Karst Formation Research Articles

Investigation of the geological and hydrogeological structure of chalk cliffs with visible, thermal infrared and electrical resistivity imaging

Investigation of the geological and hydrogeological structure of chalk cliffs with visible, thermal infrared and electrical resistivity imaging

Cooling of hydrothermal fluids rich in carbon dioxide can create large karst cave systems in carbonate rocks

Karst systems, comprising interconnected voids and caves, are ubiquitous in carbonate formations and play a pivotal role in the global water supply. Accumulating evidence suggests that a significant portion of the global karst is hypogenic, formed via rock dissolution by groundwater ascending from depth (rather than by infiltration from the surface), yet the exact formation mechanism remains unclear. Here we show that cooling of carbon dioxide-rich geothermal fluids, which turns them into highly corrosive agents due to their retrograde solubility, can dissolve and sculpt large caves on short geological timescales. A conceptual hydro-thermo-geochemical scenario is numerically simulated, showing cave formation by rising hot water discharging into a confined layer. Our models predict field observations characteristic of hypogenic caves, including enigmatic locations of the largest passages and intricate maze-like networks. Finally, we suggest that deep-seated carbon dioxide consumption during karst formation may constitute a link to the global carbon cycle.

Residual carbonate karst reservoir reconstructed by karst planation: A case study of Ordovician paleokarst reservoir characterization in Ordos Basin, North China

Residual carbonate karst reservoir reconstructed by karst planation: A case study of Ordovician paleokarst reservoir characterization in Ordos Basin, North China

Detection for severe caves and sinkholes in non-clastic rock type using GPR technique

ABSTRACT This study examines the application of Ground Penetrating Radar (GPR) to the detection of severe caverns and sinkholes in non-clastic rock formations. Due to the presence of vertically sloping bedrock, cavities, and sinkholes, geotechnical engineers face significant challenges when designing and constructing foundations in karstic formations such as limestone. The territory under investigation is located close to the Giza limestone plateau, the northern side of which has experienced severe stability issues. The ground-penetrating radar (GPR) method was used to identify the presence and extent of exposed caves and caverns in the studied region. The research area’s geological and geomorphological background is explored, including the creation of primary and secondary caves, as well as solution caves generated by the breakdown of soluble rocks like limestone. Data collecting, processing, and interpretation procedures used in the GPR survey are described. GPR survey findings revealed the existence of a severe cave and many minor sinkholes in the studied region. GPR has shown to be a useful and efficient tool for determining geometric karst features in the subsurface, helping to a better evaluation of the dangers associated with this geological environment.

The identification of the development stages of the karstic fracture–cavity carbonate reservoirs: a case study on the lungu oilfield, Tarim basin

The challenge of identifying connectivity within karstic fracture-cavity reservoirs significantly impedes the efficient development of oil and gas resources, primarily due to our limited understanding of the developmental stages and distribution of these unique reservoirs. In this study, we employ a layered interpretation method to predict the distribution of various developmental stages within karstic reservoirs. In our approach, we first leverage our knowledge that karstic formations are primarily shaped by the water table. We reconstruct paleomorphological data and select representative wells in a chronological order from old to new. This process enables us to determine the karst base level and divide the karstic layers in individual wells. Subsequently, we identify small-scale karstic reservoirs and proceed to select isochronous sedimentary interfaces. We then flatten seismic events and map the karstic layers from wells to their corresponding seismic sections, a technique known as well-to-seismic calibration. Lastly, we provide accurate interpretations of the karstic layers, extracting root-mean-square amplitudes to predict the distribution of each reservoir. To validate the accuracy and efficiency of our method, we applied it to fracture-cavity reservoirs in the Lungu oilfield (LGX) of the Tarim Basin. Our results demonstrate the successful identification of 22 fracture-cavity reservoirs through an analysis of the distribution and connectivity of karstic reservoirs. This outcome serves as evidence that our method can significantly enhance reservoir production in terms of both efficiency and accuracy.

