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Introduction to mineral exploration
308A
SITE INVESTIGATIONS:REMOTE SENSING
967136 Electric signals recorded during uniaxial compression of rock samples: their possible correlation with preseismic electric signals V. Hadjicontis Jr C. Mavromatou, Acta Geophysics Polonica, 43(l), 1995, pp 49-61. During the uniaxial compression of various kinds of rock samples, two kinds of electric signals were recorded prior to sample’s failure: (a) slow transient electric signals, detected mainly in the macroscopic elastic region, which seem to follow the first time derivative of the externally applied load; (b) near-field electromagnetic disturbances in the frequency range from some kHz to some MHz, detected mainly at the microfracturing region, the intensity of which strongly increases while approaching to failure. (from Authors)
Identification
and classification
967137 Correlation between Barton’s Q and Bieniawski’s RMR - a new approach R. K. Goel, J. L. Jethwa & A. G. Paithankar, International Journal of Rock Mechanics & Mining Sciences, 33(2), 1996, pp 179-181. Relations between the two most widely used classification indices, the rock mass rating RMR of Bieniawski and the rock mass quality & of Barton et al., have been proposed by many researchers. None of the correlations provide a good relation between RMR and Q. A new approach to obtain a reliable relation is proposed. The proposed relation between N and RCR is better than the correlations between Q and RMR which are not equivalent. A relation is given that has a higher reliability and can be used for converting Q and RMR and vice-versa. (from Authors)
IN SITU
STRESS
Measurement
of in situ stress
967138 Crack closure pressures inferred from ultrasonic drill-core measurements to 8 km depth in the KTB wells A. Zang, H. Berckhemer & M. Lienert, Geophysical Journal International, 124(3), 1996, pp 657-674. Ultrasonic P-wave traveltimes were examined in 73 directions of cylindrical core speciments, measuring 30 mm in length and in diameter, at room temperature in a 400 MPa pressure vessel. The wave-velocity analysis was carried out on 66 crystalline drill cores taken at depths of between 127 and 3888 m in the KTB-VB well and on 18 drill cores taken at depths of between 4195 and 8080 m in the KTB-HB well. Based on omnidirectional wave velocities versus pressure, a method is developed to separate crack-caused and textural velocity anisotropies. The crack-caused part of the velocity anisotropy is used to infer crack closure pressures. Results support the previously determined average &-direction of N162”E at the drill site only in the suite of metabasites at depths ranging from 3629 to 3746 m. (from Authors)
SITE INVESTIGATION OBSERVATION
AND FIELD
General 967139 Introduction to mineral exploration
ed A. M. Evans, (Blackwell Science), ISBN (paperback) 0 632 02427 5, price f27.50, 1995, 396 pp, index. This book covers the nature of mineral exploration, including its economics, and the principle techniques employed in prospecting programmes. It also discusses other factors and
decisions essential to an exploration programme: target evaluations and pre-development studies. Part 1 contains 10 chapters on principles, and part 2 comprises 6 case studies of deposit types, selected for their variety and different geochemical, geophysical and other problems that they present to the mineral prospector. (from Publisher) 967140 Deep-sea mineral activity in Japan S. Nakao, Marine Technology Society Journal, 29(3), 1995, pp 74-78. The Ministry of International Trade and Industry and the Metal Mining Agency of Japan have been conducting longterm projects to prospect deep-sea minerals represented by manganese nodules since 1975 in mostly high sea areas. At the same time, the Japan International Cooperation Agency has been supporting deep-sea mineral prospecting in SOPAC (South Pacific Applied Geoscience Commission) country waters. The Technology Research Association of the Ocean Resources Development System has been acting in research and development of mining systems for deep-sea manganese nodules since 1981 under the Agency of Industrial Science and Technology, Ministry of International Trade and Industry. Field tests of the prototype machines will be carried out in a few years. (Author)
Remote sensing and photographic techniques 967141 Precise emissivlty of rock samples B. Rivard, P. J. Thomas & J. Giroux, Remote Sensing of Environment, 54(2), 1995, pp 152-160. To differentiate among geological materials and vegetation using thermal infrared spectra, radiometric measurements require corrections for local temperature variations and reflected radiation. A laboratory technique is described for the determination of spectral emissivity signatures for nature1 geological samples using a Fourier Transform Infrared Spectrometer and the self-emission of the scene. (from Authors) 967142 The application of imaging spectrometry data to mapping alteration zones associated with gold mineralization in southern Spain G. Ferrier & G. Wadge, International Journal of Remote Sensing, 17(2), 1996, pp 331-350. This study indicates that radiative transfer modelling, using only atmospheric information derived from the imaging spectrometry data, can satisfactorily correct the atmospheric effects involved in retrieving apparent surface reflectance. The alteration at Rodalquilar is characterized by propylitic (vermiculite), illitic, kaolinitic (pyrophyllitic), alunitic and silicic zones with an increasing degree of alteration towards the formative hydrothermal cells in whose fossil cores the gold mineralization is found. However, several factors act against the usefulness of the AVIRIS data for manoinz these r&era1 zones: the mine site is heavily disturbed w&h exposed workings, often of high albedo altered rocks, whilst unworked areas have partial iron-rich soil and dry vegetation cover; the alteration itself is highly discontinuous at the scale of 10 m and the shortwave infrared (SWIR) data where much of the diagnostic information for these hydrothermal minerals lies is very noisy. Nevertheless it has proved possible to map successfully, at the individual pixel level, the zones of goldbearing alunitic alteration. (from Authors) 967143 Spectral reflectance of carbonate mineral mixtures and bidirectional reflectance theorv: auantitative analvsis techniques for application in remote sensing ~7.V~ der Meer, Remote Sensing Reviews, 13(1-2), 1995, pp - .
