DGL. Artículos

Thermal impact of Heinrich stadials in cave temperature and speleothem oxygen isotope records

2026-04-15T00:01:35Z

[EN]During each Heinrich stadial (HS), temperatures in southern Europe typically dropped several degrees during several hundred to few thousand years. We have developed a one-dimensional thermal conduction model that transfers the typical surface temperature anomaly of a HS to a series of hypothetical underlying caves. The results show that with increasing depth, the thermal anomaly is attenuated, the lag time increases, and the signal structure experiences larger modifications. The model suggests that in most cases, it is not acceptable to assume a synchronous thermal variability and similar average temperature values between the surface atmosphere and the cave interior at millennial timescales. We also simulated the thermal impact of the modeled HS on speleothem δ18O records. The outputs of most model scenarios suggest that temperature changes associated with the HS produce δ18O anomalies capable of contributing significantly or even decisively to the speleothem isotope variability. Therefore, despite controls other than temperature often being considered more important when interpreting Pleistocene speleothem δ18O records in temperate climates, this research suggests that temperature is expected to be one of the major controls of δ18O values in most cave sites outside the tropics and should be included as a significant parameter affecting Pleistocene speleothem δ18O records.

Characterization of soil drainage dynamics on karst terrains by developing a site-specific reservoir cascade scheme hydrological model with preferential flows

2026-04-15T00:01:29Z

[EN]Models provide quantitative solutions that enable better understanding of karst soils hydrology. A location in central Spain was selected to implement a 1-D hydrological model that uses a reservoir cascade scheme (RCS) approach to simulate soil water content (SWC) at daily resolution. The model simulates SWC for six soil layers and includes additional modules to reproduce preferential flow regime. The soil profile in the model is 0.5 m deep, developed in silt loam soil on top of dolomite marbles. Three different configurations of the model were considered. Configuration 1 considers a basic RCS module, whereas other configurations include preferential flows. Thus, Configuration 2 considers RCS module together with a continuous preferential flow module, where 1 to 5% of available SWC from each layer is drained every day along preferential pathways. Configuration 3 contains a discontinuous preferential flow module in addition to previous modules. The discontinuous preferential flow is only activated during rainfall events occurring after long dry periods. Simulated SWC values are compared with measured SWC values, so model parameters are iteratively adjusted to optimize the model results. The model produces the best simulations implementing the Configuration 3, when matrix flow and two preferential flow regimes are considered. The model shows that preferential flows significantly contribute to recharge and should not be neglected in soil hydrological models and recharge estimations in karst areas.

Characterisation of pedogenic carbonates in Calcocambisol at a location within the Dinaric part of Croatia

2026-04-15T00:01:20Z

[EN]Pedogenic carbonates are secondary carbonate deposits and are a constitutional part of many soils. We analysed a 95 cm deep Calcocambisol soil profile at a location in the Dinaric part of Croatia. Here, pedogenic carbonates are more abundant in the deeper part of the profile (>23 cm), and their amount and size increase with depth corresponding to soil properties along the profile. These pedogenic carbonates are spherical to irregular in shape and can be classified as nodules. Microscopical analysis of these nodules shows that dissolution and re-precipitation of carbonate take place in situ, without considerable movement through the soil profile. The growth of the nodules starts from multiple centres of nucleation, and their internal structure is a result of spatial and temporal environmental conditions in the soil matrix during carbonate precipitation. The inclusion of noncarbonate particles and preservation of the original soil structure confirm the replacive nature of nodule growth. Furthermore, the internal structure of nodules reveals multiple stages of calcite precipitation, indicating seasonal or event-based precipitation of carbonate.

Investigations of short-term denudation rates on the North Dalmatian Plain (Croatia)

2026-04-15T00:01:30Z

[EN]Studies of denudation rates in carbonate areas are an important step to understand rates of karst landscape development. Weathering of carbonate rocks is an essential process in soil formation and has a significant role in the global CO2 budget. We studied short-term weathering and denudation rates at a location in the Dinaric karst using the rock tablet method while monitoring surficial and soil environmental parameters. We exposed “standard” rock tablets and those from local lithologies to the natural environment at the surface and buried them at two depths (20 and 50 cm) in the soil profile. Our results show that the average actual denudation rate measured at this site is 2.28 μm/a (for rock tablets exposed at the surface and buried in the soil). Furthermore, this rate is higher at the surface (2.95 μm/a) than those recorded in the soil (1.46 μm/a and 1.99 μm/a at 20 and 50 cm depth, respectively) and is dominated by physical weathering processes driven by diurnal temperature cycles. On the other hand, weathering of rock tablets buried in the soil profile is dominated by chemical weathering processes strongly dependent on the availability of CO2 in the soil, resulting in higher denudation rates deeper in the soil profile. Furthermore, the denudation rate strongly depends on lithology; thus, local lithologies should be used to obtain actual denudation rates.

