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ABSTRACT Travertines are non‐marine sedimentary rocks, which are typically hydrothermal in origin and characterized by high depositional rates. Despite great advances in the understanding of the geomorphological, petrological and geochemical aspects of travertines, the recognition of these rocks in the geological record is not an easy task due to the multiple parameters involved in their formation, the variable potential of preservation and the lack of a facies model with application to the geological record. This study applies classic sedimentological and stratigraphic methods, looking for vertical and lateral facies distribution at the Vega Botijuela, Salar de Antofalla, Argentina. Travertines are geomorphologically compartmentalized into proximal, intermediate and distal zones, with spring waters in the proximal zone and mixed carbonate–siliciclastic sedimentation observed towards the distal zone. The presented data corroborate previous assumptions that these systems are dominantly progradational to aggradational. Vertical facies stacking is typically coarsening‐upward, with a dominance of carbonate mudstone interbedded with grainstone, rudstone and boundstone. Distinct facies associations are observed in the Vega Botijuela and are defined here as dome, fissure ridge, gently and steeply inclined slopes, stepped slope and terminal, according to morphological criteria applied elsewhere. Biotic and abiotic travertine precipitation occurs along the geomorphological zones and is related directly to different slope gradients. Throughout the depositional history of travertines, the carbonate facies occur interbedded with siliciclastic deposits from the Salar de Antofalla, generating local facies heterogeneity in the marginal areas of the basin. This is one of the first attempts to establish vertical stacking patterns to characterize facies associations, adding important insights towards the building of a travertine facies model. In this context, these findings can be applied to recognize travertines of the geological record developed in extensional sedimentary basin margins under arid climatic conditions. [ABSTRACT FROM AUTHOR]

This study determined natural and artificial radionuclide concentrations to evaluate natural radioactivity and health risk levels of nine travertines in the Yaprakhisar and Balkayası regions in Turkey. The samples coded B1-M, B2, B5, B7, B8, and B10 represent waste derived from the Yaprakhisar travertines, as well as samples T5-M, T12, and Z1 travertines derived from Balkayası. The levels of natural and artificial radionuclide concentrations (232Th, 40K, and 137Cs) were measured using a high-purity germanium (HpGe) detector system. The travertine activity ranged from 2.09 to 12.07 Bq kg−1 for 232Th, 4.21 to 13.41 Bq kg−1 for 40K, and 0.42–3.26 Bq kg−1 for 137Cs. The results showed that the activity concentration values for 232Th, 40K, and 137Cs were coherent with the travertine analysis results in the UNSCEAR, 2000; 2008 publications. The values obtained were lower than the average values in the UNSEAR reports. The radiological hazard parameters calculated in this study were absorbed gamma dose rate (D), radium equivalent activity (Raeq), annual gonadal dose equivalent (AGDE), exposure dose (ER), total annual effective dose (AEDEtotal), excess lifetime cancer risk (ELCRtotal), gamma representative level (GRL), internal hazard index (Hin) and external hazard index (Hex). [ABSTRACT FROM AUTHOR]

A multidisciplinary study, involving hydrogeological, geochemical, and mineralogical analyses, was conducted to define the evolution of thermal mineral springs in the Sabatini Volcanic District (SVD) (Central Italy) in a historic period. The outcomes were integrated with the archeological findings to improve the knowledge of the evolution of Veii, a settlement established since the Iron Age and later expanded by Etruscans and Romans. During the archeological excavations, water-related buildings were identified, especially at the Campetti Southwest site in the Veii settlement. Votive inscriptions also suggest the presence of buildings linked to sacred waters, even if a clear definition of the source and type of water is missing. In the SVD, some low-flow thermal mineral springs are present as a result of the mixing of thermal and CO2-rich groundwater from the deep carbonate aquifer and the cold, shallow volcanic aquifer. Mineralogical and chemical analyses characterized the travertine and Fe-hydroxide deposits on Roman tanks and walls in Campetti Southwest and in a nearby ancient Roman bath along the Valchetta River. These deposits showed different relative concentrations of sedimentary and volcanic-related elements, testifying a geochemical evolution of the groundwater mixing and the presence of a paleothermal mineral spring in Campetti Southwest. [ABSTRACT FROM AUTHOR]

Abstract Continental spring carbonates are perfect examples of the interaction of biotic and abiotic processes, and they preserve evidence of the velocity of the flow and the chemical composition of the spring water. This study focuses on non‐marine carbonates from fossil and active springs from the Bongongo and Ngol areas along the Cameroon Volcanic Line in South‐West Cameroon. Here, hydrothermal fluids reach the surface giving rise to small thermal springs, with temperatures between 31 and 49°C, and streams creating waterfalls, terracettes and barrage carbonate deposits. Petrographic analyses of these carbonates revealed that they are made up of stacked laminae of fibrous coarse crystals of low‐Mg calcite and laminae of alternate microsparite and micrite. The fibrous coarsely crystalline calcite, often with feather‐like fabric, grows from thin layers of micrite and peloids. Filaments of putative microbial origin are preserved within this peloidal micrite. The laminated microsparite and micrite microfacies is characterised by an intricate mesh of hollow filaments of microbial origin. The long feather‐like crystals of calcite formed in fast‐flowing water where the enhanced CO2 degassing has favoured the precipitation of CaCO3. The laminated micrite and microsparite, on the other hand, are probably formed in ponds where degassing and CO2 removal was lower and the calcite precipitation was fostered by microbial activity. The fast‐forming carbonates show higher Ce contents and very low total rare earth elements, revealing a preferential uptake of Ce with respect to other rare earth elements. This process would explain the positive or null Ce anomaly in continental spring carbonates elsewhere. The geochemical composition of these carbonates can be used as proxy for the characterisation of fluid/rock interactions between the groundwater and the substratum and for the characterisation of the sources of calcium and other elements that constitute tufa and travertines. The samples from Ngol are characterised by light rare earth element enrichment while those from Bongongo are overall enriched in heavy rare earth elements. Carbonates from both localities have a strong positive Eu anomaly (>4), suggesting a contribution from deep‐seated, hydrothermal, crustal fluids in contact with volcanic rocks and the breakdown of plagioclase from the Cameroon Volcanic Line alkali basalts.

