a numerical investigation of squall lines part iii sensitivity to precipitation processes and the coriolis force abstract the effects of various microphysical processes and the coriolis force on the dynamics of squall systems were investigated with a two dimensional anelastic numerical model the incorporation of ice phase microphysics into the model has been found to be important in the successful simulation of realistic storm structure and evolution of squall lines the significance of the ice phase microphysics is largely accounted for by the small terminal velocities of ice particles and cooling by melting the response of the atmosphere to the cooling by melting is a complicated one and has been shown to play an important role in shaping the kinematic and precipitation characteristics of the observed and modeled squall systems the interaction between the front to rear ftr flow and cooling by melting would both intensify by enhancing the mesoscale updraft and the ftr flow above the melting layer and limit by partially driving the rear to front flow at the back of the stratiform region the stratiform prec

the mesoscale and microscale structure and organization of clouds and precipitation in midlatitude cyclones viii a model for the seeder feeder process in warm frontal rainbands abstract previous field studies have indicated that warm frontal rainbands form when ice particles from a seeder cloud grow as they fall through a lower level feeder cloud in this paper we present results from a parameterized numerical model of the growth processes that can lead to the enhancement of precipitation in a seeder feeder type situation the model is applied to two types of warm frontal rainbands in the first type 1 situation the vertical air motions are typical of those associated with slow widespread lifting in the vicinity of warm fronts in the second type 2 situation the vertical air motions are stronger and more characteristic of the mesoscale the model simulations show that in the type 1 situations the growth of the seed ice crystals within the feeder zone is due to vapor deposition the feeder zone in this case is slightly sub saturated with respect to water due to the presence of the seed crystals in regions where the feeder zone is not seeded from aloft snow cryst

predicting ice shape evolution in a bulk microphysics model abstracta novel bulk microphysics scheme that predicts the evolution of ice properties including aspect ratio shape mass number size and density is described tested and demonstrated the scheme is named the ice spheroids habit model with aspect ratio evolution ishmael ice is modeled as spheroids and is nucleated as one of two species depending on nucleation temperature microphysical process rates determine how shape and other ice properties evolve a third aggregate species is also employed diversifying ice properties in the model tests of ice shape evolution during vapor growth and riming are verified against wind tunnel data revealing that the model captures habit dependent riming and its effect on fall speed lagrangian parcel studies demonstrate that the bulk model captures ice property evolution during riming and melting compared with a bin model finally the capabilities of ishmael are shown in a 2d kinematic framework with a simple updraft a direct result of predicting ice shape e

the evolution of the carpathians pannonian system interaction between neotectonics deep structure polyphase orogeny and sedimentary basins in a source to sink natural laboratory abstract the carpathians pannonian basin system provides a natural laboratory for analysing lithospheric to surface controls on tectonic topography development in a coupled source to sink environment to link processes taking place at depth and at the surface recent research focused on the interplay between basin evolution active tectonics topography evolution and intraplate folding mechanisms neotectonic processes control landscape development and natural hazards in particular the seismicity during the late stage late neogene quaternary evolution of both the carpathians pannonian basin system and its interaction with the adjacent dinarides and balkans the deep structure of the se carpathians exerts a strong control on the post collisional evolution of the system new constraints are available from seismic tomography deep seismic reflection and refraction profiling and detailed studies of the vreancea seismicity inherited orogenic fabric and structure of the active black sea sink has a strong influence on the localisation of the neogene sediment pathways a close relationship has been established between the timing and mechanisms of stress changes in the pannonian and transylvania basins and structural episodes in the surrounding thrust belts pointing to an intrinsic mechanical coupling with these basins the orogen and its foredeep basin inversion taking place during the pliocene quaternary times in the entire carpathians pannonian system is related to changes in the regional stress field leading to differential vertical movements associated with a laterally variable folding mechanism active in the entire system short crustal folding patterns alternate with lithospheric wavelengths in the se carpathians foreland east and south carpathians transylvania and pannonian basins the lateral variability is the result of a marked contrast in rheology between these areas directly related to the crustal configuration thermal properties and late stage collision kinematics with the carpathians foreland lateral variations in the properties of the downgoing plates largely control the collision mode in the carpathians and the post collisional evolution of the entire system

fault controlled dolomite bodies as palaeotectonic indicators and geofluid reservoirs new insights from gargano promontory outcrops the upper jurassic to lower cretaceous platform slope to basinal carbonate strata cropping out in gargano promontory southern italy are partly dolomitized fieldwork and laboratory analyses petrographic petrophysical and geochemical allowed the characterization of the dolomite bodies with respect to their distribution within the carbonate succession their dimensions geometries textural variability chemical stability age porosity genetic mechanisms and relation with tectonics the dolomite bodies range from metres to kilometres in size are fault related and fracture related and probably formed during the early cretaceous at 500 m burial depths and temperatures 50 c the proposed dolomitization model relies on mobilization of early cretaceous seawater that flowed downward and then upward along faults and fractures and was modified in its isotopic composition moving through triassic and jurassic strata that underlie the studied dolomitized succession despite the numerous cases reported in literature this study demonstrates that hydrothermal and or high temperature fluids are not necessarily required for fault controlled dolomitization distribution and geometries of dolomite bodies can be used for palaeotectonic reconstructions as they partly record the characteristics size attitude and kinematics of the palaeo faults even if not preserved that controlled dolomitization in gargano promontory dolomites record early cretaceous palaeo faults from metres to kilometres long striking north west south east to east west and characterized by normal to strike slip kinematics dolomitization increases the matrix porosity by up to 7 and therefore can improve the geofluid storage capacity of tight platform slope to basinal limestones the results have a great significance for characterization of geofluid for example hydrocarbons reservoirs hosted in similar dolomitized carbonate successions distribution size and shapes of reservoir rocks i e dolomite bodies could be broadly predictable if the characteristics of the palaeo fault system present at the time of dolomitization are known this article is protected by copyright all rights reserved

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

rapid cold water formation and recrystallization of relict bryophyte tufa at the fall creek cold springs alberta canada the fall creek tufa is a relict mid to late holocene freshwater carbonate spring deposit that is formed almost entirely of calcite encased cratoneuron commutatum gametophytes the spring is presently active emitting 13 c meteorically derived waters but it is not precipitating calcite wood embedded in the youngest part of the tufa yielded a radiocarbon 14c date of 310 50 years bp the oldest parts of the deposit could not be dated by radiocarbon methods because of a lack of embedded organics the fall creek tufa however probably began forming 5000 years bp in response to the same wet climatic conditions that initiated calcite precipitation at miette hot springs in jasper national park and the cave and basin hot springs in banff national park the relict deposit is composed largely of calcite cements that were precipitated around the bryophytes with lesser amounts of internal sediments the tufa formed through a repeated four stage developmental process that involved i encrustation ii enc

