Development Of Karst Features Research Articles

Contribution of Remote Sensing and GIS to the Inventory and Analysis of Factors influencing on the Development of Karst Features in the Middle Atlas, Morocco

The development of karst features is a complex and interactive process of many factors with varying influence over time. The following main factors seem to have influenced the occurrence and development of karst features in the Middle Atlas in Morocco: Precipitations after extreme weather events depending on the precipitation pattern modified by orographic effects and exposition of the terrain towards the main rain-bearing clouds are determining surface water input and infiltration as well as the outline of morphologic watersheds and drainage basins. The lithologic conditions such as the outcrops of lower Jurassic limestones, the geomorphologic disposition, the volcanic activity within limestones combined with hydrothermal dissolution processes, and the structural conditions influencing water permeability in fault and fracture zones and, thus, the dissolution intensity, are further factors. Ongoing aseismic vertical and horizontal neotectonic movements due to plate tectonic activities and shallow earthquake activities are causing the development and reactivation of fault zones and as consequence modifying groundwater flow conditions in the karst hydrologic systems. Seismic activity can lead as well to the development of sinkholes and the collapse of caves. The development of a systematic Karst-Geo Information System (GIS) is recommended that should be updated regularly.

Siliciclastic content controls the sealing behavior of layers and karst development in a carbonate-siliciclastic sequence, Salitre Formation, Brazil

Although caves formed in carbonate units play a crucial role in fluid flow, most subsurface voids are below seismic resolution. This study investigates how sedimentary facies control the vertical distribution and the development of karst features from small vugs to caves in a carbonate succession with terrigenous input. We analyzed the sedimentary succession and the potential of layers to behave as sealing and conduit units in the karst system. The study area is located in the Neoproterozoic Salitre Formation in the Una-Utinga Basin, São Francisco Craton, Brazil. We selected two caves and their hosting units as analogs of carbonate reservoirs affected by karstification. Our findings indicate that the caves have similar sedimentary and petrographic patterns, composed of three sedimentary facies at a 20–30 m vertical section from the bottom to the top. At the bottom, the lime mudstone facies contains 10% siliciclastic content, which is the pure conduit facies that host most cave passages. A heterogeneous calcarenite containing lime mudstones and siliciclastic intercalation facies occurs in the middle portion, where the siliciclastic content varies between 10-30% and 30–50%. This aforementioned facies exhibits conduit and sealing layers. At the top, a mixed limestone siliciclastic facies has siliciclastic content above 50% and a high degree of compaction. It behaves as a sealing facies. The conduit-sealing system has the same pattern at various scales: macro (observed in drone imagery), meso (Light Detection and Ranging imagery - LiDAR), and microscale (thin section). We conclude that the siliciclastic content of layers controls the degree of karstification at various scales in a carbonate-siliciclastic sequence.

Cave Density of the Greenbrier Limestone Group, West Virginia

The Greenbrier Limestone Group, known in West Virginia as the “Big Lime,” is an extensive, calcium-pure limestone unit of Mississippian Age (350–340 million years). Deposited in a shallow ocean basin during the Carboniferous, the Big Lime is more than 1,000 feet thick in the Greenbrier Valley of West Virginia. The wet climate of central Appalachia provides the hydraulics and corrosive carbonic acid action necessary to form frequent and sizable karst dissolution features, such as caves, sinkholes, and springs. Some of the world's largest caves form here as contact caves, where the Big Lime meets the underlying McCrady Shale Formation, including Scott Hollow Cave (29.5 miles), Organ Cave (38.5 miles), and The Hole (23 miles). Likewise, thousands of sinkholes and pits have formed via dissolution of bedrock and collapse into subsurface cave passage. These features create geohazards to infrastructure and provide pathways for aquifer contamination through sediment and pollutant transport, thereby requiring a geographic understanding of karst feature density. This research uses the geographic and geologic analysis capabilities of ArcGIS 10 to examine spatial relationships between this stratigraphic unit and the development of karst features to explore any structural or geographic controls on their genesis. Data are derived from the West Virginia Speleological Survey database of more than 5,600 caves and pits, including length, depth, elevation, and stratigraphic unit attributes. Hexagonal bins with a variety of diameters were used for autocorrelational, Getis-Gi hot spot, and Getis-Ord high–low cluster analysis. Each of these tests showed statistically significant spatial relationships for cave sites at all levels of analysis.