Abstract This study aims to compare the fabrics of anthropogenic carbonates downstream of lime and steel disposal sites with models of carbonate precipitation from natural systems to elucidate potential drivers, precipitation mechanisms, morphological similarities, predictability in 3D facies distributions and depositional models of these systems. For this purpose, a combination of sedimentological, mineralogical and geochemical approaches is conducted including the analysis of microfacies (petrographic microscope and electron microscopy), X‐ray diffraction and hydrochemistry. The data show that both anthropogenic and natural systems exhibit clear proximal, middle and distal zones of carbonate precipitation. The main macroscopic differences are the dominance of swamp environments in the proximal zone and the prevalence of tufa‐like barrage‐and‐pool sequences in the middle and distal zones. Microfabrics in anthropogenic sites are comparable to travertines but lack the sub‐surface facies and at extreme pH exhibit sparry crusts without clear equivalents in travertines. This sedimentology of anthropogenic carbonates shows that calcite mineral formation is complex and not homogeneous or purely driven by thermodynamic processes. Considering the sedimentology of these human‐induced systems will help us understand precipitation mechanisms which will aid both efforts to utilise anthropogenic alkaline wastes for carbon capture and manage their environmental impacts.

Cyanobacteria are considered to be among the first microorganisms to settle in hot springs where they form a favourable environment for further biological establishment. Nevertheless, the exact pioneer species and how early they start participating in the biomineralisation processes remain unknown. The aim of the present study was twofold, that is, to identify the pioneer Cyanobacteria in hot springs (i.e. Aedipsos area, Greece) and to record their early biomineralisation processes. The in situ experimental approach included the setup of sterile glass and/or plexiglass slides in several locations to facilitate colonisation by Cyanobacteria, and removal of slides for study after 48–202 h. Synechococcales (37%) and Oscillatoriales (33%) were the dominant orders, followed by Chroococcales (15%) and Spirulinales (11%); whereas Chroococcidiopsidales (4%) was found only in a few sites. The order Nostocales was not observed at the early stages of colonisation although it was present in mature stages. Forty‐three species of Cyanobacteria were identified as pioneer microorganisms, with Spirulina subtilissima being the most frequently found. The most common pioneers were multicellular filamentous Cyanobacteria, that is, organisms with a large surface area able to form significant amounts of extracellular polymeric substances. Among the pioneers, thermophilic species of Cyanobacteria were typical such as Chroococcidiopsis thermalis, Chroococcus thermalis, Leptolyngbya thermalis, S. subtilissima and Symploca thermalis, as well as typical limestone substrate species such as Chroococcus lithophilus and Leptolyngbya laminosa. Temperature seems to affect biodiversity. Also, pioneers were found to contribute to the biomineralisation processes from their first appearance. In the studied samples, three biomineralisation processes were identified, that is, (i) calcification of cyanobacterial sheaths, (ii) trapping of carbonate crystals on a crystal retention lattice formed by extracellular polymeric substances and filaments and (iii) trapping and confinement of carbonate crystals around filamentous Cyanobacteria. [ABSTRACT FROM AUTHOR]

This study aims to compare the fabrics of anthropogenic carbonates downstream of lime and steel disposal sites with models of carbonate precipitation from natural systems to elucidate potential drivers, precipitation mechanisms, morphological similarities, predictability in 3D facies distributions and depositional models of these systems. For this purpose, a combination of sedimentological, mineralogical and geochemical approaches is conducted including the analysis of microfacies (petrographic microscope and electron microscopy), X‐ray diffraction and hydrochemistry. The data show that both anthropogenic and natural systems exhibit clear proximal, middle and distal zones of carbonate precipitation. The main macroscopic differences are the dominance of swamp environments in the proximal zone and the prevalence of tufa‐like barrage‐and‐pool sequences in the middle and distal zones. Microfabrics in anthropogenic sites are comparable to travertines but lack the sub‐surface facies and at extreme pH exhibit sparry crusts without clear equivalents in travertines. This sedimentology of anthropogenic carbonates shows that calcite mineral formation is complex and not homogeneous or purely driven by thermodynamic processes. Considering the sedimentology of these human‐induced systems will help us understand precipitation mechanisms which will aid both efforts to utilise anthropogenic alkaline wastes for carbon capture and manage their environmental impacts. [ABSTRACT FROM AUTHOR]