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

microphysical characteristics of squall line stratiform precipitation and transition zones simulated using an ice particle property evolving model abstracta quasi idealized 3d squall line case is simulated using a novel bulk microphysics scheme called the ice spheroids habit model with aspect ratio evolution ishmael in ishmael the evolution of ice particle properties e g mass shape maximum diameter density and fall speed are predicted during vapor growth sublimation riming and melting allowing ice properties to evolve from various microphysical processes without needing separate unrimed and rimed ice categories ishmael produces both a transition zone and an enhanced stratiform precipitation region and ice particle properties are analyzed to determine the characteristics of ice that lead to the development of these squall line features rimed particles advected rearward from the convective region produce the enhanced stratiform precipitation region the transition zone results from hydrometeor sorting the evolution of ice particle properties in the convective region leads to fall speeds that favor ice advecting rearward of the tran

hot spring systems geobiology abiotic and biotic influences on travertine formation at mammoth hot springs yellowstone national park usa multiple abiotic and biotic factors combine in nature to influence the formation of calcium carbonate limestone deposits systems geobiology studies of how micro organisms respond to or sometimes even control the coupled effects of environmental change and mineralization will permit more accurate interpretation of the fossil record of ancient microbial life mammoth hot springs in yellowstone national park usa serves as a natural laboratory for tracking how the dynamic interplay of physical chemical and biological factors come together to form hot spring limestone called travertine systematic downstream correlations occur at mammoth hot springs between travertine deposition geomorphology crystalline structure and geochemistry microbial communities mat morphology pigmentation and phylogenetic and metabolic diversity and spring water conditions temperature ph geochemistry and flow field based microscale and mesoscale experimentation indicates that microbes directly influence travertine growth rate and crystalline structure at the macroscale time lapse field photography and numerical modelling suggest that travertine terrace geomorphology is influenced strongly by hydrology heat dispersion and geochemistry these results from mammoth hot springs allow establishment of a conceptual framework across broad spatial and temporal scales in which to track how multiple geological and biological factors combine to control caco3 crystal precipitation and the resulting formation of travertine deposits

intrinsic and extrinsic controls of spatial and temporal variations in modern fluvial tufa sedimentation a thirteen year record from a semi arid environment sedimentological and hydrochemical parameters of the river piedra north east spain were monitored every six months from 1999 to 2012 at 24 sites at which tablets were installed all along the river the river water is of hco3 so4 ca type and is notably influenced by inputs from upstream karstic springs tufa deposition was first detected 8 km downstream of these springs and greatly increased from there primarily along the steeper stretch i e within the monasterio de piedra natural park then deposition decreased through the most downstream stretch with smaller ground water inputs the spatial evolution of the tufa thickness with parallel variations of pwp plummer wigley parkhurst rates was thus determined by the river water pco2 which was controlled by ground water inputs and by the river bed slope five fluvial subenvironments and seven sedimentary facies were characterized the water flow conditions are the primary factor responsible for the distinct deposition rates of facies mainly through co2 outgassing stromatolites and moss tufa and alga tufa had the highest rates whereas loose tufa formed in slow flowing water and tufa of spray areas had thinner deposition a six month pattern in the deposition rate was detected through thickness measurements that pattern was parallel to the seasonal pwp rates the increased deposition during warm periods spring and summer mean 5 08 mm compared with cool periods autumn and winter mean 2 77 mm is linked chiefly to temperature which controlled the seasonal changes in the physico chemical and biological processes this finding is supported by a principal components analysis seasonal variations of insolation and day duration also contributed to such a deposition pattern large discharge events which provoked erosion of tufa deposits and dilution of water caused the reversal of the seasonal deposition rate pattern stromatolites are likely to preserve the most complete sedimentary record although tufas are a potentially sensitive record of climate related parameters erosion is an intrinsic process that may overwhelm the effects of such parameters this issue should be considered in palaeoclimatic studies based on the tufa record particularly in semi arid conditions

searching for travertines calcretes and speleothems in deep time processes appearances predictions and the impact of plants common models for modern calcite precipitation in and around caves soils springs and streams involve co 2 supplied by thick high p co 2 biogenic soils which were probably thin or non existent before vascular plants indeed plant influenced chemical weathering might have caused accelerated terrestrial carbonate production from the devonian onwards however terrestrial carbonates have also been documented from the archaean proterozoic cambrian ordovician and silurian mechanisms which could have caused non marine carbonates to precipitate without organic rich soils are described and some geological events likely to have influenced non marine carbonate precipitation up to the origin of vascular plants are highlighted as organisms have evolved so have the petrographic characteristics of non marine carbonates some examples of this are also given here

pleistocene vertebrate faunas of the suttő travertine complex hungary numerous fossil remains vertebrates molluscs and plants were found in more than twenty sites of the sutt travertine complex during the last 150 years the majority of these remains were recovered from fissures of the travertine but also from the travertine and an overlying loess paleosol sequence the aims of this study were to review the fossil content to determine the stratigraphical positions of the various vertebrate faunas of sutt and provide paleoecological interpretation of the periods on the basis of their faunas and floras in addition this paper describes new faunas and floras from the sites sutt 16 20 and provides 14c dates for sutt 16 on the basis of the new uranium series isotope and optical dating osl the age of the travertine complex is middle pleistocene 235 21 314 45 ka mis 7 9 while the age of the loessepaleosol sequence in superposition of the travertine is middleelate pleistocene mis 2 mis 6 in contrast the fossils of the travertine indicated an older pliocene early pleistocene age a fissure sutt 17 and a red clay layer sutt 19 contained mammal faunas of early middle pleistocene age these results indicated the existence of older travertine in certain quarries hegyhati quarry cukor quarry sedimentological and osl data of well dated layers of the loess paleosol sequence sutt lps at sutt o allowed a correlation with the layers of sutt 6 the paleosol layer in the upper part of the sequence of sutt o 6 was correlated with a pedocomplex of the overlying loess paleosol sequence which was dated to mis 5c upper dark soil and mis 5e lower reddish brown soil the paleoecological analysis of the mammal and mollusc faunas supported the former interpretation of novothny et al 2011 inferring warm dry climate during the sedimentation of the upper layers and more humid climate for the lower layers however the fauna of the lower soil layer indicated cold climate so an age of mis 5d is suggested dating of the fissure faunas is based on similarity studies for some faunas this method cannot be used because of the low number of species on the basis of the species compositions and former interpretations these faunas originated mainly from sediments that were deposited under cold climatic conditions other fissure faunas were dated by ams 14c sutt 16 or by correlation with soil layers of sutt 6 according to these results most of the fissure faunas can be correlated with different phases of mis 5 however there are a younger mis 2 and an older early middle pleistocene fissure fauna also

