding trends or erosive surfaces traceable over tens to hundreds of meters quantification of facies specific coverage at mhs shows that proximal and distal slope facies deposits cover as much as 90 of the total mapped surface area in addition only 7 of the surface is found to be marked by a waterfilm related to an active flowing spring slope statistics reveal that strong slope breaks can often be related to transgressive apron and channel facies belts and that variable but steep slopes up to 40 are dominated by proximal slope facies in agreement with the cakmak exposures integrating travertine facies and architecture of deposits formed in distinct geological contexts can improve the prediction of general spring facies distributions and controls in other modern and ancient subsurface travertine systems

origin and evolution of the thermal waters from the pamukkale geothermal field denizli basin sw anatolia turkey insights from hydrogeochemistry and geothermometry abstract the pamukkale geothermal field pgf of the denizli basin sw turkey is one of the most distinguished active geothermal fields known in the world the thermal waters from the pgf are subdivided into two groups group 1a ca hco3 and group 1b ca so4 types the cold waters are also classified into two groups group 2a ca hco3 and group 2b mg hco3 types the hydrogeochemical properties of the pgf thermal waters suggest interactions with the basal metamorphic rocks of the menderes massif tectonically overriding by the carbonate rocks of the lycian nappes and sedimentary rocks of the neogene formations the bedrock units are stratigraphically overlain by the neogene sedimentary units of the denizli group the thermal springs of the pgf are affected by several hydrothermal processes including mixing water rock interaction and input of mantle volatiles the thermal water plots of the pgf deviate from the full equilibrium line indicating a low water maturity and or mixing processes mixing models and na k mg ternary diagram suggest mixing between meteoric and thermal waters during the uprising of the deep originated fluids the water rock interaction leads saturation of calcite and induces travertine precipitation in the discharge area low tritium this study proposes a conceptual hydrogeological hydrogeochemical tectonic model for the pgf the thermal waters are derived from the infiltration of rainwater through fractures and faults in high recharge areas to the deep hot reservoir heating produced by the high geothermal gradient is interpreted in relation with the regional crustal thinning thermal waters upwell along wnw ese trending deep faults and fractures the pamukkale fault system that act as hydrothermal pathways favouring migration of a huge amount of co2 rich gas from deep geothermal reservoir the geochemical and isotopic data of the thermal waters and gas indicate that the degassing of both metamorphic co2 and mantle derived co2 occurs in the pgf helium isotope data indicate that mantle volatiles produce possibly an upwelling into asthenosphere and ascent along these tectonic discontinuities in this context the pgf is one of the best example of geothermal fields as an interaction of active magmatism in the actively extending crustal setting

review of calcium carbonate polymorph precipitation in spring systems abstract many spring deposits throughout the world are characterized by spectacular deposits of calcium carbonate that are formed of various combinations of aragonite and calcite and in very rare cases vaterite the factors that control the precipitation of the aragonite and calcite have been the subject of considerable debate that has been based on natural precipitates and information gained from numerous laboratory experiments synthesis of this information indicates that there is probably no single universal factor that controls calcite and aragonite precipitation in all springs instead the reason for aragonite as opposed to calcite precipitation should be ascertained by considering the following ordered series of possibilities for each system first aragonite commonly with calcite as a co precipitate will form from spring water that has a high co 2 content and rapid co 2 degassing irrespective of the mg ca ratio and scale of precipitation second aragonite can be precipitated from waters that have low levels of co 2 degassing provided that the mg ca ratio is high enough to inhibit calcite precipitation third the presence of biofilms may lead to the simultaneous precipitation of aragonite and calcite irrespective of co 2 degassing or mg ca ratio either within the different microdomains that develop in the biofilm or because of diurnal changes in various geochemical parameters associated with the biofilm although the precipitation of calcite and aragonite has commonly been linked directly to water temperature there is no clear evidence for this proposition it is possible however that temperature may be influencing another parameter that plays a more direct role in the precipitation of these caco 3 polymorphs despite the advances that have been made the factors that ultimately control calcite and aragonite are still open to debate because this long standing problem has still not been fully resolved

depositional facies and aqueous solid geochemistry of travertine depositing hot springs angel terrace mammoth hot springs yellowstone national park u s a petrographic and geochemical analyses of travertine de positing hot springs at angel terrace mammoth hot springs yellow stone national park have been used to define five depositional facies along the spring drainage system spring waters are expelled in the vent facies at 71 to 73 8c and precipitate mounded travertine composed of aragonite needle botryoids the apron and channel facies 43 728c is floored by hollow tubes composed of aragonite needle botryoids that encrust sulfide oxidizing aquificales bacteria the travertine of the pond facies 30 62 8c varies in composition from aragonite needle shrubs formed at higher temperatures to ridged networks of calcite and aragonite at lower temperatures calcite ice sheets calcified bubbles and aggregates of aragonite needles fuzzy dumbbells pre cipitate at the air water interface and settle to pond floors the prox imal slope facies 28 54 8c which forms the margins of terracette pools is composed of arcuate aragonite needle shrubs that create small microterracettes on the steep slope face finally the distal slope facies 28 30 8c is composed of calcite spherules and calcite feather crys tals despite the presence of abundant microbial mat communities and their observed role in providing substrates for mineralization the com positions of spring water and travertine predominantly reflect abiotic physical and chemical processes vigorous co 2 degassing causes a 12 unit increase in spring water ph as well as rayleigh type covariations between the concentration of dissolved inorganic carbon and corre sponding d 13 c travertine d 13 c and d 18 o are nearly equivalent to aragonite and calcite equilibrium values calculated from spring water in the higher temperature 50 738c depositional facies conversely

plateau versus fissure ridge travertines from quaternary geothermal springs of italy and turkey interactions and feedbacks between fluid discharge paleoclimate and tectonics abstract morphologically different deposits of thermal travertines are known worldwide but what factors controlled their morphology volume and growth for tens of thousands of years is only partially understood two main morphotypes of quaternary thermal travertines are reconsidered here to understand the reasons for their differential growth the fissure ridge travertines of denizli basin western turkey and the travertine plateau of tivoli central italy for comparable longevities and average vertical deposition rates the main differences between the studied travertines are as follows 1 volume of the travertine plateau is about one hundred times larger than each fissure ridge 2 despite a larger volume the travertine plateau does not produce relief whereas the fissure ridges produce a characteristic prominent topography 3 the travertine plateau grew primarily through lateral progradation whereas the fissure ridges through vertical aggradation 4 travertine deposition occurred in different environments principally low energy flat or shallow environments at tivoli and high energy inclined environments at denizli 5 the growth of the tivoli plateau occurred in a subsiding basin whereas the fissure ridges were not influenced by significant subsidence 6 c and o isotope signatures from the two studied travertines are different 7 despite similar annual precipitations the present water discharge in the tivoli area is about ten times greater than that of the denizli basin u series ages from the two deposits are correlated with paleoclimate oscillations at regional and global scales geological field evidence together with paleoclimate correlations suggest that in both the study cases the main body of travertine deposits the bedded travertine grew preferentially when the water table was high warm and or humid periods conversely when the water table was depressed cold and or dry periods the tivoli travertine underwent partial erosion and the denizli ridges were cut by axial veins and lateral sill like structures filled by banded sparitic travertine a comparative model is proposed where the main factor driving the difference in the morphostratigraphic architecture of fissure ridges and travertine plateaus is the volume of water discharge a high discharge rate resulted in the precipitation of caco3 far away from the springs hence driving the lateral progradation of the tivoli plateau a reduced discharge rate caused travertine precipitation close to the springs thus causing the vertical aggradation of the denizli fissure ridges paleoclimate oscillations must have controlled the amount of fluid discharge which in turn must have influenced the opening of the feeding fractures by an increased pore pressure