Laminated tufa sediments formed from overflow karst springs: Controls on their deposition and carbon-oxygen isotope records

2026-04-14T07:40:03Z

[EN]Tufa sediments are freshwater carbonates that precipitate in karst regions after degassing of carbon dioxide from groundwater in contact with the atmosphere. When laminated, these carbonates can provide high-resolution records for the study of climate, hydrological and environmental conditions at the time of their precipitation. The formation of these carbonates directly depends on the hydrological regime, and in karst regions discontinuous discharges are often recorded. This study investigates the record of recent laminated tufa sediments precipitated downstream overflow springs in Trabaque Canyon (central Spain). The hydrological dynamics of the karst system were monitored for over three years and a stable isotope record was obtained from laminated tufa carbonates precipitated from an overflow spring. Additionally, a hydrological model of overflow springs was generated and a tufa δ18O record under constrained parameters was simulated. Temperature is the dominant control of the variation in tufa δ13C and δ18O values within each lamina, although when comparing different laminae, δ13CDIC and δ18O of river water are also major controls. The positive correlation between tufa δ13C values and water temperature is caused by the fractionation occurred by carbon dioxide degassing due to the thermal dependence of carbon dioxide solubility. Additionally, the system recorded a temperature-independent degassing process caused by the large gradient between groundwater and atmospheric carbon dioxide that is limited to the proximity of the spring. This study cautions on the risk of assuming continuous deposition when studying laminated tufa sediments and highlights the potential of their stable isotope records to provide hydrological information of their aquifers during the past.

Basic Properties of Calcocambisol from a Location on North Dalmatian Plain

2026-04-14T00:01:19Z

[EN]Calcocambisol is the most dominant soil type developed on Dinaric karst. It is formed by pedogenic processes acting on carbonate rocks, which include weathering, accumulation of insoluble residue, organic matter, and allogenic material and braunification. Further development of Calcocambisol includes leaching of clay from upper soil horizons and secondary accumulation in lower horizons. Calcocambisols are exclusively developed on carbonate rocks characterised by diverse relief forms resulting in variable soil depth over short distances and consequently different phases of soil development. Thus, the goal of this study was to analyse morphological, physical, and chemical properties of Calcocambisols in different stages of development from a location within the Krka National Park. Results of soil analysis showed similarities in morphological properties, soil field and air capacity, density and SOC content. On the other hand, differences in properties included different carbonate content and pH values of topsoil and difference in particle size distribution. These differences can be attributed to irregular rocky surface which plays important role in allogenic particles distribution and water percolation. Increased leaching of clay particles to deeper horizons results in diversification of Bt (argic) horizon, indicating more advanced stage of soil development towards Luvisol formation.

Parent material as a key determinant of soil properties in southern part of National park Krka, Croatia

2026-04-14T00:01:18Z

[EN]Parent material is an important factor in soil formation, especially in soils formed in Mediterranean region dominated by calcareous sedimentary rocks. Their basic properties (mineralogical composition, coherence, and permeability for water) influence the resistance to weathering and type of weathering products, its amount, particle size distribution, as well as the intensity of hysicochemical transformations within the original rock residue. Thus, the aim of this study was to investigate the impact of parent material on soil properties in southern part of Krka National Park, Croatia. Weathering of carbonate parent material (limestones, dolomites, conglomerates, marls) along with other soil forming factors was the base for soil development in this area. Thus, Calcocambisols and Terra rossa, typical and ilimerized are the most widespread soil types, while Calcomelanosols, Colluvium and Rendzinas are as well represented, but in much lesser extent. Soil depth, presence of coarse fragments and carbonate content in these soils vary considerably depending on parent material, although factors such as relief, vegetation and anthropogenic impact cannot be neglected. In general, shallow soils (< 35 cm) were formed on limestones and conglomerates, while medium deep soils (35-70 cm) were formed on marly substrates. The content of coarse fragments of variable size in soils (fine gravel 2-6 mm to boulders 60-200 cm) is related to different weathering processes of parent material. The presence of carbonate nodules on soil surface and within soil profile also indicates pedogenetic processes related to different types of carbonate parent material.

