Acta Carsologica

Cave development in the Qatar peninsula: insights on their origin and associated geohazards

Mon, 17 Aug 2026 00:00:00 +0200

The geology of the State of Qatar comprises large spans of carbonate rocks at the surface and evaporitic rocks at shallow depth, and a number karst features (depressions, caves) spread across the country that may cause challenges during land development or infrastructure construction. The government of Qatar has identified that existing geodatabases and geological and hydrogeological maps require improvement to mitigate this risk. In this framework, a thorough assessment of the karst geohazard has been performed including a karst features survey, geologic study of karstification, and an assessment of associated ground subsidence related to karst. The main findings indicate the existence of two types of caves: one corresponding to shallow subsurface dissolution caves developed under phreatic conditions in the past and truncated by erosion at a later stage, the other corresponding to large roof collapse caves originating at depth (intrastratal karst). These latter caves are systematically located on the edge of large depressions. In agreement with the existing literature, it is proposed that the depressions and collapse caves are part of a same collapse/sagging process caused by loss of material at depth (e.g., dissolution of evaporites, compaction of weathered dolostone, or incremental collapse of coalesced relict caves). To extract the karst collapse depressions among the large number of depressions mapped using a recent (2017) LiDAR DTM dataset, it is hypothesized that the karst depressions shall have the same geometrical characteristics (width, length, area, depth) than the few ones containing a roof collapse cave. This results in the identification and mapping of 3537 karst depressions spread across the entire Qatar peninsula. Presently, these karst features seem mostly inactive and thus inherited from a geoclimatic context, which was more favorable to karstification. Under the present geoclimatic conditions, the karst subsidence geohazard appears to be generally low, as caves are inherited, and ongoing karstification processes are limited. However, this geohazard is present across large spans of the territory and any future land development shall include plans and strategies to consider the presence of karstified rocks in the subsurface and ensure that karst is not reactivated by human activity.

A 700 m long pseudokarst cave in calcareous sandstone in the interior of a dolomitic karst cave (Dachstein, Eastern Alps)

Lukas Plan, Robert Seebacher, Veronika Koukal, Susanne Gier — Mon, 17 Aug 2026 00:00:00 +0200

The Südwandhöhle, located in the Dachstein karst massif, is a 12 km long cave system. It is primarily formed in dolomite (Middle Triassic Wetterstein Formation), a rare occurrence in the Northern Calcareous Alps. The cave is 509 m deep and notable for its rock overburden of 1.5 km, and its huge passage cross-sections of up to 250 m². In the remote parts, there is a 0.7 km-long tube that is almost entirely formed in lithified clastic cave sediments. The setting suggests that this relatively small tube (cross-sections: 0.5 to 2 m²) developed as a continuation of a large palaeo-phreatic gallery. The walls and ceilings of the tube are made up of well-lithified sandstone, which often shows erosional features. The sandstone components consist of calcite, partly dedolomite, as well as some quartz, small amounts of dolomite, and iron hydroxide. The cement is calcite, giving a total calcite content of 40–70% in the analysed thin sections. Unusually, the tube does not run along the ceiling of the corridor, as is common in many caves, but winds its way through the large, sediment-filled corridor. As there are no structures in the calcareous sandstone or active tectonics that could have acted as initial fissures, the formation of the proto-conduit is difficult to explain. One possible explanation is that the sand was cemented by pore water from the surrounding dolomite host rock, with parts inside being less lithified or not consolidated at all. Water migrating through this porous sand could have dissolved carbonate grains, and subsequent mechanical erosion and eventually piping could have created a tube. Due to the carbonate content, dissolution probably played only a limited role. Therefore, we interpret this tube as a pseudo-karst cave, that was formed primarily through mechanical erosion of sandstone that had deposited within a karst cave.