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

imprints of hydrocarbon bearing basinal fluids on a karst system mineralogical and fluid inclusion studies from the buda hills hungary calcite veins and related sulphate sulphide mineralisation are common in the buda hills also abundant hypogenic caves are found along fractures filled with these minerals pointing to the fact that young cave forming fluids migrated along the same fractures as the older mineralising fluids did the studied vein filling paragenesis consists of calcite barite fluorite and sulphides the strike of fractures is consistent nnw sse concluding a latest early miocene maximum age for the formation of fracture filling minerals calcite crystals contain coeval primary hydrocarbon bearing and aqueous inclusions indicating that also hydrocarbons have migrated together with the mineralising fluids hydrocarbon inclusions are described here for the first time from the buda hills mixed inclusions i e petroleum with water tail were also detected indicating that transcrystalline water migration took place the coexistence of aqueous and petroleum inclusions permitted to establish the entrapment temperature 80 c and pressure 85 bar of the fluid and thus also the thickness of sediments having been eroded since latest early miocene times was calculated 800 m low salinity of the fluids 1 7 nacl eq wt implies that hydrocarbon bearing fluids were diluted by regional karst water ft ir investigations revealed that co2 and ch4 are associated with hydrocarbons groundwater also contains small amounts of hc and related gases on the basin side even today based on the location of the paleo and recent hydrocarbon indications identical migration pathways were reconstructed for both systems hydrocarbon bearing fluids are supposed to have migrated north westward from the basin east to the buda hills from the miocene on

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

numerical simulation of a midlatitude squall line in two dimensions abstract a two dimensional anelastic cloud model was used in attempts to numerically replicate the observed structure of a midlatitude squall line initial conditions were adapted from observations of the 22 may 1976 oklahoma line model simulations were made with and without considering the ice phase of water these model storms have within the constraints of the model s geometry replicated the basic multicellular character and general line normal airflow typical of these lines in addition the structure and intensity of the subcloud cold air pool and the propagation speeds developed by the storms appear to be reasonable further it was found that the initial conditions chosen resulted in model storms which were not only long lasting but also essentially repetitive indicating that a state of quasi equilibrium had been attained the storms did not decay because the environmental conditions ahead of the storms were favorable and essentially unchanged during the course of the simulations the inclusio

a multidisciplinary approach to understanding carbonate deposition under tectonically controlled hydrothermal circulation a case study from a recent travertine mound in the euganean hydrothermal system northern italy a multidisciplinary study was carried out on an upper pleistocene travertine mound montirone hill abano terme south of padova veneto italy with the aim of developing a comprehensive understanding of the processes interacting in structurally controlled thermal springs and the consequent deposition of thermal limestones the sedimentology geochemistry structural characteristics and hydrogeology of the mound which is associated with the euganean geothermal field and the related complex structural framework of the schio vicenza fault system were investigated a palaeo environmental model of the deposit has been reconstructed clarifying the connection between the travertine deposition and the regional structural setting calcium rich thermal waters rose from spring orifices estimated temperature from 54 c to 61 c based on geochemical calculations and produced a mound made of coalescent shield like bodies the dominant lime mudstone facies resulted from the accumulation of lime mud at the bottom of shallow crater like basins located on top of stacked cones soft sediment deformations affecting the lime mud sediment were most probably produced by the recurrent uprising of gas bubbles the overlying crystalline crusts were deposited on the flanks of the mound by waters overflowing from the vents with laminar flux a deep hydrothermal circuit with a long period of water rock interaction is supported by geochemical analyses furthermore a local extensional regime enhancing the migration of thermal fluids to the surface is inferred based on the results of the structural analysis carried out on the fault fracture mesh that affects the mound these results corroborate the well established relation among travertine deposits hydrothermal systems and fault systems and substantiate the structurally controlled conceptual model of the euganean hydrothermal system suggesting that both the thermal and the fault systems were active at least since 34 ka

reconnaissance of the general circulation of the north western european continental shelf by means of a three dimensional turbulent closure model abstract the general circulation of the north western european continental shelf is investigated by means of a three dimensional macroscale mathematical model results corresponding to typical winter and summer conditions are described in detail prominent features are explained from a dynamic point of view by referring to the main forcing factors of the macroscale circulation on the north western european continental shelf seasonal mean wind stress and atmospheric pressure large scale sea surface slope non linear interactions of the higher frequency processes and density differences the role of the bottom topography is also highlighted the largest seasonal variations are mainly due to the occurrence of a thermal stratification in summer over large parts of the shelf in such conditions there is only a weak interaction between the surface and bottom layers that have therefore significantly different dynamics

tufas and travertines of the mediterranean region a testing ground for freshwater carbonate concepts and developments actively forming travertine and tufa sites are widespread in temperate and warm climates such as the mediterranean region but also develop in other climatic regimes from the arctic to equatorial latitudes the terms travertine and tufa are sometimes applied indiscriminately today however each has a specific definition most studied deposits are active or of quaternary especially holocene age there are fewer tertiary and even less late mesozoic examples on record in part this is because of a recognition problem as these deposits commonly preserve as fragmentary erosional remnants physico chemical precipitation of calcium carbonate is commonly considered to be the main mechanism contributing to tufa and travertine deposition rapid cooling of waters further aids the process in thermal travertine sites however biomediation of calcium carbonate associated with prokaryote microphyte biofilms is now recognized to be equally important in slow flowing and near static sites much of this precipitation occurs in close association with cyanobacterial heterotrophic bacterial and diatoms the mediterranean region figures significantly in the development of travertine and tufa research consequently this article employs key literature on mediterranean examples to illustrate developments and concepts in freshwater carbonate research modern work started in the 1950s and defined many previously unknown outcrops many such sites became the targets for early radiocarbon dating studies since the late 1970s a number of laboratory based and field based classification schemes have been proposed some schemes were based on associated macrovegetation types others were based on petrological characteristics or on geometry and sedimentary facies characteristics of late the sedimentological modelling has benefited greatly from the use of shallow geophysical techniques in order to better define the internal geometries of the deposits two distinct research strands were developed during the 1990s both aimed at a better understanding of environmental change the first considered biocomponents the research was multifaceted and ranged from exploring the role of micro organisms in cement and lime mud precipitation to biostratigraphic analysis of contained pollen and invertebrate remains these provided proxy environmental information which has helped to define past climate variability in the region the second research strand focussed on geochemical signatures as a proxy tool for defining environmental change this definition was made possible by new petrological studies which have greatly aided the recognition of primary depositional fabrics this improved knowledge has reduced the sampling dangers of diagenetic contamination inherent in earlier geochemical studies lithofacies modelling has also brought to light important early post depositional neomorphic changes which obscure primary fabrics and complex diagenetic histories have been revealed stable isotope signatures of carbon and oxygen have also been used to define palaeo water temperature fine tuning of depositional time frames has also been achieved from absolute dating techniques employing radiocarbon and uranium thorium

