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Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That reservoir is 1. a recipient for the collection of small amounts of liquid [16]. 2. a surface water impoundment [16].?

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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
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Your search for fracture network (Keyword) returned 28 results for the whole karstbase:
Showing 1 to 15 of 28
Modeling of regional groundwater flow in fractured rock aquifers, PhD Thesis, 1990, Kraemer, S. R.

The regional movement of shallow groundwater in the fractured rock aquifer is examined through a conceptual-deterministic modeling approach. The computer program FRACNET represents the fracture zones as straight laminar flow conductors in connection to regional constant head boundaries within an impermeable rock matrix. Regional scale fracture zones are projected onto the horizontal plane, invoking the Dupuit-Forchheimer assumption for flow. The steady state flow solution for the two dimensional case is achieved by requiring nodal flow balances using a Gauss-Seidel iteration. Computer experiments based on statistically generated fracture networks demonstrate the emergence of preferred flow paths due to connectivity of fractures to sources or sinks of water, even in networks of uniformly distributed fractures of constant length and aperture. The implication is that discrete flow, often associated with the local scale, may maintain itself even at a regional scale. The distribution of uniform areal recharge is computed using the Analytic Element Method, and then coupled to the network flow solver to complete the regional water balance. The areal recharge weakens the development of preferential flow pathways. The possible replacement of a discrete fracture network by an equivalent porous medium is also investigated. A Mohr's circle analysis is presented to characterize the tensor relationship between the discharge vector and the piezometric gradient vector, even at scales below the representative elementary volume (REV). A consistent permeability tensor is sought in order to establish the REV scale and justify replacement of the discrete fracture network by an equivalent porous medium. Finally, hydrological factors influencing the chemical dissolution and initiation of conduits in carbonate (karst) terrain are examined. Based on hydrological considerations, and given the appropriate geochemical and hydrogeological conditions, the preferred flow paths are expected to develop with time into caves.

Tectonic Speleogenesis of Devils Hole, Nevada, and Implications for Hydrogeology and the Development of Long, Continuous Paleoenvironmental Records, 1994, Riggs Alan C. , Carr W. J. , Kolesar Peter T. , Hoffman Ray J. ,
Devils Hole, in southern Nevada, is a surface collapse into a deep, planar, steeply dipping fault-controlled fissure in Cambrian limestone and dolostone. The collapse intersects the water table about 15 m below land surface and the fissure extends at least 130 m deeper. Below water, most of the fissure is lined with a >30-cm-thick layer of dense maxillary calcite that precipitated continuously from groundwater for >500,000 yr. The thick mammillary calcite coat implies a long history of calcite-supersaturated groundwaters, which, combined with the absence of dissolutional morphologies, suggests that Devils Hole was not formed by karst processes. Devils Hole is located in a region of active extension; its tectonic origin is shown by evidence of spreading of its planar opening along a fault and by the orientation of its opening and others nearby, perpendicular to the northwest-southeast minimum principal stress direction of the region. Most Quaternary tectonic activity in the area, including seismicity and Quaternary faults and fractures, occurs on or parallel to northeast-striking structures. The hydrogeologic implications of this primarily structural origin are that fracture networks and caves opened by extensional tectonism can act as groundwater flowpaths functionally similar to those developed by karst processes and that, during active extension, transmissivity can be maintained despite infilling by mineral precipitation. Such extensional environments can provide conditions favorable for accumulation of deposits preserving long, continuous paleoenvironmental records. The precipitates in Devils Hole store chronologies of flow system water-level fluctuations, hydrochemistry, a half-million-yr proxy paleoclimate record, evidence of Devils Hole's tectonic origin, and probably atmospheric circulation

The problem of modeling limestone springs: The case of Bagnara (north Apennines, Italy), 1997, Angelini P, Dragoni W,
The Bagnara spring (Central Italy), fed by a fractured, carbonate, and, in some areas, karstic aquifer, was examined. The available information is derived from geological mapping and daily flows over a period of 20 consecutive years. There are no data on the hydrogeological parameters nor on the aquifer hydraulic head, which is known only at the elevation of the spring. The objective of the work was to construct an appropriate mathematical model for the spring despite the scarcity of available information. The MODFLOW code was used to simulate the system following the equivalent porous media approach. The hydraulic conductivity and the specific yield equivalents were estimated by calibrating the model on the master depletion curve and taking into consideration the topographic elevation of the system's surface. The size of the protection area around the spring was investigated on the basis of the isochrons constructed from the results of the model