The Analyses of Land Use and Prevention in High-Density Main Urban Areas under the Constraint of Karst Ground Subsidence: Study of Wuhan City, China

The development and utilization of land in the main urban area have significantly impacted the stability of the regional geological environment through various means, such as increased load and subway construction, primarily manifested as rock and soil mass deformation leading to geological hazards. Therefore, it is worth exploring how to reduce the occurrence of karst ground subsidence (KGS) through reasonable land development and control measures in the main urban areas with large-scale developments of buried karst formations. This study focuses on the main urban area of Wuhan City. An evaluation model for KGS was constructed using the analytic hierarchy process (AHP) and comprehensive index evaluation method by analyzing the geological conditions that affect KGS. The susceptibility zoning of KGS was obtained with GIS spatial analysis technology. The results show that the susceptible areas can be divided into extreme, high, medium, and weak susceptibility, accounting for 4.93%, 15.30%, 33.21%, and 46.56%, respectively, which are consistent with the distribution density of past KSGs. Furthermore, by selecting the subway construction as a human activity type, it indirectly discusses the influence of land development intensity on KGS. The results show that past KSGs are mainly concentrated in areas with high engineering construction density and significant land development intensity. Based on the above, strategies for regional land development and prevention and control of KGSs are proposed.

REPRESENTING INTANGIBLE CULTURAL HERITAGE OF HUMANITY: FROM THE DEEP ABYSS OF THE PAST TO DIGITAL TWIN AND XR OF THE NEANDERTHAL MAN AND LAMALUNGA CAVE (ALTAMURA, APULIA)

Abstract. The Altamura Man and the paleontological remains are situated within a complex context encompassing logistical, geological, paleoenvironmental, and cultural perspectives. This context is exceptionally well-preserved but also fragile, requiring its preservation due to its unique nature. Unresolved inquiries exist in various disciplines, such as archaeology, biocultural studies, ecology, and geology, pertaining to karst formation, taphonomic dynamics, and the cultural and ecological context of the Neanderthal individual found in the cave. Interdisciplinary research was necessary to address these complex questions and understand the broader context of the Lamalunga Cave. Climate change also necessitated attention to preserving the cave’s microclimate and monitoring potential biodegradation. Digital technologies, including photogrammetry and laser scanning, were crucial for monitoring and safeguarding the cave’s cultural heritage. Digital representation, 3D modelling and Digital Twin were essential for managing the cave’s intricacies, analysing its values, and enhancing visual communication. The management of the Lamalunga cave aimed to promote scientific interpretation, safeguard the cave, and provide tools for understanding, storytelling, and further investigation. It was essential to utilise available methodologies and technologies while avoiding destructive interventions. Contemporary technologies have revolutionised the archaeological and paleoanthropological domains, enabling remote study and preservation. Protecting and comprehending the cultural heritage of the cave is linked to its usability, which can be enhanced through digital documentation methodologies to inform visitors about the karst context and promote social and economic development.

Use of Microbiological and Chemical Data to Evaluate the Effects of Tourism on Water Quality in Karstic Cenotes in Yucatan, Mexico

Cenotes are spectacular karst formations in Yucatan, Mexico, often used for recreation. However, their impact on water quality has yet to be explored in detail. Therefore, during Easter, water samples were collected from four cenotes to identify variations in water quality associated with the presence of tourists. PCO of water quality, before (PH) and during Holy Week (HW) in 2019, explained 49.02% of the total variation. The indicators contributing to the first principal coordinate’s variation were Sr, K, sulfate, and chloride (0.89). Whereas, alkalinity, temperature, conductivity, nitrate, and ORP contributed to the second PC. PERMANOVA indicated a significant interaction between “cenote” and “condition” factors, and post hoc paired comparisons indicated significant differences between PH and HW conditions. Significant correlations varied among the four cenotes as the result of hydrogeological differences. Whereas, numbers of visitors were correlated with at least one fecal-matter indicator, demonstrating anthropogenic influence on the cenotes’ water quality.

A new species of Hemiphyllodactylus (Squamata, Gekkonidae) from Ha Giang Province, Vietnam.

An integrative analysis recovered a new species of the Hemiphyllodactylustypus group from a karst formation in Lung Cu Commune, Dong Van District, Ha Giang Province, northeastern Vietnam. Hemiphyllodactyluslungcuensissp. nov. is embedded within clade 6 of the typus group, bearing an uncorrected pairwise sequence divergence of 4.6-20.2% from all other species based on a 1,038 base pair segment of the mitochondrial NADH dehydrogenase subunit 2 gene (ND2). It is diagnosable from other species in clade 6 by statistically significant mean differences in normalized morphometric, meristic, and categorical characters. A multiple factor analysis using the three aforementioned character types recovered its unique, non-overlapping placement in morphospace as statistically significantly different from that of all other species in clade 6. The description of this new Hemiphyllodactylus species contributes to a growing body of literature underscoring the high degree of herpetological diversity and endemism in karst landscapes in Vietnam as well as in the genus Hemiphyllodactylus.