diagenesis or dire genesis the origin of columnar spar in tufa stromatolites of central greece and the role of chironomid larvae two greek pleistocene tufa stromatolites were examined petrographically and with stable isotope geochemistry to determine whether calcite spar is of primary or diagenetic origin the younger ca 100 ka tufa from zemeno primarily is micritic with primary columnar calcite spar restricted to areas immediately above chironomid larval tubes this relationship suggests that chironomid larval feeding behaviour is responsible for the development of zemeno tufa columnar calcite probably involving biological substances smeared onto the tufa surface most micritic crystals are not suitably oriented to allow later post depositional growth resulting in columnar fabrics the older ca 1 ma predominantly sparry tufa from nemea contains some chironomid tubes and organic cyanobacterial filaments preserved in crystal fans but also contains many fabrics found in primary speleothem spar columnar spar here is unlikely to be the result of post depositional crystal growth a comparison of stable isotopic trends between the two tufa deposits suggests that both contain interpretable seasonal trends and implies little or minor post depositional alteration of either tufa consequently there is no basis for the common assumption that sparry tufa fabrics must be of diagenetic origin

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

sedimentology three dimensional geobody reconstruction and carbon dioxide origin of pleistocene travertine deposits in the ballik area south west turkey the denizli basin in the west anatolian extensional province in western turkey is well known for its numerous travertine occurrences a combined sedimentological diagenetic and geochemical investigation is executed on the ece and faber travertines of the ballk area the largest travertine site in the denizli basin the first aim of this study is the reconstruction of a three dimensional geo model in combination with a detailed sedimentological description from fabric to lithotype lithofacies and geobody scale with a focus on integrating pore typing the second aim involves the delineation of the co2 origin of ancient travertine precipitating waters peloidal phyto and dendritic lithotypes dominate the studied travertines and honeycomb and bacteriform shapes and encrusted bacterial or fungal filaments related to their fabrics suggest a microbial influence the environment of travertine precipitation evolved from dominantly sub aqueous as represented by the sub horizontal and biostromal reed travertine facies to dominantly sub aerial in a thin water film resulting in the cascade waterfall and biohermal reed travertine facies a general progradation of the travertine mound is indicated by the occurrence of stacked waterfall travertines this results in sigmoidal clinoforms inside a general mound boundary configuration strontium and oxygen carbon isotope signatures of the travertines point to a mixing mechanism of palaeofluids with deeply originated heavy carbon co2 with lighter carbon co2 of shallow origin these deposits can thus be considered as endogenic travertines carbonates of the lycian nappes acted as main parent carbon source rocks the relative contribution of the lighter carbon isotopes is most likely to have originated from organic matter or soil co2 this study provides a unique three dimensional insight into the ballk travertine architecture that potentially can be used as an analogue for subsurface travertine reservoirs worldwide and illustrates the importance of the combined use of c 13 and sr 87 sr 86 signatures in the delineation of the co2 origin of travertine precipitating waters

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

acoustic properties in travertines and their relation to porosity and pore types abstract sonic velocities of pleistocene travertines were measured under variable confining pressures combined with petrographical characteristics and petrophysical data i e porosity permeability and density it was determined that travertine porosity pore types and cementation control compressional wave vp and shear wave velocity vs at 40 mpa confining pressures vp ranges between 3695 and 6097 m s and vs between 2037 and 3140 m s velocity variations in travertines are as with all carbonates primarily linked to sample heterogeneity i e differences in fabric texture and porosity they thus not necessarily emanate from changes in mineralogy or composition body wave velocities have a positive correlation with sample density and an inverse correlation with porosity the travertines sampled in extensional settings with normal faulting activity define a specific compressional wave velocity y axis versus porosity x axis equation i e log y 0 0048x 3 7844 that differs from the vp porosity paths defined by marine carbonates acoustic wave velocities are higher for travertines than for marine carbonates travertine precipitates form rigid rock frames often called framestone with large primary pores marine carbonates on the other hand often consist of cemented transported sediments resulting in a rock frame that permits slower wave propagation when compared to the continental limestones acoustic velocity variations are linked to variations in pore types mouldic pores macropores show faster wave propagation than expected from their total porosities microporosity interlaminar and interpeloidal porosity result in slower acoustic velocities framework pores and micro moulds are associated with lowered acoustic velocities while vug porosity is found above on and below the general velocity porosity trend not only the pore type but also pore shapes exert control on body wave velocities cuboid and rod like pore shapes increase the velocity while plate and blade like pore shapes have a negative effect on the velocity the study demonstrates how seismic sections in travertine systems can contain seismic reflections that are not caused by non carbonate intercalations but relate to geobody boundaries in which the seismic expression is function of porosity pore types and shapes this study provides and relates petrophysical data i e porosity permeability and acoustic velocities of travertines and is of importance for the interpretation of seismic reflection data in subsurface continental carbonate reservoirs

continental carbonates as a hydrocarbon reservoir an analog case study from the travertine of saturnia italy the pleistocene saturnia travertine central italy represents a possible analog of the pre salt continental carbonate reservoirs discovered in the santos and other basins in the south atlantic margin of brazil two subhorizontal travertine tabular bodies several tens of meters thick and extending over an area of have been studied in two quarries facies variations and associated petrophysical properties were reconstructed applying a multidisciplinary approach the saturnia travertine formed from a warm water spring is composed of various stacked carbonate banks separated by subaerial erosive phases and paleosols the lacustrine tabular bodies terraces and sills are made of crystalline crust shrub pisoid paper thin raft coated bubble reed and lithoclast breccia facies the from 4 to 8 supports an interpreted volcanic mantle source whereas the from 9 to 5 is in agreement with warm meteoric waters the ratio isotopic signature indicates a carbonate from dissolution of deep seated carbonates the facies reservoir properties were studied via porosity and permeability analysis of plugs three dimensional x ray computer tomography as well as image analysis on microscale under thin section and macroscale on large rock slabs to define various porosity indices a strong heterogeneity of the petrophysical properties and variable connectivity were observed porosity from 4 to 30 and permeability up to hundreds of md but no compartmentalization of the carbonate bodies is present

