The use of geophysical surveying methods in the detection of natural cavities and mineshafts, 1987, Mccann D. M. , Jackson P. D. , Culshaw M. G. ,

The use of geophysical methods for the location of cavities and mineshafts is reviewed in relation to engineering problems at the site investigation stage. Their success is limited by the resolution and penetration achieved by the particular method applied in a given situation. It is shown that no one single geophysical method will provide the answer to all the problems associated with cavity location but considerable improvement can be achieved by the application of several methods to a given problem. It is suggested that for most standard geophysical methods it is possible to detect a cavity whose depth of burial is less than twice its effective diameter. The concept of effective diameter is shown to be of considerable importance since the presence of the cavity or mineshaft does affect the physical properties of the surrounding rock mass and, hence, gives rise to a far larger anomalous zone than that produced by the cavity on its own

IMPACT OF PAST SEDIMENT ECOLOGY ON ROCK FRACTURATION AND DISTRIBUTION OF CURRENT ECOSYSTEMS (JURA, FRANCE), 1991, Gaiffe M, Bruckert S,

Differences in the fracture type of limestone rocks have resulted in the formation of several main plant soil ecosystems in the montane and subalpine zones of the Jura (800-1 700 m). The sites were on stable landscape with slope < 5%. Locations were chosen to reflect the variation in physical properties of the bedrock and lithic contact. The rock fractures (densities and size), the shape and size of the fragments and the hydraulic conductivities were described and analyzed to characterize the 3 main bedrocks in the area studied (table 1): 1), lapiaz, ie, large rock fragments separated from each other by wide fractures (figs 1-2), 'broken' rocks traversed by numerous fine fractures (fig 2-3), paving-stones crossed by infrequent narrow fractures (fig 3). The effects of rock fracturing on vegetation (table II) and soil formation were significant in reference to porosity and permeability relationships (figs 6-7). Under similar precipitation, meteoric waters flow through the soil and porosity is relative to fracture systems (figs 4, 5). The weathering of cobbles in the soil profiles and along the lithic contacts maintains different soil solution Ca levels and is an important variable in soil and ecosystem formation (table III). Regarding the regional orogenic phases and the tectonic origin of the fractures, we postulate that the different types of fracturation originated from the different chemical and mineralogic composition of the rocks. Significant differences exist in both the calcite and dolomite content, in the insoluble residue content (table IV) and in the percentage of organic matter of the carbonate-free residues (table V, fig 8). The results indicate that the differences in rock composition arose early at about the period of sedimentation. The origin of the differentiation might be due to the sedimentation conditions and environment (fig 9). It is concluded that the present-day plant soil ecosystems may be related to the marine sediment environments of the Jurassic period (fig 10)

The detection of cavities using the microgravity technique: case histories from mining and karstic environments, 1997, Bishop I, Styles P, Emsley Sj, Ferguson Ns,

The presence of mining-related cavities (workings, shafts and tunnels) or karstic (solution cavities and sinkholes in limestone) within the top 100 m in the rock mass restricts land utilisation, and their migration to the surface may damage property or services or cause loss of life. Confirmation of features marked on existing plans prior to design and construction may be sufficient but it is often necessary to determine the detailed sub-surface structure. The standard method of siteinvestigation is to drill a pattern of boreholes to locate the spatial extent of any cavities. However, unless the spacing is less than the cavity dimensions it is possible to miss it completely. A cavity may be filled with air, water, or collapse material resulting in a contrast in physical properties which may be detected using appropriate geophysical methods. One powerful technique is microgravity which locates areas of contrasting sub-surface density from surface measurements of the earth's gravity. Although the method is fundamentally simple, measurement of the minute variations in gravity (1 in 108) requires sensitive instruments, careful data acquisition, and data reduction and digital data analysis. Final interpretation must be performed in conjunction with independent information about the site's history and geology. This paper presents three examples in both mining and karstic environments demonstrating that microgravity is a very effective technique for detectingand delineating cavities in the sub-surface

Karst geoindicators of environmental change: The case of Lithuania, 2002, Taminskas J. , Marcinkevicius V. ,

Karst is the result of an epigenetic geomorphologic process that may involve rapid changes to landscapes and their physical properties, with the newly formed relief complicating regional economic development and the protection of nature. The intensity of the karst process is closely linked with the circulation of surface and groundwater, so that the parameters characterising water circulation and chemical denudation can serve as indicators of the intensity of karstification. In this article, we describe the North Lithuanian karst region, and evaluate the influence of climate and hydrological conditions on karstification. Upper Devonian gypsum and dolomites occur beneath the Quaternary sediments here. Sinkholes frequently appear where the latter are particularly thin and underlain by gypsum, suggesting that karstification is intensifying. This is perhaps related to climate change expressed by an increase in mean annual temperature and runoff, especially during warm winters. To identify the main determinants of the karst processes, monitoring was carried out between 1994 and 1999, and data on river runoff and water chemistry from 1962 to 1999 were examined. From 1978 to 1999, the mean chemical denudation rate in the active gypsum karst zone was 30% higher than from 1962 to 1977, a change mirrored by the increased total volume of new sinkholes that appeared in the 1980s and 1990s. We have calculated the rate of chemical denudation and sink-hole formation in the last four decades and discuss karst activitiy as a geoindicator of environmental change

Coastal and submarine karstic discharges in theGokova Bay, SW Turkey, 2002, Bayari Cs, Kurttas T,

Hydrochemical, stable isotopic (18O and 2H) and thermal infrared data of LANDSAT 5 TM for sea surface temperature anomalies have been used to determine the extent and spatial variation of salinization in coastal and submarine karstic groundwater discharges in the Gokova Bay area, located in the SW Turkey. The bay is an active graben extending in an east-west direction. An artesian aquifer in the eastern tidal plain is the only source of fresh groundwater, whereas Tertiary and Mesozoic carbonates contacting with sea along the northern coastline provide abundant but saline water. Physical properties, major ion chemistry and stable isotope composition indicate a westward increase in the salinity of the karstic springs. The temporal variation of salinity in groundwater is either related to variations in sea level or in seasonal recharge rates, while some springs have time-invariant salinity. Submarine groundwater discharges were determined successfully from satellite images and verified by ground measurements of pH, temperature and electrical conductivity. Some of these discharges are also characterized by the existence of a halocline, as observed during Scuba diving. The westward-increasing salinity appears to be related to decreasing groundwater discharge in this direction