sedimentology of quaternary perched springline and paludal tufas criteria for recognition with examples from guadalajara province spain outcrop scale geometries and bed relationships of ambient temperature freshwater carbonates are poorly understood because many described tufas have been dismantled by erosion and present only part of a particular depositional model at the field scale four end member models encompass the tufa continuum 1 perched springline 2 paludal 3 fluvial and 4 lacustrine tufas individual bed types can occur with variable dominance within several of these models but one or more beds are characteristically dominant only within a single tufa model so it can be differentiated from relatively isolated outcrop fragments two models perched springline tufas and paludal tufas are known in outline only in the literature despite being present within the quaternary deposits of most karstic regions perched springline tufas generally form lobate fan shaped mound morphologies on hillslopes and develop from single or multiple spring resurgences mature deposits show a subhorizontal top and a steep face on the downflow side the steep outer zones of tufa mounds may be developed into cascades with moss curtains or can be dominated by shallow rimstone pools according to face angle tufa deposits lying downslope of the mounds are usually detrital in nature especially if some dismantling of the mound has occurred the relatively thin subhorizontal lobe top deposits commonly contain organic rich deposits paludal tufas develop predominantly in waterlogged valley bottom situations where line sourced waters emerge from valley side and bottom aquifers lime mud precipitation predominates in these sites mud is deposited as subhorizontal laminites that thin towards the valley axis and downstream of resurgences tufa spring mounds may form where lesser volumes of water are involved individual tussocks phytoherm cushions of grasses and rushes are the most diagnostic feature of the model but sapropels and peats may be intercalated diagenesis in both models is rapid lithification of individual beds is virtually instantaneous and always occurs before the decay of the associated living vegetation the resulting highly porous and permeable fabrics remain fresh in holocene tufas but aggrading neomorphism and partial spar infill of vegetation moulds is common in older deposits dissolution in many perched springline tufas is small scale many large cavities are primary but with later coatings of speleothems early removal of organics from paludal tufas is responsible for autobrecciation and differential compaction

a convective line with leading stratiform precipitation from bamex abstract on 31 may 2003 a front fed convective line with leading stratiform precipitation ffls was observed during the bow echo and mesoscale convective vortex experiment bamex the high resolution bamex measurements provided one of the first opportunities to thoroughly observe the characteristics of an ffls system the 31 may system had an overturning updraft during its early stages and produced leading stratiform precipitation as the system matured a jump updraft developed and the system began to produce trailing stratiform precipitation it appears that this transition was facilitated by a local decrease in the low level line perpendicular vertical wind shear over time as well as an increase in the surface cold pool s strength the bamex data further help to address the question of how ffls systems can be long lived when their inflow passes through the line leading precipitation preline soundings suggest a destabilization mechanism resulting from the vertical profile of cooling within the lea

tectono sedimentary characteristics of late miocene quaternary extensional basins of the northern apennines italy abstract extensional and compressional regimes exist at the same time in adjacent parts of the northern apennines italy and the former regime succeeded the latter at the same place as the thrust mountain front moved eastward since miocene times numerous extensional basins have developed west of the present mountain divide the westernmost ones formed over attenuated continental crust since late miocene and have been subjected to several subsidence and uplift events with rates of subsidence generally faster than rates of sedimentation they contain continental deposits overlain by gypsum bearing upper miocene marine sequences and siliciclastic marine pliocene deposits these basins were affected by shallow magmatism and are still experiencing high geothermal gradient and late to post magmatic activities such as in the renowned thermal region of larderello to the east closer to the present mountain divide the extensional basins formed later from pliocene to quaternary contain continental fluvial and lacustrine deposits and have not experienced near surface magmatic activities the sedimentary fill architecture of the apennine extensional basins is similar to that of other european american and african extensional or transtensional systems for instance a common characteristic is the prevalence of large alluvial fan deposits at the hanging wall shoulder of half grabens coarser smaller alluvial fans at the footwall shoulder and some fluvial deposits introduced longitudinally unlike the african rifts though the sedimentary facies distribution of extensional basins which developed in active orogenic zones such as in the apennines may be strongly affected by uplifting steep mountain slopes and can have large thick coarse alluvial fans also on the footwall side of the half grabens