Structural control on development of karst landscape in the Salento Peninsula (Apulia, SE Italy)

Apulia region (SE Italy) is particularly prone to karst processes, due to the extensive presence of carbonate rocks. Karst marks the whole region, and represent the main landscape features, with a variety of landforms ranging from large-size dolines, to poljes, and fluvial-karstic valleys; given the configuration of Apulia, a great role is also played by coastal karst landforms. The Salento peninsula, in southern Apulia, is characterized by very low relief and cropping out of different types of carbonate rocks, ranging in age from Cretaceous to Quaternary. Recognition of karst features in this setting, and the likely implications for geohazards, is quite difficult, because of the subtleness of the features, and the facility for man to cancel or modify them. Nevrteheless, the presence of dolines is definitely a typical aspect of the area, which also implies some consequences in terms of risk to the built-up environment.This work focuses on the area of Barbarano del Capo, where two cover-collapse dolines are well known in the geological literature as Vora Grande and Vora Piccola. Despite morphometrical and stratigraphical features have already been investigated, few information are available about the hydro-geomorphological and structural settings of the area. This article presents the results of morphological and structural analyses, aimed at understanding the role played by tectonics in the development of karst features, and their evolution.

Preliminary analysis of spatial development of karst using a geostatistical simulation approach

Earth science phenomena are primarily spatially dependent with variations occurring on varying scales. Geostatistics is a well-known approach for the assessment of spatial models of regionalized variables, such as porosity. In this study, we used the results of 953 Lugeon tests (402 tests in exploratory wells and 550 tests in grouting wells) to assess effective porosity and karst development at the Tangab Dam site, Iran. Lugeon values were first normalized, following which the variogram method (i.e., range, sill, and nugget effect) was used to identify the spatial variability of Lugeon values. A high correlation range of 200 m was obtained along the grout curtain galleries, while the range was about 40 m in the vertical direction. The simple kriging method with Gaussian variograms was determined to be the best method for estimating the Lugeon values in the study area using cross validation-criteria (e.g., RMSE = 0.835 and ρ = 0.914). Spatial variation of Lugeon values was mapped using a simulated annealing approach. The analysis revealed: (1) a higher potential for karst development on the left abutment of the Tangab Dam site, (2) the average of simulated Lugeon values decreased from values of about 180 close to the ground surface at 1,440 m a.s.l. to lower values of about 50 at 1,260 m a.s.l., and (3) high Lugeon values in the abutments of the dam site approximately followed the 15° bedrock dip, which confirms the potential development of karst features in the Asmari limestone. A schematic model for development of karst at the Tangab Dam site is proposed based on hydrogeological data and results of simulated Lugeon values around the dam site.

Tectonic control on karst processes in Pasvalys Area, North Lithuania

Karst processes are active in the northern part of Lithuania and cause different problems for the local community. The activity is related to sub-cropping of the Upper Devonian (Tatula Formation) gypsum-carbonaceous succession under a thin (<25 m) Quaternary cover. The Pasvalys cluster of karst sinkholes is distinct by anomalous density of karst features. The structural conditions and lithological variations were studied in relation to karst processes in Pasvalys Town and vicinities. A close correlation of those processes with tectonic structures was recognised. Pasvalys Town is situated within the Pasvalys uplift that is characterised by intense dissolution of the upper part of the evaporitic-carbonaceous Tatula Formation suggesting intense ground water infiltration within the uplift. Therefore the potential of karst activity is rather exhausted here. By contrast, the adjacent Lėvuo-Mūsa depression, located west of the town, shows intense pervasive gypsum dissolution of the lower part of the Tatula Formation that resulted in preservation of the upper (Nemunėlis) gypsum layers from erosion processes. It is associated with the high potential of recent dissolution processes and formation of karst features. A similar scenario is identified north of Pasvalys Town in the Maskoliskės depression. The most intense karst processes occur along the high-gradient boundaries of the aforementioned structures. The Pagojis depression, defined in the south, comprises only little affected by pervasive dissolution Tatula succession that also has the high potential for development of karst features. The regular pattern of some sinkholes along lineaments suggests that the fracture system dissecting Devonian sediments also contributed to the uneven distribution of dissolution processes.