SITE INVESTIGATIONS:REMOTE SENSING
967136 Electric signals recorded during uniaxial compression of rock samples: their possible correlation with preseismic electric signals V. Hadjicontis Jr C. Mavromatou, Acta Geophysics Polonica, 43(l), 1995, pp 49-61. During the uniaxial compression of various kinds of rock samples, two kinds of electric signals were recorded prior to sample’s failure: (a) slow transient electric signals, detected mainly in the macroscopic elastic region, which seem to follow the first time derivative of the externally applied load; (b) near-field electromagnetic disturbances in the frequency range from some kHz to some MHz, detected mainly at the microfracturing region, the intensity of which strongly increases while approaching to failure. (from Authors)
Identification
and classification
967137 Correlation between Barton’s Q and Bieniawski’s RMR - a new approach R. K. Goel, J. L. Jethwa & A. G. Paithankar, International Journal of Rock Mechanics & Mining Sciences, 33(2), 1996, pp 179-181. Relations between the two most widely used classification indices, the rock mass rating RMR of Bieniawski and the rock mass quality & of Barton et al., have been proposed by many researchers. None of the correlations provide a good relation between RMR and Q. A new approach to obtain a reliable relation is proposed. The proposed relation between N and RCR is better than the correlations between Q and RMR which are not equivalent. A relation is given that has a higher reliability and can be used for converting Q and RMR and vice-versa. (from Authors)
IN SITU
STRESS
Measurement
of in situ stress
967138 Crack closure pressures inferred from ultrasonic drill-core measurements to 8 km depth in the KTB wells A. Zang, H. Berckhemer & M. Lienert, Geophysical Journal International, 124(3), 1996, pp 657-674. Ultrasonic P-wave traveltimes were examined in 73 directions of cylindrical core speciments, measuring 30 mm in length and in diameter, at room temperature in a 400 MPa pressure vessel. The wave-velocity analysis was carried out on 66 crystalline drill cores taken at depths of between 127 and 3888 m in the KTB-VB well and on 18 drill cores taken at depths of between 4195 and 8080 m in the KTB-HB well. Based on omnidirectional wave velocities versus pressure, a method is developed to separate crack-caused and textural velocity anisotropies. The crack-caused part of the velocity anisotropy is used to infer crack closure pressures. Results support the previously determined average &-direction of N162”E at the drill site only in the suite of metabasites at depths ranging from 3629 to 3746 m. (from Authors)
SITE INVESTIGATION OBSERVATION
AND FIELD
General 967139 Introduction to mineral exploration
ed A. M. Evans, (Blackwell Science), ISBN (paperback) 0 632 02427 5, price f27.50, 1995, 396 pp, index. This book covers the nature of mineral exploration, including its economics, and the principle techniques employed in prospecting programmes. It also discusses other factors and
decisions essential to an exploration programme: target evaluations and pre-development studies. Part 1 contains 10 chapters on principles, and part 2 comprises 6 case studies of deposit types, selected for their variety and different geochemical, geophysical and other problems that they present to the mineral prospector. (from Publisher) 967140 Deep-sea mineral activity in Japan S. Nakao, Marine Technology Society Journal, 29(3), 1995, pp 74-78. The Ministry of International Trade and Industry and the Metal Mining Agency of Japan have been conducting longterm projects to prospect deep-sea minerals represented by manganese nodules since 1975 in mostly high sea areas. At the same time, the Japan International Cooperation Agency has been supporting deep-sea mineral prospecting in SOPAC (South Pacific Applied Geoscience Commission) country waters. The Technology Research Association of the Ocean Resources Development System has been acting in research and development of mining systems for deep-sea manganese nodules since 1981 under the Agency of Industrial Science and Technology, Ministry of International Trade and Industry. Field tests of the prototype machines will be carried out in a few years. (Author)
Remote sensing and photographic techniques 967141 Precise emissivlty of rock samples B. Rivard, P. J. Thomas & J. Giroux, Remote Sensing of Environment, 54(2), 1995, pp 152-160. To differentiate among geological materials and vegetation using thermal infrared spectra, radiometric measurements require corrections for local temperature variations and reflected radiation. A laboratory technique is described for the determination of spectral emissivity signatures for nature1 geological samples using a Fourier Transform Infrared Spectrometer and the self-emission of the scene. (from Authors) 967142 The application of imaging spectrometry data to mapping alteration zones associated with gold mineralization in southern Spain G. Ferrier & G. Wadge, International Journal of Remote Sensing, 17(2), 1996, pp 331-350. This study indicates that radiative transfer modelling, using only atmospheric information derived from the imaging spectrometry data, can satisfactorily correct the atmospheric effects involved in retrieving apparent surface reflectance. The alteration at Rodalquilar is characterized by propylitic (vermiculite), illitic, kaolinitic (pyrophyllitic), alunitic and silicic zones with an increasing degree of alteration towards the formative hydrothermal cells in whose fossil cores the gold mineralization is found. However, several factors act against the usefulness of the AVIRIS data for manoinz these r&era1 zones: the mine site is heavily disturbed w&h exposed workings, often of high albedo altered rocks, whilst unworked areas have partial iron-rich soil and dry vegetation cover; the alteration itself is highly discontinuous at the scale of 10 m and the shortwave infrared (SWIR) data where much of the diagnostic information for these hydrothermal minerals lies is very noisy. Nevertheless it has proved possible to map successfully, at the individual pixel level, the zones of goldbearing alunitic alteration. (from Authors) 967143 Spectral reflectance of carbonate mineral mixtures and bidirectional reflectance theorv: auantitative analvsis techniques for application in remote sensing ~7.V~ der Meer, Remote Sensing Reviews, 13(1-2), 1995, pp - .