Continental spring carbonates are perfect examples of the interaction of biotic and abiotic processes, and they preserve evidence of the velocity of the flow and the chemical composition of the spring water. This study focuses on non‐marine carbonates from fossil and active springs from the Bongongo and Ngol areas along the Cameroon Volcanic Line in South‐West Cameroon. Here, hydrothermal fluids reach the surface giving rise to small thermal springs, with temperatures between 31 and 49°C, and streams creating waterfalls, terracettes and barrage carbonate deposits. Petrographic analyses of these carbonates revealed that they are made up of stacked laminae of fibrous coarse crystals of low‐Mg calcite and laminae of alternate microsparite and micrite. The fibrous coarsely crystalline calcite, often with feather‐like fabric, grows from thin layers of micrite and peloids. Filaments of putative microbial origin are preserved within this peloidal micrite. The laminated microsparite and micrite microfacies is characterised by an intricate mesh of hollow filaments of microbial origin. The long feather‐like crystals of calcite formed in fast‐flowing water where the enhanced CO2 degassing has favoured the precipitation of CaCO3. The laminated micrite and microsparite, on the other hand, are probably formed in ponds where degassing and CO2 removal was lower and the calcite precipitation was fostered by microbial activity. The fast‐forming carbonates show higher Ce contents and very low total rare earth elements, revealing a preferential uptake of Ce with respect to other rare earth elements. This process would explain the positive or null Ce anomaly in continental spring carbonates elsewhere. The geochemical composition of these carbonates can be used as proxy for the characterisation of fluid/rock interactions between the groundwater and the substratum and for the characterisation of the sources of calcium and other elements that constitute tufa and travertines. The samples from Ngol are characterised by light rare earth element enrichment while those from Bongongo are overall enriched in heavy rare earth elements. Carbonates from both localities have a strong positive Eu anomaly (>4), suggesting a contribution from deep‐seated, hydrothermal, crustal fluids in contact with volcanic rocks and the breakdown of plagioclase from the Cameroon Volcanic Line alkali basalts. [ABSTRACT FROM AUTHOR]

The relevance. Yamkun spring is known as one of the few radioactive springs in Transbaikal region. Its waters were used for the treatment of Kaschin–Beck disease (Urov disease), nowadays the regional center of medical rehabilitation for the treatment of diseases of the musculoskeletal and nervous systems, including cerebral palsy, and diseases of the skin is working on the basis of this spring. The main aim of the research is to identify mineralogical and geochemical characteristics of Yamkun spring components. Objects: lake and stream water, travertines, ferruginous sediments in the stream bed, salt sediments on the tube of soak well, vegetation (lichens, mosses, pine straw, poplar leaves). Methods: inductively coupled plasma mass-spectrometry, instrumental neutron activation analysis, X-ray diffractometry, scanning electron microscopy. Results. Water of Yamkun spring is bicarbonate, calcium-magnesium, radioactive of radon nature. It is significantly enriched in Mn, Fe, Be, As, Zr, Cs, Hg, Tl, Li, Co and Ba relative to water of Lake Baikal. Water enrichment with rare alkaline and alkaline-earth elements (Li, Be, Cs), as well as Hg, Tl, As and Zr suggests that their source is rare-metal granitoids. During water discharge we observed modern mineral formation on the surface of water baths as «Yamkun foam» (aragonite), tubes of soak well (nesquehonite) and in the stream (ferruginous sediments). Ferruginous sediments and travertines are represented mainly with magnesian calcite. In the ferruginous sediments we identified in large quantities Fe and Mn compounds, probably hydroxides. The hydroxides of Mn also include Ba, K, Cl compounds, Fe hydroxides – As, P, Si, Al. Rare microinclusions in the travertines are represented with intermetallic phases of Cu and Sn, La-Ce carbonate and As sulphide (loellingite?). The inheritance of composition of modern ferruginous sediments and travertines is established. The forming travertines are enriched with the same elements as the water in the spring.

Hydrothermal palaeoenvironments are very uncommon in Upper Jurassic and Lower Cretaceous deposits worldwide. We present new plant and insect remains from travertines formed during the Jurassic-Cretaceous boundary in northern Spain (Aguilar Fm., Palencia province). A total of 136 plant specimens and three insect wings were collected and studied. This entomofauna consists of dragonfly (Odonata) wings including Cymatophlebiidae and an undetermined new genus and species of Aktassiidae, representing the first report of these families for the Iberian Peninsula. The fossil flora shows different morphotypes of plants, which have been tentatively assigned to three different genera. The taphocoenosis of the flora was dominated by Bennettitales (98.5%) including cf. Pterophyllum sp., Ptilophyllum cf. acutifolium, Ptilophyllum cf. pecten, Ptilophyllum cf. pectiniformis and cf. Ptilophyllum sp., and the occasional presence of ferns (1.5%) represented by the taxon Cladophlebis cf. denticulata. The presence of the Anisoptera Cymatophlebia cf. longialata suggests a higher affinity for a Tithonian age of the studied site, and the anatomy and palaeogeographical distribution of this species suggest capacity to migrate for rather long distances. The floristic composition of the site differs remarkably from other Tithonian-Berriasian floras of the Iberian Peninsula. The presence of Odonata and the distinctive flora in (semi)arid conditions could be due to the hot-spring providing an environmental niche with constant conditions of warmth and humidity forming an ‘ecological oasis’.

