Fissure Water Research Articles

Use of nutrient medium technique for vegetation restoration in Karst region of Southwest China

Karst rocky desertification (KRD) is a global environmental degradation problem caused by human activities and vegetation deterioration. Vegetation restoration in KRD is very difficult due to severe water loss, soil erosion and extensive bare bedrock. For achieving vegetation restoration on bare bedrock areas of KRD, the nutrient medium technique was developed, which is based on the special hydro-geological conditions that is seasonal rainfall is abundant in Karst region of Southwest China and limestone fissures are extremely developed and rich in fissure water. The objective of this research is to investigate the feasibility of using nutrient medium technique to achieve vegetation restoration in KRD region. Through the indoor and field experiments, some properties of the nutrient medium mixture were tested, including water retention, water absorption and nutrient retention. The results showed that the moisture content on the 75th day and water absorption rate of No.2 mixture was 19.9% and 1.67 mm/d, respectively, which could be used as optimum mix ratio for producing nutrient medium. The field results showed that the nutrient medium technique could effectively guarantee the survival of sapling at early age and sustainable growth at later age in the field, and the nutrient medium had less nutrient loss. This novel approach can retain and absorb moisture, and saplings do not need artificially supply water and fertiliser in the dry season, and the use of nutrient medium technique to achieve vegetation restoration in KRD region seems to be a feasible option.

Research on Seepage Properties and Pore Structure of the Roof and Floor Strata in Confined Water‐Rich Coal Seams: Taking the Xiaojihan Coal Mine as an Example

During the construction and exploitation process in the Xiaojihan coal mine, which is located in Yulin of northern Shaanxi, we find a special hydrogeological phenomenon that coal seam is acted as a confined fractured aquifer. The water‐rich coal seam has natural fissures which are confined with water storage. However, the water comes from the static and original reserves in coal seams, which have a weak link to other aquifers in the roof and floor strata. It indicates that the roof and floor strata provide a natural waterproof barrier for the fissure water in the coal seam, resulting in a relatively closed storage space of confined water. In order to further investigate the critical function that mechanical properties of permeability play in the confined fractured aquifer, the rock complete stress‐strain permeability test and pore development structure test are carried out with rock samples of the roof and floor strata in this field. Results are as follows: (1) coal seams of Xiaojihan coal mine are confined fractured aquifers, the fissure confined water in coal seams has a strong relationship with total stress‐strain permeability and development characteristics of the pore structure of the roof and floor strata. (2) The permeability of the roof and floor strata is extremely low, when the strata is less than 30 meters away from the coal seam with the magnitude order remaining less than 10−12 m/s. If they are closer to the coal seam, the watertightness and plasticity of the strata will be stronger, and the antidestructive capability of the strata during the distortion process will be also increased, resulting in the larger strain for the formation of macroscopic water‐conducting fissures. The roof and floor strata effectively cut off the hydraulic connection between the fissure water in the coal seam and other aquifers, which ensure the coal seam acts as water storage space of confined fractured aquifers. (3) For undeveloped fissures, the effective porosity is less than 2% of the roof and floor strata which are less than 30 meters away from the coal seam, and particularly, this index is less than 1% of the strata within 20 meters away from the coal seam, indicating that the strata have good water resistance. When the distance between the roof strata and the coal seam is greater than 40 meters, the effective porosity has a large fluctuation, and the effective porosity of the partial strata is greater than 10%, reflecting that the rock strata fissure has been well developed. It should be attached great importance to prevent water‐conducting fissures from getting hydraulic connection with the fractured water‐rich coal seams and other aquifers of the roof and floor, so as to reduce the risk of mining water hazards.