fracture networks and strike slip deformation along reactivated normal faults in quaternary travertine deposits denizli basin western turkey abstract the denizli basin in the west anatolian extensional province in western turkey is known for its numerous quaternary travertine occurrences travertine morphology is often dependant on the relative position of the deposition with respect to basin bounding faults the travertine occurrences examined in this study are situated at the intersection of the locally e w oriented denizli basin and the adjacent ne sw oriented baklan graben in the ne based on an extensive field campaign including lidar scanning several high resolution fault fracture maps of five large quarries 300 m in length and 60 m in height are constructed in which this world class travertine deposit is currently excavated a structural analysis is performed in order to determine the tectonic overprinting of the travertine body and to derive the stress states of the basin after travertine deposition the mostly open non stratabound joints are several tens of metres long and often bifurcate creating a dense fracture network minor infill of the joints resulted in the presence of a few colour banded calcite veins based on the e w ne sw and nw se orientation of three dominant joint sets it is concluded that the joint network is caused by local n s extension alternated by nw se and ne sw extension exemplifying the presence of stress permutations in the quaternary high angle e w to wnw ese faults cross cut the quarries faults are filled with travertine debris and clastic infill of above lying sedimentary units indicative of the open nature of the faults the specific e w fault orientation in the locally e w trending denizli basin indicates that they initiated as normal faults a paleostress inversion analysis performed on kinematic indicators such as striations on the clayey fault infill and the sinistral displacement of paleosols shows that some of the normal faults were reactivated causing left lateral deformation in a transient strike slip stress field with a ne sw oriented 1

dissected hydrologic system at the grand canyon interaction between deeply derived fluids and plateau aquifer waters in modern springs and travertine geochemical study of water and gas discharging from the deeply incised aquifer system at the grand canyon arizona provides a paradigm for understanding complex groundwater mixing phenomena and quaternary travertines deposited from cool springs provide a paleohydrologic record of this mixing geochemical data show that springs have marked compositional variability those associated with active travertine accumulations deeply derived endogenic waters are more saline richer in co2 and elevated in 87sr 86sr relative to springs derived dominantly from surface recharge of plateau aquifers epigenic waters endogenic waters and associated travertine are preferentially located along basement penetrating faults we propose a model whereby deeply derived fluids are conveyed upward via both magmatism and seismicity our model is supported by 1 gas analyses from spring waters with high he ar and he n2 and 3he 4he ratios indicating the presence of mantle derived he 2 large volumes of travertine and co2 rich gases in springs recording high co2 fluxes and 3 87sr 86sr in these springs that indicate circulation of waters through precambrian basement geochemical trends are explained by mixing of epigenic waters of the colorado plateau aquifers with different endogenic end member waters in different tectonic subprovinces endogenic waters are volumetrically minor but have significant effects on water chemistry they are an important and largely unrecognized component of the hydrogeochemistry and neotectonics of the southwestern united states

classification and environmental models of cool freshwater tufas abstract tufa deposits are common in the quaternary record facies developments are dependent upon localised carbonate precipitation generally these take the form of phytoherm build ups together with associated detrital deposits derived from disagragation of the former phytoherm cements differ from speleothems and floe calcite accumulations in being biologically mediated or modified this paper recognises the following five types perched spring line cascade fluviatile paludal and lacustrine facies each type is composed of distinctive constructional and detrital sediment associations these unique sediment combinations are the product of an interplay between angle of slope water discharge rate standing water bodies phytal and microbial colonization and ambient temperature the proposed models will be of value in the interpretation of ancient and partially exposed tufas

radionuclides as natural tracers for the characterization of fluids in regional discharge areas buda thermal karst hungary summary the buda thermal karst budapest hungary developed in the regional discharge zone of a carbonate rock aquifer system high radioactivity of the spring waters has already been reported in 1912 but there has been no detailed study and no consistent explanation for its origin in this area mixing of cold and hot karst waters was hitherto assigned to be responsible for cave formation however the dissimilarity of the discharging waters within budapest in the north rozsadomb in the south gellert hill may suggest also different cave forming processes the application of radionuclides as natural tracers represents a novel approach to investigate these questions for this study we used uranium radium and radon to identify mixing of fluids in the buda thermal karst system and to infer the temperature and chemical composition of the end members chloride as a conservative component allowed the mixing ratios for the sampled waters to be calculated their fluid compositions were modeled and through the comparison of modeled and measured values the end members were validated as the result of this study it was possible to characterize the mixing end members for the rozsadomb area whereas for the gellert hill discharge zone mixing components could not be identified with the aid of radionuclides therefore it is suggested that different processes are responsible for cave formation in these areas in the rozsadomb area structurally controlled mixing is the dominant cave forming process whereas in the gellert hill area due to the lack of mixing members other processes have to be found which are responsible for the formation of the caves such as retrograde calcite solubility and or geogenic acids such as h 2 s the application of radionuclides thus further supported the differences between the two study areas this study identified moreover the source of elevated radon content of the waters in the gellert hill area in form of iron hydroxide precipitates that accumulate in the spring caves these precipitates are highly efficient in adsorbing radium which generates radon by alpha decay and hence act as local radon source for the waters in this study we showed that uranium radium and radon naturally occurring in groundwater can be used to characterize fluids of different flow systems in regional discharge areas owing to the contrasting geochemical behaviors of these elements

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

staircase fractures in microbialites and the role of lamination related mechanical anisotropy the example of the acquasanta terme travertine deposits central italy this study describes a peculiar yet common type of fracture showing a staircase trajectory which forms in rocks with moderately weak planar anisotropies the staircase fracture trajectory is given by alternating fracture segments oriented parallel to lap or at an angle ramp with respect to the lamination layering the analyses has been accomplished on travertines which are continental microbial hydrothermal deposits having a typical poorly stratified yet strongly laminated texture in these rocks porosity and permeability have a high across lamination variability and are mostly controlled by an interconnected and locally corroded array of permeable layers fractures and faults structural analysis integrated with analytical modeling provided a conceptual model of staircase fracture localization as a function of the travertine lamination dip lamination parallel fracture segments localize within the porous laminae mostly at the interface with tight laminae ramp type fracture segments cut the lamination connecting lamination parallel segments two types of staircase fracture can be modeled the first group develops in subhorizontal to gently dipping deposits lamination dip 30 and corresponds to high energy environments major discoveries of hydrocarbon have been recently made in continental lacustrine microbial carbonates in the brazilian south atlantic margin some of which exhibit a texture similar to those usually observed in travertines understanding of the lacustrine carbonates is still at an early stage given that in modern rift settings vent related thermal travertine and nonthermal tufa carbonates are a major component the proposed conceptual model of staircase fracture localization contributes to the preparation of a model for the potential occurrence of high permeability pathways in hydrocarbon and geothermal microbial reservoirs

