Humus and till geochemistry over the Doyon, Bousquet and Williams gold deposits

Abstract The results of humus and overburden geochemical surveys over the Doyon, Bousquet and Page- Williams gold ore deposits are presented. These studies show that humus sampling for gold gives negative results over the Doyon deposit. The lack of response is probably caused by the presence of 1 m of relatively impermeable glaciolacustrine clay and silt that overlies 1 m to 2 m of till over the surface expression of the ore zone. By contrast, positive responses for gold occur in humus samples over the Page-Williams A and C gold deposits. The "A " ore zone is covered by several metres of exotic calcareous till over 0.5 m to 1 m of older, locally derived till. Anomalous values for gold in humus range from 10 to 35 ppb over the orebody. Overburden over the "C" ore zones is much thinner, generally it consists of less than 2 m of sandy till. Trenching humus anomalies that range from 10 to 1360 ppb Au uncovered the gold mineralization.
The geochemical dispersal trains in till from the Doyon ore-body and the Page- Williams "A "zone are relatively short (i.e. less than 200 m) because both deposits occur in the lee of bedrock highs that shielded them from extensive glacial quarrying. Dispersal trains from all three pyritic gold deposits can be defined using either the fine fraction or heavy mineral fraction of the till.
The intensity of the gold in till anomalies over the ore zones is variable. Therefore, it would be misleading to attach rigid significant threshold gold values to overburden drilling results. Each case must be evaluated based on bedrock topography, sample density, overburden type, thickness of till, as well as size, type and orientation of the target exposed to glacial erosion.
Keywords: Mineral exploration, Geochemical surveys, Gold ore deposits, Humus geochemistry, Till geochemistry, Overburden drilling.
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Summary: This paper illustrates the different ways grade-tonnage curves can be generated for a mineral deposit. It emphasizes systematic discrepancies between reality, estimates and actual production according to different estimation methods and grade control programs. It does not offer a universal solution to the prediction of grade-tonnage curves. Hopefully, it will inspire caution to mineral economists who use estimated grade and tonnage data in the establishment of an optimum cut-off grade for a...
Publication: CIM Bulletin
Author(s): MICHEL DAGBERT
Keywords: Geostatistics, Statistics, Estimation methods, Cut-off grades, Grade-tonnage curve, Grade distribution, Mining dilution, Selective mining units, Kriging.
Issue: 898
Volume: 80
Year: 1987
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Summary: This paper documents the characteristics of the different quartz veins, and their relation to gold, in the turbiditic Meguma domain of eastern Nova Scotia. Eleven different types have been distinguished in the greenschist fades on the basis of form, internal structure, mineralogy, wall rock alteration and crosscut-ting relationships to each other and to regional structures. Gold is present as rare visible disseminations in host rock slates and in ore-grade, early-formed veins, that pre-date...
Publication: CIM Bulletin
Author(s): S.J. HAYNES
Keywords: Mineral exploration, Gold, Greenschist facies, Quartz veins, Meguma group, Mineralogy.
Issue: 898
Volume: 80
Year: 1987
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Summary: The unconformity beneath 75 per cent or over 6000 km? of the Athabasca Basin in Alberta lies within economically exploitable depths. The basement beneath this unconformity consists of an extension of the Wylie Lake Pluton, locally faulted and containing areas ofmylonitic rocks. While the rocks of the Wylie Lake Pluton are not promising host rocks for uranium ore deposits, the areas ofmylonites, graphitic rocks and possible remnants of granite gneiss would bear closer examination. One area of...
Publication: CIM Bulletin
Author(s): JOHN WILSON
Keywords: Mineral exploration, Economic geology, Athabasca Basin, Uranium deposits, Alberta, Geochemistry.
Issue: 898
Volume: 80
Year: 1987
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Summary: Basal till sampling techniques were used to search for gold mineralization in the Timmins, Ontario area. During 1978 and 1979, approximately 90 overburden sampling drill holes were completed in Murphy and Hoyle Townships to test specific geophysically defined target areas. A conventional tricone dual tube drill system, and a unique retractable tricone/rock coring system were used to various advantages.
First pass till sampling at 800 to 1200 ft intervals perpendicular to ice transport...
Publication: CIM Bulletin
Author(s): G.A. HARRON, R.S. MIDDLETON, R.B. DURHAM, A. PHILIPP
Keywords: Mineral exploration, Geochemistry, Geophysics, Gold exploration, Till, Mineralization, Surveys, Drilling.
Issue: 898
Volume: 80
Year: 1987
Text
Summary: La scorie produite par le proc^de pyrometallurgique d'extrac-tion Noranda contlent environ 5% de cuivre. Elle est traitee comme un mineral conventionnel de cuivre au concentrateur de Mines Noranda et les rejets deflottation presentent encore des teneurs souvent superieures a 0.3% en cuivre. La scorie est principalement constitute de magnetite, de fayalite et d'un verre siliceux. Bien sur, le cuivre y est majoritairement sous forme de sulfures et d'un peu de cuivre metallique. Le verre...
Publication: CIM Bulletin
Author(s): M.A. BERUBE, M. CHOQUETTE, P.W. GODBEHERE
Keywords: Copper slags, Ore mineralogy, Ore microscopy, Electron microprobe analysis, Ore processing, Mineral liberation, Noranda Mines.
Issue: 898
Volume: 80
Year: 1987
Text
Summary: The increase in the price of gold in the last decade has led to a significant increase in placer gold exploration around the world. Placer deposits occur in depressions along ancient river and stream channels. In many instances these channels have been covered with materials from subsequent erosion or glacial activity. Use of high resolution geophysical techniques to map the bedrock and soil strata can improve the probability of finding the placer deposits. The buried bedrock surface is often...
Publication: CIM Bulletin
Author(s): J.L DAVIS
Keywords: Mineral exploration, Placer exploration, Ground probing radar, Geomorphology, Stratigraphy, Seismic sounding, Radar, Data processing.
Issue: 898
Volume: 80
Year: 1987
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