- Email: [email protected]
Magnetic features of fracture zones
23A
781220 ELECTROMAGNETIC M E ~ O D OF DET~qMINING THE DIMENSIONS OF THE ZONE OF INELASTIC DEFORMATION AROUND A MINE WORKING Z~orshchik, M P; Malyarchuk, A M Sov Min Sci, V12, N4, July-Aug 1976, P427-431 Proposes a rapid high frequency method based on the influence of the state of stress and the degree of fissuring of the rocks around the contour on their electrical resistivity. The equipment consists of a field generator, a field indicator and a transducer, the latter including a radiating magnetic dipole which is a component element of the output circuit of the field generator, and a field indicator receiving coil. 781221 APPLICATIONS OF SURFACE RESISTIVITY METHODS Schwartz, F W; McClymont, G L Ground Water, V15, N3, May-June 1977, P197-202 Reports a programme of resistivity measurements for aquifer location in the Breton area of Alberta. 781222 INTI~qPRETATION OF GRAVITY DATA WITH A PERIODICAL STRUCTURE Goldflam, P; Menzel, H; Szelwis, R Geoexploration, V15, N3, July 1977, P155-161 A method of the interpreation of gravity data is theoretically developed from models with interfaces of periodical structure. The basic equations are discussed for a single layer, whose lower boundary has a continous cosine-wave form. With the help of the principle of superposition the formula for the m-layer case is derived and tested on model data. The method described may readily be extended to more general forms of gravity-anomaly structUres. 781223 MAGNETIC FEATURES OF FRACTURE ZONES Henkel, H; Guzman, M Geoexploration, V15, N3, July 1977, P173-181 During interpretation of low-altitude aeromagnetic and ground magnetic measure~nants linear magnetic minima are frequently observed, often attributed to linear fracture zones. Detailed petrophysical studies have been made on an outcropping fracture zone showing a negative magnetic anomaly. The magnetic susceptibility has been measured in situ and the variable content of opaque minerals has been studied in polished sections. It was found that the observed linear magnetic minima are caused by a combination of a fault graben and the oxidation of magnetite to hematite. The latter effect is dominating and the alteration process (martitization) is shown on a susceptibility-Q-value diagram. 781224 REFLECTIONS ON SHALLOW SEISMIC REFRACTION RECORDS Hunter, J A; Hobson, G D Geoxploration, V15, N3, July 1977, P183-193 Reflections from the overburden-bedrock interface have been interpreted from han~em seismic refraction records and substantiated by conventional wiggle-trace records. In the areas studied, the bedroek reflection appears to be a prominent and persistent later event where overburden is thick (3Ore). Record analyses utilizing both reflected and refracted events may result in greater reliability of interpretations in shallow seismic prospecting.
781225 SHALLOW SEISMIC REFLECTION PROFILING ON LAND USING A CONTROTI.~D SOURCE Nunn~ K R; Boztas, M Geoexploration, V15, N2, April 1977, P87-97 A small seismic reflection system using a controlled source and digital recording has been developed for shallow, land-based operations. Results are presented of a short reflection profile over a section of the pre-glacial valley of the River-Teifi near Cardigan, where up to 50m of glacial deposits overlie Ordovician slates. The results are compared with a previously reported refraction profile recorded in the same area. 781226 DETECTION OF DISUSED V~qTICAL MINESHAFTS AT SHALLOW DEPTHS BY GEOELECTRICALMETHODS Worthington, P F; Barker, R D Geoexploratlon, V15, N2, April 1977, Plll-120 Concealed brick-llned mineshafts have been successfully located by electrical resistivity surveying with a configuration of four equidistant electrodes. The field interpretation makes reference to type curves derived from model studies. Using these data it is demonstrated that the characteristic resistivity anomalies also indicate the approximate shaft diameter and limiting depth of burial. The method is illustrated by field examples from levelled sites. 781227 NEAR-FIELD OF A SEISMIC SOURCE IN A LAYERED MEDIUM WITH IRREGULAR INTERFACES Bouchon, M; Aki, K Geophys J R Astr Soe, V50, N3, Sept 1977, P669-684 Considers the problem of seismic scattering at irregular boundaries in the vicinity of a complex seismic source. 781228 REFLECTION PROFILE F~DDELLING SYSTHZM Smith, S G Geophys J R Astr Soc, Vh9, N3, June 1977, P723-737 Discusses the development of a modelling system to synthesize seismic reflection profiles and gives examples for marine profiles. The system can be applied to land profiles by alteration of the source and receiver effects and the multiple generation.
Subjects Peripheral to Geomechanics 781229 RESPONSE OF FoIL STRAIN GAGES TO HYDRAULIC PRESSURE Foster, C G Exp Mech, V17, NI, Jan 1977, P26-32 Strain gauges were in~nersed in a pressurised !lyd~aulic environment and subjected to various bi~xia].~stress states as well as fluctuating pressures. It was found that the distortion of the material must be considered together with the pressure, and that rate of presstu'isation, and he/ice strain rate, h~i no me~surable effect.