skeletal crystals of calcite and trona from hot spring deposits in kenya and new zealand abstract skeletal crystals are hollow crystals that develop because their outer walls grow before their cores the presence of skeletal crystals of calcite three types trigonal prisms hexagonal prisms and plates and trona in hot 90 c spring deposits in new zealand waikite springs and ohaaki pool and kenya lorusio hot springs shows that they can form in natural sedimentary regimes analysis of samples from these deposits shows that this crystal morphology develops under disequilibrium conditions that are unrelated to a specific environmental or diagenetic setting skeletal crystals transform into solid crystals when subsequent precipitation fills their hollow cores in some cases this may involve precipitation of crystalline material that has a sieve like texture in other xamples the skeletal crystal provides a framework upon which other materials can be precipitated some of the skeletal hexagonal calcite crystals from new zealand for example are thinly coated with amorphous silica walls in the skeletal trigonal calcite prisms from waikite springs are formed of subcrystals that mimic the shape of the parent crystal similarly plate like skeletal crystals from lorusio are formed of densely packed subcrystals that are 0 5 m long conversely the walls of the skeletal hexagonal calcite crystals from ohaaki pool and the skeletal trona crystals from lorusio are not formed of subcrystals recognition of skeletal crystals is important because they represent growth that follows the reverse pattern of normal growth failure to recognize that crystal growth followed the skeletal motif may lead to false interpretations concerning the growth of a crystal for example the standard interpretation of zoned crystals using the a priori assumption that growth proceeded from the crystal core to the crystal face cannot always be used

hydrothermal co2 degassing in seismically active zones during the late quaternary natural co2 discharges are abundant in turkey as evident from ongoing deposition of recent terrace mound travertines and emplacement of significant travertine vein and breccia deposits in fractured damage zones of active fault systems we report high precision u series age data for the vein carbonates combined with important field observations and geochemical data to evaluate the travertine veining and co2 degassing history in seismically active areas field evidence suggests that travertine filled veins and associated breccias represent hydrothermal eruption products which probably formed by hydraulic fracturing in response to overpressure of co2 rich fluids stable isotope and ree data support the field observations and indicate that travertine veins formed as thermogene deposits from rapidly ascending co2 rich fluids travertine veins from the kirsehir geothermal field give u series ages in a range from 10 6 0 3 ka to 86 16 1 24 ka with a majority of ages failing between 10 6 0 3 and 11 3 0 2 ka vein samples from the pamukkale geothermal field yield u series ages between 21 1 0 1 ka and 73 6 0 6 ka two major age groups are evident in pamukkale that cluster coherently around 21 ka and 25 ka a large number of travertine veins we dated by high precision u series technique coincide with times of cold dry climate events this is different from surface sinter deposits in geothermal fields which more frequently form during warm and wet periods we propose that a significant reduction in surface discharge of co2 by spring or geothermal waters during dry climate periods may promote oversaturation of co2 in deep reservoirs host rock fracturing in response to seismic shaking and fluid overpressure results in rapid exsolution and expansion of the dissolved gas and may lead to hydrothermal eruptions crown copyright c 2009 published by elsevier b v all rights reserved

noncrystallographic calcite dendrites from hot spring deposits at lake bogoria kenya abstract complex calcite crystals are an integral component of precipitates that form around the orifices of the loburu and mawe moto hot springs on the shores of lake bogoria kenya two types of large up to 4 cm long noncrystallographic dendrites are important components of these deposits feather dendrites are characterized by multiple levels of branching with individual branches developed through crystal splitting and spherulitic growth scandulitic from latin meaning shingle dendrites are formed of stacked calcite crystals and are generally more compact than feather dendrites these developed through the incremental stacking of rectangular shaped calcite crystals that initially grew as skeletal crystals feather and scandulitic dendrites precipitated from the same waters in the same springs the difference in morphology is therefore related to microenvironments in which they grew feather dendrites grew in any direction in pools of free standing water provided that they were in constant contact with the solute conversely scandulitic dendrites grew on rims of dams where water flowed over the surface in concert with the pulses of spring water thus each calcite crystal in these dendrites represents one episode of crystal growth the orientation of the component crystals in scandulitic dendrites is controlled by the topography of the dam or surface not crystallographic criteria the noncrystallographic dendrites formed from spring waters with initial temperatures of 90 99 c surficial water cooling loss of co2 and presence of other elements that can interfere with crystal growth contributed to the formation of these unusual crystals

sedimentary facies depositional environments and palaeogeographic evolution of the neogene denizli basin sw anatolia turkey abstract the denizli basin southwestern anatolia turkey contains a record of environmental changes dating since the early miocene detailed facies analysis of the neogene formations in this half graben enables us to document successive depositional regimes and palaeogeographic settings sedimentation commenced in the early miocene with the deposition of alluvial fan and fluvial facies kizilburun formation at this stage alluvial fans sourced from elevated areas to the south prograded towards the basin centre the middle miocene time saw the establishment of marginal lacustrine and wetland environments followed by the development of a shallow lake sazak formation the uppermost part of this unit consists of evaporitic saline lake and saline mudflat facies that grade upward into brackish lacustrine deposits of late miocene pliocene age kolankaya formation the lake became shallower at the end of the pliocene time as is indicated by expansion shoreface foreshore facies in the early quaternary the denizli basin was transformed into a graben by the activation of ese trending normal faults alluvial fans were active at the basin margins whereas a meandering river system occupied the basin central part oxygen isotope data from carbonates in the successive formations show an alternation of wetter climatic periods when fresh water settings predominated and very arid periods when the basin hosted brackish to hypersaline lakes the neogene sedimentation was controlled by an active ese trending major normal fault along the basin s southern margin and by climatically induced lake level changes the deposition was more or less continuous from the early miocene to late pliocene time with local unconformities developed only in the uppermost part of the basin fill succession the unconformable base of the overlying quaternary deposits reflects the basin s transformation from a half graben into a graben system

depositional properties and geochemistry of holocene perched springline tufa deposits and associated spring waters a case study from the denizli province western turkey the guney waterfall area is a perched springline tufa site developed on the southeast slope of the buyuk menders river near guney town in the denizli province western turkey the site is away 12 km from the town and 72 km from the city center of denizli the spring waters emerge from the boundary between palaeozoic marble and micaschist and precipitated tufa deposits downslope at the altitudes ranging from 220 to 400 metres the tufa deposits cover an area of about 20 hectars flat upper surfaces of the deposits are indicative of mature stage the waters are of the ca hco3 type and supersaturated with respect to caco3 the stable isotope values of the spring waters are 49 94 for 2h and 7 15 for 18o the 13c and 18o values of active and passive tufa samples are in the range from 9 13 to 6 0 and from 8 44 to 7 40 respectively these isotopic values are typical for fresh water tufa the passive tufas give the 14c age in the range from 2000 to 5800 yr bp according to the 14c age data passive tufas are not older than holocene the stable isotope composition is similar south european examples

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

origins of elements building travertine and tufa new perspectives provided by isotopic and geochemical tracers fluid rock interaction represents a major process in the formation of calcitic or aragonitic travertine and tufa catt in most cases catt is associated to limestone dissolution somewhere along the hydrogeological pathway however a wide array of other substratum basalts rhyolites carbonatites ultramafics granites dolomites evaporites can act as potential source of elements involved in the formation of catt this study reports on the evaluation of potential geochemical tracers linking catt to their substratum and unravelling the origin of elements a large database was established from available literature data as well as new data acquired in the frame of this study for a set of modern to recent catt ligurian ophiolites italy the chaine des puys limagne graben and paris basin france reunion island indian ocean jebel oust tunisia four most reliable tracing methods are identified 1 13c and 18o cross plot allows distinguishing epigean min 13c 27 2 max 13c 0 9 mean 13c 12 3 for n 314 from hypogean systems min 13c 4 max 13c 11 7 mean 13c 2 87 for n 198 very low 13c values 4 associated to negative 13c values are specifically indicative of an ultramafic source rock 2 barium and strontium cross plot helps to discriminate different groups of source rocks amongst the hypogean catt i source rocks composed of mixed limestones evaporites and dolomites are characterised by low barium 400 ppm contents ii mafic and granitic source rocks are undifferentiated and display similar barium from 15 to 930 ppm and high strontium 200 ppm contents iii the carbonatite group is characterised by its exceptional high barium and strontium values in epigean catt a pure limestone source rock usually relates to very low barium and strontium contents 50 ppm 3 relatively high beryllium content 30 ppm in catt seems to indicate a pure granitoid source 4 high chromium concentrations 20 ppm are systematically documented in modern catt located on an ultramafic substratum the definition of diagnostic compositional fields for actively forming or recently formed catt is influenced by many factors including water composition water temperature dissolved gas composition and concentration biological activity position in the sedimentary body and early diagenesis in addition to substratum lithology however the results of this study illustrate that despite these many factors the combined use of ba sr be cr 13c and 18o may be valuable to discriminate the rock lithology prevailing in the hydrogeological or palaeo hydrogeological reservoir of catt