Determination of trace elements and lanthanide (REE) signatures in uranium mine products in South Africa by means of inductively coupled plasma mass spectrometry

The lanthanides are Rare Earth Elements (REE) that exhibit consistent patterns under varying geochemical conditions. Therefore they can be used as signatures to determine the chemical and physical change that has occurred on a uranium ore since it was mined and processed. The objective of this work was to determine the trace elements and REE (Lanthanides patterns) in uranium ore samples using a quadrupole inductively coupled plasma mass spectrometer. The REE fingerprint results presented here suggests that uranium is embedded in uraninite, phosphorite deposit in Apatite & fluorapatite minerals. The uranium is recovered from phosphoric acid, while lime used for precipitation of impurities and magnesia is used for precipitation of uranium. The REE patterns normalized to the mean of CI-Chondrites from this study, show LREE uniformity and HREE fractionation with strong positive Tb anomaly. The ΣLREE/ΣHREE, and La/Sc ratios are relatively constant in these samples. The average composition based on this study are(in μgg−1): Sc=0.000171±0.000029, Y=0.00256±0.000046, La=0.00736±0.00206, Ce=0.00648±0.00213, Pr=0.00714±0.0058, Nd=0.00462±0.00163, Sm=0.0493±0.00328, Eu=ND, Gd=0.0125±0.00643, Tb=30±13, Dy=0.0165±0.00747, Ho=ND, Er=0.00515±0.00265, Tm=ND, Yb=ND and Lu=ND. The REE pattern in the fissure water from underground typically shows enrichment in light REE (LREE), depletion in heavy REE (HREE). ND=not detected.Average values for the trace elements were: Al (567.11), Cr (4.42), Cu (0.47), Fe (1781.69) and Zn (0.46) mg/L. Based on this elemental concentration, Al, Cr, Cu and Zn are at trace level specifically for this site. This family of elements is indicative of a carry through from a precursor ore. V (0.25), Ti (1.13) and Fe represent a type of in-situ leach solution. The uranium concentrations in the Carletonville gold fields suggests strongly that gold and uranium, in detrital pyrites and uraninite, were hydrothermally recycled (uranium may have been recycled by hydrocarbon fluids) from the Witwatersrand Reefs. Also the U concentrations in the water samples is much higher than that in the tailing (except for tailing 4 which is 100years old), and is a signature for uranium processing. Also the results show a Tb-U correlation signature distinguishing between raw mineral ore and tailing (processed) uranium samples. The U concentrations are between 1.40 and 6.24ppm while that of Tb is between 0.84 and 1.58ppm in the fissure water.

Environmental Geological Features of the Red Clay Surrounding Rock Deformation under the Influence of Rock-Fracture Water

The development degree of fissure water in underground rock is a great trouble to the construction of railway tunnel, which will cause a series of environmental geological problems. Take the surrounding rock-section of the typical red clay in Lvliang-Mt. railway tunnel below the underground water level as an example, several aspects about the red clay surrounding rock will be researched, including pore water pressure, volume moisture content, stress of surrounding rock, vault subsidence and horizontal convergence through the field monitoring. Taking into account the importance of railway tunnel engineering, the large shear test of red clay was carried out at the construction site specially and the reliable situ shear strength parameters of surrounding rock will be obtained. These investigations and field tests helped to do a series of work: Three dimensional finite element numerical model of railway tunnel will be established, the deformation law of the red clay surrounding rock will be investigated, respectively, for the water-stress coupling effect and without considering it, the variation of the pore water pressure during excavation, the influence degree about the displacement field and stress field of water-stress coupling on red clay-rock will be discussed and the mechanism of the surrounding rock deformation will be submitted. Finally, the paper puts forward the feasible drainage scheme of the surrounding rock and the tunnel cathode. The geological environment safety of tunnel construction is effectively protected.