Timing of uplift at the Periadriatic Line evidenced by cave sediments

Andrej Mihevc, Philipp Haeuselmann, Markus Fiebig — Mon, 17 Aug 2026 00:00:00 +0200

Subhorizontal epiphreatic caves are good morphological markers of valley deepening or uplift processes, since they reflect the position of the spring, which is related to the valley bottom. In Northeast Slovenia, transpressional activity along the Periadriatic Fault System caused dextral strike-slip as well as possible uplift of the areas adjacent to the fault. The presence of four cave levels near the Periadriatic Fault System documents uplift processes; and, the datings presented here of two levels indicate a Plio-Pleistocene incision history. These dates are in accordance with cave and sediment datings in other parts of NE Slovenia, and they are in line with more recent activity of the conjugated Salzach-Enns-Mariazell-Puchberg (SEMP) Fault in the Northern Calcareous Alps. The major fault systems, therefore, seem to be active not only in the Miocene (as postulated elsewhere), but up to the recent Quaternary.

Seasonal control of cave microclimate by surface conditions: evidence from a density-driven exchange flow in Samograd Cave (Croatia)

Mon, 17 Aug 2026 00:00:00 +0200

This study investigates the seasonal microclimate dynamics of Samograd Cave (Croatia), a vadose karstic cave characterized by a single large entrance, a concave longitudinal profile, and active atmospheric coupling with the surface. Continuous air-temperature monitoring using data loggers was conducted along a surface-entrance-interior transect at five fixed locations over the period December 2022 – February 2024, covering two winters and one warm season. To independently assess ventilation efficiency and confirm microclimatic bimodality, air CO₂ concentrations were measured using a combination of spot monthly measurements along the cave and high-resolution continuous monitoring at the lowest point of the cave. The primary aim of the study was to evaluate how temperature differences between the surface and the cave controls seasonal air circulation and to determine whether air circulation in the cave is governed by temperature- and density-driven exchange flow. Results show that Samograd Cave exhibits a distinctly bimodal microclimate. During the cold season, negative surface-cave temperature differences promote the inflow of cold, dense air, activating an exchange flow that ventilates the cave interior and leads to an evident decrease in CO2 concentrations. In contrast, during the warm season, such circulation is switched off, resulting in thermal stratification, microclimatic stability, and elevated CO2 levels, with the cave acting as an efficient cold-air trap. Statistical analysis of air-temperature variability, surface-cave correlations, and CO2-temperature relationships demonstrates that the magnitude and persistence of seasonal thermal gradients, rather than the frequency of cold events alone, govern ventilation intensity. The combined temperature and CO2 evidence provides robust confirmation of the seasonal coupling between surface conditions and cave microclimate and supports the interpretation of Samograd Cave as a bimodal microclimate system.

Testing the applicability of a non-contact IR thermometer for wall surface temperature measurements in a cave environment: A case study from the dynamic Císařská Cave (Moravian Karst)

Marek Lang, Jiří Faimon, Markéta Gregorová, Jindřich Štelcl, Filip Chalupka — Mon, 17 Aug 2026 00:00:00 +0200

The surface temperature of cave walls is important, particularly as a factor controlling water condensation and calcite corrosion, as well as in paleoclimatic reconstructions of external annual temperatures. The use of a non-contact IR thermometer (NCT) could provide an alternative method for monitoring wall surface temperature in inaccessible passages of the cave. However, temperatures obtained by the standard NCT showed increased error. The accuracy of the NCT was tested by comparison with a calibrated contact thermometer (CCT), which revealed a systematic error of –8.2 ± 1.2 °C for the right wall and –8.3 ± 0.9 °C for the left wall. Calibration with the equations T = 0.478×NCT + 8.254 (right wall) and T = 0.554×NCT + 8.308 (left wall) corrected this error. Uncertainty was tested by repeated measurements on a calibration area of 1.7 m2 in the cave, resulting in a random relative error of 4.25 % for dry wall surfaces and 4.95 % for wet wall surfaces. Although a relative error of 5 % is common for major instrumental methods, it is near the applicability limit for karstological interpretations.