3 d modelling of a fossil tufa outcrop the example of la pena del manto soria spain abstract classical studies of tufas lack quantitative outcrop descriptions and facies models and normally do not integrate data from subsurface in the stratigraphic and evolutive analysis this paper describes the methodology followed to construct one of the first digital outcrop models of fossil tufas this model incorporates 3 d lines and surfaces obtained from a terrestrial laser scanner electric resistivity tomography ert profiles and stratigraphic and sedimentologic data from 18 measured sections this study has identified seven sedimentary units from su 1 to su 7 which are composed of tufa carbonates su 1 3 5 6 and clastics su 2 4 7 facies identified occur in different proportions phytoherm limestones of bryophytes represent 43 of tufa volume bioclastic limestones 20 phytoherm limestones of stems 12 oncolitic limestones 8 and clastics 15 three main architectural elements have been identified 1 steeply dipping strata dominated by phytoherm limestones of bryophytes 2 gently dipping strata dominated by phytoherm limestones of stems and 3 horizontal strata dominated by bioclastic and oncoid limestones the alternation of tufa growth and clastic input stages is interpreted as the result of climatic changes during mid late pleistocene

porosity in bacterially induced carbonates focus on micropores bacteria are responsible for the precipitation and accumulation of some significant carbonate deposits prime examples are hot spring travertine accumulations bacteria induce precipitation of carbonate minerals immediately surrounding their cell walls and in doing so entomb themselves within the crystals subsequently a generation of abiotically precipitated clear spar commonly cements cell colonies as well as the initial bacterially induced carbonate the relatively rapid decay of the bacterial fossils consequently results in localized abundances of unconnected microporosity this submicron to micron size porosity is not normally detected by standardized porosity evaluations these pore systems which are especially abundant in hot spring travertine deposits can influence density measurements and therefore any calculations in which density is a factor the pores have been found to be abundant within different bacterially induced features such as shrubs peloids and oncoids other forms of porosity common in hot spring travertines include shelter porosity foam rock and some highly irregular early dissolution of the carbonate caused by the abundance of nonmarine waters coursing through these rocks

quantification of quaternary vertical movements in the central pannonian basin a review of chronologic data along the danube river hungary abstract this study aims at a new quantification of neotectonic deformation of the central part of the pannonian basin we use terrace levels and associated travertine as well as speleothem data along the danube river to quantify its incision rate and thus estimate the amount and rate of uplift at the axis of the hungarian mountain range hmr several terrace levels and other geomorphic features along the danube river are indicative for quaternary uplift of the axial part of the emerging hungarian mountain range while the correlative terraces are at considerable height at the axis of the hmr the terraces are gradually dipping below the basin fill of the adjacent lowlands the correlation of the terrace segments is difficult because of their poor preservation small size and variable height the geomorphologic horizons indicate gradual incision of the river throughout the quaternary during simultaneous deformation however no reliable chronological data have been available so far to quantify landscape forming processes such as uplift incision or erosion rates a reconsideration of existing published data for three consecutive segments of the danube valley yields incision rates between 0 14 and 0 41 mm year for the last 360 ky with the highest value for the area of the danube bend accordingly the middle to late quaternary uplift rate of the axial zone of the hmr exceeded significantly that of the marginal areas these rates represent an approximation as some quantitative data are still controversial our results suggest that formation of the danube terraces is result of river incision triggered by the uplift of the hmr and modified by periodic climate changes

dating the homo erectus bearing travertine from kocabas denizli turkey at at least 1 1 ma abstract since its discovery within a travertine quarry the fragmentary cranium of the only known turkish homo erectus the kocabas hominid has led to conflicting biochronological estimations first estimated to be 500 ka old the partial skull presents a combination of archaic and evolved features that puts it as an intermediate specimen between the dmanisi fossils homo georgicus and the chinese zhoukoudian skulls homo erectus respectively dated to 1 8 to 0 8 ma here we present a multidisciplinary study combining sedimentological paleontological and paleoanthropological observations together with cosmogenic nuclide concentration and paleomagnetic measurements to provide an absolute chronological framework for the upper fossiliferous travertine unit where the kocabas hominid and fauna were discovered the 26 al 10 be burial ages determined on pebbles from conglomeratic levels framing the upper fossiliferous travertine unit which exhibits an inverse polarity constrains its deposition to before the cobb mountain sub chron that is between 1 22 and 1 5 ma the alternative match of the normal polarity recorded above the travertine with the jaramillo subchron lower limit 1 07 ma may also be marginally compatible with cosmogenic nuclides interpretation thus the proposed minimum age of 1 1 ma for the end of massive travertine deposition the actual age of the fossils is likely to be in the 1 1 1 3 ma range this absolute date is in close agreement with the paleoanthropological conclusions based on morphometric comparisons implying that kocabas hominid belongs to the homo erectus s l group that includes chinese and african fossils and is different from middle and upper pleistocene specimens furthermore this date is confirmed by the large mammal assemblage typical of the late villafranchian because it attests to the antiquity of human occupation of the anatolian peninsula and one of the waves of settlements out of africa this work challenges the current knowledge of the homo erectus dispersal over eurasia

a wind tunnel and theoretical study of the melting behavior of atmospheric ice particles iv experiment and theory for snow flakes abstract an experiment in the mainz vertical cloud tunnel is described in which natural and laboratory made aggregates of snow crystals snow flakes were melted under free fall conditions in the vertical air stream of the tunnel which was allowed to warm up at the rates experienced by falling snow flakes in the atmosphere the variation of the fall mode the fall velocity and the percentage of ice melted as a function of percentage of distance travelled for 99 melting was recorded by cinematography the laboratory results were confirmed by the results of a theoretical heat transfer model which we developed for the melting of a snow flake in this model a snow flake was idealized by an oblate spheroid in which as confirmed by observation the melt water did not remain at the periphery of the flake but penetrated inside the flake the computed distances needed by snowflakes to melt under various atmospheric conditions were found to agree well with recent radar observations