Study on the Instability Mechanisms and Monitoring Control of Stratified Rock Slope with Water-Rich Strata

Water is one of the leading factors in the sliding geological disasters of rock slope, and the harm of fissure water to slope rock mass more and more becomes one of the hotspot research problems in transportation infrastructure construction in mountainous area. Based on the current research status quo of effect of fissure water on rock mass, the interaction mechanisms of water and rock in stratified rock slope were analyzed by related theories such as rock mass mechanics, fluid mechanics and soil mechanics including softening dissolution, scour hole enlargement and padding effective stress, and the influence of water–rock interaction on slope sliding disasters. Then, the influence of rainfall on the displacement field distribution of slope was analyzed during one year of monitoring a typical,natural slope in the Sichuan–Chongqing region. Observations include surface displacement, deep displacement, water level and rainfall. Finally, a targeted reinforced disposal scheme was proposed that considered the rainfall effect. The results provide reference for the instability theory and treatment measures for a high-risk stratified slope.

TDS load contribution from acid mine drainage to Hartbeespoort Dam, South Africa

Evidence of a mine-water impact on groundwater in the karst aquifer downstream of the actively draining West Rand Goldfield can be traced back to the early 1980s. This is attributed to the dewatering of ‘fissure water’ encountered during mining, and its discharge into the Bloubank Spruit catchment. Rewatering of the subsurface void following the cessation of mining in the late 1990s culminated in mine-water issuing from various point sources (shafts and boreholes) in 2002. The past 6 hydrological years have periodically produced the greatest volume and worst quality of mine-water discharge, causing widespread concern for the receiving aquatic environment. In this regard, the proximal Cradle of Humankind World Heritage Site attracts a much sharper focus than the distal, regionally important Hartbeespoort Dam. Objectivity requires that an assessment of the mine-water impact on the receiving surface water resources must recognise both the subregional and regional scales. The evaluation presented in this communication examines the temporal mine-water impact at both scales, and interprets the results in terms of the influence exerted by the natural hydrosystem in mitigating adverse impacts on the water resources environment. An analysis of the respective contributions of each of the major drainages to the quantity and quality of water impounded in Hartbeespoort Dam indicates that the median total dissolved solids (TDS) load delivered by the Bloubank Spruit system amounted to ~26 kt/a in the past 6 hydrological years. This is ~12% of the regional median total of ~224 kt/a entering the impoundment in the same period. By comparison, the preceding long-term record dating back 30 years to 1979 reflects a 66% lower median annual contribution of 8.6 kt, representing ~10% of a regional median total of ~89 kt/a. Proportionally, therefore, the recent 6-year period of high volume and poor-quality discharge from the Bloubank Spruit catchment represents only a marginally greater TDS load contribution to Hartbeespoort Dam than that which characterises the previous 30 years. Keywords : acid mine drainage, allogenic water, autogenic water, Cradle of Humankind, karst springs, karst terrane, TDS load

Permeability evolution and mesoscopic cracking behaviors of liquid nitrogen cryogenic freeze fracturing in low permeable and heterogeneous coal

Fracking to approach permeability enhancement is indispensable to enhance coalbed methane recovery, which can significantly reduce greenhouse gas emissions and produce substantial clean energy. To access efficient fracking, samples of Permian low permeable coal reservoir were cracked into different sizes or scales of blocks and particles with liquid nitrogen cryogenic freeze fracturing (FF) by maximizing the underlying heterogeneity of coal. To investigate the crack efficacy, this study systematically examined the permeability evolution and mesoscopic cracking behaviors of coal with different water contents and cleat–fracture systems in the context of cryogenic FF. Results showed that the permeability enhancement and microcracking tended to occur with increasing water content of coal sample; and the efficacy of cryogenic FF on the tighter coal sample was more remarkable. However, the permeability does not strictly increase with the cycles of cryogenic FF and has a close relationship with water content, structural plane direction, efficacy of cryogenic FF, and porosity compaction. The mesoscopic cracking behaviors indicate that numerous smaller pores are iteratively, not strictly sequentially, cracked and become connective in this process. The permeability evolution of coal sample is identified as significantly associated with the mesoscopic cracking behaviors. Notably, the first cycle of cryogenic FF acted on the detected several scales of pores and micro fissures, and partially caused these structures to be opened and interconnected to be permeable. Two main changes were observed in the microcracking of the coal samples in this study: 1) nonuniform shrinkage deformation and micro fissure expansion; and 2) pores opening mostly in the macropore and mesopore scale. It is reasoned that thermal cracking and intermittent opening of seepage pores due to the phase transition of free water in pores or micro fissures ultimately contribute to the permeability enhancement in low permeable and heterogeneous coal.