Morphometrical Features of the Vis Island

2026-04-14T00:01:09Z

[EN]The object of this study are hillslopes of the Vis island. The slopes can be defined as relief surfaces determined by geographical position, slope inclination (related with horizontal surface) and slope aspect. Recent slope shapes can be defined as result of series of natural and anthropogenic factors during relief genesis and evolution. It is possible to correlate slope characteristics with geological structure and other natural geographic features (climate, soils, vegetation etc.) using geomorphometrical analysis. The main aims of this study are: a) analysis of morphometrical relief indicators (hypsometry, slope inclination and slope aspect), b) analysis of relationships between morphometrical indicators, and c) analysis of relatioships between morphometrical parameters, structural and lithological features, in order to gain more detailed understanding of exogeomorphological and morphostructural features of the investigated area. The final intention is to assess extent and intensity of dominant geomorphological processes. Special attention was given to detailed geomorphometrical analysis of morphostructures of Vis island in GIS environment based on DMR. Applied geomorphometrical relief analysis included use of different methods for precise calculation of numerical relief parameters of investigated area, which enabled mutual comparison of specified parameters and comparison with maps of tectonic units and lithology. The aim of this approach is more exact analysis and interpretation of morphometrical relief parameters as indicators of characteristics of endogenous and exogenous processes in the investigated area.

Some Basic Indices of Horizontal Landscape Structure of the Southern Part of Vis Island, Croatia

2026-04-14T00:01:17Z

[EN]This research is based on application of landscape metrics in GIS environment for determination of the basic features of horizontal landscape structure of the southern part of Vis island, Croatia. Landscape elements (or geocomplex types) are determined based on their abiotic (lithological and geomorphological features) and biotic elements (natural vegetation cover). Anthropogenic impact during historical-geographic development (agriculturally cultivated land and urbanized areas) are also considered. By means of GIS tools, the three layers of abiotic and biotic parameters were overlayed (lithology, slope inclinations and types of vegetation cover) and 2556 basic units (geocomplexes) were obtained. Generalization of this basic units by criterion of similarity enabled extraction of 132 types of geocomplexes. This types represent generalised homogenous spatial units which were basis for all further analyses. In the next phase, landscape metrics has been applied in order to determine basic characteristics of horizontal landscape structure: total area of each geocomplex type (including minor elements or basic geocomplexes included in each type), frequency, average areas of individual geocomplexes within types and spatial variability index. The main goals of the research are precise determination of abiotic and biotic features of landscape elements, their spatial structure and interrelationships, classification, typology and determination of existence of specific dominant/stable and vulnerable/labile geocomplex types. The results should serve as methodological framework for evaluation of the current state and future development trends of landscape elements of the researched area. They can be applied in planning and preserving landscape of the southern part of Vis island, and other areas as well.

Vertical landscape structure of the southern part of Vis Island, Croatia

2026-04-14T00:01:15Z

[EN]The paper presents some basic features of vertical landscape structure of the southern part of Vis Island, Croatia. Its aim is the determination of geocomplex types with a certain degree of stability and resistance to external influences, and confirmation or rejection of hypothesis that with the application of appropriate methods, the spatial relation between geocomplex types as well as the identification of specific dominant/stable and vulnerable/labile geocom-plex types can be precisely determined. The results should serve as the basis for estimation of current status and future trends in the development of geocomplex types as well as the environmental changes.

Some Climate Features of the Island of Vis

2026-04-14T00:01:06Z

[EN]Due to the geographical position of the island of Vis, its climate features are under the strong impact of the sea. The data analysed for the period between 1981. and 2009. show positive rising trend of mean annual air temperature and mean annual precipitation, and they are inversely proportional to mean annual humidity. Changes in the values of air temperature and humidity (in the period analysed) are mainly in accordance with the data for the Mediterranean region (except from its eastern part). The changes of the values of mean annual precipitation are not in accordance with the data for the Mediterranean region where the amount of precipitation is mainly decreasing. In the period analysed, there is a great variability of air temperature and precipitation values which is more pronounced in summer precipitation, which emphasizes the negative impact of summer aridity in the years when the deviation from the average is negative.

Typology of Vis Island based on influence of geological, geomorphological and pedological characteristics on natural and cultural landscape

2026-04-14T00:01:02Z

[EN]The basic assumption of this paper is that the relationship between geological basics, geomorphological and pedological characteristics, with structural features of the natural and cultural landscape can serve as a criterion to determine landscape typology with respect to sensitivity to natural processes and anthropogenic influences. Karst natural and cultural landscape of Vis Island, continuously developed under the influence of traditional agriculture, transformed Vis Island into landscape of unique identity and relevance in the wider context of the Adriatic and the Mediterranean. Its characteristics are significant typological variations, authenticity and interdependence of natural and cultivated landscape structure, which makes significant difference respective to appearances of natural and human environment on other Adriatic islands. In this paper character and scope of the impact of natural and social features of the landscape were assessed and sensitivity of areas to existing and potential adverse natural and anthropogenic influences was estimated. This is especially important due to the fact that in the future the island of Vis can expect significant transformation of natural and cultural landscape, as a result of synergic effect of recent natural and social processes. The last are represented through the stronger trend of abandonment of agricultural land, parallel with the spreading of tourism and related activity which leaves the consequences on the natural and cultural landscape.