Study of karst manifestations in Solotvyno based on aerial photography from a UAV

Abstract This article is devoted to the study of surface karst manifestations on the territory of inactive salt mines of Solotvyno, Transcarpathian region, Ukraine. The historical development of the salt mine from the moment of the creation of the first mine (the end of the 18th century) to the present is considered. Based on the results of previously published studies, monitoring of karst manifestations from 2010 to 2020 was implemented. The last stage of monitoring in 2021 was the aerial survey of the territory obtained by the Arrow UAV using the Sony QX1 camera. Pix4Dmapper software was used for image processing. The aim of the work is to estimate the scale of destructive geological processes by the method of photogrammetry. During the execution of the work, the methods of processing materials of aerial photography, analysis of developments in the direction of photogrammetry were applied. As a result of the study, the volume-planar characteristics of karst formations on the territory of Solotvyno were calculated using the photogrammetry method. This scientific work is relevant for assessing the scale of the development of degenerative geological processes on the territory of Ukraine, in particular within the Transcarpathian region. The practical significance of the obtained results lies in their application in order to ensure environmental monitoring. The results of the study can be used to predict the impact on economic and infrastructure objects, followed by the development of a plan of specific actions for prevention, localization and work with the consequences of man-made processes in the adjacent territory.

Accelerated optimization of CO2-miscible water-alternating-gas injection in carbonate reservoirs using production data-based parameterization

Enhancing oil recovery in reservoirs with light oil and high gas content relies on optimizing the miscible water alternating gas (WAG) injection profile. However, this can be costly and time-consuming due to computationally demanding compositional simulation models and numerous other well control variables. This study introduces WAGeq, a novel approach that expedites the convergence of the optimization algorithm for miscible water alternating gas (WAG) injection in carbonate reservoirs. The WAGeq leverages production data to create flexible solutions that maximize the net present value (NPV) of the field, while providing practical implementation of individual WAG profiles for each injector. The WAGeq utilizes an injection priority index to rank the wells and determine which should inject water or gas at each time interval. The index is built using a parametric equation that considers factors such as producer and injector relationship, water cut (WCUT), gas–oil ratio (GOR), and wells cumulative gas production, to induce desirable effects on production and WAG profile. To evaluate WAGeq’s effectiveness, two other approaches were compared: a benchmark solution named WAGbm, in which the injected fluid is optimized for each well over time, and a traditional baseline strategy with fixed 6-month WAG cycles. The procedures were applied to a synthetic simulation case (SEC1_2022) with characteristics of a Brazilian pre-salt carbonate field with karstic formations and high CO2 content. The WAGeq outperformed the baseline procedure, improving the NPV by 6.7% or 511 USD million. Moreover, WAGeq required fewer simulations (less than 350) than WAGbm (up to 2000), while delivering a slightly higher NPV. The terms of the equation were also found to be essential for producing a WAG profile with regular patterns on each injector, resulting in a more practical solution. In conclusion, WAGeq significantly reduces computational requirements while creating consistent patterns across injectors, which are crucial factors to consider when planning a practical WAG strategy.

Prediction of Permian karst reservoirs in the Yuanba gas field, northern Sichuan Basin, China

Karst reservoir has great hydrocarbon potential, however karst reservoir prediction is inhibited by the strong lateral and vertical heterogeneity of karstification which in turn results in recognition difficulty when geological and geophysical methods are used in isolation. Combined geological and geophysical methods, including core observation, thin section analysis, well log interpretation, seismic attributes and seismic inversion are applied to understand the depositional environment, types of karstification, the geophysical response and distribution of karst reservoir and the controls over and evolution model of karst reservoir in Permian Yuanba gas field, northern Sichuan Basin. The results show that there are four types of major seismic facies recognized in the study area, which correspond to platform margin reef, carbonate platform, platform margin inter-bay and platform margin slope. Karstification can be divided into 3 zones: the supergene karst zone, the vertical seepage zone and the horizontal underflow zone, among which the supergene karst zone have the strongest karstification. Karstification is highlighted with low seismic impedance, low Poisson's ratio, and high seismic attenuation on seismic inversion as well as micro scale paleo geomorphology recognized by trend surface analysis. By comparing the distribution of karstification with paleo geomorphology, fault distribution and gas contents, it can be observed that the karstification have a good matching relationship with these factors. The dominant type of karstification is epigenic karst, which is strongly influenced by depositional facies and paleo geomorphology. Fracture networks have contributed to karstification but are not the dominant factor of karst formation. The integration of geological and geophysical methods can predict karst reservoir with high accuracy within large area and can be applied to karst reservoir hydrocarbon exploration of similar geological setting.