Application of comprehensive prediction method of water inrush hazards induced by unfavourable geological body in high risk karst tunnel: a case study

ABSTRACTWhile tunnelling in karst terrains, karst fissure water may endanger the safety of tunnel engineering and cause geological disasters such as water inrush. To ensure the safety of tunnel construction, in investigation stage, engineering geological and hydrogeological conditions of Jigongling Tunnel was analysed firstly. In design stage, a reasonable prediction method combining with optimization principle was selected to calculate the water inflow according to the geological and hydrogeological conditions analysed in the investigation stage. Then the advanced geological prediction was divided into different classes based on the water inflow. To make an accurate prediction, tunnel seismic prediction method, transient electromagnetic method, induced polarization method and advanced geological drilling were comprehensively applied in construction stage. This method combined with geology analysis, water inflow calculation and classification of advanced geological prediction is successfully applied in the Jigongling Tunnel of Fanba Expressway, and has provided a reference for the similar engineering constructions.

The Impact of Mine Tailings on the Witwatersrand and the Surrounding Water Bodies in Gauteng Province, South Africa

The gross alpha and beta activity in treated water from one of the numerous gold mines in Gauteng province averaged 1.15 ± 0.13 and 0.87 ± 0.11 Bq L−1, respectively. The average readings of the fissure water from the same mine were 0.56 ± 0.10 and 0.52 ± 0.11 Bq L−1, respectively. Water samples collected at the foot of the Princess gold mine tailings dump in Gauteng province and from downstream, before the drainage joins other water sources, also had high average gross alpha and beta activity and high average concentrations of radionuclides. The hazard quotient value evaluated, based on 238U of the water sample types in these vicinities, was far above one, indicating that it may pose serious health risks to the inhabitants.

Coupling Analysis of Fracture Seepage and Rock Deformation in DDA Method

Seepage in fractured rock mass is of great significance to the safety of rock engineering. On the basis of Louis’ experimental results, this paper introduces the simulation of water flow in fracture network, according to which fissure water pressure is applied to the surface of rock fissure in the form of linearly distributed load. The DDA equilibrium equation, which takes fissure water load into account, has been deduced based on the minimum potential principle. After each iteration step of DDA, the equivalent hydraulic fracture aperture is updated. By using the method abovementioned, the fluid solid coupling model of fractured rock is established in this paper. Then the model is used to analyze the stability of the Bank Slope of a hydroelectric power station. A comparison of seepage field and stress field of the bank slope is made before and after the reservoir water level uplift. Instability process of the slope is simulated as well. The results show that the fluid solid coupling model is valid.

A Novel Numerical Algorithm for Simulation of Initiation, Propagation and Coalescence of Flaws Subject to Internal Fluid Pressure and Vertical Stress in the Framework of General Particle Dynamics

A novel numerical model in the framework of General Particle Dynamics is proposed to simulate the coupling effects of the vertical stress and the internal hydraulic pressure on the stress field around the tips of the flaw as well as the propagation and coalescence of cracks. In this proposed method, interaction among discrete particles is formulated using the virtual-bond method. Fractures of the virtual bonds among particles are determined by the Hoek–Brown damage evolution law of rocks. The fractured virtual bonds can only bear the compressive and frictional behaviors between two particles, while the unbroken virtual bonds can bear the tensile, shear and compressive behaviors. Furthermore, a novel generated particle method is proposed to simulate the flow of fissure water. The numerical results show that the water pressure plays a key role in the stress fields around flaw tips as well as the propagation paths and the coalescence pattern of wing and secondary cracks.