The Argens upper watershed, upstream to the Valley Sourn gorges, is rich in remarkable travertine deposits: active waterfalls on Argens and old sites of Varages and Barjols. The work makes the synthesis of geomorphological observations realized by the author during its long practice (several decades) of this area. We find in it a lot of already published information, but also complements, cartographics in particular. If the inherited forms hold an important place, the current conditions of the travertine genesis are not neglected, due to the hydrological measures of the DREAL and to an hydrochemical study led in the years 1985-90. The development of travertines constructions seems forced by the conditions of the actual environment: reduction of the flows of low water levels under the influence of anthropogenic takings, water pollution and solid transport linked to the agricultural soil erosion during floods.

The understanding of the relationship between the geochemistry of fluids circulating during travertine deposition and the presence of active faults is crucial for evaluating the seismogenetic potential of an area. Here we investigate travertines from Pamukkale and Reşadiye (Turkey), sited in seismic regions and next to thermal springs. These travertines formed ~24,500–50,000 (Pamukkale) and ~240–14,600 years (Reşadiye) BP. We characterize fluid inclusions (FIs) and studied concentration of H2O, CO2, O2 + N2, and 3He, 4He, 20Ne, and 40Ar, and bulk composition (trace elements and δ13C‐δ18O). FIs from both localities are mainly primary with low salinity and homogenization temperature around 136–140 °C. H2O is the major component followed by CO2, with the highest gas content measured in Pamukkale travertines. Concentrations of Ne‐Ar together with O2 + N2 indicate that travertines from both areas precipitated from atmosphere‐derived fluids. The 3He/4He is 0.5–1.3 Ra in Pamukkale and 0.9–4.4 Ra in Reşadiye. Samples with R/Ra > 1 are modified by cosmogenic 3He addition during exposure to cosmic rays. Excluding these data, FIs of Reşadiye are mostly atmosphere‐derived. This implies a shallow formation where the circulation was dominated by meteoric waters, which is consistent with their young age. Instead, FIs of Pamukkale show mixing of mantle‐, crustal‐, and atmosphere‐derived He, indicating that these travertines formed in lithospheric fractures. Based on the δ13CCO2 and δ18O of bulk rocks, we infer that travertines formed involving crustal‐ (mechanochemical rather than organic) and mantle‐derived CO2. Trace elements of Pamukkale and Reşadiye show comparable rare earth element patterns. We conclude that travertines formed in response of seismogenetic activity. Key Points: We studied the geochemistry of fluid inclusions in travertine deposits from Pamukkale and Reşadiye areas (Turkey).Concentrations of Ne‐Ar and O2+N2 indicate that travertines from both areas precipitated from atmosphere‐derived fluids.The 3He/4He values indicate that Reşadiye travertines formed at shallow depth, while Pamukkale in an active system of lithospheric fractures [ABSTRACT FROM AUTHOR]

Quantification of carbon fluxes between solid Earth and its atmosphere is necessary to understand the global geological carbon cycle. Some of the main CO 2 contributors are metamorphism and magmatic-mantle degassing. CO 2 is discharged from active and quiescent volcanoes, fault zones, geothermal systems and CO 2 rich groundwater. Here a new method for the estimation of the geogenic flux of CO 2 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 CO 2 charged groundwater. Results show that the study areas are characterized, since Middle Pleistocene, by diffuse CO 2 degassing processes with time averaged CO 2 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 CO 2 flux from high heat flow regions. The review of the available 234U/230Th and 14C data shows that the CO 2 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 CO 2 flux in different geodynamic settings within system Earth. Image 1 • Geogenic flux of CO 2 is estimated from the volume and age of travertine deposits. • Western central Italy is a globally relevant case for the study of Earth degassing. • The proposed approach is a reliable tool to estimate the CO 2 flux worldwide. [ABSTRACT FROM AUTHOR]

Elemental data from travertines are a treasure of depositional and diagenetic information. However, correct interpretation requires proper data acquisition and treatment. This study shows how results from elemental analyses complement sedimentological and other geochemical, i.e. isotopic, data and thereby contribute to our understanding of fossil travertines. Multivariate statistical element analyses, after multiple travertine digestion methods, demonstrate the link between elements, their mineralogical phases, and ultimately their origin. This study reveals that carbonate-phase related elements in travertines (Sr, S, Ba, Mg and Na) originate dominantly from the fluid source rocks. In combination with the δ18O and δ13C signatures, they are thus key geochemical variables for comparison of different travertine geobodies. Geochemical data analysis (elemental concentrations and isotope signatures), as illustrated here for the Turkish Ballık travertines, supports interpretation with regard to fluid source rock, distance from the vent and relative intensity of processes like evaporation and degassing. For fossil travertines, geochemical data can thus provide crucial insights for understanding the hydrologic system. In particular when information is restricted to borehole data, like in subsurface reservoirs, their application could be decisive. • Multiple element comparisons of travertines require a standardised full digestion • Multivariate statistical analyses help to link elements to their mineral phase • Carbonate-phase elements (Sr, S, Ba, Mg, Na) originate from the fluid source rocks • Carbonate-phase elements and δ18O - δ13C are key for comparison of travertines • Geochemical data unravels vent proximity and evaporation-degassing intensity [ABSTRACT FROM AUTHOR]