Karstic behaviour of groundwater in the English Chalk

Although the Chalk is only weakly karstified, tracer testing from stream sinks has demonstrated groundwater flow velocities comparable to those observed in highly karstic aquifers. Field survey of surface karst features in the catchments of the Pang and Lambourn rivers in southern England demonstrates the importance of overlying and adjacent Palaeogene strata in the development of karst features. Tracer techniques employed within the catchments enable further characterisation of the range and connectivity of solutional voids in this area of the Chalk, and allow assessment of the relative importance of different mechanisms of contaminant attenuation. Quantitative tracer test results suggest that groundwater flow may be through a complex combination of small conduits, typically 10–1000 mm in diameter, and more laterally extensive fissures with apertures of 1–50 mm. Evidence of connectivity between conduits and fissures suggest that in areas of the Chalk with rapid groundwater flow, fissures supplying abstraction boreholes may be connected to karst conduit networks with low potential for contaminant attenuation.

Specific Features of Carbonate Platform Formation: Evidence from the Middle Carboniferous East Ural Gulf

During the Moscovian Age, the eastern part of the Russian Platform was occupied by the shallow-water East European Basin (EEB) characterized by predominantly carbonate sedimentation. In the Cis-Ural region of this basin, the deep Cis-Ural Sea (CUS) occupied the Ural Foredeep. The Paleo-Ural Range separated the CUS from the narrow and long East Ural Gulf, which was connected in the south with the main part of the EEB and a sea within the Turan Plate. The Moscovian paleogeographic setting is shown in three paleogeographic maps. Middle Carboniferous organogenic buildups from the eastern slope of the Urals have been time and again described previously. However, the repeated study of these features did not prove the biogenic nature of all of them. This work presents characteristics of two, newly discovered, unique (in terms of nature and structure) coastal bioherms. One bioherm lies at the base of the Moscovian stage and consists of phylloid algae. The second bioherm, located at a higher level, has a complex structure and is made up of foraminifers, algae, and stromatolites. After the desiccation and development of karst features on the surface, the bioherm was buried under sandy–clayey sediments accumulated in freshened water.

Evaporite dissolution and development of karst features on the rolling plains of the texas panhandle

AbstractMore than 400 dolines, consisting of collapse sinkholes and closed depressions, occur in Hall and Briscoe Counties, Texas. Of these, at least 36 sinkholes and two depressions formed between 1940 and 1972. Collapse sinks are typically circular and range up to 100 m in diameter and 15 m in depth. Closed depressions are irregularly‐shaped, internally‐drained depressions up to 2.4 km in length. Surface fractures up to 1.5 km in length are associated with certain closed depressions.Karst features are forming as a result of intrastratal dissolution of Upper Permian evaporites, primarily halite and secondarily gypsum. Salt dissolution and overburden collapse are evident from geophysical log cross‐sections and occur at depths ranging from 195 to 275 m. Dissolution is progressing down dip and mean dissolution rates for salt beds in the Hall County area range from 0.29 to 7.73 cm/yr.The valley of the Prairie Dog Town Fork of the Red River is an area of ground‐water discharge for flow systems moving eastward from topographically high areas of the Rolling Plains and from the eastern rim of the High Plains. Halite beds in contact with these waters undergo dissolution. Salt springs and brine seeps, some associated with sinkholes and depressions, occur in the discharge area and indicate that dissolution is an ongoing process.

The Caballos Novaculite Revisited Part I: Origin of Novaculite Members

ABSTRACT Examination of the two novaculite members for additional clues to the origin of novaculite (white, pelletal, spiculitic chert) yielded the discovery of several features: early-formed fractures and breccias, and pockets and fractures filled with quartz sand and silt. Early-formed fractures are chiefly narrow (<4 mm wide) cracks up to several decimeters long which are sub-perpendicular to bedding and which are filled by slightly darker non-fibrous colorless microquartz. Breccias are formed of angular novaculite clasts in a black organic-rich siliceous sediment containing various amounts of pellets, quartz silt, sponge spicules, and locally spherulites of chalcedony or lutecite. Local pockets and veins of brown, very-fine quartz sand up to a few decimeters across are present within the upper member. The contact between the sand and novaculite host rock is crinkly, possibly from solutional enlargement of the pockets prior to filling and partly from later stylolitic solution. Two hypotheses are proposed for these features. One hypothesis is that protonovaculite underwent subaerial exposure, fracturing, development of karst features, and subsequent filling of open fractures partly by windblown sand and, after submergence, partly by dark marine muck. The other hypothesis is that fractures and breccias formed in unevenly lithified sediment, that fractures were filled by indigenous sediment, and that filling took place during continuous subsidence in deep water. Possible origins of fractures include differential compaction, crustal stresses generated by plate motion or vertical motion of basement rocks, and the passage of storm waves.