内蒙古某矿区水文地质特征及矿坑涌水量计算分析

根据水文地质条件，矿区分为基岩裂隙水区及第四系洪积层和冲积层孔隙水区两个水文地质区。矿区所在区域水文地质单元属阴山西部岩浆岩、变质岩裂隙较贫水区，山脉属阴山山系大青山山脉以北构造剥蚀的低山丘陵区，区内无常年性地表水流，间歇性河流因远离矿区又地势低洼，对矿床充水无影响。通过水均衡法及相关分析法计算确定矿区涌水量计算参数。计算预测结果与1987年勘察时预测结果比较接近，说明本次计算采用的公式比较合理，水文地质参数选取的比较准确，并符合实际，可以做为矿山今后开采的依据。 The mine area is divided into bedrock fissure water area and Quaternary alluvium and alluvial pore water area. The hydrogeological unit in the area where the mining area belongs is magmatic rock and no annual surface water flow in the western Yinshan. Because of the distance from the mining area and low- lying, there is not effect on water filling. The calculation parameters of the water inflow in the mining area are determined. The results are close to the prediction results in 1987, which indicates that the calculation formula is reasonable and can be used as the basis for the future mining.

Geological characteristics of strata in Chongqing, China, and mitigation of the environmental impacts of tunneling-induced geo-hazards

This study investigated the geological characteristics of strata in Chongqing and the tunneling-induced geo-hazards therein. The urban area of Chongqing contains six syncline–anticline pairs and is bounded by the Huayingshan basement fault to the west and by the Changshou-Zunyi basement fault to the east. The bedrock, containing sandstone and mudstone of the Upper Shaximiao formation resulting from Middle Triassic strata, is occasionally outcropped. During urbanization, many valleys in Chongqing require to be backfilled to create more flat ground. Thus, the extent and thickness of the loose backfill layer varied from place to place. While tunneling in Chongqing, the following geological characteristics may cause geo-hazards: (1) backfill with a loose structure, poor gradation, high permeability, and large void ratio, (2) highly, or moderately weathered mudstone and sandstone that can easily become softened once subjected to groundwater seepage, and (3) syncline folding containing perched water or confined fissure water. The potential geo-hazards include groundwater ingress, ground surface settlement, and strata collapse. While tunneling within backfill synclines, sandstone synclines, or weak fractured rock, significant amount of groundwater may be encountered, thus leading to a high risk of groundwater ingress. Ground surface settlement can be triggered due to the disturbances of tunnel construction to the backfill or consolidation effect after groundwater ingress. Strata collapse can be caused by the blasting-induced disturbances to poor surrounding geology or by inadequate overburden thickness or by an increase in the effective stress resulting from groundwater loss caused by leakage. To mitigate the environmental impacts of the tunneling-induced geo-hazards, a series of countermeasures; that is, advance geological drilling, advance ground improvement including full-face grouting, and grouting of the surrounding geologic media, and advance pipe umbrella use, are proposed in this paper. The results from a case study indicate that the proposed countermeasures can greatly decrease the ground surface settlement and amount of groundwater ingress during tunneling in Chongqing verifying the effectiveness of the proposed countermeasures.

Hydrochemical characteristics of natural water and selenium-rich water resources in the Northern Daba Mountains, China.