Relation entre ecoulements et fractures ouvertes dans un systeme aquifere compartimente par des failles et mise en evidence d'une double porosite de fractures, 1999, Bruel T, Petit Jp, Massonnat G, Guerin R, Nolf Jl,
Hydrodynamic characterisation of real fracture systems is necessary to improve modelling of fracture reservoirs as well as nuclear waste disposal sites. This characterisation is usually considered globally and theoretically but very few studies have aimed to identify the real physical environment of flow (matrix, faults, joints etc.) before establishing hydrodynamical models. We present a case study in a fractured reservoir aiming to give an example of how and why fluids actually flow within a given fracture at the various scales of fracturation of a fracture network. This study demonstrates that the determination of type and orientation of fractures actually supporting flow is necessary for accurate interpretation of the pumping tests within a fractured reservoir. It also shows that there is no simple relationship between the fault offset and the importance of flow, probably due to the influence of in situ stress. It is shown that the combination of various methods can be used to determine the fracture-flow relationship and behaviour at subseismic scale in subsurface conditions

The role of western Mediterranea tectonic evolution in the geometry of a karstic domain in the Betic Cordilleras (Sierra Gorda, Spain): importance of a tardy extensional regime, 1999, Pistre S. , Lopezchicano M. , Pulidobosch A. , Drogue C. ,
Located in the central part of the Betic Cordilleras, the large carbonate Sierra Gorda Massif provides an example of a west-Mediterranean karstic aquifer. In spite of a complex polyphased tectonic history, the fracturing presents, from aerial views and at outcrop scale a quite organised geometry. Four fracture directions are found over the massif: N000-010, N050-070, N090-100 and N140-170. The statistical and geostatistical approach allows the characteristics (lengths, orientations) and the spatial structure for each fracture set to be determined. The N000-010 and N140-170 sets are grouped in packers whereas the two other sets are grouped in bands. The microtectonic study describes the evolution of the massif in the geodynamic context of this part of Mediterranea, distinguishing three recent stages of brittle tectonic activity in the gu massif: a WNW-ESE Middle Miocene compression, then a NNW-SSE to NW-SE compression with a poorly wrenching regime, and finally a probably pre-Quaternary N-S radial distension. This last stage is essential for the karstification of the massif and groundwater circulation. From the combined analysis of fracture network geometry and palaeostresses a multiple porosity model in agreement with hydrological observations made inside the massif can be proposed: in particular, the hectometric N090-100 land N050-070) fractures which are essential for the network connectivity, and have a major drainage role at aquifer scale, while the N000-010 and N140-170 ones have a more local drainage role. This extensive tardy regime, which is for the first time described separately from the internal zones of the Cordilleras, must be considered as a significant phenomenon on a regional scale, and henceforth integrated in future geodynamic schemes of this part of Mediterranea. (C) Elsevier, Paris

Structure, flow, and generalized conductivity scaling in fracture networks, 1999, Margolin G. , Berkowitz B. , Scher H.

We present a three-dimensional (3-D) model of fractures that within the same framework, allows a systematic study of the interplay and relative importance of the two key factors determining the character of flow in the system. The two factors of complexity are () the geometry of fracture plane structure and interconnections and (2) the aperture variability within these planes. Previous models have concentrated on each separately. We introduce anisotropic percolation to model a wide range of fracture structures and networks. The conclusion is that either of these elements, fracture geometry and aperture variability, can give rise to channeled flow and that the interplay between them is especially important for this type of flow. Significant outcomes of our study are (1) a functional relationship that quantifies the dependence of the effective hydraulic conductivity on aperture variability and on the network structure and fracture element density, (2) a relation between aperture variability and the Peclet number, and (3) a basis for a new explanation for the field-length dependence of permeability observed in fractured and heterogeneous porous formations.