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. • Travertines can be used as analogue of some Pre-salt Cretaceous rocks. • Travertine outcrops provide fundamental quantitative data suitable to better understand inaccessible reservoirs as the Pre-salt. • Geometries of travertine depositional systems are similar to some of seismic reflectors encountered in Pre-salt. • Travertine depositional systems can be schematized in 3D models. [ABSTRACT FROM AUTHOR]

Abstract The terrains of the Western Costa del Sol in the westernmost Mediterranean represent an outstanding example of the influence of major tectonic and climatic factors in the development of the landscape. This region belongs to the Alboran domain, which is a small continental lithosphere fragment embedded between the large Eurasian and African plates. The territory between Malaga and Marbella is composed mainly of the Sierra de Mijas and three adjacent subsidence areas: Malaga, Torremolinos, and Fuengirola basins. From the late Miocene, dip-faults of approximate directions N-S, NE-SW and NW-SE limited the Sierra de Mijas with respect to the adjacent subsidence areas and have marked the main features of the coastal morphology. Since then, the Sierra underwent mainly erosive processes linked to strong uplifting, while the surrounding basins were subjected to alternate stages of sedimentation and erosion. Thus, the paleogeographic and geomorphological evolution has been driven both by the regional tectonics and by significant base-level changes ranging from the spectacular Messinian low-stand to the catastrophic overflow at Gibraltar, followed by the global Late Tertiary and Quaternary sea-level changes. In the mountain relief, three different erosive leveling surfaces have been recognized, which developed in a staggered sequence during the Miocene, and are currently fragmented by tectonics at different elevations. The first two leveling surfaces, continental in origin, were carved during the Middle Miocene pro-part. The late one, correlating with Upper Miocene marine deposits from the Malaga basin, appears to correspond partially to an abrasion platform developed during the highstand of the late Tortonian. The strong incision of the fluvial network, especially due to the low sea-level during the Messinian salinity crisis, but also to the tectonic rise of the Sierra, has largely eroded these surfaces, which can be recognized only in narrow inter-fluvial areas. The noteworthy marine transgression in the Miocene-Pliocene transition reached the edge of the Sierra de Mijas, developing both a broad marine abrasion platform around it and the main stage of sedimentary filling in the Malaga basin. Tectonics combined with sea-level changes influenced the formation of a lower, second abrasion platform in the Torremolinos sector and along the S edge of the Sierra, showing continuity with the late Zanclean marine deposits in the Torremolinos and Fuengirola areas. During most of the late Pliocene and the Gelasian, the region remained emerged and subjected to erosion. Conversely, climate-eustatic changes throughout the Pleistocene and Holocene led to the development of three major generations of progradant alluvial fans interrupted by stages of erosion and incision of the fluvial network. In parallel, up to five episodes of travertine build-up occurred, usually coinciding with the humid and warm, odd-numbered isotopic stages. Highlights • Neogene tectonics form the main features of the landscape of the Costa del Sol. • The MSC and Pliocene re-flooding left strong traces in the relief of the region. • Quaternary climate cycles drive the development of alluvial fans and travertine. [ABSTRACT FROM AUTHOR]

A study of a late Pleistocene 30 m-thick travertine borecore drilled in the north-western sector of the Acque Albule basin (Tivoli, Rome), type area for these freshwater calcareous deposits, it is here presented. The Tivoli travertines have been traced sideways from the core into wire-cut surfaces well exposed in nearby active quarries. They normally appear well bedded and show erosional-non depositional discontinuities, recurring at a centimetric to metric-decametric scale and show a variable penetration by younger sediments (Ca-carbonates as well as reddish soils), as evidenced by their karstic and/or pedogenetic features. The microstratigraphic and sedimentologic analysis has revealed a number of lithofacies grouped in three associations, suggesting environmental domains spanning from gentle slope to shallow lake. This sedimentary organization and stable isotope (O, C) analyses carried out at cm scale have allowed to recognize a hierarchy of higher to lower frequency cycles. On these bases, it is argued and proposed that the higher frequency cyclicity is due to water table fluctuations, as a consequence of millennial-scale climatic changes that in turn may be linked to the solar perturbations (short-term cycles). The lower frequency, instead, cycles (metres to decametres in thickness) suggest medium-term (sub-Milankovitch) and longer term, precession-driven (Milankovitch) periodicities. These conclusions are supported by the correlation of the hierarchical organization of the travertine cycles with a number of radiometrically dated discontinuity surfaces outcropping along the quarry walls and traceable into the borecore. This correlation allows the cyclostratigraphic analysis to be constrained into late Quaternary geochronology and fits well within the precession and obliquity periodicities, as predicted for this time interval. [ABSTRACT FROM AUTHOR]

The mineralogical and geochemical features of the Khoito-Gol ecosystem (fresh thermal waters-microorganisms-travertines) of the Baikal Rift Zone and the aspects of the interaction among its components were studied. The research has shown that the behavior, distribution, and accumulation of trace elements are determined mostly by the geochemical barriers of geologic and biologic genesis in the flowing-water habitat of bacteria of the Khoito-Gol spring. Formation of biominerals by different functional groups of its bacterial community is considered. [ABSTRACT FROM AUTHOR]

A geomorphological and sedimentological analysis makes it possible to identify the different Quaternary formations in the Orbieu valley. Then, the reconstruction of the longitudinal and transversal profiles shows the evolution of tectonic deformations since the formation settling. Neotectonics have been active up to the accumulation of the alluvial deposits of the Weichselian lower terrace. The dating of the Graffan travertines would allow adjust the Orbieu terraces system chronology.