The Northern Daba Mountains (NDM) of Shaanxi Province, China, are a well-known selenium (Se)-rich area, and the area is also known for endemic fluorine (F) and arsenic (As) poisoning. In order to study the hydrochemical characteristics and trace element contents of the natural waters of this region, 62 water samples were collected from Lan'gao area in the NDM. The hydrochemical composition was principally characterized by Ca·Mg-HCO3·SO4. F and As concentrations ranged from 0.01 to 0.67 mg/L and from 0.33 to 6.29 μg/L, respectively, lower than Chinese national standard and international guidelines for drinking water quality. One year of monitoring proved that F and As in natural water were not the sources of the local fluorosis and arseniasis in the NDM. The average Se concentration in fissure water was 5.20 μg/L. The average Se content of river water was 2.82 μg/L, 14 times that of the world's surface level (0.2 μg/L). The Se content in eight samples reached the Chinese national standards for mineral drinking water quality (>10 μg/L). Contrasting the water samples of May, July, and September in 2015 shows that the Se content is relatively stable and the increase of humidity might be beneficial to increase the content of selenium and strontium in water.

Geotechnical characteristics of weathered granitic gneiss with geo-hazards investigation of pit excavation in Guangzhou, China

This paper presents a comprehensive investigation into weathered granitic gneiss in Guangzhou, China, including its formation, grading, classification, and the geotechnical characteristics of different weathered states. The granitic weathering profiles are graded into five weathered states: fresh rock, slightly weathered, moderately weathered, highly weathered, and completely weathered. The fresh rock and the slightly weathered rock have good mechanical behaviour. The highly weathered granitic gneiss was found to possess a relatively higher permeability than the other weathered states, in which the fissure water is usually stored. Geotechnical characteristics of the weathered granitic gneiss that poses geohazards during excavation are identified, including: (1) uneven grain size distribution, (2) water softening of the residual soils, and 3) spherical weathered boulder. The following potential geohazards are identified: (1) quicksand and piping, (2) water–ground settlement or even collapse due to water softening, (3) trenching difficulties in a diaphragm wall, and (4) instability of the lattice columns. Countermeasures for preventing these geo-hazards are proposed, including (1) rate-controlled drilling of dewatering wells, (2) grouting in both sides of retaining walls, and (3) deep hole blasting of large-size residual gravel boulders. These measures has been demonstrated to be useful in construction of Zhongxin Station.

Geological formation and geo-hazards during subway construction in Guangzhou

This paper summarises the stratigraphy, tectonic structure, geomorphology, hydrogeology and engineering geology in Guangzhou, China, and analyses the relevant geo-hazards and countermeasures during subway construction. The ages of the geological materials found in Guangzhou range from the Proterozoic era to the Cenozoic era. The bedrock is generally made up of sedimentary rock and weathered granite strata covered by soil with a thickness ranging from 2 to 20 m. The presence of underground karst caves, active faults and fissure water together with high piezometric levels leads to difficulties in shield tunnelling in Guangzhou. A case history, where two tunnels and one subway station on the Guangzhou Metro Line 7 were constructed, is referred to in order to analyse the mechanism between geological formations and geo-hazards. Three potential geo-hazards are listed: (1) water ingress and strata erosion, (2) ground surface settlement and (3) sinkholes; and their implications for shield tunnelling in Guangzhou are summarised and discussed. To mitigate the risk of these geo-hazards, a series of countermeasures, comprising (1) optimising TBM cutting tool design, and tunnelling parameters, (2) grouting to enhance watertightness and stiffness of strata and (3) injecting bentonite slurry and foam into the head chamber, are recommended in this paper.

Determining sources of mine water based on hydraulic characteristics analysis of a fault system

To analyze mining hydrogeological conditions and determine the sources of mine water, a hydrothermal deposit of China is taken as an example in this paper. On the basis of detailed geological and hydrogeological analysis of conditions in the mining area, the hydrogeological characteristics of a fault system of F1 in this mine are determined using a pumping test method and isotope technology. Hydraulic connections between the Majiagou group and Xiaoxian group are given a detailed illustration. The results show that the F1 group of faults is channeling water. Under significant drawdown, fissure water and Lower Pleistocene porous confined water are indirect sources of mine water, but water supply in unit time is limited. According to the analysis results, water will enter the pit during mining at a rate of 12,680 m3/d. In contrast, if the transmission performance of the F1 group of faults is ignored, the porous confined water will not enter the pit, and the mine water inflow will be 9700 m3/d. This is a decrease of 2980 m3/d, accounting for 30.72 % of mine water inflow. Therefore, the effect of water sources on mine water inflow cannot be ignored.

