Genetic concepts versus observational data in governing ore exploration

Abstract Over the years, ore geologists have made innumerable observations as to the relationships of certain kinds of ore deposits to particular types of rocks and to the types of primary and secondary structures that these rocks contain. On the basis of these, the places in which to look for new ore deposits are more clearly defined than they would be in an exploration program based largely or solely on concepts of ore genesis. This paper discusses the affinity of certain rock types and structures for such ore deposits as: (1) tin-tungsten associated with granitoid rocks; (2) lead-zinc of simple mineralogy in carbonate rocks; (3) massive base-metal sulphides in sedimentary or volcanic rocks; (4) massive base-metal sulphides and oxides at, or near, contacts with igneous rocks; (5) gold or gold-uranium in, or adjacent to, conglomerates; (6) shale- or sandstone-hosted copper; and (7) porphyry coppers. Additional varieties could be considered, but it appears that these examples are sufficient to demonstrate the validity of the suggestion that the use of observational characteristics is far more useful in mineral exploration than that of theories of ore genesis.
As by-products of the theory of plate tectonics, many concepts have been put forward to explain how ore deposits of different kinds have been formed. Most, if not all, of these theories seem to be as valid as present-day informatin permits. However, do these ideas add to the ability of the ore geologist to find ore deposits? I doubt it, and offer reasons as to why I think so.
To produce maximum results in any exploration program, the one that makes the greatest use of information produced about the geologic environment of the area being investigated is the one that will provide the greatest return in deposits found for the sponsors of the program. Such exploration is best designated as total exploration, and it certainly is the most effective way of uncovering such new deposits as may exist in the area being studied in particular and of adding to the sum total of non-fuel minerals deposits available to the industrial world in general.
It is reasonably estimated that, in searching for deposits of non-fuel minerals, the contribution provided by the totality of tools available for exploration (excluding geochemical, geophysical and remote sensing data) derives 75 per cent from an understanding of the stratigraphy of the area, including the relationships of all rocks to each other—sedimentary, igneous and metamorphic. Of the remaining 25 per cent, three-quarters of that is made up of a comprehension of the structures—internal and external—of the rocks involved, with both mega- and microstructures being determined and used. The final quarter of that 25 per cent is provided from all other geologic knowledge obtained by the team engaged in the exploration process. Such knowledge includes the identities of the minerals present—ore, gangue and wall-rock; their paragenetic relationships (mega- and microscopic) to each other (in the narrow sense); the temperatures at which they were introduced (or metamorphosed), as determined by fluid inclusion, isotope and other studies; and concepts as to how the deposits sought may have been formed.
Keywords: Mineral exploration, Economic geology, Exploration geology, Plate tectonics, Tin-tungsten deposits, Lead-zinc deposits, Sulphide deposits, Gold deposits, Uranium deposits, Porphyry copper deposits.
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Publication: CIM Bulletin
Author(s): N. SARACOGLU, R.H. WALLIS, J.J. BRUMMER, J.P. GOLIGHTLY
Keywords: Mineral exploration, McClean deposits, Uranium, Saskatchewan, Canadian Occidental Petroleum Ltd., Inco Limited, Rabbit Lake, Track-Etch survey, Geophysics, Drilling, INPUT survey.
Issue: 852
Volume: 76
Year: 1983
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Summary: The Fond-du-Lac uranium deposit was delineated primarily by percussion drilling and a small program of diamond drilling. Drillcore samples from three diamond drill holes as well as digitized gamma logs from percussion and diamond drill holes were utilized to define and implement an algorithm for the conversion of gamma-log data to equivalent-grade data. The procedures and detailed analysis for the provision of assay data for uranium reserve estimation are documented.
Publication: CIM Bulletin
Author(s): J.H. AHRENS, D.M. WARD
Keywords: Mineral exploration, Fond-du-Lac deposit, Uranium deposit, Diamond drilling, Percussion drilling, Gamma logs, Eldorado Nuclear Ltd., Famok Limited.
Issue: 852
Volume: 76
Year: 1983
Text
Summary: Induced polarization/resistivity and magnetometer surveys have been carried out over the Casmo molybdenite deposit in mountainous terrain of northern British Columbia. Molybdenite occurs in quartz-bearing fractures with or without pyrite along a zone of hydrothermal alteration and intense fracturing, believed to be a northerly dipping fault zone, within medium-grained equigranular and porphyritic quartz monzonite.
The molybdenite-bearing zone is characterized by a significant resistivity low,...
Publication: CIM Bulletin
Author(s): A. SACIT SAYDAM
Keywords: Mineral exploration, Casmo deposit, Molybdenite deposit, Magnetometer surveys, IP resistivity surveys, Geophysics.
Issue: 852
Volume: 76
Year: 1983
Text
Summary: Cominco Ltd.'s Polaris Mine, located on Little Cornwallis Island, Northwest Territories (latitude 75 degrees 30') went into production in late 1981, becoming the world's most northerly base metal mine. The concentrator, powerhouse, shops, offices, dry and warehouse, were uniquely designed and constructed on a 100 ft wide by 400 ft long by 65 ft high barge. This process barge was constructed in southern Canada, at Trois Rivieres, then towed 3,500 miles into the High Arctic Islands and beached...
Publication: CIM Bulletin
Author(s): JAMES K. GOWANS
Keywords: Arctic Mining, Polaris process barge, Flotation, Concentrator, Grinding, Crushing, Lead, Zinc, Cominco Ltd.
Issue: 852
Volume: 76
Year: 1983
Text
Summary: Zinc, which once enjoyed an unchallenged position in the field of decorative applications, has lost a substantial share of its markets to other materials, particularly plastics. This turn of events has led the zinc industry to explore new market areas, particularly those applications where the engineering properties of zinc can be utilized. This paper gives an overview of the zinc industry's efforts to develop the data base and product development technology which have enabled zinc alloys to...
Publication: CIM Bulletin
Author(s): GENE O. COWIE
Keywords: Materials engineering, Zinc, 1LZRO, Zinc alloys, Product development, Design technology, Die casting.
Issue: 852
Volume: 76
Year: 1983
Text
Summary: This paper describes the development of a milling circuit for the complex Midwest orebody, containing a high-arsenic uranium ore typical of that found in northern Saskatchewan. The results of preliminary bench-scale testwork are summarized. Data from a pilot-plant program carried out at the Ontario Research Foundation are provided for the selected mill flowsheet. Also described are waste circuits which have been established to produce effluents of acceptable quality. Pilot-plant testing of...
Publication: CIM Bulletin
Author(s): L.A. MELIS, K.S. FRASER, V. LAKSHMANAN
Keywords: Uranium, Midwest uranium deposit, Waste treatment, Leaching, Atmospheric leaching, Caro's acid, Pressure acid leachingi Grinding, Solvent extraction.
Issue: 852
Volume: 76
Year: 1983
Text
Summary: Sample drops were evaporated on Lexan disks on which fission tracks were etched and counted after neutron irradiation. [U] < 0.01 ppb could be measured. This method is rapid, cheap, simple and accurate when sufficient control and checking is possible, but several types of error were encountered in its use, the natures and sources of which were investigated but not always determined. The most troublesome were "annealing" processes which sometimes altered the fission tracks so that...
Publication: CIM Bulletin
Author(s): R.H. McCORKELL
Keywords: Geochemical exploration, Uranium exploration, Fission-track, Chemical analysis, Uranium analysis, Water analysis, Natural waters.
Issue: 852
Volume: 76
Year: 1983
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