Connectivity and integration analysis of karst tourism objects in Wonogiri with Space Syntax Method

Gunung Sewu in Wonogiri Regency has been recognized by UNESCO with its designation as a Global Geopark Natural Heritage. The recognition is based on its karst formation which considered to have universal value therefore needs to be protected. The recognition is a significant capital for tourism development. However, this global geopark is still underdeveloped in Wonogiri area. To plan tourism development in Wonogiri area which has been marginalized in decades in tourism development, we use space syntax tool. This tool which is developed in University College London has a strength in analyzing spatial configuration that can help predict human spatial behavior. The results show that the distribution of Karst formations in Gunung Sewu, Wonogiri Regency has variations in the value of the level of connectivity and integration that can be used as priority considerations in its development.

FORMULATING STRATEGIES BASED ON LOCAL COMMUNITY’S PERCEPTIONS FOR CAVE AND BAT ECOTOURISM DEVELOPMENT: A CASE STUDY OF TOGENRA CAVE IN BARRU, SOUTH SULAWESI

Togenra cave in Madello Village, Barru Regency (South Sulawesi) is located in the Tonasa Karst Formation, known as one of the largest formations in Asia and is also popular for its unique features and functions. Currently, the local government has not yet established a regulation on the management of the cave, and locals are free to access the cave for calcium and guano mining which can threaten the ecosystem of the cave. Therefore, it is necessary to develop non-consumptive use of the cave, through ecotourism that can provide long-term benefits to the local communities. This study aimed to examine the community’s perceptions toward the cave, bats and conservation; formulate strategies by assessing the potency of the cave and bat species as an ecotourism spot based on the local’s perceptions; and provide recommendations for the local government in supporting both ecotourism and conservation in the area. The study was conducted from August 2020 to February 2021. A set of questionnaires were to 31 respondents living within a radius of 1 km from Togenra cave. Formulation of strategies were done by using combined analyses of Strength, Weakness, Opportunity, Threats and Analysis of Hierarchy Process. Our analyses indicate a growth strategy trend. Several strategies drawn emphasize on improving local’s knowledge and perceptions, active involvement of locals, establishment of local management initiatives and regulations, capacity enhancement, and implementation of a stakeholders’ forum. These findings can become a baseline in planning and developing both bat-cave tourism as well as conservation efforts in the area.

Investigation of buried karst sinkholes under a bog using ground penetrating radar (GPR) and electrical resistivity tomography (ERT)

AbstractActive evaporite karst processes in the Baltic states are associated with a few relatively small regions where gypsum rocks can be found close to the Earth's surface. One of these areas lies in the vicinity of the Pandu bog. However, such a possibly active karst region, which is covered by peat and in which the mapping of karst formations is complex, has not been previously investigated. In this study, we present a buried and peat‐filled karst cover‐collapse sinkhole mapping approach that involves a combination of ground‐penetrating radar (GPR), electrical resistivity tomography (ERT) and conventional boreholes. A detailed map of the bog's substratum topography was constructed from a geophysical surveying dataset. It reveals 15 distinctly expressed sinkholes with diameters of several tens of metres. Overall, 140 potential sinkholes were also mapped using remote sensing data in the vicinity of the bog. Higher electrical resistivity anomalies were identified inside the peat; they coincide with scatter‐free zones in GPR data and water layers in boreholes. Highly disturbed internal peat layering was also detected in these sinkholes. It is suggested that these water layers and disturbed peat layering may have formed due to the subsidence of the lower peat layers, and thus they represent relatively younger sinkholes. This is also supported by evidence from orthophoto maps, which showed the formation and disappearance of surficial lakes and depressions on the bog surface. Our results revealed the presence of active and widespread karst processes under the bog that have not been previously noticed despite the fact that they have implications for the assessment of geohazards in this area.

Geological Field Guide of Montes Claros Karst, Minas Gerais

The Montes Claros Karst is located on the eastern margin of the Bambuí Basin, one of the covers of the São Francisco Craton affected by the Brasiliano Event, which deformed the limestones of the Lagoa do Jacaré Formation, creating a westward folding system and a pair of fractures F1 (NNE-SSW) and F2 (WNW-ESE). These structures control the circulation of water in the limestone massifs, leading to the development of the Montes Claros karst. The main features of the karst landscape are caves, valleys, dolines and limestone massifs. The caves are the best place to observe the main sedimentary facies of the limestones of the Lagoa do Jacaré Formation, as well as sedimentary and deformational structures. The main controls of the cave conduits are the F1 and F2 fractures. These are the same directions described on a regional and local scale, which shows us that the structural control of the exocarst is the same as that of the endocarst. This geological field guide shows in a didactic way the main facies and sedimentary structures of the limestone of the Lagoa do Jacaré Formation, the deformational structures that favoured the karst formation and the typical karst morphologies in limestone rocks.