Groundwater resources and vulnerability in the Cretaceous Chalk of Northern Ireland, 2000, Barnes S,
A confined Cretaceous Chalk aquifer underlies approximately one quarter of Northern Ireland, yet little is known about its groundwater resource potential. This issue has been addressed on the catchment scale by analysing spring discharge and hydrochemical fluctuations. The Chalk springs are recharged by allogenic leakage and surface runoff from overlying Tertiary basalts. Sources connected to river-sinks show greater variation in flow and quality reflecting a much shorter residence time than those predominantly derived from the diffuse recharge. Discharge from the confined region becomes proportionally significant during prolonged dry spells, but is typically a minor component compared with groundwater circulation volumes in the unconfined region. Spring flood recessions are rapid (recession coefficients up to 0.125 per day) and suggest that the Chalk has a high hydraulic conductivity and a low storage capacity. These characteristics together, with the essentially impermeable matrix, are consistent with an aquifer dominated by a dispersed fracture network. Conceptual aquifer classification suggests that the outcrop region is a highly sensitive karst aquifer. The subcrop areas can only be exploited via boreholes and are likely to be less productive, although the water quality has been shown to be more stable and less vulnerable to contamination

Flow behavior in a dual fracture network., 2002, Jourde H. , Cornaton F. , Pistre S. , Bidaux P.

Karst aquifer evolution in a changing water table environment - art. no. 1090, 2002, Kaufmann G. ,
[1] A vertical cross section through a karst aquifer is modeled by means of the finite element method to study the evolution of fractures and flow in the aquifer. The karst aquifer receives a constant recharge along the top boundary by precipitation and drains toward a resurgence assumed to be the base level in a valley. Flow is allowed both in the permeable rock matrix and the fracture network, and the fractures are enlarged with time by chemical dissolution. Hence during the early evolution of the karst aquifer the conductivity increases over several orders of magnitude, and the initially high water table drops to a steady state base level niveau. As a consequence, fractures above the final water table change from phreatic to vadose flow conditions. A systematic parameter study is carried out to investigate the aquifer evolution over a wide range of parameters, such as recharge rate, initial fracture width and density, and initial calcium concentration. The numerical models cover a wide range of drainage patterns, from phreatic water table caves to deep bathyphreatic caves to vadose river caves. The models suggest that a single theoretical approach is capable of explaining most common cave passage patterns

Modelling unsaturated flow in an evolving karst aquifer, 2003, Kaufmann G. ,
A two-dimensional cross-section of a karst aquifer, in which chemical dissolution enlarges fractures with time, is studied. The karst aquifer is recharged by precipitation and drains towards a resurgence. The initial aquifer has low conductivities both in the rock matrix and the fracture network, and the initial water table is high. As the enlargement of fractures by dissolution increases the fracture conductivity, the water table drops, until it reaches a steady-state along the level of the resurgence. Several parameterisations are discussed for flow in the unsaturated zone above the water table. It is shown that different approaches result in similar cave passage patterns, with a large water-table cave draining the recharge towards the resurgence. However, flow patterns in the unsaturated zone can be very different for the different parameterisations. (C) 2003 Elsevier Science B.V. All rights reserved

Evolution of Karst Aquifers in Natural and Man Made Environments: A Modeling Approach. Ph.D. thesis, 2003, Romanov, Douchko