comment on first records of syn diagenetic non tectonic folding in quaternary thermogene travertines caused by hydrothermal incremental veining by billi et al tectonophysics 700 701 2017 60 79 abstract billi et al 2017 proposed a new interpretation for the origin and internal structure of thermogene travertine deposits on the basis of evidence from two quarries located in southern tuscany italy they interpreted some travertine beds as calcite veins and argued that undulating travertine beds formed by syn diagenetic i e non tectonic folding that was caused by laterally confined volume expansion caused by incremental veining they assumed that such a process causes changes to the rock properties including porosity reduction rock strengthening and age rejuvenation the interpretations by billi et al 2017 challenge and question the current understanding and interpretation of thermogene travertine deposits this understanding based on numerous studies since the 1980s is that these deposits form from thermal water flowing downslope and precipitating calcium carbonate here we explain how the comparison with active depositional systems is essential for the understanding the origin of structures in older inactive travertine deposits such as those studied by billi et al 2017 we further argue that the three dimensional setting of travertine deposits should be taken into account in order to discuss the possible development of secondary structures indeed travertine deposition on slopes typically leads to the formation of terraced morphologies with pools bordered by rounded rims and separated from each other by steep walls the resulting three dimensional structures can be misinterpreted as asymmetric folds in two dimensional views i e in saw cut walls of quarry in this paper we debate the interpretations offered by billi et al 2017 and their criteria to recognise syn diagenetic non tectonic folds in travertine deposits and explain why many of their ideas are questionable

sloping fan travertine belen new mexico usa abstract pliocene to quaternary age travertines are very well exposed in quarries near belen new mexico u s a on the western edge of the rio grande rift system a series of hillside springs produced travertine tongues tens of meters thick and hundreds of meters long the accumulations represent deposits from individual springs as well as the amalgamation of deposits the overall architecture is predominantly composed of sloping fans with a smaller component of terrace mounds the sloping fan deposits commonly have a dip of

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

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

jurassic evolution of the gulf of mexico salt basin we present a new hypothesis for the jurassic plate tectonic evolution of the gulf of mexico basin and discuss how this evolution influenced jurassic salt tectonics four interpretations some based on new data constrain the hypothesis first the limit of normal oceanic crust coincides with a landward dipping basement ramp near the seaward end of the salt basin which has been mapped on seismic data second the deep salt in the deep water gulf of mexico can be separated into provinces on the basis of position with respect to this ramp third paleodepths in the postsalt sequence indicate that salt filled the gulf of mexico salt basin to near sea level fourth seismic data show that postsalt sediments in the central louann and the yucatan salt basins exhibit large magnitudes of late jurassic salt detached extension not balanced by equivalent salt detached shortening in our hypothesis callovian salt was deposited in preexisting crustal depressions on hyperextended continental and transitional crust after salt deposition ended rifting continued for another 7 to 12 m y before sea floor spreading began during this phase of postsalt crustal stretching the salt and its overburden were extended by 100 to 250 km 62 155 mi depending on location sea floor spreading divided the northern gulf of mexico into two segments separated by the northwest trending brazos transform the eastern segment opened from east to west leaving the walker ridge salient in the center of the basin as the final area to break apart in some areas salt flowed seaward onto new oceanic crust first concordantly over the basement as a parautochthonous province then climbing up over stratigraphically younger strata as an allochthonous province