the marine record of the onset of farming around the arabian sea at the dawn of the bronze age the rise and fall of human cultures are strongly modulated by the strong environmental changes taking place during the holocene here we use the sedimentological and geochemical records of a core

origin and diagenesis of quaternary travertine shrub fabrics rapolano terme central italy millimetre to centimetre sized arborescent shrub like calcite precipitates are common constituents of hot water travertine shallow pool deposits of quaternary age at rapolano terme tuscany italy in the presently forming travertines the shrubs consist of apparently random associations of i micrite aggregates and ii subhedral to euhedral rhombic spar crystal aggregates in thin section the micrite aggregates appear dark and the spar rhomb aggregates light giving the shrubs a mottled appearance travertines are basically produced by caco3 precipitation due to degassing and evaporation of the spring waters although biological influence may also stimulate precipitation the formation of masses of erect shrubs rather than dense crystal crusts that form on slopes is probably due to limited water flow in the pool environments microbes including bacteria and diatoms are important influences on shrub microfabric and external shape the micrite aggregates are associated with bacteriform bodies seen as tiny rods and spheres the micrite precipitates around these bodies and in adjacent biofilm spar rhomb precipitation appears to be external to the biofilm and may be related to the presence of diatoms which are locally closely associated with the spar rhombs although an essentially inorganic origin particularly for the more euhedral rhombs cannot be ruled out in the older quaternary travertines the original microfabric of the shrubs has been diagenetically altered the original mottled appearance of the shrubs has become uniformly dark and micritic and the evidence for the dual micritic and spar rhomb origin of the shrubs is obscured or destroyed spar micritization of the shrubs is probably due to abiotic and locally biotic dissolution previous studies did not recognize the diagenetic micritization and attributed shrub formation entirely to bacterial activity

lateral and vertical variations in sedimentology and geochemistry of sub horizontal laminated travertines cakmak quarry denizli basin turkey abstract the laterally extensive sub horizontal laminated travertine deposits outcropping in the cakmak quarry denizli basin turkey allows reconstructing their three dimensional geobody architecture based on field observations detailed petrographic and geochemical analyses stable carbon and oxygen isotopes major and trace elements the most important controlling porosity permeability parameters in this lacustrine dominated facies in relation to microfacies and diagenetic modifications were constrained sedimentological analyses and the observed architectural geometries allowed to subdivide the sub horizontal carbonate succession into three main depositional units these units in turn based on macro and microscopic observations were subdivided into nine dominant lithotypes reflecting an overall shrub flat and a marsh pool depositional setting the shrub flat facies mainly comprises dendritic shrub crusts boundstone pustular grainstone and clotted micrite mudstone to boundstone in contrast the marsh pool environment is dominated by coated reed rudstone to boundstone cryptalgal silty bioclast rich bioturbated mudstone and peloidal packstones the diagenetic study revealed that the sediments were affected by dissolution cementation sparmicritization recrystallization and local formation of fe oxi hydroxides and chalcedony among the diagenetic products in particular the calcite cements were investigated applying micro analysis of stable carbon and oxygen isotopes accordingly the co variation between the obtained isotopic values and the elemental concentrations sr mg na and s point to a thermogene fluid system that likely circulated through the subsurface limestones dolomites and evaporites of the lycian nappes these findings ensure an in depth understanding of continental carbonate deposition i e sub aqueous travertines in the context of a lacustrine depositional system

sedimentology of coexisting travertine and tufa deposits in a mounded geothermal spring carbonate system obruktepe turkey the recent discoveries of deeply buried cretaceous reservoir bodies in the atlantic ocean revealed that relationships between the distribution of spring carbonate deposits and faults are poorly understood the well exposed quaternary deposits at obruktepe denizli basin turkey provide an opportunity to reconstruct the three dimensional sedimentary architecture of such a system integration of sedimentological lithofacies and geochemical analyses reveals complexity in the lateral relationships between sedimentary environments faults and geothermal spring carbonates five environmental systems are distinguished based on the lithofacies analysis i vent ii smooth slope iii travertine terrace iv tufa barrage and v flood systems encrusting baffling and settling sedimentary processes are reflected in data acquired at several scales from lithofacies observations to the morphology and arrangement of geobodies together with microfabrics and stable carbon and oxygen isotope data mean values of 4 9 parts per thousand delta c 13 and 8 74 parts per thousand delta o 18 vienna peedee belemnite reflect geothermal circulation of springwaters the environmental distribution and lithofacies indicate a lateral continuum between travertine and tufa deposits within this hot spring system this finding supports two depositional models in which water flow variation is the main control on both caco3 precipitation and the resulting formation of travertine and tufa the proposed models address the factors responsible for the development of these complex mound shaped carbonate spring deposits and how they are related to fluid circulation at depth and in association with faults

the azuaje travertine an example of aragonite deposition in a recent volcanic setting n gran canaria island spain the azuaje travertines in the north of gran canary island crop out in the azuaje gorge which is incised into miocene volcanic breccias of the roque nublo formation this travertine is interesting because of the scarcity of travertines in the canary islands and its close relationship with recent volcanic events part of the travertine overlies a lava flow dated at 2420 40 years bp the travertine is composed mainly of aragonite in both perched systems on the gorge walls and in gorge bottom deposits parallel to the present stream perched systems include deposits from the feeder conduits within the roque nublo formation that spilled out through waterfalls and over barriers the gorge valley bottom system includes barrier and pool deposits the main laminated facies are composed mostly of large fibrous aragonite crystals while there are also common micritic and porous microfabrics shrubs coated grains coated bubbles and rafts are present in many of the deposits detailed study of the microfacies shows the presence of sparsely distributed biogenic features the 13c values are between 4 0 and 11 0 and the 18o values range between 11 0 and 2 0 vpdb these 13c values lie within the range of those of thermogene travertines fed by thermal waters that cooled downstream as indicated by the increase of the carbon and oxygen isotope values in that direction the common occurrence of fibrous radial fabrics is interpreted to be due to disequilibrium conditions during aragonite precipitation disequilibrium was likely caused by rapid co2 degassing of the thermalwaters that led to a rapid increase in the degree of aragonite saturation thus themorphology of the aragonite crystals and the isotopic composition indicate that the formation of the azuaje travertine was mostly due to abiogenic processes induced by rapid degassing of thermalwaters linked to the presence of a recent lava flow within the gorge in short the azuaje travertine shows the important role of volcanic activity in travertine deposition in the facies distribution as well as in the geochemical signatures of the deposits and so can be used as a recent analogue for ancient travertine deposits in volcanic settings

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

pleistocene holocene tectonic reconstruction of the ballik travertine denizli graben sw turkey de formation of large travertine geobodies at intersecting grabens abstract travertine geobodies have been identified as potential reservoir analogues to carbonate build ups in pre salt hydrocarbon systems to investigate travertine geobody deformation faults were mapped in 35 travertine quarries that excavate the ballik travertine i e a c 12 5 km2 large travertine geobody that precipitated at the intersection of the ne margin of the denizli basin and neighbouring baklan graben sw turkey this travertine precipitated from cooling carbonate saturated thermal spring waters that resurfaced along the margin fracture fault network and through neogene unconsolidated underlying sediments from the denizli basin floor to the uplifted graben shoulders fault orientation is dominantly wnw ese oriented with major basin faults showing a left stepping trend along the upper denizli margin travertine is only deformed by extensional normal faults along the lower margin travertine starts with a subhorizontal facies but evolves to a travertine facies formed by a sloping topography with a domal architecture paleostress inversion of fault slip data reveals that an early pleistocene nne ssw extensional transtensional phase initiated the wnw ese oriented graben facing normal fault network in the middle pleistocene the ballik fault network was left lateral strike slip reactivated because it acted as a transfer zone between the nw se extending neighbouring baklan basin and nw se extension along ne sw oriented margin faults of the dghs in this stress configuration travertine precipitated along the sw margin fault of the baklan graben after strike slip reactivation a late pleistocene to current nne ssw extensional stress regime reinstalled during which margin faults widened and active travertine precipitation moved to more central parts of the dghs as different tectonic regimes affect graben intersections reservoir analogues can have a complex deformation history driven by fault reactivation and recurrent stress permutations this study concludes that large travertine geobodies can form at graben intersections because of their susceptibility to enhanced fluid flow through the complex fault fracture network