Detailed Geoseismic Structure of the Riphean Deposits in Buolkalakh–Lena Area Based on Deep Drilling and Seismic Exploration Data

Abstract —The work considered an integrated approach to the study of deep-lying Riphean strata of the Buolkalakh–Lena region, which have certain prospects in terms of oil and gas potential. The method of revision and synthesis of acoustic and density logs is described in detail using the example of wells drilled in 80–90 for the purpose of correct reference to seismic sections. It has been shown that the Khaipakh, Debengdin, Arymas, Kyutingdinsky, and Sygynakhtakh formations of the Early and Middle Riphean eras overlook the pre-Permian surface in the middle part of the Lena–Anabar trough. The region also developed older Riphean deposits that are not exposed on the Olenek uplift and are not studied by deep drilling. The prospects for the oil and gas content of Riphean strata in the region are mainly associated with carbonate reservoirs formed in the top of the Riphean sequence and cropping out on the pre-Permian erosive surface, the most promising rocks are those constituting large carbonate platforms that were partially eroded and subjected to processes of hypergenesis and karst formation.

First insights into an exceptionally deep blue hole in the Western Caribbean: The Taam ja’ Blue Hole

Coastal karst formations may remain unexplored by the global marine scientific research community. Knowledge provided by fishermen coupled with scientific research on karstic formations prompted us to explore the geomorphometric and physicochemical features of a submerged blue hole in the large tropical estuary of Chetumal Bay in the southeastern coast of the Yucatán Peninsula, Mexico. Differently from the well-known literature on cenotes in the Yucatán Peninsula, no references are made to blue holes in the region. Sampling and surveying of the blue hole were conducted in September 2021 by scuba, echosounders, CTD profilers, and the collection of water samples. This study revealed a previously unknown maximum water depth for the Taam ja’ Blue Hole, as it is now named, of 274.4 meters below sea level (mbsl), making it the second deepest known blue hole in the world. The Taam ja’ Blue Hole has a nearly circular shape at its surface, encompassing an area of ~13,690 m2. The sides of the blue hole are steep, with slopes >80° that form a large conic structure covered by biofilms, sediments, limestone, and gypsum ledges. The blue hole mouth locates at ~4.5-5.0 mbsl, at which water properties change significantly with temperature and salinity gradients of 4.9°C/m and 9.8 PSU/m, respectively. Hydrographic profiles show a stratified water column inside the blue hole consisting of a hypoxic layer (5-20 mbsl), a chemocline (50-80 mbsl), and an anoxic layer (>110 mbsl). Evaluation of anions and cations indicated that the water inside corresponds mainly to that of diluted seawater.

Geoelectrical and hydro-chemical monitoring of karst formation at the laboratory scale

Abstract. Ensuring sustainable strategies to manage water resources in karst reservoirs requires a better understanding of the mechanisms responsible for conduits formation in the rock mass and the development of detection methods for these hydrological and geochemical processes. In this study, we monitored the electrical conductivity of two limestone core samples during controlled dissolution experiments. We interpret the results with a physics-based model describing the porous medium as effective structural parameters that are tortuosity and constrictivity. We obtain that constrictivity is more affected by calcite dissolution compared to tortuosity. Based on our experimental results and data sets from the literature, we show that the characteristic Johnson length is a valuable structural witness of calcite dissolution impact linking electrical and hydrological properties.

Revision of the Genus Lacunipotamon Dai, Song, He, Cao, Xu & Zhong, 1975 (Crustacea: Decapoda: Brachyura: Potamidae), with Descriptions of Eight New Species from Vietnam.

The taxonomy of the potamid genus Lacunipotamon Dai, Song, He, Cao, Xu & Zhong, 1975, is revised. Three species are known from southern China: L. albusorbitum Dai, Song, He, Cao, Xu & Zhong, 1975 (type species); L. yuanshi Huang, Shih & Ahyong, 2020; and L. cymatile Huang, Shih & Ahyong, 2020. Eight new species are here described from northern Vietnam: L. globus, L. panda, L. contrastum, L. sublividum, L. mimicum, L. thuanchau, L. pectum and L. purpureum. This is the first record of the genus in Vietnam, with all the new species obtained from karst formations. The species are differentiated by the characters of carapace shape, anterolateral armature, posterior margin of the epistome, male sternopleonal cavity, chelipeds, ambulatory legs, male thoracic sternum, male pleon, and structures of the male first gonopods and vulvae.