Paleotectonic settings of volcanogenic massive sulphide deposits in the Dunnage Zone, Newfoundland Appalachians

Abstract sulphide (VMS) deposits. Geochemical, isotopic and geochronological studies show that the vestiges of lapetus in Newfoundland probably record a complex series of island arcs and back-arc basins that were marginal to, rather than part of, the main ocean basin of lapetus. The geochemical and isotopic data provide a means of characterizing the tectonic environment of individual volcanic sequences, and allow us to identify a number of distinct tectonic environments in which VMS deposition took place.
Four tectonic environments have been identified as being associated with VMS deposition: (1) back-arc environments hosting VMS deposits include both N-MORB-type ophiolites (e.g. Skidder?) and volcanic sequences with oceanic island (or within plate) tholeiite characteristics (e.g. Great Burnt Lake); (2) primitive arc environments include both supra-subduction zone (SSZ) ophiolites (e.g. BettsCove, Rambler) and volcanic/epiclastic sequences (e.g. Point Leamington, Duck Pond) and are characterized by abundant arc tholeiites, with lesser refractory lavas and rhyolites; (3) mature arc environments comprise dominantly thick felsic and mafic volcanic piles in the Buchans - Robert's Arm Belt (including the Buchans camp) and are characterized by dominantly calc alkalic basalt and andesite; and (4) continental rift environments occur in the Hermitage Flexure area (e.g. Strickland deposit) and are characterized by dominantly felsic volcanic sequences.
Island arc environments are by far the most prolific hosts to VMS deposits. Patterns of VMS distribution in central Newfoundland show that similar tectonic settings may be recorded by very different stratigraphic sequences (e.g. both ophiolites and thick volcanic/epiclastic sequences may record primitive arc rifting) and emphasize the importance of the rifting in VMS generation, irrespective of the details of the tectonic or stratigraphic setting. The ability to judge the prospectiveness of a volcanic sequence by using whole rock geochemistry to evaluate its tectonic environment may prove useful in area selection at the grassroots exploration level.
Keywords: Exploration, Volcanogenic massive sulphide deposits, Mineral deposits, Dunnage Zone, Newfoundland Appalachians.
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Summary: Pilot plant testwork on autogenous and semi-autogenous grinding was conducted at the Centre des Recherches Minerales du Quebec (CRM) to investigate the effect of ball addition, solids concentration in the feed, specific energy consumption and feed size distribution.
A mathematical model that incorporates breakage and surface mechanisms of loss of mass was developed to predict load size distribution of autogenous and semi-autogeneous mills. An empirical model was used to predict product size...
Publication: CIM Bulletin
Author(s): Mary Goldman
Keywords: Autogenous grinding, Semi-autogenous grinding, Abrasion, Breakage, Modelling.
Issue: 946
Volume: 84
Year: 1991
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Summary: The pendulum in Ottawa has swung dramatically from fiscal policy to monetary policy over the last several years. International trends indicate that the pendulum has to start its swing the other way, if Canada's mining industry is to maintain its preeminent position in the global mining arena. This article, which is based on a paper presented by the author at the 37th Annual Meeting of the Newfoundland Branch of CIM, identifies these trends and how they could interact with Canadian policy.
Publication: CIM Bulletin
Author(s): Robert B. Parsons
Issue: 946
Volume: 84
Year: 1991
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Summary: It is well known that the classification system of volcanogenic massive sulphides (VMS) is based upon their metal content. This metal content, the result of hydrothermal solutions circulating within strata underlying the deposits, is generally thought to be related directly to two parameters: (1) the nature of the underlying stratigraphic sequence; and (2) the physico-chemical conditions that existed at the time of the hydrothermal event. Furthermore, these two parameters are, in turn,...
Publication: CIM Bulletin
Author(s): Jacques Trottier, Michel Gauthier
Keywords: Exploration, Base Metal deposits, Eastern Townships.
Issue: 946
Volume: 84
Year: 1991
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Summary: A mineralogical and trace element analysis was performed on the Kiire historical slags in order to evaluate the possible recovery of copper and cobalt. Reflected light microscopy, electron microprobe and image analysis were combined to determine the Cu and Co distribution in the slag.
The results indicate that 81% of the total cobalt is chemically combined in thefayalite whereas only 3.4% is in the mechanically entrapped sulphides. The remainder being in hercynite and wustite. On the other...
Publication: CIM Bulletin
Author(s): Eric Pirard
Keywords: Applied mineralogy, Cobalt, Slag, Image analysis.
Issue: 946
Volume: 84
Year: 1991
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A brief review is made of geology, level of technology, management and labour situations, and range of production costs in coal producing countries. This comparison shows keen competition for Canadian coals, especially from the People's Republic of China, South Africa and Australia. Domestic competition comes from nuclear energy, hydro-electric generation, natural...
Publication: CIM Bulletin
Author(s): George E. Davies, David M. Parkes
Keywords: Coal mining, Production costs, Lignite, Sub-bituminous coal, Productivity comparisons.
Issue: 946
Volume: 84
Year: 1991
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