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

stable isotopic and elemental characteristics of recent tufa from a karstic krka river south east slovenia useful environmental proxies tufa samples from 16 consecutive barrages along a 13 km section of a groundwater fed krka river slovenia were analysed for their petrographical mineralogical elemental and stable carbon 13c and oxygen 18o isotope composition to establish their relation to current climatic and hydrological conditions waters constantly oversaturated with calcite and the steep morphology of the krka riverbed stimulate rapid co2 degassing and subsequent tufa precipitation the carbon isotope fractionation 13c between dic and tufa in the krka river evolves toward isotopic equilibrium being controlled by continuous co2 degassing and tufa precipitation rate downstream the 13c increased from 1 9 to 2 5 vienna peedee belemnite however since tufa precipitation rates remain similar downstream the major controlling factor of carbon isotope exchange is most probably related to the continuous 12co2 degassing downstream leaving the carbon pool enriched in 13c in the case of oxygen the isotope fractionation was found to be from 1 0 to 2 3 smaller than reported in the literature the observed discrepancies are due to different precipitation rates of calcite deposits as krka tufas on cascades grow relatively faster compared to slowly precipitated calcite deposits in cave or stream pools due to non equilibrium oxygen isotope exchange between krka tufa and water the 18o proxy showed from 1 2 to 8 2 c higher calculated water temperatures compared to measured water temperatures demonstrating that 18o proxy based temperature equations are not reliable for water temperature calculations of fast growing tufa on cascades because mg is bound to the terrigenous dolomite fraction in the krka tufa samples the mg ca was also found to be an unreliable temperature proxy yielding over up to 20 c higher calculated water temperatures this article is protected by copyright all rights reserved

automated segmentation of hillslope profiles across ridges and valleys using a digital elevation model abstract we developed a three step algorithm to automate the recognition and segmentation of hillslopes across ridges and valleys using a gridded digital elevation model dem the first step involves the delineation of a side slope profile by locating the lower and upper boundaries in the second step the cross profile pattern of a ridge or a valley floor which is defined and bounded by a pair of side slopes is examined in order to distinguish upland flats from ridges and lowlands from valley floors the width and gradient of these landform units are also measured in the third step a side slope profile is segmented into lower mid and upper slopes with a line simplification algorithm to identify changes and breaks in the slope in this step the footslope and crestslope can also be distinguished within the lower and upper slopes respectively using a 15 m dem this method was applied to five sites in low to high relief fluvial landscapes in japan the results showed good agreement 86 9 2 7 with manual slope segmentation indicating the effectiveness of our algorithm

facies character and depositional architecture of hydrothermal travertine slope aprons pleistocene acquasanta terme central italy abstract hydrothermal travertines develop various depositional geometries from tabular to high relief mounds or aprons with steep slopes under the control of local topography location and geometry of the vents fault activity hydrology water physico chemical properties rates of thermal water flow and carbonate precipitation rates this study focuses on two pleistocene tens of metres thick travertine slope aprons accumulated on fluvial terraces in the tronto river valley acquasanta terme central italy to investigate their facies character geochemical signature porosity and evolution of the depositional geometry through time the two travertine aprons consist of four aggradational progradational units vertically and laterally stacked with onlap and downlap stratal terminations separated by erosional unconformities produced by events of non deposition and erosion due to temporary interruptions of vent activity shifts of the vent location and or deviation of the flow directions the travertine units include various depositional environments 1 smooth slope 2 terraced slope with metre scale sub horizontal pools separated by rounded rims and vertical walls and 3 sub horizontal tens of metres wide ponds smooth slope clinoforms are made of centimetre to decimetre thick layers of crystalline dendrite cementstone laminated boundstone and radial coated grain grainstone precipitated by fast flowing water on inclined substrates rims and walls of terraced slopes are built by crystalline dendrites and laminated boundstone sub horizontal layers of terrace pools and ponds consist of facies precipitated by slow flowing to standing water clotted peloidal micrite dendrite coated bubble boundstone raft rudstone associated with radial coated grains and laminated boundstone carbonate coated reeds occur in distal ponds adjacent to toe of slopes or overlie packstone rudstone with travertine intraclasts and substrate extraclasts marking events of subaerial exposure and erosion travertine facies porosity and permeability range from 4 to 21 and 0 03 to 669 md respectively showing no direct correlation stable isotope values 13 c 5 7 9 3 18 o 9 6 to 12 2 are similar to other travertines precipitated by thermal water in central italy this study identifies the centimetre scale travertine facies variability linking it to the environment of deposition and to the depositional geometry of travertine units affected by the substrate topography and lateral shifts of the active springs despite the different scale and facies composition the geometry of aggradational progradational units of travertine aprons might resemble marine flat topped high relief carbonate platforms travertine units in the subsurface if present with sizes that can be seismically resolved might be wrongly interpreted as carbonate platforms with steep slopes without a detailed facies analysis

uranium series dating of travertine from suttő implications for reconstruction of environmental change in hungary abstract terrestrial carbonate formations such as travertines speleothems and lake sediments are important archives of terrestrial climate forcing at the sutt section in hungary a complex succession of travertine is covered by a loess palaeosol sequence both are high resolution terrestrial archives of climate and environment change uranium series 230th u dating was carried out to set up a more reliable chronological frame for the travertine as the growth of travertine is very complex pore cements may cause serious problems for precise dating the state of alteration of primary spar and micrite was characterised by microscopic cathodoluminescence and microprobe analyses the travertine from sutt showed homogeneous phases of primary calcite minor micropores and rare pore cements the carbon isotopic composition indicates that the source of carbon was a mixture of atmospheric and soil derived co2 calculated water temperatures based on oxygen isotope data range from 22 c to 31 c an attempt to provide an independent relative dating approach by palaeomagnetic techniques failed 230th u ages were determined applying an isochron approach using the leachate leachate method as the travertine deposits have a dense structure the bulk sampling method was successfully applied in determining uranium series ages with much higher precision than former studies with alpha spectrometry travertines from sutt yielded mid pleistocene ages ranging from the antepenultimate glacial to the penultimate interglacial 310 240 ka these results are in agreement with those from optically stimulated luminescence osl dating and amino acid racemisation aar dating of the overlying sediment indicating at least an mis 7 age for the travertine

chemical and stable isotope composition of recent hot water travertines and associated thermal waters from egerszalok hungary depositional facies and non equilibrium fractionation abstract combined petrographical mineralogical geochemical and stable isotope analyses were conducted on an actively forming egerszalok travertine mound to determine the factors that govern carbonate precipitation and thus influence the use of travertines in paleoclimate reconstruction stable isotope analyses of oxygen carbon and hydrogen demonstrate both biological and abiological factors to control travertine deposition processes of morphology related outgassing had major effects upon isotopic composition continuous co 2 degassing and temperature change of the thermal water between the spring orifice and distal parts of the system caused stable carbon and oxygen isotope compositions of the precipitating travertines to increase from 2 7 to 4 3 relative to v pdb and from 10 5 to 14 7 relative to v smow respectively the travertines at the spring orifice t 67 c are composed of almost pure calcite with a 13 c value of 2 7 relative to v pdb enabling classification as intermediate between thermometeogene and thermogene in lower temperature water away from the spring orifice various amounts of aragonite 5 35 with higher sr concentrations precipitate from solution this phenomenon is exceptional in hot spring carbonate deposits and could be explained by fast carbonate precipitation due to the morphology related outgassing oxygen and hydrogen isotope measurements of the thermal water confirmed evaporation to be causing limited kinetic isotope fractionation however 18 o values of the travertine do show isotope shifts away from the equilibrium fractionation curve which is most probably related to the rapid calcite precipitation and transportation along the flow path our data closely follow the temperature 18 o calcite water relationship observed for other travertine localities this is slightly displaced from the experimental curve and determines an empirical travertine curve our study shows that this shift may result in an approximately 8 c difference in paleotemperature calculations depending upon which fractionation curve is used