timing of post depositional events in the burano formation of the secchia valley upper triassic northern apennines clues from gypsum anhydrite transitions and carbonate metasomatism the burano evaporite formation from the secchia river valley is an up to 2200 m thick sequence composed of meter to decameter scale interbeds of gypsum anhydrite and dolostones with minor halite the deposit has been affected by a complex array of post depositional modifications thermal events and large scale evaporite dissolution preventing a satisfactory reconstruction of the environment of deposition the modifications are intense because these rocks were the main decollement horizon during the formation of the northern apennines chain the carbonate rocks are massive and or laminated dolomitic mudstone wackestone oolitic packstones and oolitic peloidal bioclastic grainstones which commonly appear as mega boudins within a sulfate groundmass the dolostones to 3 7 to 3 0 pdb have been affected by mg metasomatic replacement by magnesite to 2 6 to 1 4 pdb induced by hydrothermal circulation total homogenization temperatures of fluid inclusions in hydrothermal magnesite range from 275 to 310 c the anhydrite rocks are characterized by flow structures such as centimeter scale pseudo lamination composed of aligned prismatic crystals with transposed isoclinal folds outlined by dolostones fragments homogenization temperatures of fluid inclusions in authigenic quartz incorporated into sulfate rocks range from 260 to 305 c emilia and from 230 to 315 c tuscany the gypsum rocks are composed of xenotopic irregular cloudy crystals and more rarely by centimeter scale idiotopic crystals showing the same structures as the anhydrite rocks the origin of the gypsum rocks is due to late alteration of anhydrite by migration of sharp hydration fronts the hydration is a two step process and is revealed by the presence in the gypsum rocks of corroded anhydrite micro relics and authigenic quartz crystals which include anhydrite the role of the burano evaporites during the apennines tectogenesis can be depicted as follows a prevalent deposition of gypsum in the upper triassic b gypsum dehydration at burial conditions to form anhydrite cretaceous c syn tectonic flow of anhydrite rocks brecciation of dolostones syn tectonic growth stage of quartz euhedra at deep burial conditions possibly related to the development of the oligocene miocene greenschist facies apuane metamorphic complex d hydrothermal deposition of sparry magnesite and partial mg metasomatic replacement of dolostones by magnesite e sub surface dissolution of halite to form thick matrix supported residual caprock like anhydrite mega breccias f complete gypsification of anhydrite at sub surface conditions and g evaporite dissolution at surface exposure producing dolostone breccias with partial calcitization and removal of most clasts calcare cavernoso

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

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

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

tertiary extensional tectonics in tuscany northern apennines italy abstract two extensional events have been recognized in the tertiary evolution of tuscany the first event occurred in the period between the late oligocene and late tortonian and caused a stretching of 120 or greater the second event occurred between the late tortonian and quaternary periods and caused a stretching not greater than 10 the first event is characterized by the exhumation of middle crust rocks and therefore by the development of core complexes the most significant structures of the first event are low angle normal faults which characterize the upper plate of the core complexes and ductile shear zones which characterize the lower plate the low angle normal faults tend to die out in the late triassic evaporite level which constitutes the main detachment of the core complexes the main structures of the second extensional event are high angle normal faults which dissect all the previous tectonic features these faults border tectonic depressions which were the site of clastic sedimentation from late tortonian to quaternary time these normal faults may tend to flatten in a seismic lozenge shaped band explained as an active extensional shear zone which is located at the brittle ductile boundary a similar explanation is given for the detachment located in the late triassic evaporite level during the first extensional event while the first extensional event is in the framework of the northern apennine post collisional evolution the second extensional event because it affects an already stretched crust could be attributed to the southern tyrrhenian opening which began during late tortonian

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

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

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

hierarchical approach to define travertine depositional systems 3d conceptual morphological model and possible applications abstract 3d modelling represents a powerful tool to characterize the geobody architecture of depositional systems several examples have been proposed in literature both for marine carbonates and siliciclastics rocks for modelling quantitative data related to orientation shape and dimension are fundamental continental carbonates however are not considered yet likely because they cover a large range of deposits such as speleothems tufas lacustrine carbonates and travertines the interpretation of the depositional environments of the latter is still in fact debated by the scientific community however the interest in continental carbonates and especially travertines increased over the last decades due to the discovery of supergiant unconventional reservoirs in the southern atlantic i e the so called pre salt play aim of this paper is to present an innovative workflow to investigate and describe continental carbonates as geobodies based on a hierarchical approach applied to three large scale travertine settings i e terme di san giovanni italy pamukkale turkey and the lapis tiburtinus travertines italy travertine depo systems are divided in three different depo zones namely proximal intermediate and distal that are characterized by different depo elements depo shapes and depo facies finally a 3d morphological model is created based on numerical and vector approaches and interpolation of both the model can be applied to seismic data of brazilian and angolan pre salt highlighting the similarities between these systems and for the first time the scale independence of these depositional system representing an important advantage in their interpretation the 3d model and the approach proposed facilitates seismic interpretation allowing to define and characterize geometries of inaccessible geological contexts