sedimentation pattern in a trans himalayan quaternary lake at lamayuru ladakh india abstract located on the indo tsangpo suture zone lamayuru lake in western ladakh was created by neotectonic instability around 35 40 ka the valley fill sequence about 110 m thick reveals an interplay of lacustrine to fluvio deltaic to colluvial processes operating in response to changing climate and tectonic conditions based on integrated approach of sedimentology and palaeontological analysis we propose a sedimentation model for lamayuru lake with reference to changing climatic conditions and neotectonics the coarsening upward succession was divided into five lithofacies associations associations a e each association comprising one or more lithofacies represents a specific depositional environment and marks an independent episode of sedimentation a dominantly muddy sequence of facies association a a product of a lacustrine environment is followed by coarsening upward cycles association b composed of silt to sand that implies laterally shifting deltas thereafter thick sand and gravel deposits constituting fining upward fu unit cycles associations c and d represent deposition in a fluvial domain the upper part of association d composed of matrix supported gravel horizons was deposited as debris flows and marks the termination of sedimentation in the valley the clastic lithofacies facies associations a to d with plant fragments and charcoal presumably indicate warm humid climatic conditions in contrast association e comprising marl lithofacies occurring at four different levels is biogenic and indicates arid to semi arid climatic phases five main types of trace fossils including rhizoliths seem to be representatives of scoyenia ichnofacies and animal burrows indicating a thin population of soft bodied annelid and arthropod communities living under low energy condition nine fossiliferous horizons have yielded characteristic ostracods charophytes and gastropods indicating shallow low energy and cold water ecological conditions coarsening up lake succession extensive synsedimentary deformation tilting of lake beds and the entrenchment of the lamayuru drainage indicate basin evolution under an effective role of neotectonics in the area

simulated polarimetric fields of ice vapor growth using the adaptive habit model part i large eddy simulations abstractthe bulk adaptive habit model ahm explicitly predicts ice particle aspect ratio improving the representation of microphysical processes and properties including ice liquid phase partitioning with the unique ability to predict ice particle shape and density the ahm is combined with an offline forward operator to produce fields of simulated polarimetric variables an evaluation of ahm forward simulated dual polarization radar signatures in an idealized arctic mixed phase cloud is presented interpretations of those signatures are provided through microphysical model output using the large eddy simulation mode of the weather research and forecasting model vapor grown ice properties are associated with distinct observable signatures in polarimetric radar variables with clear sensitivities to the simulated ice particle properties including ice number size and distribution shape in contrast the liquid droplet number has little influence on both polarimetric and microphysical variables in the

early dolomitisation of late triassic platform carbonates in the transdanubian range hungary abstract in the late triassic a large carbonate platform system came into existence in the transdanubian range tr producing a 1 5 to 2 km thick carbonate succession the lower part of the platform carbonate series is made up of cyclic peritidal dolomite main dolomite formation while the upper one consists of cyclic peritidal limestone dachstein limestone formation however there is a transitional member of remarkable thickness between them consisting of partially dolomitised limestone and calcitic dolomite this study focuses on the transitional member where the process of early dolomitisation was halted at various stages in the investigated sections the early dolomitisation was controlled by the climate and high frequency sea level oscillation which led to periodic subaerial exposure of large areas and palaeo hydrological conditions increasing humidity and gradual extension of the permanently inundated outer platform led to cessation of early dolomitisation in the middle to late norian

diagenesis of laminated travertine crusts arbuckle mountains oklahoma abstract waterfall travertine deposits in the arbuckle mountains of oklahoma contain laminated coarsely crystalline neomorphic crusts which retain virtually no evidence of their organic origin the precursors of these neomorphic crusts are laminated organic crusts composed of two basic alternating layers 1 layers of filamentous cyanophyte bushes in which each bush is encased by one or more elongate spar crystals and 2 layers in which equidimensional crystals surround individual cyanophyte filaments as diagenesis commences the elongate calcite spar crystals enclosing algal bushes grow into the overlying more finely crystalline calcite layers by aggradational neomorphism forming coarse columnar crystals oriented perpendicularly to the laminae as the crystals increase in size they incorporate the inclusion rich laminae of the surrounding material thereby maintaining the laminated appearance the end product of this diagenetic process is a dense laminated crust composed almost entirely of columnar calcite crystals which commonly reach lengths of more than 1 cm such crusts display almost no evidence of their former constituents however after immersion in hydrochloric acid and application of an organic stain remains of algal bushes are visible within thin sections many other nonmarine carbonate deposits include similar looking crusts that appear to be solely inorganic in origin in light of the present findings caution certainly is warranted before automatically assuming an inorganic origin for such crusts

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

geochemistry of quaternary travertines in the region north of rome italy structural hydrologic and paleoclimatic implications in the tyrrhenian region of central italy late quaternary fossil travertines are widespread along two major regional structures the tiber valley and the ancona anzio line the origin and transport of spring waters from which travertines precipitate are elucidated by chemical and isotopic studies of the travertines and associated thermal springs and gas vents there are consistent differences in the geochemical and isotopic signatures of thermal spring waters gas vents and present and fossil travertines between east and west of the tiber valley west of the tiber valley 13c of co2 discharged from gas vents and 13c of fossil travertines are higher than those to the east to the west the travertines have higher strontium contents and gases emitted from vents have higher 3he 4he ratios and lower n2 contents than to the east fossil travertines to the west have characteristics typical of thermogene thermal spring origin whereas those to the east have meteogene low temperature characteristics including abundant plant casts and organic impurities the regional geochemical differences in travertines and fluid compositions across the tiber valley are interpreted with a model of regional fluid flow the regional mesozoic limestone aquifer is recharged in the main axis of the apennine chain and the groundwater flows westward and is discharged at springs the travertine precipitating waters east of the tiber valley have shallower flow paths than those to the west because of the comparatively short fluid flow paths and low normal heat flow the groundwaters to the east of the tiber valley are cold and have co2 isotopic signatures indicating a significant biogenic contribution acquired from soils in the recharge area and limited deeply derived co2 in contrast spring waters west of the tiber valley have been conductively heated during transit in these high heat flow areas and have incorporated a comparatively large quantity of co2 derived from decarbonation of limestone the elevated strontium content of the thermal spring water west of the tiber valley is attributed to deep circulation and dissolution of a triassic evaporite unit that is stratigraphically beneath the mesozoic limestone u series age dates of fossil travertines indicate three main periods of travertine formation ka 220 240 120 140 and 60 70 based on the regional flow model correlating travertine deposition at thermal springs and precipitation in the recharge area we suggest that pluvial activity was enhanced during these periods our study suggests that travertines preserve a valuable record of paleofluid composition and paleoprecipitation and are thus useful for reconstructing paleohydrology and paleoclimate