Landslide monitoring in southwestern China via time-lapse electrical resistivity tomography

The dynamic monitoring of landslides in engineering geology has focused on the correlation among landslide stability, rainwater infiltration, and subsurface hydrogeology. However, the understanding of this complicated correlation is still poor and inadequate. Thus, in this study, we investigated a typical landslide in southwestern China via time-lapse electrical resistivity tomography (TLERT) in November 2013 and August 2014. We studied landslide mechanisms based on the spatiotemporal characteristics of surface water infiltration and flow within the landslide body. Combined with borehole data, inverted resistivity models accurately defined the interface between Quaternary sediments and bedrock. Preferential flow pathways attributed to fracture zones and fissures were also delineated. In addition, we found that surface water permeates through these pathways into the slipping mass and drains away as fissure water in the fractured bedrock, probably causing the weakly weathered layer to gradually soften and erode, eventually leading to a landslide. Clearly, TLERT dynamic monitoring can provide precursory information of critical sliding and can be used in landslide stability analysis and prediction.

Eukaryotic opportunists dominate the deep-subsurface biosphere in South Africa.

Following the discovery of the first Eukarya in the deep subsurface, intense interest has developed to understand the diversity of eukaryotes living in these extreme environments. We identified that Platyhelminthes, Rotifera, Annelida and Arthropoda are thriving at 1.4 km depths in palaeometeoric fissure water up to 12,300 yr old in South African mines. Protozoa and Fungi have also been identified; however, they are present in low numbers. Characterization of the different species reveals that many are opportunistic organisms with an origin due to recharge from surface waters rather than soil leaching. This is the first known study to demonstrate the in situ distribution of biofilms on fissure rock faces using video documentation. Calculations suggest that food, not dissolved oxygen is the limiting factor for eukaryal population growth. The discovery of a group of Eukarya underground has important implications for the search for life on other planets in our solar system.

Deep subsurface mine stalactites trap endemic fissure fluid Archaea, Bacteria, and Nematoda possibly originating from ancient seas.

Stalactites (CaCO3 and salt) from water seeps are frequently encountered in ceilings of mine tunnels whenever they intersect water-bearing faults or fractures. To determine whether stalactites could be mineralized traps for indigenous fracture water microorganisms, we analyzed stalactites collected from three different mines ranging in depth from 1.3 to 3.1 km. During sampling in Beatrix gold mine (1.4 km beneath the surface), central South Africa, CaCO3 stalactites growing on the mine tunnel ceiling were collected and observed, in two cases, to contain a living obligate brackish water/marine nematode species, Monhystrella parvella. After sterilization of the outer surface, mineral layers were physically removed from the outside to the interior, and DNA extracted. Based upon 16S and 18S rRNA gene sequencing, Archaea, Bacteria, and Eukarya in different combinations were detected for each layer. Using CT scan and electron microscopy the inner structure of CaCO3 and salt stalactites were analyzed. CaCO3 stalactites show a complex pattern of lamellae carrying bacterially precipitated mineral structures. Nematoda were clearly identified between these layers confirming that bacteria and nematodes live inside the stalactites and not only in the central straw. Salt stalactites exhibit a more uniform internal structure. Surprisingly, several Bacteria showing highest sequence identities to marine species were identified. This, together with the observation that the nematode M. parvella recovered from Beatrix gold mine stalactite can only survive in a salty environment makes the origin of the deep subsurface colonization enigmatic. The possibility of a Permian origin of fracture fluids is discussed. Our results indicate stalactites are suitable for biodiversity recovery and act as natural traps for microorganisms in the fissure water long after the water that formed the stalactite stopped flowing.