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TitleSulphur in archean volcanic rocks of the Canadian shield
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorCameron, E M
SourceGeological Survey of Canada, Paper 74-18, 1974, 10 pages, Open Access logo Open Access
Mediapaper; on-line; digital
File formatpdf
ProvinceQuebec; Northwest Territories; Nunavut
NTS32D/02; 32D/03; 32D/06; 32D/07; 85I/05; 85I/12; 85J/08; 85J/09; 86B/03; 86B/06; 76M/07; 76M/08; 76M/09; 76M/10
Lat/Long WENS-79.5000 -78.5000 48.5000 48.0000
Lat/Long WENS-114.5000 -113.5000 62.7500 62.2500
Lat/Long WENS-115.5000 -115.0000 64.5000 64.0000
Lat/Long WENS-111.0000 -110.0000 67.7500 67.2500
Subjectsgeochemistry; industrial minerals; sulphur; archean; Canadian Shield; Precambrian
Released1974 04 01; 2016 03 11
AbstractA total of 1098 samples of Archean volcanic rocks from four localities in the Canadian Shield have been analyzed for sulphur. Two of these areas - Noranda, Quebec and High Lake, Northwest Territories - contain massive sulphide deposits of copper and zinc. The other two localities - Yellowknife and Indin Lake, Northwest Territories - are not known to contain massive sulphides, but do contain gold deposits. The samples have been classified into basic, intermediate or acidic groups on the basis of their chemically-determined silica contents. The frequency distributions of sulphur in these rocks are approximately lognormal. The distribution curves of the samples of basic rocks from Noranda, from Yellowknife, and from Indin Lake are similar and the average sulphur contents of these three groups are close to the limit of solubility of sulphur in basaltic melts of ~0.1% The sulphur contained in the original melt has probably been largely retained in the lavas as a result of rapid submarine quenching. The cumulative frequency distribution curves for acidic rocks from Yellowknife and lndin Lake are parallel to those for basic rocks from the same areas, but at much lower sulphur levels. Curves for intermediate rocks lie midway between the basic and acidic groups. The lower sulphur content of the more siliceous volcanic rocks may, in part, be caused by lower sulphur solubility in silica-rich melts. The major cause is, however, likely to be loss of sulphur by degassing, for many of the more silicic volcanic sequences contain a high proportion of pyroclastic rocks. For the Noranda and High Lake samples the right-hand side of the frequency distributions are skewed to higher sulphur levels. This effect is greater for acidic than for basic samples. The net result is that for these two areas, it is the acidic groups that contain more sulphur than the basic samples. This finding is in accord with the long known association of massive sulphide deposits with silicic volcanic rocks. It is caused by the introduction of sulphides into nearby volcanic rocks during the formation of massive sulphide deposits. The sulphur content of Archean volcanic rocks may provide some basis for distinguishing mineralized from barren sequences. It is by no means certain, however, that such methods are more practical than surficial geochemical methods or lithogeochemical techniques based on major element changes around massive s ulphide deposits.

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