781220 ELECTROMAGNETIC M E ~ O D OF DET~qMINING THE DIMENSIONS OF THE ZONE OF INELASTIC DEFORMATION AROUND A MINE WORKING Z~orshchik, M P; Malyarchuk, A M Sov Min Sci, V12, N4, July-Aug 1976, P427-431 Proposes a rapid high frequency method based on the influence of the state of stress and the degree of fissuring of the rocks around the contour on their electrical resistivity. The equipment consists of a field generator, a field indicator and a transducer, the latter including a radiating magnetic dipole which is a component element of the output circuit of the field generator, and a field indicator receiving coil. 781221 APPLICATIONS OF SURFACE RESISTIVITY METHODS Schwartz, F W; McClymont, G L Ground Water, V15, N3, May-June 1977, P197-202 Reports a programme of resistivity measurements for aquifer location in the Breton area of Alberta. 781222 INTI~qPRETATION OF GRAVITY DATA WITH A PERIODICAL STRUCTURE Goldflam, P; Menzel, H; Szelwis, R Geoexploration, V15, N3, July 1977, P155-161 A method of the interpreation of gravity data is theoretically developed from models with interfaces of periodical structure. The basic equations are discussed for a single layer, whose lower boundary has a continous cosine-wave form. With the help of the principle of superposition the formula for the m-layer case is derived and tested on model data. The method described may readily be extended to more general forms of gravity-anomaly structUres. 781223 MAGNETIC FEATURES OF FRACTURE ZONES Henkel, H; Guzman, M Geoexploration, V15, N3, July 1977, P173-181 During interpretation of low-altitude aeromagnetic and ground magnetic measure~nants linear magnetic minima are frequently observed, often attributed to linear fracture zones. Detailed petrophysical studies have been made on an outcropping fracture zone showing a negative magnetic anomaly. The magnetic susceptibility has been measured in situ and the variable content of opaque minerals has been studied in polished sections. It was found that the observed linear magnetic minima are caused by a combination of a fault graben and the oxidation of magnetite to hematite. The latter effect is dominating and the alteration process (martitization) is shown on a susceptibility-Q-value diagram. 781224 REFLECTIONS ON SHALLOW SEISMIC REFRACTION RECORDS Hunter, J A; Hobson, G D Geoxploration, V15, N3, July 1977, P183-193 Reflections from the overburden-bedrock interface have been interpreted from han~em seismic refraction records and substantiated by conventional wiggle-trace records. In the areas studied, the bedroek reflection appears to be a prominent and persistent later event where overburden is thick (3Ore). Record analyses utilizing both reflected and refracted events may result in greater reliability of interpretations in shallow seismic prospecting.
781225 SHALLOW SEISMIC REFLECTION PROFILING ON LAND USING A CONTROTI.~D SOURCE Nunn~ K R; Boztas, M Geoexploration, V15, N2, April 1977, P87-97 A small seismic reflection system using a controlled source and digital recording has been developed for shallow, land-based operations. Results are presented of a short reflection profile over a section of the pre-glacial valley of the River-Teifi near Cardigan, where up to 50m of glacial deposits overlie Ordovician slates. The results are compared with a previously reported refraction profile recorded in the same area. 781226 DETECTION OF DISUSED V~qTICAL MINESHAFTS AT SHALLOW DEPTHS BY GEOELECTRICALMETHODS Worthington, P F; Barker, R D Geoexploratlon, V15, N2, April 1977, Plll-120 Concealed brick-llned mineshafts have been successfully located by electrical resistivity surveying with a configuration of four equidistant electrodes. The field interpretation makes reference to type curves derived from model studies. Using these data it is demonstrated that the characteristic resistivity anomalies also indicate the approximate shaft diameter and limiting depth of burial. The method is illustrated by field examples from levelled sites. 781227 NEAR-FIELD OF A SEISMIC SOURCE IN A LAYERED MEDIUM WITH IRREGULAR INTERFACES Bouchon, M; Aki, K Geophys J R Astr Soe, V50, N3, Sept 1977, P669-684 Considers the problem of seismic scattering at irregular boundaries in the vicinity of a complex seismic source. 781228 REFLECTION PROFILE F~DDELLING SYSTHZM Smith, S G Geophys J R Astr Soc, Vh9, N3, June 1977, P723-737 Discusses the development of a modelling system to synthesize seismic reflection profiles and gives examples for marine profiles. The system can be applied to land profiles by alteration of the source and receiver effects and the multiple generation.
Subjects Peripheral to Geomechanics 781229 RESPONSE OF FoIL STRAIN GAGES TO HYDRAULIC PRESSURE Foster, C G Exp Mech, V17, NI, Jan 1977, P26-32 Strain gauges were in~nersed in a pressurised !lyd~aulic environment and subjected to various bi~xia].~stress states as well as fluctuating pressures. It was found that the distortion of the material must be considered together with the pressure, and that rate of presstu'isation, and he/ice strain rate, h~i no me~surable effect.