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

elastic properties of continental carbonates from controlling factors to an applicable model for acoustic velocity predictions we have provided new insights into the controlling factors of elastic properties in continental carbonate rocks and introduced an applicable model for acoustic velocity predictions in such a medium petrophysical properties porosity permeability p and s wave velocities from laboratory measurements have been coupled with thin section observations and characterizations and x ray diffraction xrd analyses a major achievement is the establishment of the link between the mineralogical composition and the p and s wave velocity dispersion at a given porosity this reflects the subtle interplay between physico chemical and biological precipitation of continental carbonates which can also be associated with a strong influence of detrital mineralogical inputs the result is a mineralogical commixture coupled to a wide array of pore types inherited from the strong ability of carbonate rocks to undergo diagenetic alteration the proposed model takes into account the elastic moduli of the minerals porosity and pore shape and it is based on the effective medium theory we have considered the case in which the medium contained randomly oriented pores with different aspect ratios overall the fit between the predicted trends and the experimental data is fairly good especially for calcite and quartz matrix mineralogy the results are even better when considering mineralogy inferred from xrd data although in some case and despite the aspect ratio variation in both simulations the model fails to accurately predict the p wave velocities this probably means that another factor is at stake beside mineralogy this can be explained by the limitation of the effective medium approach which oversimplifies the reality and fails to account for the variability of some aspect ratio from one inclusion to another

frictional and hydraulic behaviour of carbonate fault gouge during fault reactivation an experimental study abstract we present a novel experimental approach devised to test the hydro mechanical behaviour of different structural elements of carbonate fault rocks during experimental re activation experimentally faulted core plugs were subject to triaxial tests under water saturated conditions simulating depletion processes in reservoirs different fault zone structural elements were created by shearing initially intact travertine blocks nominal size 240 110 150 mm to a maximum displacement of 20 and 120 mm under different normal stresses meso and microstructural features of these sample and the thickness to displacement ratio characteristics of their deformation zones allowed to classify them as experimentally created damage zones displacement of 20 mm and fault cores displacement of 120 mm following direct shear testing cylindrical plugs with diameter of 38 mm were drilled across the slip surface to be re activated in a conventional triaxial configuration monitoring the permeability and frictional behaviour of the samples as a function of applied stress all re activation experiments on faulted plugs showed consistent frictional response consisting of an initial fast hardening followed by apparent yield up to a friction coefficient of approximately 0 6 attained at around 2 mm of displacement permeability in the re activation experiments shows exponential decay with increasing mean effective stress the rate of permeability decline with mean effective stress is higher in the fault core plugs than in the simulated damage zone ones it can be concluded that the presence of gouge in un cemented carbonate faults results in their sealing character and that leakage cannot be achieved by renewed movement on the fault plane alone at least not within the range of slip measureable with our apparatus i e approximately 7 mm of cumulative displacement additionally it is shown that under sub seismic slip rates re activated carbonate faults remain strong and no frictional weakening was observed during re activation

studying travertines for neotectonics investigations middle late pleistocene syn tectonic travertine deposition at serre di rapolano northern apennines italy middle late pleistocene tectonic activity has been inferred through studies on travertine deposits exposed in a tract of the hinterland northern apennines a detailed study on the relationships between tectonics and travertine deposition coupled with 230th 234u age determination of travertines at cava oliviera quarry located close to serre di rapolano village southern tuscany northern apennines allowed us to recognise pleistocene faults whose activity has been referred to 157 24 ka at least travertine deposition was tectonically controlled by wsw ene striking oblique and normal faults associated to a main fault named as the violante fault this structure dissected a regional normal fault known as the rapolano fault early middle pliocene in age which bounded the eastern side of the pliocene siena basin and gave rise to space accommodation for clayey and sandy marine sediments hydrothermal circulation and related travertine deposition was favoured by the damaging enhancement due to the fault fault intersection tectonic activity has been also documented by deformation recorded by travertines which suggest a main tectonic event between 64 5 and 40 5 ka the tectonic activity described for the study area agrees with the quaternary tectonic evolution documented in the surrounding areas e g mt amiata and mt vulsini as well as the tyrrhenian margin of the central apennines indicating that a widespread tectonic activity affected the inner part of the apennines until the latest quaternary