In the valleys of inner Provence, numerous travertine formations are wide extension in relation with important karstic springs. Because the geomorphological evolution, the old travertines are maked up balconies and terraces. The recent period of main travertine construction begins as far back as in the Preboreal (even in Bölling at southern Luberon) and appears generalized in the Atlantic. In the late Neolithic (around 4000 BP), this sedimentation decreases with the climatic deterioration and the opening of forest cover under the weight of human pressure. However some tufa dams (stromatolite doms) and associated wetland with peat deposits continues up to the historic times. In the Middle Var County, these tufa deposits on the dams remains active in some refuge sites, in the upper and woody valleys, near the karstic springs, and in any high waterfalls. More along the rivers, some waterfalls with tufa deposits proceeds from the old mills and irrigation canal fitting. This tufa sedimentation is in relation with the interference of multiple factors, whose:- carbonate mineralization of the karstic springs,- seasonal working of the hydrosystem,- regional and local ecosystem (forested land, important riparian cover),- algo-bryophitic biotope.Nowadays, the stromatolitc sedimentation is in critical situation because the impact of multiple factors in relation with increased urbanization and environmental change:- river pollution, increased turbidity in little tributaries flowed from agricultural mecanization,- decreased flow in seasonable times (spring - summer), the most favourable to the algo-bryophytic activity, because the common increasing water sample.The recent drought period (2006-2008) has maked worse these impacts on the tufa dams. And the protection of these sites of large environmental and patrimonial interest put complex problems.

Two major earthquakes occurred on October 23rd, 2011 (M=7.1) and November 9th, 2011 (M=5.6) in Tabanli and Edremit districts of Van province in Turkey, respectively. New settlement areas for Van city were determined after these destructive earthquakes. One of the most important areas for new settlements to be built was Edremit region, consisting travertine where nearly 80% of new housing units (12.384) were built by TOKI (Housing Development Administration of Turkey). Travertines have different lithotypes depending on their depositional process such as crystalline crust, shrub, reed which can affect mechanical and engineering properties of travertine and each level has different handicaps. The purpose of this study is to investigate the relationship between lithotype and physico-mechanical properties of travertines. According to the results, lithotype has an effect on physical, mechanical and rock mass properties of travertine. It is ascertained by several research methods that various handicaps may occur on such areas when the active tectonic structure of the area is evaluated along with the karstic cavities within the travertine and different lithotype qualities. [ABSTRACT FROM AUTHOR]

Springs are biodiversity hotspots and unique habitats that are threatened, especially by water overdraft. Here we review knowledge on ambient-temperature (non-geothermal) freshwater springs that achieve sufficient oversaturation for CaCO 3 -by physical CO 2 degassing and activity of photoautotrophs- to deposit limestone, locally resulting in scenic carbonate structures: Limestone-Precipitating Springs (LPS). The most characteristic organisms in these springs are those that contribute to carbonate precipitation, e.g.: the mosses Palustriella and Eucladium , the crenophilous desmid Oocardium stratum , and cyanobacteria (e.g., Rivularia ). These organisms appear to be sensitive to phosphorus pollution. Invertebrate diversity is modest, and highest in pools with an aquatic-terrestrial interface. Internationally, comprehensive legislation for spring protection is still relatively scarce. Where available, it covers all spring types. The situation in Europe is peculiar: the only widespread spring type included in the EU Habitat Directive is LPS, mainly because of landscape aesthetics. To support LPS inventorying and management to meet conservation-legislation requirements we developed a general conceptual model to predict where LPS are more likely to occur. The model is based on the pre-requisites for LPS: an aquifer lithology that enables build-up of high bicarbonate and Ca 2 + to sustain CaCO 3 oversaturation after spring emergence, combined with intense groundwater percolation especially along structural discontinuities (e.g., fault zones, joints, schistosity), and a proper hydrogeological structure of the discharging area. We validated this model by means of the LPS information system for the Emilia-Romagna Region (northern Italy). The main threats to LPS are water diversion, nutrient enrichment, and lack of awareness by non-specialized persons and administrators. We discuss an emblematic case study to provide management suggestions. The present review is devoted to LPS but the output of intense ecological research in Central Europe during the past decades has clearly shown that effective conservation legislation should be urgently extended to comprise all types of spring habitats. [ABSTRACT FROM AUTHOR]

The present paper deals with the investigation of abiotic and biotic influence on thermogenic travertine formation in Thermopylae hot springs, one of the largest active thermogenic travertine systems in Greece. Geological, mineralogical and microbiological data from three different types of travertines (cascades, terraces and fluvial crusts) revealed different cyanobacterial communities. Microscopic analysis of fresh and cultured material has shown that epilithic and endolithic cyanobacteria are almost the exclusive components of travertines' photosynthetic microflora. Thirty-one (31) taxa of cyanobacteria are presented here, among them the frequently found, in such environments, Phormidium incrustatum and Aphanocapsa thermalis, as well as the taxonomically interesting diazotrophic morphotype identified as Chlorogloeopsis sp. Sampling sites I and II have similar formation conditions characterized by laminated travertines with low porosity and shrub lithotypes, with the cyanobacterium Leptolyngbya ercegovicii occupying an endolithic zone, while the upper part is occupied by colonial chroococcalean species. On the contrary, sampling site III is characterized by laminated travertine with fenestrial type porosity and absence of shrub lithotypes resulting in a completely different community of cyanobacteria. [ABSTRACT FROM AUTHOR]