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

calcite veining and feeding conduits in a hydrothermal system insights from a natural section across the pleistocene golemezli travertine depositional system western anatolia turkey abstract linking the architecture of structural conduits with the hydrothermal fluids migrating from the reservoir up to the surface is a key factor in geothermal research a contribution to this achievement derives from the study of spring related travertine deposits but although travertine depositional systems occur widely their feeding conduits are only rarely exposed the integrated study carried out in the geothermal golemezli area nearby the well known pamukkale area denizli basin western anatolia turkey focused on onyx like calcite veins banded travertine and bedded travertine well exposed in a natural cross section allowing the reconstruction of the shallower part of a geothermal system the onyx like veins represent the thickest vein network 150 m so far known new field mapping and structural kinematic analyses allowed to document a partially dismantled travertine complex bedded travertine formed by proximal fissure ridges and distal terraced pools depositional systems the banded calcite veins wnw trending and up to 12 m thick developed within a 200 m thick damaged rock volume produced by parallel fault zones th u dating indicates a long lasting middle late pleistocene fluids circulation in a palaeo geothermal system that due to its location and chemical characteristics can be considered the analogue of the nearby still active pamukkale system the isotopic characteristics of the calcite veins together with data from fluid inclusions analyses allow the reconstruction of some properties i e temperature salinity and isotopic composition and processes i e temperature variation and intensity of degassing that characterized the parent fluids and the relation between degassing intensity and specific microfabric of calcite crystals elongated microsparite micrite bands controlled by changes fluctuations of the physico chemical fluid characteristics

genesis and diagenesis of travertine futamata hot spring japan abstract genetic and diagenetic processes of travertine were examined at futamata hot spring where both active and inactive subfossil and fossil travertines are present geochemical and geomicrobiological analyses of active travertines reveal that abiotic process of caco3 precipitation is predominant photosynthetic inhibition of caco3 precipitation occurs at the upstream while the cyanobacterial population is low in the downstream resulting in photosynthesis induced caco3 precipitation only in the midstream nonetheless microorganisms have an effect upon depositional fabrics and filamentous cyanobacteria possessing non acidic sheaths contribute to the particle trapping binding and the generation of pore space both active and inactive travertines are mainly composed of calcite however active travertine in the up midstream also contains some aragonite due to high rates of co2 degassing active and subfossil travertines are characterized by domal topography and relatively high flow rates are assumed due to the dominance of slope facies on the other hand fossil travertines are characterized by fissure ridge topography and relatively low flow rates are assumed due to the dominance of crest and marsh facies the elemental composition of travertines primarily reflects their constituent minerals and the active travertines consisting of both aragonite and calcite show higher sr ba na and k contents whereas travertines consisting solely of calcite show higher mg and mn contents due to elevated mn content bright cathode luminescence is exhibited by the primary calcite of active travertines most fossil travertines have experienced prominent diagenetic alteration in the vadose zone and are commonly cemented and recrystallized in addition to meteoric water percolating hot spring water was also involved in the diagenetic process combined with the results of u th dating our results suggest that the formation of fissure ridge travertines at futamata hot spring began approximately 20 thousand years ago ka via fault activity which terminated at around 7 ka and the domal travertines were formed by hot spring water discharging from several vents

sedimentological and geochemical characteristics of a fluvial travertine a case from the eastern mediterranean region a sedimentological and geochemical study was performed on the travertines in the southern part of the usak geothermal field western turkey to assess the applicability of a fluvial tufa facies model in interpreting late quaternary travertine deposits developed along the stream valleys that follow fault and fracture systems modern thermal 31 to 38 c springs are found on the floor of the valley between 480 m and 520 m above sea level the distribution and nature of travertine facies were determined from natural outcrops samples of the travertines and spring water were characterized using a range of geochemical and petrographic methods waterfall slope and pool facies associations consist of various combinations of travertine facies and subordinate detrital facies waterfall and slope facies associations of the older deposits occur where the springs emerged onto a hillslope or topographic break in contrast the pool facies association developed in depressions or flat areas that were fed by thermal springs the youngest generation 1 85 ka precipitated at lower elevations than the older ones 147 to 153 ka stable carbon and oxygen isotope values of the aksaz travertines range between 4 3 and 6 3 vienna pee dee belemnite and 12 6 and 7 2 vienna pee dee belemnite respectively the high d 13 c values suggest that the thermal waters were charged with isotopically heavy co2 of deep origin based on palaeotemperature calculations the temperatures of the palaeosprings are slightly higher up to 44 c than the present equivalents but sometimes the temperature is lower probably due to mixing with the stream water although the thermal waters occasionally are impeded by fluvial activity travertine precipitation occurs in the protected parts of the aksaz stream valley this contribution highlights the applicability of the fluvial facies model for tufa for the interpretation of travertine deposits worldwide

habit of bacterially induced precipitates of calcium carbonate and the influence of medium viscosity on mineralogy abstract marine bacteria can and do induce the precipitation of calcium carbonate in the laboratory and in nature which results in single crystals and aggregates of crystals crystal bundles the end member forms of the crystal bundles observed are rods and spheres with numerous variations in between these forms the most common of which is the dumbbell rounded dumbbells and single crystals resembling brushes appear to be unique to bacterially induced precipitates and consequently may serve to identify bacterially induced precipitates in the rock record viscosity of the growth medium is the single most important control over the mineral precipitated in the experiments conducted the medium viscosity controls the ion diffusion rate and thus the rate of precipitation and consequently the mineral precipitated in a liquid medium circulation and the ion diffusion rate are both high precipitation is rapid and aragonite forms in a gelatinous medium there is little circulation the ion diffusion rate is slow the rate of precipitation is slow and calcite is precipitated the overall form of the resultant precipitate rods or spheres was the same regardless of the mineral composition

controls on aragonite and calcite precipitation in hot spring travertines at chemurkeu lake bogoria kenya subfossil travertines precipitated around hot spring orifices at chemurkeu on the western shore of lake bogoria kenya are composed of calcite aragonite and minor dolomite aragonite crystal beds which form 5 10 of the travertine by volume are formed of large pseudohexagonal prisms whereas the calcite crystal beds are composed mainly of feather dendrites dolomite is only found between aragonite crystals boundaries between aragonite and calcite crystals commonly display evidence of dissolution but there is no evidence to indicate that calcite formed by inversion of aragonite or that the dolomite replaced the aragonite thus the aragonite calcite and dolomite are each treated as primary precipitates reticulate gelatinous coatings with a high si and mg content cover most external and internal surfaces of the aragonite and calcite crystals the travertines may have formed under more humid conditions than today when the spring waters contained more ca2 the physiochemical conditions at the mo

growth of a pleistocene giant carbonate vein and nearby thermogene travertine deposits at semproniano southern tuscany italy estimate of co2 leakage abstract a giant carbonate vein 50 m thick fissure ridge travertines and nearby travertine plateaus in the semproniano area mt amiata geothermal field southern tuscany italy are investigated through a multidisciplinary approach including field and laboratory geochemical analyses u th geochronology c nd o and sr isotope systematics ree abundances and fluid inclusion microthermometry the main aim of this work is to understand 1 modes and rates for the growth of the giant vein and nearby travertine deposits within a quaternary volcano tectonic domain 2 implications in terms of the co 2 leakage and 3 possible relationships with quaternary paleoclimate and hydrological oscillations results show that the giant vein was the inner portion of a large fissure ridge travertine and grew asymmetrically and ataxially through repeated shallow fluid injections between 650 and 85 ka with growth rates in the 10 2 10 3 mm a order the giant vein developed mainly during warm humid interglacial periods partially overlapping with the growth of nearby travertine plateaus estimated values of co 2 leakage connected with the vein precipitation are between about 5 10 6 and 3 10 7 mol a 1 km 2 approximately representing one millionth of the present global co 2 leakage from volcanic areas temperature estimates obtained from o isotopes and fluid inclusion microthermometry indicate epithermal conditions 90 50 c for the circulating fluid during the giant vein growth with only slight evidence of cooling with time geochemical and isotope data document that the travertine deposits formed mainly during pleistocene warm humid periods within a tectonically controlled convective fluid circuit fed by meteoric infiltration and maintained by the regional geothermal anomaly hosted by the carbonate reservoir of the mt amiata field