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

bacterial shrubs crystal shrubs and ray crystal shrubs bacterial vs abiotic precipitation hot water travertine deposits commonly contain shrub like morphologies on the centimeter to meter scale that range from highly irregular forms bacterial shrubs to features that display regular geometric patterns crystal shrubs and ray crystal crusts the bacterial shrubs have been previously recognized as the product of bacterially induced precipitation whereas the ray crystal crusts have been described as due to dominantly abiotic precipitation the bacterial shrubs have a highly irregular morphology similar to woody plants in contrast end member crystal shrubs display distinct crystal habits and regular repeating morphologies i e they commonly have attributes of noncrystallographic as well as crystallographic dendrites there is a complete gradational relationship between the bacterial shrubs and crystal shrubs ray crystal crusts are large fan shaped features composed of subparallel extremely coarse bladed crystals of calcite all three types bacterial shrubs crystal shrubs and ray crystal crusts contain either a dense tangle of bacterial body fossils and or micron sized pores the micropores are bacterial molds the immediately enveloping spar crystals around all three morphologic types are devoid of bacterial body fossils and micropores the bacterial shrubs crystal shrubs and ray crystal crusts are to differing degrees the product of bacterially induced precipitation as well as abiotic mineral precipitation the differences in morphology are due to the relative contribution of bacterially induced precipitation as compared with that of abiotic mineral precipitation bacterially induced precipitates can form in environments too chemically harsh or otherwise inhospitable for other taxa to thrive epiphyton and renalcis commonly formed in occult environments under conditions inhospitable to other taxa consideration of the published descriptions and interpretations concerning epiphyton and renalcis and by analogy the origin of bacterial shrubs have led to the conclusion that epiphyton and renalcis also are bacterially induced precipitates

deposition and diagenesis of mammoth hot springs travertine yellowstone national park wyoming u s a strata forming a 113 m long core through mammoth hot springs record the holocene evolution of this travertine accumulation from deposition as part of a lacustrine to a terraced mound environment the deposit is readily divided into four intervals 113 67 m carbonate cemented volcaniclastic with intercalated layers of travertine 67 60 m moderately pure travertine with some volcaniclastics 60 50 m carbonate cemented volcaniclastic rich interval and 50 0 m essentially pure travertine lithologic composition sedimentary structures and the rare ostracode fossils indicate that the lower 67 m predominantly accumulated in a lacustrine environment whereas the upper 40 m are terraced mound deposits all of the travertine is calcite some after aragonite layers of shrubs oncoids and peloids all bacterial in origin form the dominant allochems within the travertine stable isotopic carbon and oxygen values n 128 are strongly positively correlated and decrease up core 4 and 8 respectively reflec

the shape and density evolution of snow aggregates abstractsnow aggregates evolve into a variety of observed shapes and densities despite this diversity models and observational studies employ fractal or euclidean geometric measures that are assu

incision of a river curvature due to exhumed miocene volcanic landforms danube bend hungary a new model for the formation and relief evolution of the danube bend northern hungary is discussed on geomorphological and volcanological grounds we propose that the present day u shaped loop of the danube bend was partly inherited from the horseshoe caldera morphology of keser s hill volcano a mid miocene ca 15 ma lava dome complex with an eroded central depression open to the north according to combined palaeogeographical data and erosion rate calculations the drainage pattern in the danube bend region was formed when pleistocene tectonic movements resulted in river incision and sedimentary cover removal formation of the present curvature of the river was due to the exhumation of the horseshoe shaped caldera as well as the surrounding resistant volcaniclastic successions i e visegrad castle hill and a hilltop lava dome szent mihaly hill the process accelerated and the present narrow gorge of the danube bend was formed by very rapid as young as late quaternary differential tectonic uplift also enhancing the original volcanic morphology on the basis of comparative long term erosion rate calculations we estimated successive elevation changes of the volcanic edifice including partial burial in late miocene time in comparison with various order of magnitude changes the mid to late quaternary vertical movements show increased rates and or base level drop in the pannonian basin

a comprehensive habit diagram for atmospheric ice crystals confirmation from the laboratory airs ii and other field studies abstract recent laboratory experiments and in situ observations have produced results in broad agreement with respect to ice crystal habits in the atmosphere these studies reveal that the ice crystal habit at 20 c is platelike extending to 40 c and not columnar as indicated in many habit diagrams found in atmospheric science journals and texts these diagrams were typically derived decades ago from laboratory studies some with inherent habit bias or from combinations of laboratory and in situ observations at the ground observations that often did not account for habit modification by precipitation from overlying clouds of varying temperatures habit predictions from these diagrams often disagreed with in situ observations at temperatures below 20 c more recent laboratory and in situ studies have achieved a consensus on atmospheric ice crystal habits that differs from the traditional habit diagrams these newer results can now be combined to give a comprehensive description of ice crystal habits

abiotic versus biotic controls on the development of the fairmont hot springs carbonate deposit british columbia canada the relict fairmont hot springs deposit formed largely of carbonates covers an area of 0ae 5k m 2 and is up to 16 m thick the triangle shaped discharge apron which broadens down valley is divided into a proximal part with beds dipping at 10 and a distal part with beds dipping at 10 to 15 the deposit is formed of the 1 basal macrophyte 2 lower carbonate 3 middle clastic 4 upper carbonate and 5 upper clastic sequences two charcoal samples embedded in the lower carbonate sequence yielded dates of 8690 90 and 8270 70 cal yr bp indicating that much of the deposit formed post glacially during the early to mid holocene deposit aggradation ceased in the mid to late holocene when the fairmont creek valley was incised the lower and upper carbonate sequences which are the thickest sequences are composed of nearly equal parts of travertine abiotic and tufa biotic with feather dendrite travertine radiating dendrite travertine and stromatolite tufa dominating competition between calcite precipitation rates and biotic growth rates controlled the distribution of tufa and travertine across the discharge apron calcite and biotic growth rates were controlled largely by flow velocity across the apron which in turn was controlled by topography and regular fluctuations in spring water discharge volume during times of high spring discharge slow sheet flow over the proximal part of the apron promoted stromatolite growth whereas fast turbulent flow on the distal part of the apron induced rapid feather dendrite formation during times of low spring discharge quiescent shallow evaporative pools conducive to radiating dendrite formation formed on the proximal part of the apron whereas slow flow on the distal part promoted stromatolite growth facies with high calcite supersaturation experienced rapid abiotic dendrite growth that precluded most biotic growth

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