The evolution of karst aquifers under various hydrological and chemical boundary conditions is studied.
In the first part the influence of exchange flow from a prominent fracture into a two-dimensional network of fissures is compared to the evolution of a fracture isolated from this net. The modeling domain is 742.5 m long and 375 m wide dissected by fractures into 100 by 51 blocks. The wide prominent fracture extends along its center, thus constituting a part of the network. Under constant head conditions between the left and the right hand side of the domain it looses flow into the network. We have studied the influence of the fracture widths of the fine net to the breakthrough time (BT) of the system. Because of loss of flow from the central fracture to the net, aggressive solution from the input enhances dissolution and breakthrough times are reduced. This effect is most effective, when the aperture width of the fine net is only smaller by about 1% than the widths of the prominent fracture, such that a large amount of water can flow into the net. To obtain further information on the processes involved, an isolated one-dimensional fracture with an additional single point of outflow from it, is investigated.
As an application of the results above, the evolution of a karst aquifer below dam sites is studied. The modeling domain is a 2D, 1 m wide vertical section of soluble rock (gypsum and limestone), perpendicular to the dam. The block extends 750 m horizontally and 375 m vertically. It is divided by fractures and fissures into blocks of 7.5 m x 7.5 m x 1m. The chemical composition of the inflowing water is equal at all input points. Because of dissolution along the fractures, a large zone of increasing permeability is created below the structure, causing high unbearable water losses from the dam site and also endangering the mechanical stability of the dam. The dependence of BT on the basic parameters - the height of the impounded water, the depth of the grouting curtain, the initial aperture widths of the fractures and the fissures, and the chemical parameters of the inflowing water (equilibrium concentration with respect to calcite and input concentration) is investigated. For fracture aperture widths larger than 0.02 cm breakthrough occurs within the lifetime of the structure.
In the second part the effect of chemical boundary conditions on the evolution of a karst aquifer is studied. The model domain is 500 m x 225 m, divided into blocks of 5 m x 5 m x 1 m by fracture network. There are two input points at constant head (25 m) at the inflow side of the block. The outflow side is open at constant head – 0 m. The hydrological boundaries are equal for all simulated scenarios. The chemical composition of the inflowing water at both inputs is varied, and the reaction of the aquifer is studied. Mixing corrosion is the reason for zones of increased permeability deep inside the aquifer along the boundary, where the solutions mix. The influence of mixing corrosion for various values of the input Ca concentration is studied. The results show two types of evolution. Breakthrough (BT) governed evolution – for values of cin<0.96?ceq, and mixing corrosion (MC) - governed evolution for values of cin>0.96?ceq. The BT - type is characterized by enlarged pathways connecting an inflow point with the outflow boundary. For increasing values of the input concentrations the effect of MC becomes stronger. For high Ca concentrations, MC is dominating. There is no considerably widened connection between the inflow points and the out flow boundary. but an enlarged channel along the mixing zone is observed. The timescale for this type of evolution is considerably longer. For solutions saturated with respect to calcite, the mixing zone is the only area of widening inside the aquifer.

Mechanical stratigraphic controls on fracture patterns within carbonates and implications for groundwater flow, 2006, Cooke Ml, Simo Ja, Underwood Ca, Rijken P,
Groundwater flow in low matrix-permeability carbonate rocks is largely controlled by fracture networks. The stratigraphic features that control fracture initiation and termination within a sequence of sedimentary rock strata define the mechanical stratigraphy of the sequence. We investigate the effectiveness of various types of stratigraphic horizons in terminating opening-mode fractures in two different carbonate rock sequences: a relatively homogeneous dolomite sequence, in Door County, WI and an interbedded chalk and marl sequence within the Austin Chalk, TX. Additionally, we present analog and numerical modeling results that delineate the specific mechanisms that facilitate fracture termination. The combination of model results and empirical relationships between observed sedimentary features and mechanical stratigraphy shows: (1) fractures terminate at weak contacts (e.g. thin organic layers), shallowly buried contacts or thick fine-grained units adjacent to thin fractured beds, (2) fractures propagate across strong contacts (e.g. intracycle contacts between different lithology) and thin fine-grained units adjacent to thick fractured beds and (3) fractures step-over at moderate strength contacts. We use these guidelines to predict fracture network from sedimentary stratigraphy by qualitatively assessing the mechanical stratigraphy of a portion of the relatively complex Cretaceous shelf-margin sequence at Sant Corneli, Spain. This predictive demonstration illustrates the utility of assessing the mechanical stratigraphy of subsurface strata within which fractures are not directly observable. We conclude that for a variety of carbonate mechanical stratigraphic sequences, dominant fluid flow characteristics, such as horizontal high flow zones and flow compartmentalization, can be evaluated using fracture spacing and connectivity within fracture networks that is predicted from sedimentary stratigraphy. Although the resulting heterogeneous flow networks do not rely on every fracture present, they are highly dependent on the mechanical stratigraphy