shrub and pore type classification petrography of travertine shrubs from the ballik belevi area denizli sw turkey petrographical and petrophysical properties of the turkish ballik belevi travertine shrubs demonstrate the necessity of reservoir oriented classifications for shrub related lithotypes and associated pore types the presented shrub related lithotype classification incorporates morphology size and fabric which are linked to specific pore types and sizes the travertines show highly complex pore networks as observed from computed tomography reconstructions making them of interest for the development and optimization of pore characterization methodologies and techniques following an upscaling approach porosity 3 15 and permeability 0 505 md strongly vary for the ballik belevi travertines the highest porosities and permeabilities are measured for horizontal samples dominated by slightly dissolution enlarged intershrub and interdigit growth framework porosity mostly found for dendritic shrubs the presented shrub and pore type classification can be applied to shrubs worldwide studying outcrop analogues of continental carbonates helps to better understand heterogeneities lateral variability and properties of pre salt cretaceous continental carbonate reservoirs offshore brazil and angola

fluid inclusions in sedimentary and diagenetic systems abstract some of the major problems in sedimentary geology can be solved by using fluid inclusions in sedimentary and diagenetic minerals important fluids in the sedimentary realm include atmospheric gases fresh water of meteoric origin lake water seawater mixed water evaporated water formation waters deep in basins oil and natural gas preserving a record of the distribution and composition of these fluids from the past should contribute significantly to studies of paleoclimate and global change research is essential for improving understanding of diagenetic systems and provides useful information in petroleum geology applications of fluid inclusions to sedimentary systems are not without their complexities some fluid inclusions exposed to natural conditions of increasing temperature may be altered by thermal reequilibration which results in stretching or leakage and refilling of some fluid inclusions similarly overheating in the laboratory can also cause reequilibration of fluid inclusions so fluid inclusions from the sedimentary realm must be handled carefully and protected from overheating natural overheating of fluid inclusions must be evaluated through analysis of the most finely discriminated events of fluid inclusion entrapment fluid inclusion assemblages fia consistency in homogenization temperatures within a fluid inclusion assemblage consisting of variably sized and shaped inclusions is the hallmark of a data set that has not been altered through thermal reequilibration in contrast fluid inclusion assemblages yielding variable data may have been altered through thermal reequilibration if a fluid inclusion assemblage has not been altered by thermal reequilibration its fluid inclusions may be useful as geothermometers for low and high temperature systems or useful as geobarometers applicable throughout the sedimentary realm if a fluid inclusion assemblage has been altered partially by thermal reequilibration techniques for distinguishing between altered and unaltered fluid inclusions may be applied in studies of global change fluid inclusions can be used as sensitive indicators of paleotemperature of surface environments fluid inclusions also preserve microsamples of ancient seawater and atmosphere the analysis of which could figure prominently into discussions of past changes in chemistry of the atmosphere and oceans in petroleum geology fluid inclusions have proven to be useful indicators of migration pathways of hydrocarbons they can delineate the evolution of the chemistry of hydrocarbons and they remain important in understanding the thermal history of basins and relating fluid migration events to evolution of reservoir systems in studies of diagenesis fluid inclusions can be the most definitive record most diagenetic systems are closely linked to temperature and salinity of the fluid thus fluid inclusions are sensitive indicators of diagenetic environments

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

hidden sinkholes and karst cavities in the travertine plateau of a highly populated geothermal seismic territory tivoli central italy abstract sinkholes and other karst structures in settled carbonate lands can be a significant source of hazard for humans and human works acque albule the study area of this work is a plio pleistocene basin near rome central italy superficially filled by a large and thick deposit of late pleistocene thermogene travertine human activities blanket large portions of the flat territory covering most evidence from geological surface processes and potentially inducing scientists and public officials to underestimate some natural hazards including those connected with sinkholes to contribute to the proper assessment of these hazards a geomorphologic study of the basin was performed using digital elevation models dems recent aerial photographs and field surveys historical material such as old aerial photographs and past geomorphologic studies both pre dating the most part of quarrying and village building was also used together with memories of the elderly population this preliminary study pointed out the presence of numerous potentially active sinkholes that are at present largely masked by either quarrying or overbuilding where this first study pointed out the apparent absence of sinkholes in areas characterized by high density of buildings a detailed subsurface study was performed using properly calibrated electrical resistivity tomography ert and dynamic penetration measurements dpsh together with some borehole logs made available from the local municipality this second study highlighted the presence of sinkholes and caves that are this time substantially hidden to the resolution of standard methods and materials such as aerial photographs dems and field surveys active sinkhole subsidence in the acque albule basin may explain at least in part the frequent damages that affect numerous buildings in the area the main conclusion from this study is that the mitigation of sinkhole hazard in highly populated areas has to pass through a thorough search of hidden sinkholes that can be masked by the anthropocenic molding and blanketing of the territory for these purposes data from historical pre anthropocene documents as well as where possible subsurface investigations are fundamental