contrasting fault fluids along high angle faults a case study from southern apennines italy abstract this work focuses on two fault controlled deposits the atella and rapolla travertines which are associated with high angle extensional faults of the bradano trough southern apennines italy the atella travertine is along a nw se striking deep seated extensional fault already described in literature which crosscuts both apulian carbonates and the overlying foredeep basin infill the rapolla travertine is on top of a ne sw striking shallow seated fault here described for the first time which is interpreted as a tear fault associated with a shallow thrust displacing only the foredeep basin infill the results of structural sedimentological mineralogical and c and o isotope analyses are here reported and discussed to assess the provenance of mineralizing fluids and to evaluate the control exerted by the aforementioned extensional faults on deep mantle derived and shallow meteoric fluids sedimentological analysis is consistent with five lithofacies in the studied travertines which likely formed in a typical lacustrine depositional environment mineralogical analysis show that travertines mainly consist of calcite and minor quartz feldspar and clay minerals indicative of a terrigenous supply during travertine precipitation the isotope signature of the two studied travertines shows different provenance for the mineralizing fluids at the atella site the 13cpdb values range between 5 2 and 5 7 and the 18opdb values between 9 0 and 7 3 which are consistent with a mantle derived co2 component in the fluid in contrast at the rapolla site the 13cpdb values vary from 2 7 to 1 5 and the 18opdb values from 6 8 to 5 4 suggesting a mixed co2 source with both biogenic derived and mantle derived fluids the results of structural analyses conducted along the footwall damage zone of the fault exposed at the rapolla site show that the whole damage zone in which fractures and joints likely channeled the mixed fluids acted as a distributed conduit for both fault parallel and cross fault fluid migration

superimposed basin formation during neogene quaternary extensional tectonics in sw anatolia turkey insights from the kinematics of the dinar fault zone abstract in the extensional province of sw anatolia the cross cutting relationship between the nw and ne oriented neogene and quaternary basins is an ongoing debate in the understanding of the tectonic evolution of this area in order to contribute to this issue we carried out a structural and kinematic study along the seismogenic nw trending dinar fault zone dfz this structure was initially controlled by the sedimentary and tectonic evolution of the ne oriented neogene baklan acigol and burdur basins and later by the nw oriented quaternary dinar basin on the basis of 1000 structural and kinematic data in conjunction with basin stratigraphy the dfz can be divided into three almost parallel and continuous bands that are a the hangingwall where quaternary sediments are deformed by normal faults with mechanical striations b the inner zone corresponding to the present dinar fault scarp where nw trending normal faults with mechanical striations are dominant and c the outer zone located in the footwall of the structure comprising the area between the fault scarp and undeformed bedrock where faults exhibit variable orientation and kinematics from strike slip to normal dip slip these kinematics are mainly indicated by calcite shear veins and superimposed mechanical striations respectively this suggests that the dfz changed kinematics over time i e the dfz initiated as dominant dextral strike slip to oblique slip fault system and continued with a dominant normal movement therefore we hypothesize that the nw trending dfz was initially a transfer zone during the late miocene pliocene coeval to the sedimentary and structural evolution of the ne trending baklan acigol and burdur basins during the quaternary the dfz representing an already weakened crustal sector played the role of a normal fault system providing the accommodation space for the quaternary dinar basin hydrothermal circulation and volcanism at ne nw trending faults intersection implies structurally driven conduits channeling fluids from depth to surface

hydrochemical evolution and reaction simulation of travertine deposition of the lianchangping hot springs in yunnan china located in western yunnan of china the lianchangping hot springs are of so 4 hco 3 ca na type with total dissolved solids tds ranging from 3560 to 4240 mg l large amounts of travertine are deposited near the hot springs with a variety of travertine morphology including travertine terrace slope and ridge travertine is precipitating along the slope near one of the spring s thresholds chemical compositions of the hot water samples collected along travertine slope show that p co 2 p co 2 tds and contents of hco 3 and ca decrease downstream along the travertine slope due to travertine deposition the initial milliequivalent ratio of ca 2 hco 3 is greater than 1 5 before travertine precipitation and there is an increasing trend in the ratio downstream along the travertine slope high levels of sulphate are probably the result of gypsum dissolution in the sediments widespread in the lianchangping area the spring waters issuing from the land surface are slightly supersaturated with respect to calcite dolomite fluorite kaolinite halite plagioclase and carbon dioxide hydrochemical evolution of the lianchangping spring water along the slope is calculated with the phreeqc interactive 2 12 5 sets of minerals and gases reacted in appropriate amounts are recognized through reaction simulation quantitatively accounting for the variations in chemical compositions especially depositing minerals along the flow path on the travertine slope

the quaternary travertine deposits of europe and asia minor abstract a summary is provided of the published information relating to all aspects of quaternary travertine formation in europe west of the ural mountains the deposits have been divided into two broad groups the meteogene travertines which result primarily from the degassing of soil borne aqueous co 2 and thermogene deposits resulting from the degassing of thermally generated co 2 meteogene deposits are rare above latitude 58 n and in regions where the mean annual air temperature is below 5 c a significant positive correlation exists between mean air temperature and travertine deposit thickness the combined effects of temperature and rainfall are used to provide a zoned map showing the travertine forming potential of limestones within the region information from 14 c dating indicates that deposition reached a maximum in the period 5 10 ka bp and is currently limited by land and water management practices in the populated areas thermogene deposits occur in regions of high co 2 discharge resulting from tectonic activity such as italy and turkey where there is much vulcanism these travertines are frequently more massive and less readily weathered than meteogene deposits fully referenced information is provided for 320 important mostly well studied sites 227 meteogene 93 thermogene of which 156 are currently active

temperature dependence of oxygen and clumped isotope fractionation in carbonates a study of travertines and tufas in the 6 95 c temperature range conventional carbonate water oxygen isotope thermometry and the more recently developed clumped isotope thermometer have been widely used for the reconstruction of paleotemperatures from a variety of carbonate materials in spite of a large number of studies however there are still large uncertainties in both 18o and 47 based temperature calibrations for this reason there is a need to better understand the controls on isotope fractionation especially on natural carbonates in this study we analyzed oxygen carbon and clumped isotopes of a unique set of modern calcitic and aragonitic travertines tufa and cave deposits from natural springs and wells together these samples cover a temperature range from 6 to 95 c travertine samples were collected close to the vents of the springs and from pools and tufa samples were collected from karstic creeks and a cave the majority of our vent and pool travertines and tufa samples show a carbonate water oxygen isotope fractionation comparable to the one of tremaine et al 2011 with some samples showing higher fractionations no significant difference between the calcite water and aragonite water oxygen isotope fractionation could be observed the 47 data from the travertines show a strong relationship with temperature and define the regression 47 0 044 0 005 106 t2 0 205 0 047 the ph of the parent solution mineralogy and precipitation rate do not appear to significantly affect the 47 signature of carbonates compared to the temperature effect and the analytical error the tufa samples and three biogenic calcites show an excellent fit with the travertine calibration indicating that this regression can be used for other carbonates as well this work extends the calibration range of the clumped isotope thermometer to travertine and tufa deposits in the temperature range from 6 c to 95 c