Calcium-Enriched Irrigation Drives Plant-Mediated Carbon Sequestration Dynamics in Karst Soils

Hui Yang, Yang Ma, Mitja Prelovšek, Jianhua Cao, Tongbin Zhu — Mon, 17 Aug 2026 00:00:00 +0200

Mineral-organic complexes are key regulators of soil organic carbon (SOC) sequestration in agricultural ecosystems. As a dominant soil mineral, calcium (Ca) plays a particularly important role in SOC stabilization. Although numerous studies have indicated that Ca can enhance SOC storage, particularly in the karst regions of Southwest China, the specific mechanisms underlying Ca-SOC interactions and their associated biological processes remain poorly understood. In this study, we used a controlled pot experiment with maize (Zea mays L.) irrigated for 112 days with allogenic waters containing different Ca²⁺ concentrations (2, 54, and 108 mg L^-1). Soil respiration, in situ soil CO₂ concentrations, and leachate carbon fractions were monitored at 7-day intervals, and leachate carbon fractions including total organic carbon (TOC), dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC). The results showed that: (1) soil respiration rates and CO₂ concentrations were progressively higher in maize rhizosphere soils than in unvegetated controls and displayed pronounced temporal dynamics; (2) TOC, DOC, and DIC concentrations in leachates were significantly elevated in vegetated systems compared with bare soils, indicating enhanced carbon mobilization and transformation driven by plant activity; (3) DIC sources differed between treatments, with carbonate-derived carbon being the predominant contributor to DIC in maize-cultivated soils, while soil/atmospheric CO₂ was the main source in bare soils. These findings highlight that Ca-rich irrigation, in combination with plant and microbial activity, can substantially modify C fluxes and carbonate weathering pathways in calcareous soils, providing mechanistic insights into biologically mediated carbon sequestration processes in Southwest China’s karst agroecosystems.

Kef El Ghar cave (Taza, Morocco): Geological, hydrological, ecological and cultural significance of a karst geosite

Mon, 17 Aug 2026 00:00:00 +0200

Kef El Ghar cave, located in the Taza region of northeastern Morocco, is a remarkable karst feature of significant natural and cultural value. This study aims to characterize the cave’s geodiversity and assess its significance as a karst geosite. Field investigations and descriptive analyses reveal well-developed karst morphologies, stratigraphic exposures, active hydrological systems, and diverse speleothems, highlighting the cave’s natural significance. In addition, evidence of historical human use, archaeological traces, and aesthetic features emphasize its cultural importance. Despite these attributes, the site faces increasing threats from uncontrolled access, lack of formal protection, and anthropogenic degradation. Based on these findings, this study proposes conservation and management strategies to preserve the cave’s integrity and promote its integration into regional geotourism and public education initiatives. Kef El Ghar cave thus represents a valuable component of the karst heritage of the Taza region and supports initiatives aimed at the establishment of a regional geopark.

360° virtual tours of caves: An innovative tool for cave cadastre and public accessibility

Mon, 17 Aug 2026 00:00:00 +0200

Recent technological advances have opened up new possibilities for collecting, analysing and sharing information about speleological sites. This study explores the integration of 360° spherical imagery and Virtual Tours (VTs) to document five hard-to-access natural caves in the classic karst region. These immersive VTs experiences were embedded in the official speleological cadastre of the Friuli-Venezia Giulia Region, Italy (https://catastogrotte.regione.fvg.it/).
The Autonomous Region of Friuli Venezia Giulia has officially integrated underground VTs into its institutional cave registry. This innovation not only improves the functionality of the cadastre but also sets a precedent for how immersive technologies can be effectively utilized within public geological and environmental databases.
We analyse the benefits of integrating 360° VTs into a regional cave cadastre from the perspective of scientific documentation, promotion of speleological heritage, knowledge dissemination and public engagement. We also address the technical challenges that have been encountered during acquisition and post-processing and provide guidelines and future perspectives for the application of these technologies in cave research and digital documentation.

Initial steps of insect fossilisation in cave flowstone

Tone Novak, Peter Kozel, Luka Gale, Ljuba Slana Novak, Katja Adam — Mon, 17 Aug 2026 00:00:00 +0200

In a small, abandoned coal mine in northeastern Slovenia, there is an area with intensive flowstone deposition. We found about two hundred carcasses of the mosquito Culex pipiens s. l., as well as a few remains of a winter crane fly Trichocera sp., a rove beetle Atheta cf. spelaea, and a false diamondback moth Digitivalva pulicariae on the wall, partly or entirely embedded in the flowstone. We describe the initial taphonomic steps in these carcasses and discuss the probable reasons why the insect remains disintegrate completely, interrupting the process of fossilisation.