The role of gypsum and/or dolomite dissolution in tufa precipitation: lessons from the hydrochemistry of a carbonate–sulphate karst system

2026-04-14T00:01:01Z

[EN]The precipitation of freshwater carbonates (tufa) along karstic rivers is enhanced by degassing of carbon dioxide (CO2) downstream of karstic springs. However, in most karstic springs CO2 degassing is not enough to force the precipitation of tufa sediments. Little is known about the role of dissolution of gypsum or dolomite in the hydrochemistry of these systems and how this affects the formation of tufa deposits. Here we present a monitoring study conducted over a year in Trabaque River (Spain). The river has typical karst hydrological dynamics with water sinking upstream and re-emerging downstream of the canyon. Mixing of calcium–magnesium bicarbonate and calcium sulphate waters downstream of the sink enhances the dissolution of carbonates and potentially plays a positive role in the formation of tufa sediments. However, due to the common-ion effect, dissolution of dolomite and/or gypsum causes precipitation of underground calcite cements as part of the incongruent dissolution of dolomite/dedolomitization process, which limits the precipitation of tufa sediments. Current precipitation of tufa is scant compared to previous Holocene tufa deposits, which likely precipitated from solutions with higher saturation indexes of calcite (SIcc values) than nowadays. Limited incongruent dissolution of dolomite/dedolomitization favours higher SIcc values. This circumstance occurs when waters with relatively high supersaturation of dolomite and low SO4 2 composition sink in the upper sector of the canyon. In such a scenario, the process of mixing waters enhances the exclusive dissolution of limestones, preventing the precipitation of calcite within the aquifer and favouring the increase of SIcc values downstream of the springs. Such conditions were recorded during periods of high water level of the aquifers and during floods. This research shows that the common-ion effect caused by the dissolution of gypsum and/or dolomite rocks can limit [or favour] the precipitation of tufa sediments depending on the occurrence [or not] of incongruent dissolution of dolomite/dedolomitization.

Strukturne znacajke suhozidne mreze kao pokazatelji antropogenog utjecaja na krajobraz: primjer juznog dijela otoka Visa, Hrvatska

2026-04-14T00:01:04Z

[EN)This paper deals with analysis of the dry stonewall network structural features and their relationship with the natural landscape. Thus, specific approach was applied – elements of dry stonewall network are analyzed within previously determined spatial units (geocomplex types) that are defined by their internal vertical structure. Based on this set of relations, it is possible to reconstruct the spatial distribution and characteristics of the areas under impact of anthropopression which directly affected the degree of fragmentation and diversity. Landscape metrics (indicators of the composition and configuration of the landscape) was applied in analysis of dry stonewalls structure. Several basic research objectives were set: a) to determine the characteristics of size of dry stonewall network and to select landscape indicators that are most appropriate to define its structure, b) to determine the basic features of the dimension of landscape elements (geocomplex types) within which parts of dry stonewall network are contained c) to determine the nature and the degree of their relationship (relationship between dry stonewall network and anthropogenic impact on the landscape). Data obtained from GIS analysis were further processed by landscape metrics methods and statistical methods of linear correlation and factor analysis. To determine the nature and degree of correlation between eleven analysed variables, method of multiple linear correlation was used. Factor analysis was conducted in order to reduce a number of variables to a smaller number of factors that define the structure and complexity of dry stonewall network and the degree of anthropogenic impact on the landscape. The authors presume that the achievement of these goals will enable to define the features of the current structure and the associated landscape of southern part of Vis Island. Additionally, it will enable definition of general patterns of impact of the socio-geographic processes during historical and geographical development that led to their present appearance and condition. All this should serve as guidance when deciding on the method and degree of protection of specific natural and cultural landscapes ; and eventual revitalization to sustainable tourism valuation. On the basis of the analysis we can conclude the following: 1. Anthropogenic impact (in spatial terms) is very unevenly expressed in the southern part of Vis Island, primarily due to its geographic predisposition (diversity of geomorphological, climatic and soil conditions, distance from populated areas, availability, etc.), as indicated by the high variability in the values of the analyzed parameters on the level of geocomplex types which is reflected in the landscape as a whole. 2. Dry stonewall network shows great complexity of the structure, defined by variables of configuration and composition. This complexity is expressed through significant differences in the mutual relations of the analyzed variables of 92 geocomplex types, represented by a matrix of correlation coefficients. 3. Shapes of geocomplex types are in significant correlation with almost all variables of dry stonewall network (except the average length of drywall). Relatively high correlation with the variables of diversity and dominance confirms the importance of anthropogenic impact. 4. Factor analysis of thirteen variables of dry stonewall structure and associated landscape reduced this to two factors. The first factor is defined as the factor of the landscape structure (caused by changes in biotic / abiotic features due to anthropogenic activities), and the other as a factor of anthropopression or anthropogenically caused fragmentation and diversification of the landscape (as a consequence of the mode and intensity of construction of dry stonewall network) that represent the structural characteristics of the dry stonewall network within the individual elements of the landscape. Within the second factor, based on the factor points, individual impact of variables on transformation of the natural landscape is determined. Analyses have shown that used methodologies can serve to reconstruct anthropogenic impact on the landscape and the degree of intensity of land use during historical and geographical development. Extensive database containing information on structure of dry stonewall network and natural features of the landscape allows precise selection of the areas that are most suitable for reconstruction in terms of reconstruction and interior of dry stonewall network for tourism or renewal of traditional agriculture, in line with sustainable development.