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

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

evaluating the geogenic co2 flux from geothermal areas by analysing quaternary travertine masses new data from western central italy and review of previous co2 flux data abstract quantification of carbon fluxes between solid earth and its atmosphere is necessary to understand the global geological carbon cycle some of the main co2 contributors are metamorphism and magmatic mantle degassing co2 is discharged from active and quiescent volcanoes fault zones geothermal systems and co2 rich groundwater here a new method for the estimation of the geogenic flux of co2 from tectonically active regions based on the volume composition and age of travertine deposits is proposed the method is applied to the travertine deposits of western central italy where travertine deposition is driven by degassing of co2 charged groundwater results show that the study areas are characterized since middle pleistocene by diffuse co2 degassing processes with time averaged co2 fluxes ranging between 1 24 0 12 106 mol y 1 km 2 and 1 38 0 42 106 mol y 1 km 2 these values are of the same order of magnitude of carbon dioxide fluxes measured by different methods in western central italy and are higher than the global baseline co2 flux from high heat flow regions the review of the available 234u 230th and 14c data shows that the co2 degassing processes that affects western central italy nowadays were already active at least 350 ka ago proving that this region is a globally relevant case for the study of earth degassing considering the widespread occurrence of travertine deposits in tectonically active areas worldwide the proposed approach can be used as a reliable tool to estimate the co2 flux in different geodynamic settings within system earth

travertine deposition and faulting the fault related travertine fissure ridge at terme s giovanni rapolano terme italy in this paper we describe an example of travertine fissure ridge development along the trace of a normal fault with metre displacement located in the eastern margin of the neogene quaternary siena basin in the terme s giovanni area rapolano terme italy this morphotectonic feature 250 m long 30 m wide and 10 m high formed from supersaturated hot waters 39 9 c flowing from thermal springs aligned along the trace of the normal fault dissecting travertines not older than late pleistocene 24 3 ka a straight continuous fissure with a maximum width of 20 cm occurs at the top of the ridge along its crest hot fluids flow from cones mainly located at the extremities of the ridge where travertine is depositing the travertine fissure ridge shows an asymmetrical profile since it buries the fault scarp the difference in height of slopes corresponds to the vertical displacement of the normal fault fissuring of the recent travertine deposits along the strike of the crestal fissure as well as recent hydrothermal circulation lead us to believe that the terme s giovanni normal fault may be currently active on the whole the terme s giovanni fissure ridge can be defined as a travertine fault trace fissure ridge adding a helpful example for studying the relationship between faulting and travertine deposition

pore structure and fractal analysis of lower carboniferous carbonate reservoirs in the marsel area chu sarysu basin abstract evaluation of carbonate heterogeneity closely related to pore geometry and connectivity is important in oil and gas field production and reservoir prediction to profoundly understand the heterogeneity of lower carboniferous carbonate reservoirs in the marsel area including visean c1v and serpukhovian c1sr the pore structure and fractal characteristics are investigated using routine petrophysical measurements x ray diffraction xrd cast thin section analysis scanning electron microscopy sem and mercury injection capillary pressure micp tests the origin of potentially prolific reservoir the relationships between fractal dimension and reservoir physical properties mineral composition and pore structure are also discussed xrd results reveal that the mineral compositions are highly heterogeneous in c1v and c1sr routine petrophysical experiments indicate that c1v and c1sr are generally tight however some high porosity permeability zones exist in c1sr which is described as a potentially prolific reservoir the cast thin section and sem analyses identify three main pore types in the potentially prolific reservoir interparticle dissolution pores intercrystalline dissolution pores and moldic pores the micp data reflect that the pore throat radii in the prolific reservoir range from 0 29 to 4 6 m whereas those in tight section are typically

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

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