Aluminum toxicity is a major limitation to crop production on highly weathered and leached soils in Rwanda. Moreover, sulfur though widely deficient in Rwanda acidic soils has received little attention by soil fertility researchers. A field experiment on maize response and soil nutrients status to liming materials of travertines at 3.4 t ha−1, ash wood 1.2 t ha−1of CaO equivalent and sulfur at 10 kg ha−1combined with NPK at 80, 60, and 45 kg ha−1respectively was conducted in Rubona Ultisol and Nyamifumba Oxisol. Results revealed that travertine and wood ash increased the soil pH from 4.7 to 5.8 or higher and decreased exchangeable Al3+and H+to near 0 cmolc kg−1. Soil nutrients generally increased to high or medium ranges for crop production. Leaf dry biomass, plant height and maize grain yields were significantly higher in Rubona Ultisol than in Nyamifumba Oxisol. Plots that received wood ash, with NPKS or with NPK, generally had higher maize yields, followed by those which received travertines and NPKS or NPK which had maize growth response as compared to the control plots which received NPK only. Thereby, a combination of wood ash with NPKS or NPK, travertines with NPKS was found to neutralize soil aluminum toxicity, increase soil nutrients status to required levels for plant growth and increase maize yields significantly. [ABSTRACT FROM PUBLISHER]

Résumé: Le site de Kocabaş, est situé dans le Bassin de Denizli, en Anatolie occidentale, à 400km au sud-ouest d’Ankara, à 360km au sud d’Istanbul, à 200km à l’est-sud-est d’Izmir et à 150km au nord-ouest d’Antalya. La dépression du Bassin de Denizli, à la jonction du Buyuk Menderes et du Gediz graben, dont la formation a débutée au début du Miocène, a été comblée à ses marges, au niveau des plans de failles, par d’importantes formations de travertins dont certains sont encore actifs actuellement. L’âge des travertins de Kocabaş, d’où provient la calotte crânienne d’Homo erectus de Kocabaş, a été évaluée par la méthode de la thermoluminescence à 828 000ans, par celle de la résonance électronique de Spin (ESR) à 1 110 000ans et par la méthode des nucléides cosmogéniques 26Al/10Be à un âge supérieur à 1,22 Ma et plus jeune qu’environ 1,5 Ma, datation qui est confirmée par la magnétostratigraphie et la biochronologie. [ABSTRACT FROM AUTHOR]

Résumé: La révision et l’étude de nouveaux fossiles de grands mammifères provenant des dépôts de travertins du bassin de Denizli ont permis de reconnaître les espèces suivantes : Archidiskodon meridionalis meridionalis, Stephanorhinus cf. etruscus, Equus cf. altidens s. l., E. cf. apolloniensis, Metacervoceros rhenanus, Cervalces (Libralces) ex gr. minor-gallicus, Palaeotragus sp., Bovinae gen. et sp. indet. Biochronologiquement, cette association ressemble à celles reconnues au Villafranchien supérieur au Sud et à l’Est de l’Europe, et en partie à l’Ouest de l’Asie, et serait plus ancienne qu’1,2 Ma. [ABSTRACT FROM AUTHOR]

Abstract: Well-preserved Quaternary staircased marine terraces appear on Ras Leona limestone relief. This is a peculiar sector of the Betic-Rif Cordillera, lying in the four-way junction between the Atlantic and the Mediterranean, and Europe and Africa. The age and altitude correlation of the Ras Leona terraces with travertine-covered lateral equivalent terraces fashioned in the neighbouring Beni Younech area, and comparison with those along the Moroccan Atlantic coasts, would suggest that the Ras Leona terraces were mainly formed by eustatic factors. The importance of the eustasy is supported by further comparisons with Spanish and Moroccan Mediterranean terraces and with different marine terraces developed on passive-margin coasts around the world. A tectonic event occurred mainly during the period between the formation of the Maarifian and the Ouljian terraces (i.e., between 370 and 150ka). The moderate Quaternary tectonic uplift deduced from the marine terraces and its comparison with uplifted marine terraces developed in active subduction setting disagrees with the model of an active eastwards subduction below the Gibraltar tectonic arc. [Copyright &y& Elsevier]

Microscopically, modern tufas, sinters, and travertines (TSTs) may contain filaments, spirilla, clotted micrite (peloids and/or grumeleuse), tubules, coccoids, or spheres that suggest a biological component to their constitution. However, examination of progressively older TST deposits reveals that the preservation of primary depositional features, including biological morphologies, is commonly obscured by diagenetic overprinting that may mask or obliterate original features. In the study reported here, we examined modern and ancient spring deposits to determine which biological morphologies remain identifiable through geologic time. The focus is on the preservation potential of fossil microorganisms, independent of the mineralogy or formation temperature of the original TST. Biologically induced biomineralization likely fossilizes microorganisms in situ within TST deposits. Biofilms, composed primarily of extracellular polymeric substances, bind calcium or silica ions, serve as nucleation sites, and change local microchemistries to favor precipitation of calcite, aragonite, or chert (less commonly, other minerals). The resultant precipitation entombs microbial material and may yield a fossilized remnant of the microbe’s former presence, albeit lacking details beyond general morphology. The preserved dimensions are almost always larger than those of the original microorganism. Recrystallization and the formation of cement, either calcite (or aragonite) or silica, are diagenetic processes that may occur early and rapidly, with resultant blurring of primary fabrics. Curiously, the commonly recognized spherule and coccoid forms from Holocene and Cenozoic deposits are rarely observable in Mesozoic and Paleozoic deposits, except as indistinct clots in thin section or as rounded mineralized forms. Filaments, however, retain much of their original dimensions, particularly their diameter, and if discovered stretching across a primary pore space may be considered one of the more reliable indicators of former microbial activity in ancient spring deposits. [ABSTRACT FROM AUTHOR]