Seasonal variations of CO2 and 222Rn in a Mediterranean sinkhole-spring (Causse dAumelas, SE France)., 2007, Batiotguilhe Christelle, Seidel Jeanluc, Jourde Herv, Hbrard Olivier, Baillycomte Vincent
Carbon dioxide and 222Rn monitoring of the atmosphere of a Mediterranean sink hole - spring (SE France) during two hydrological cycles (from September 2004 to September 2006) showed seasonal variations with very high concentrations during summer (greater than 6% and 20000 Bq/m3, respectively). Gas dynamics in caves often show seasonal variations. Meteorological parameters (barometric pressure and temperature mainly), cave geometry and fracture networks control exchanges between the cavity and outside atmosphere. Carbon dioxide and 222Rn may have different sources (atmosphere, soil, bedrock, deep gas diffusion, in situ oxidation of organic matter and, in some caves, the key role of swift underground streams). For a CO2 origin, 13C measurements on water and gas samples taken into the cavity suggest a superficial origin. Radon-222 appears to be locally produced and transported by biogenic CO2. Further investigations will be carried out in order to study the relationship of gas-level variations with barometric pressure variations and piezometric level fluctuations within the aquifer.

Seasonal variations of CO2 and 222Rn in a Mediterranean sinkhole-spring (Causse dAumelas, SE France), 2007, Batiotguilhe Christelle, Seidel Jeanluc, Jourde Herv, Hbrard Olivier, Baillycomte Vincent
Carbon dioxide and 222Rn monitoring of the atmosphere of a Mediterranean sink hole - spring (SE France) during two hydrological cycles (from September 2004 to September 2006) showed seasonal variations with very high concentrations during summer (greater than 6% and 20 000 Bq/m3, respectively). Gas dynamics in caves often show seasonal variations. Meteorological parameters (barometric pressure and temperature mainly), cave geometry and fracture networks control exchanges between the cavity and outside atmosphere. Carbon dioxide and 222Rn may have different sources (atmosphere, soil, bedrock, deep gas diffusion, in situ oxidation of organic matter and, in some caves, the key role of swift underground streams). For a CO2 origin, 13C measurements on water and gas samples taken into the cavity suggest a superficial origin. Radon-222 appears to be locally produced and transported by biogenic CO2. Further investigations will be carried out in order to study the relationship of gas-level variations with barometric pressure variations and piezometric level fluctuations within the aquifer.

Karst and Early Fracture Networks in Carbonates, Turks and Caicos Islands, British West Indies, 2007, Guidry Sean A. , Grasmueck Mark, Carpenter Daniel G. , Gombos Andrew M. Jr. , Bachtel Steven L. , Viggiano David A. ,
Historically, studies of Quaternary carbonates have not adequately addressed the influence of early fracture networks on diagenesis. Because of this lack of detail, understanding and predicting fracture-related diagenetic heterogeneities and preferential fluid flow pathways in ancient carbonate successions is particularly challenging. The Pleistocene oolitic grainstones of the Caicos platform provide an excellent opportunity to evaluate the relative importance of fractures on early diagenetic alteration styles, and are a suitable analog for subsurface carbonate reservoirs. Detailed analyses of fractures (e.g., orientation, aperture, spacing, fill material) from Caicos outcrops combined with high-resolution, three-dimensional ground-penetrating radar (3D GPR), assisted in exploring the causality and distribution of fractures and relationship to karst. Four models were evaluated to explain the observed distribution of dolines: (1) gravitational, fractured-margin controlled, (2) tectonic-fracture controlled, (3) antecedent-topography controlled, and (4) a hybrid model. Based on observations of numerous fractures (n = 306) on the western Caicos platform, early fractures are abundant and dominantly margin-parallel. These fracture networks are well established in limestones prior to mineralogical stabilization, thereby indicating that diagenetic heterogeneities evolve very early in carbonate diagenesis. The spatial distribution of dolines on Providenciales is likely the result of a complex interplay between the antecedent topography, margin-parallel fracture systems, and meteoric fluids. Resultant diagenetic alteration is far more complicated than simple, unconfined, meteoric lenses associated with topographic highs. Any attempts to model early diagenesis in carbonates should not dismiss the role of fractures as diagenetic facilitators and diagenetic anisotropy templates

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