Magnetobiochronology of the Izaga section (South Pyrenean Foreland basin): Implications for defining the global boundary stratotype section and point (GSSP) of the Bartonian Stage and unravelling climate change across the Middle Eocene Climate Optimum

2026-02-21T01:01:22Z

[EN]We present a new magnetobiostratigraphic study of the Izaga composite section (South Pyrenean foreland basin), performed to investigate the possibility of defining the Bartonian GSSP and to assess the yet unexplored sedimentary expression of the Middle Eocene Climate Optimum (MECO) in the deep palaeoenvironments of the basin. Our results indicate that the section spans from the uppermost part of Chron C19r to the uppermost part of C18n.2n, comprising calcareous nannofossil biozones CNE14 and CNE15. As found in most prospective sections studied previously, the occurrence of delayed magnetizations has prevented precise delineation of the marker of the Bartonian GSSP, the short lived Chron C19n, which reinforces the idea that an alternative biostratigraphic event might need to be chosen as the primary marker of the GSSP. In this regard, we propose the highest occurrence of Sphenolithus furcatolithoides B, whose persistent location close to the top of C19n has been corroborated at the Izaga composite section. If this datum accepted, the Izaga composite section can be regarded as one of the best prospective successions to host the Bartonian GSSP due to its expanded nature and superb outcrop conditions. Our results also reveal an increase in the input of reworked calcareous nannofossils and organic matter of continental origin concurring with a negative shift in the carbonate carbon and oxygen stable isotope record around the C19r/C18n.2n boundary, and hence demonstrate that the enhanced hydrological cycle induced by the MECO is manifested along a complete continental to deep marine transect along the South Pyrenean basin.

Preliminary laboratory studies on hydrogen storage in a salt cavern of the Eocene Barbastro Formation, Southern Pyrenees, Spain

2026-02-21T01:01:18Z

[EN]Underground hydrogen storage (UHS) is emerging as a promising tool for managing surplus energy derived from renewable energy sources. Rock salt (halite) formations, particularly solution-mined salt caverns, offer a secure and efficient storage medium due to their low permeability, self-healing properties, and chemical stability. Laboratory experiments simulating reservoir-like conditions are essential for reducing uncertainties surrounding hydrogen–rock interactions prior to large-scale deployment. This study investigates the response of rock salt to hydrogen exposure under controlled conditions (10 MPa, 60 °C, 30 d) in an autoclave. Two samples from the Eocene Barbastro Formation (Southern Pyrenees), recovered from a deep borehole within a potential salt cavern-type storage site, were tested. The halite samples included impurities such as anhydrite, quartz, feldspars, dolomite, calcite, and phyllosilicates, allowing assessment of non-halite phase reactivity also. Results indicate no significant mineralogical changes after hydrogen exposure. Observed alterations were minor and limited to localised halite recrystallization, slight particle detachment, and occasional chloride precipitation. These findings suggest an overall mineralogical stability of the salt matrix and impurities under the tested conditions and scales. By improving our understanding of hydrogen–rock interactions in evaporitic settings, this study contributes to ongoing efforts to develop safe, science-based solutions for underground hydrogen storage in salt caverns.