Simple Summary: In this study, we show and identify new plant and insect remains found in travertine deposits from the Jurassic-Cretaceous boundary of the Aguilar Formation (Palencia, North Spain). From this hot-spring palaeoenvironment, we have identified the presence of dragonflies of the families Cymatophlebiidae and Aktassiidae, representing the first report of these families for the Iberian Peninsula. In addition, we find a flora dominated by Bennettitales and the presence of ferns that differ from other floras of the same age and geographical area. The unusual environmental and palaeoecological conditions of this hot-spring environment are also discussed, suggesting that this niche was an "ecological oasis" for some plants and insects. Hydrothermal palaeoenvironments are very uncommon in Upper Jurassic and Lower Cretaceous deposits worldwide. We present new plant and insect remains from travertines formed during the Jurassic-Cretaceous boundary in northern Spain (Aguilar Fm., Palencia province). A total of 136 plant specimens and three insect wings were collected and studied. This entomofauna consists of dragonfly (Odonata) wings including Cymatophlebiidae and an undetermined new genus and species of Aktassiidae, representing the first report of these families for the Iberian Peninsula. The fossil flora shows different morphotypes of plants, which have been tentatively assigned to three different genera. The taphocoenosis of the flora was dominated by Bennettitales (98.5%) including cf. Pterophyllum sp., Ptilophyllum cf. acutifolium, Ptilophyllum cf. pecten, Ptilophyllum cf. pectiniformis and cf. Ptilophyllum sp., and the occasional presence of ferns (1.5%) represented by the taxon Cladophlebis cf. denticulata. The presence of the Anisoptera Cymatophlebia cf. longialata suggests a higher affinity for a Tithonian age of the studied site, and the anatomy and palaeogeographical distribution of this species suggest capacity to migrate for rather long distances. The floristic composition of the site differs remarkably from other Tithonian-Berriasian floras of the Iberian Peninsula. The presence of Odonata and the distinctive flora in (semi)arid conditions could be due to the hot-spring providing an environmental niche with constant conditions of warmth and humidity forming an 'ecological oasis'. [ABSTRACT FROM AUTHOR]

Abstract: Spring waters (17°C), rich in and flowing along artificial channels, precipitate carbonate incrustations at Pontecagnano (Salerno, southern Italy). The incrustations have been analysed and monitored for two years and compared them with fossil incrustations (travertines). In the present-day precipitates, the δ 18O and δ 13C values suggest seasonal variations and inorganic CO2 origin, respectively. In the fossil travertines, three main environments have been identified and described: slope, shallow-lake and rapid–waterfall. Their interplay resulted in a progradational and aggradational travertine growth, recording recurrent interruptions due to lowering of groundwater levels and decrease in spring-water outflow. Isotope analyses, from different lithologies, suggest analogy of fossil accumulations with present-day incrustations also documenting seasonal changes. These data indicate that the present-day carbonate waters and travertines are responsive to regional hydrologic-climatic variations and that their fossil equivalents can be used to outline patterns of depositional processes and related climatic constraints for tens of thousands of years. [Copyright &y& Elsevier]

Abstract: The Guadix–Baza basin is one of a number of intramontane depressions located within the Betic Cordillera (SE Spain), where the geological and geomorphological evolution is controlled by tectonic activity. The basin ceased to be closed after capture by the Atlantic network, when five main land systems developed. Late Pleistocene geological evolution basically consisted of erosional modelling, when badlands were deeply incised in highly erodible materials (marls and silts). Three travertine platforms and several Palaeolithic sites were used to determine that this main incision period fell within a 115,000–48,000 yr range. There are few signs of geomorphological evolution of this basin in the last 48,000 yr. Based on these geomorphological data and soil development, tectonic uplift of the basin probably played a secondary role in its evolution, and climatic conditions in southern Iberia in the 144,000–48,000 yr period were more humid and variable than later. [Copyright &y& Elsevier]

Abstract: The Denizli basin, which is famous by its modern travertine accumulations such as that of Pamukkale is located at the eastern junction of Büyük Menderes and Gediz grabens in the western Anatolian extensional province. This basin contains large travertine formations, the origin and age of which are still debated. This study briefly recalls the tectonic and stratigraphic context of travertine occurrences and describes some vertebrate remains, which have recently been recorded in travertines. The material mainly consists of jaw fragments referred to Equus aff. suessenbornensis Wüst, 1901, lower teeth and antlers of Dama sp. and some lower teeth of Bos sp. The presence of E. aff. suessenbornensis, indicates a Middle Pleistocene age in agreement with thermoluminescense dating of the travertines. [Copyright &y& Elsevier]