multidisciplinary approach for palaeoclimatic signals of the non marine carbonates the case of the sarikavak tufa deposits afyon sw turkey abstract non marine carbonates such as travertine tufa and speleothem are quite sensitive for climatic fluctuations this study presents the new dating and the first pollen records from afyon sarikavak tufas sw turkey together with lithofacies descriptions geochemical and petrographic results obtained from drilling cores sl 2 sl 6 and sl 7 the data extensively provides insight into palaeoenvironmental and palaeoclimatic changes during the middle late pleistocene period according to core samples these fluvial tufa occurrences formed in high gradient and stepped fluvial conditions have been defined as barrage dammed and terraced slope systems in the investigated area the depositional lithofacies are moss tufa included macrophytes bryophytes and vertical stems phytoclastic tufa peloidal tufa micritic tufa microbial tufa intraclastic tufa extra formational tufa lime muddy clay and paleosol level in respectively the new u th radiometric dating and stable isotopes are evaluated together with previously published results in regard to new radiometric data tufa deposits occurred predominantly during the marine isotopic stages at 313 3 21 mis 9 295 8 63 mis 8 9 230 8 42 mis 7d e 228 8 12 mis 7d 215 7 17 mis 7c and 188 2 16 mis 6 7a ka respectively the climatic changes occurring between glacial and interglacial periods such as during the middle late pleistocene might probably influenced the precipitation of tufas in the area in addition the less negative and the more positive carbon isotopic values between 0 8 and 1 3 v pdb could be related to the progressive downstream co2 degassing from host rocks enhanced by high velocity current conditions changes in the soil co2 contribution and photosynthesis the changes of 18o values between 8 3 and 10 1 v pdb are most probably related to variable effects of evaporation in depositional environment palynofloral data gives important clues about the paleovegetation and paleoclimate of the region this field survey has been conducted the first time in this area both carbon values and palynological findings show that drought conditions were dominantly present in the pleistocene period but in some processes drought conditions decreased depending on the amount of rainfall the increasing amount of gymnosperm pollens is more likely to appear in more humid conditions due to the decreasing of drought condition in this time interval

hydrogeology and geochemistry in the curuksu denizli hydrothermal field western turkey curuksu is a low temperature hydrothermal system located within the upper sector of the b menderes graben the hydrologic structure of the curuksu hydrothermal system is largely controlled by major graben faults where it is characterized by the presence of two thermal reservoirs one is formed by paleozoic quartzite schist and marble units and the second consists of pliocene limestone travertine units the thermal conditions in the curuksu region indicate that the regional tectonics and resulting local stress field control low temperatures activity temperatures of 30 springs emerging in the study area range between 15 and 55 c these springs are classified as cold fresh warm mineral and thermal waters pamukkale karahayit and honaz springs are steam condensate waters whereas curuksu springs are commonly steam heated waters with respect to the major anion concentrations the reservoir temperatures have been estimated from chemical compositions by utilizing simultaneously geothermometers and mixing models according to these thermometric methods the most probable subsurface temperature is in the range of 62 90 c however the mixing models suggest a temperature level of 80 c for the parent water the system has low total dissolved solid tds of 1000 1500 mg l which indicate that these waters undergo conductive cooling within the reservoir

neogene evolution of the denizli region of western turkey the denizli region contains one of the easternmost neogene sedimentary basins in the part of western turkey that takes up ssw extension this isolated active normal fault zone which contains closely spaced en echelon normal fault branches is investigated using field measurements of fault exposures and tilted sediments and seismological observations as a case study to address its style of extension the denizli basin is no more than 1 km thick and has accommodated up to 4 km of extension substantial 20 sediment dips are readily explicable assuming extension is accompanied by distributed vertical simple shear with initial and present day dips of the main normal faults that control extension most likely 54 57 and 45 50 other aspects of the form of this basin require regional uplift at 0 1 mm yr 1 providing the first indication of major tectonic elevation changes in this actively extending region that are not directly related to throw on normal faults

travertines depositional morphology and the bacterially constructed constituents abstract investigation of travertine accumulations throughout central italy and the west central u s has shown that the carbonate is precipitated in response to both inorganic and organic processes individual deposits range up to 85 m thick and hundreds of square kilometers in areal extent all of the carbonate is low magnesian calcite water chemistry temperature and morphology of the accumulation greatly influence the constituents comprising these deposits harsh environmental situations favor inorganic deposits while increasingly more moderate conditions result in the formation of a greater abundance of organically precipitated material morphological variations of travertine deposits recognized include 1 waterfall or cascade 2 lake fill 3 sloping mound fan or cone 4 terraced ound and 5 fissure ridge gross morphology internal stratification and constituents comprising these deposits vary systematically depending upon the type of accumulation and chemistry of the waters bacterially precipitated calcite forms a large percentage of the carbonate in many travertine accumulations exceeding 90 of the framework grains comprising some of the lake fill deposits bacteria are among the first taxa to inhabit and reproduce in harsh spring environments and produce a variety of fascinating constituents the bacteria are primarily rods generally 0 2 m in diameter and less than 1 0 m in length the rods readily decay resulting in calcite crystals loaded with micropores the basic building block of bacterially constructed travertine is a clump of bacteria averaging 20 m in diameter enclosed in a single crystal of calcite aggregates of these crystals produce a variety of deposits including 1 crudely laminated carbonate mud 2 finely laminat d layers of mud 3 intraclasts 4 foam rock and 5 shrubs the shrubs are most striking commonly forming layers 1 3 cm thick but also producing bacterial pisoids at some locales bacterial stromatolites composed of layers of shrubs alternating with finely laminated layers of bacterial mud comprise essentially the entire deposit the shrub layers are the result of flourishing summer growth of bacteria and furthermore show remarkable daily laminae 0 1 0 5 mm thick the importance of bacteria in the formation of travertine and their universally recognized abundance in modern sediments provides an impetus for a reexamination of the role of bacteria in the origin of other types of ancient deposits

geobody architecture genesis and petrophysical characteristics of the budakalasz travertines buda hills hungary subsurface pre salt lower cretaceous reservoir systems encountered offshore brazil and angola that consist of porous continental carbonates are difficult to access because of the limited core material that is under concession therefore it is important to study comparable continental carbonate analogues such as travertines and lacustrine carbonates that potentially possess similar porosity and permeability characteristics the budakalasz pleistocene travertines buda hills hungary have been studied from a sedimentological geochemical and reservoir properties point of view in order to understand their formation petrophysical properties and 3d reservoir architecture the three dimensional geobody architecture of the budakalasz travertines illustrates the potential complexity of kilometre scale continental carbonate systems heterogeneous low angle sloping travertine lobes consisting of terrace slope smooth slope and reed facies are covered by a lime mudstone dominated gastropod and charophyte rich marsh pool facies the observed facies represent a change from a subaerial travertine to a palustrine to lacustrine system reflecting the ceasing of the system due to tectonic uplift the dominant paleo flow direction of the sloping lobes was towards the danube depression with several subordinate flow systems identified the srco isotope geochemical signatures reflect travertine precipitation at ambient to superambient temperatures from meteoric derived fluids with a mixed co2 origin of the marine carbonate substrate rocks a potential atmospheric and a soil derived component although the uniform signatures of the stable oxygen and carbon isotopes in addition to petrographic observations suggest partial diagenetic isotopic resetting the primary isotope trends seem to have been preserved a reservoir oriented facies evaluation in the three dimensional geobody frame of the budakalasz carbonates based on porosity and permeability core plug analyses reveals their heterogeneous nature terrace smooth slope and marsh pool facies have considerable porosities of 5 15 while the porosity of the reed facies may reach up to 27 permeability of all facies is strongly anisotropic mainly controlled by a better connectivity along layer parallel primary pores the reconstruction of the 3d geobody architecture of the budakalasz lobe complex coupled to its geochemical and petrophysical properties provides a unique dataset that contributes in understanding fossil travertine systems

diagenetic calcite varieties from travertines of central italy abstract quaternary travertines in latium and tuscany italy were deposited by warm springs containing abundant co2 and h2s the major rock formers were bacteria that precipitated calcite to form shrubs pisolites mats foamrock and clastic silt size sediment the calcite cement in these rocks shows extraordinary morphology the elementary building block is a subspherical clump of bacteria 10 to 40 m in diameter which becomes surrounded by a single crystal of calcite shaped like a pecan shell sem shows that these crystals are riddled with cavities voids representing bacteria and contain internal moats later the bacteria rich crystals became coated with clear chemically precipitated inorganic calcite cement but even these crystals are strange s they have curving edges and consist of a series of scales parallel to the rhomb faces like superimposed gothic arches other cement crystals bear a forest of sharp spikes parallel to the c axis like a fakir s bed the final sparry calcite that fills large pore spaces occurs as large bladed crystals with apparent basal parting planes primarily inorganic sediment includes ray crystals and pisolites ray crystals can be up to 1 m 39 in long and in some places show daily bacteria rich growth bands indicating deposition rates of as much as 1 m 39 in per year these formed as travertine dams on sloping surfaces and at ancient spring orifices crystals can be shaped like cedar tree needles or club shaped stromatolites show undulose extinction and in the sem consist of helically twisted calcite ribbons inorganic pisolites formed in hot spring mouths and are made of smoothly concentric rings of tightly bundled radial rods like fasces end of article last page 461

