Geophysical logging for mineral exploration and development

Abstract In today's mining industry, it is possible to retrieve, from small-diameter holes, geophysical data for qualitative interpretation in exploration and quantitative interpretation in the development of orebodies. The primary objectives in the exploration stage are to identify where, within a hole, economic minerals are, and to help in lithological interpretations. Other aspects, which are more quantitative, are the interpretation of downhole logs for parameters which can be used in surface geophysical methods (i.e. density for gravity surveys, acoustic velocities for seismic surveys, and magnetic susceptibility for airborne and ground magnetic surveys). Recent advances in equipment design, portability and durability have made downhole logging in exploration more inexpensive and reliable. This new equipment is being used to generate very precise quantitative results. This is especially true on uranium development projects. The interpretation of gamma logs for eU3O8 values has finally become precise enough that they have begun to replace chemical values in reserve calculations. Another part of development data is density and equilibrium information, which, with today's technology, is being derived from downhole probing. In the years to come, the trends for many metals are toward neutron activation techniques, or "in-situ assaying", and the use of multiple logs for better lithological and physical rock property determinations.
Keywords: Exploration, Geophysical exploration, Logging, Downhole logging, Uranium exploration, Radioactive logging, Electrical logging, Magnetic logging, Spontaneous potential, Resistivity, Induced polarization, Acoustic logs, Caliper logs, Temperature logs, Gamma-ray logging, Neutron logging.
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Summary: Previous methods have employed statistical analysis to model future mineral resources. The method presented in this paper uses Zipf's Law to determine the size and grade of tin deposits still to be discovered. The law is applied independently to both known deposit tonnage and grades. A probability distribution for both tonnage and grade is computed for those deposits still to be located and then, by applying a correlation between tonnage and grade, a distribution of the probability of metal...
Publication: CIM Bulletin
Author(s): VICTOR RUDENNO
Keywords: Exploration, Tin deposits, Statistical analysis, ZipPs Law, Tonnage, Grade, Tasmania.
Issue: 828
Volume: 74
Year: 1981
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Summary: Soil-gas Rn was measured by two types of alpha-particle-track detectors, by emanometry and by counting alpha-activity on Rn-decay-product collectors. Soil samples were analyzed for U by fluorimetric and fission-track methods, their Rn-emanation by decay-product collectors and their total alpha activities with track detectors. The same uranium anomalies were revealed by each method. Fission-track analysis of leaves for U showed only random variations with sampling site, and the Rn emanation of...
Publication: CIM Bulletin
Author(s): R.H. McCORKELL, J.W.M. PORRITT, M.P. BRAMELD
Keywords: Exploration, Geochemical exploration, Uranium, Copper, South March deposit, Soil sampling, Radon measurements, Biogeo-chemistry, Etched-track methods, Alpha particles, Emanometry, Fission-track analysis.
Issue: 828
Volume: 74
Year: 1981
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Summary: A new exploration procedure is proposed for volcanogenic massive sulphide deposits of the Abitibi belt. "Samples" of acidic volcanic rocks (SiO2 > 60%) were compiled from the literature. From the 574 samples collected, 322 were used in each of a number of experiments. Forward inclusion linear discriminant analysis performed on the untransformed geochemical data shows a general depletion in Na2O and CaO along with an enrichment in MgO for a "proximal" group of samples...
Publication: CIM Bulletin
Author(s): D. MARCOTTE, M. DAVID
Keywords: Exploration, Target definition, Kuroko deposits, Abitibi district, Discriminant analysis, Geochemical data, Massive sulphides, Normetal deposit.
Issue: 828
Volume: 74
Year: 1981
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Summary: New terrain maps provide information on the ground conditions in northern Ontario. This information has a relevance to mineral exploration because it assists the user in determining ground conditions prior to entering the area. The prospector, geologist, geophysicist and geochemist can then plan for the optimum use of exploration techniques best suited for these ground conditions.These terrain maps are the result of the Northern Ontario Engineering Geology Terrain Study—a program...
Publication: CIM Bulletin
Author(s): JOHN F. GARTNER
Keywords: Exploration, Terrain mapping, Ontario, Ground conditions, Overburden, Aerial surveys, Maps.
Issue: 828
Volume: 74
Year: 1981
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Summary: A summary is presented of the report completed by the Coal Mining Research Centre in 1980. This report was of a cross-pit conveyor system applied as an auxiliary mining complement to the major stripping unit, a dragline. The purpose of the CMRC report was to evaluate selective mining and replacement of the upper horizons of the strata as an aid in reclamation. These strata were the topsoil, subsoil and glacial till.Past utilization of cross-pit conveyor systems and related engineering studies...
Publication: CIM Bulletin
Author(s): R.W. ZEINDLER, D.A. FAWCETT
Keywords: Open-Pit mining, Conveyor systems, Cross-pit conveyors, Bridge conveyors, Coal mining, Stripping, Draglines, Reclamation, Bucket-wheel excavators.
Issue: 828
Volume: 74
Year: 1981
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Summary: The Norita deposit is an Archean volcanogenic-exhalative Fe-Zn-Cu sulphide accumulation of the distal type, consisting of six overlapping stratiform massive sulphide lenses, interbed-ded with exhalative cherts and thin pillow basalt flows, which formed down-topographic-slope from a mineralized hydrothermal discharge zone in the Norita rhyolite. The sulphide lenses are of two main types: channel-fill deposits such as the Main Zone and Main Zone West, composed of intricately layered pyrite-spha...
Publication: CIM Bulletin
Author(s): PJ. MacGEEHAN, W.H. MacLEAN, A.J. BONENFANT
Keywords: Exploration, Sulphide deposits, Massive sulphides, Ore genesis, Norita Mine, Matagami district, Zinc, Copper, Volcanic stratigraphy, Hydrothermal alteration.
Issue: 828
Volume: 74
Year: 1981
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Summary: Geophysical data are often presented on maps, sections or profiles with minimal data processing. A common example is magnetic data, in which the diurnal-free raw readings are merely contoured on a map. Other examples include profile presentation of VLF-EM data, IP pseudo-sections and airborne EM anomalies which may be shown on a map with only the measured amplitudes indicated.In recent years, efforts have been directed to the portraying of data in more useful forms. A number of algorithms...
Publication: CIM Bulletin
Author(s): DOUGLAS C. FRASER
Keywords: Exploration, Geophysical exploration, Algorithms, Data processing, Electromagnetic methods, Induced polarization, Resistivity, Magnetometers, Magusi River deposits.
Issue: 828
Volume: 74
Year: 1981
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