tectonic control on travertine and calcareous tufa deposition in a low temperature geothermal system sarteano central italy this paper presents an integrated study directed toward an understanding of the tectonic control on the hydrothermal circulation and resulting deposition of middle late pleistocene travertine in a low temperature geothermal field of southern tuscany located in the sarteano area central italy the study area is characterized by thermal springs c 25 c and related continental carbonate deposits structurally controlled by sw ne trending oblique to strike slip faults dissecting previous normal faults sedimentological stratigraphical data and 230 th 234 u radiometric age determination for the travertine indicate that continental carbonates were deposited in a tectonically controlled perched spring system from 268 22 ka at least to the present the hydrothermal system is and was characterized by meteoric waters with a minor contribution from fluids of deeper origin meteoric waters infiltrated to depth through tectonically damaged zones of mesozoic and cenozoic carbonate rocks and overheated as a result of localized anomalous geothermal gradient then fluids enriched in bicarbonate sulphate moved up along highly fractured rock masses at the intersection between strike slip faults and normal faults this paper highlights the use of continental carbonates in the reconstruction of palaeohydrothermal systems in terms of the location of the main conduits for hydrothermal fluid flow age of faulting and physical properties of hydrothermal fluids

speleothems travertines and paleoclimates abstract age data for about 660 speleothems and about 140 spring deposited travertines were collected including many unpublished results these data were plotted as histograms and also as error weighted frequency curves on a 350 000 yr scale these plots clearly show periods of increased speleothem travertine growth as well as times of cessation the periods of most frequent speleothem growth were between approximately 130 000 and 90 000 yr ago and since about 15 000 yr ago such periods before 150 000 yr ago however cannot be yet recognized because of a lack of sufficient data and the associated uncertainties of dates in this age range a comparison with the oxygen isotope record of deep sea core v28 238 shows a clear relationship indicating that terrestrial calcite formation is controlled by paleoclimatic fluctuations the evident climatic stimulation of quaternary calcite formation is readily explained geochemically and is substantiated by the obvious difference in speleothem travertine growth as a function of geographic position

c and o stable isotope variability in recent freshwater carbonates river krka croatia three types of recent carbonate precipitates from the river krka croatia were analysed 1 bulk tufa from four main cascades in a 34 km long section of the river flow through the krka national park 2 a laminar stromatolite like incrustation formed in the tunnel of a hydroelectric power plant close to the lowest cascade and 3 recent precipitates collected on artificial substrates during winter spring and summer periods stable isotope compositions of carbon d 13 c and oxygen d 18 o in the carbonate and organic carbon d 13 corg were determined and compared with d 18 o of water and d 13 c of dissolved inorganic carbon dic the source of dic which provides c for tufa precipitation was determined from the slope of the line dic dic0 1 vs d 13 c dic dic dic0 sayles curry 1988 the d 13 c value of added dic was 13ae6 corresponding to the dissolution of co2 with d 13 c between 19ae5 and 23ae0 vienna pee dee belemnite vpdb the observed difference between the measured and calculated equilibrium temperature of precipitation of bulk tufa barriers indicates that the higher the water temperature the larger the error in the estimated temperature of precipitation this implies that the climatic signals may be valid only in tufas precipitated at lower and relatively stable temperatures the laminar crust comprising a continuous record of the last 40 years of precipitation shows a consistent trend of increasing d 13 c and decreasing d 18 o the lack of covariation between d 13 c and d 18 o indicates that precipitation of calcite was not kinetically controlled for either of the elements d 13 c and d 18 o of precipitates collected on different artificial substrates show that surface characteristics both of substrates and colonizing biota play an important role in c and o isotope fractionation during carbonate precipitation

anomalously low δ18o values of high latitude permo triassic paleosol siderite abstract the most severe extinction in earth history occurred during a time of extreme climate change caused in part by a massive release of carbon into the atmosphere isotopic measurements of siderite occurring in paleosols during intervals of global warming suggest high latitude depletions in 18 o of precipitation often attributed to an amplified hydrologic cycle here late permian and early triassic paleosol siderite from alaska antarctica eastern australia siberia and south africa indicate similar or greater meridional gradients in siderite 18 o compared to other past warm intervals an isotope tracer enabled version of the global environmental and ecological simulation of interactive systems genesis general circulation model gcm was used to compare to siderite 18 o data the model when deriving siderite 18 o at a specified paleoatmospheric co 2 concentration of 12 7 the preindustrial atmospheric level pal matches a small subset of relatively less depleted high latitude siderites but does not produce the conditions necessary to explain the most depleted siderite 18 o values siderite has been thought to record mean annual precipitation 18 o though this study suggests that many may not a seasonal bias where siderite growth occurs in the summertime in wetlands that receive most of their recharge from melting winter precipitation may be responsible genesis indicates soil moisture recharge during the spring ahead of the rainy season for high latitude permo triassic pt siderite localities that reach below freezing winter temperatures drainage from high altitude regions throughout the growing season may also be responsible biological cloud feedbacks and monsoon related amount effects are not likely the cause for low siderite 18 o because the enrichment of water vapor 18 o associated with warming is too significant

helium isotope variations in turkey relationship to tectonics volcanism and recent seismic activities the distribution of helium isotope ratios in the various tectonic provinces of turkey is examined through a synthesis of previously published data and the results of a recent survey along the north anatolian fault zone nafz following the catastrophic 1999 earthquakes the r ra values where r sample 3he 4he and ra air 3he 4he cover a wide range from 0 05 to 7 87 and the mantle derived helium is clearly identified in most locations the mantle derived component is high 50 of total he in a regions of central and eastern anatolia both of which are associated with historically active volcanoes and b the seismically active west to central segment of nafz while the mantle contribution reaches a maximum at nemrut volcano in eastern anatolia a region of dominantly compressional tectonics and with moderate enthalpy geothermal fields it is relatively low 50 in the western anatolian extensional province even though this region has the highest geothermal potential the average 3he enthalpy ratios estimated for the different provinces suggest lithospheric stretching and rise of the geotherm as the major mechanism of high heat flow yet limited intrusive activity in western anatolia is suggested as the reason for the comparatively low he additions and consequently low 1 7 106 atoms j 3he enthalpy ratios a more extensive magmatic activity appears to be responsible for the greater input of both heat and helium in eastern and central anatolia with intra province 3he enthalpy variations from 3 1 106 atoms j in eastern to 0 25 106 atoms j in central anatolia reflecting the ageing of hydro magmatic systems the relatively high 3he concentrations in low enthalpy waters of northern anatolia 2 8 106 atoms j are particularly significant since there is no evidence of volcanic activity associated with the strike slip motion along the seismically active segment of nafz continuous monitoring of he isotope compositions along nafz should lead to a better understanding of this apparent anomaly as well as the relationship if any between he isotope variations and seismic activities in this region

a multi methodological approach to reconstruct the configuration of a travertine fissure ridge system the case of the cukor quarry suttő gerecse hills hungary abstract travertines are continental carbonates that precipitate from spring waters mainly due to co2 degassing they are widely quarried as building stone which has led to numerous often abandoned travertine quarry outcrops these and other outcrops however merely represent the surface expressions of the complex architecture of travertine bodies and their deep rooted feeding systems integration of field observations and geochemical analyses with crucial subsurface geophysical data is required in order to fully understand travertine systems and their relationship to the local geological framework such a multi methodological approach is illustrated here for the case of the abandoned cukor quarry radio magnetotelluric rmt and electrical resistivity tomography ert surveys provide unique insights into local tectonics geobody architecture and the topography preceding travertine deposition altogether the lens shaped isolated domal geobody with spring proximal lithofacies and subvertical bedding in addition to the contrasting geochemistry and age with surrounding travertine enabled the unequivocal reconstruction of the dismantled cukor fissure ridge this study illustrates the high potential of this multi methodological approach on poorly exposed strongly weathered quarried and tectonically deformed travertine bodies and provides information on the complex feeding system beneath travertine deposits their reconstruction can be interpreted in light of the neo tectonic expression of regional uplift helps to complete the regional tectonic history and provides insights into older landscapes that lack preservation or would no longer be immediately recognized at the surface