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A study of the composition, distribution, and genesis of pyrrhotite in the Copper Cliff Offset, Sudbury, Ontario, Canada

Sarah C. Gordon and Andrew M. McDonald
A study of the composition, distribution, and genesis of pyrrhotite in the Copper Cliff Offset, Sudbury, Ontario, Canada (in A tribute to John Leslie Jambor, Robert F. Martin (prefacer))
The Canadian Mineralogist (September 2015) 53 (5): 859-878

Abstract

Pyrrhotite (Po) from five orebodies (830, 865, 880, 890, and 100 OB) in the Copper Cliff Offset Dike (CCOD) at Sudbury, Ontario was studied using powder X-ray diffraction data and Rietveld analysis, SEM-EDS, magnetic colloid, optical petrographic techniques, and Laser Ablation-ICP-MS in order to: (1) quantify the distribution of NC (non-magnetic, symmetry higher than monoclinic) and 4C (magnetic, monoclinic in symmetry) Po; (2) characterize the major, minor, and trace-element chemistries of both polymorphs; and (3) determine the factors enhancing the stability of NC Po. Results confirm that both NC and 4C Po are present, with ratios varying between 0 to 0.97. In general, 4C Po is the dominant polymorph within the sampled OB, with the exception of the 100 OB, which is dominated by NC Po. Mineral chemistry indicates that there is an almost complete compositional overlap between the major, minor, and trace-element compositions of NC and 4C Po from the CCOD. The data also show that both polymorphs are slightly metal-deficient relative to the ideal chemistry of 4C Po, Fe (sub 7) S (sub 8) There were no significant differences found in the Ni contents of either polymorph. Data revealed that the main mineralogical difference between the five OB was the presence of ilmenite in the 830, 865, 880, and 890 OB, whereas magnetite dominates in the 100 OB. Mineralization occurs along the eastern margin of the 830-890 OB, in contrast to the 100 OB, where mineralization occurs in the center of the dike. The increased abundance of NC Po in the 100 OB may be explained by this difference in the style of mineralization, specifically, the proximity of ore to the surrounding country rock. Therefore, fO (sub 2) may have directly influenced the distribution and stabilization of NC Po, which would then impact the observed NC:4C Po ratios in the selected OB.


ISSN: 0008-4476
EISSN: 1499-1276
Coden: CAMIA6
Serial Title: The Canadian Mineralogist
Serial Volume: 53
Serial Issue: 5
Title: A study of the composition, distribution, and genesis of pyrrhotite in the Copper Cliff Offset, Sudbury, Ontario, Canada
Title: A tribute to John Leslie Jambor
Author(s): Gordon, Sarah C.McDonald, Andrew M.
Author(s): Martin, Robert F.prefacer
Affiliation: Laurentian University, Department of Earth Sciences, Sudbury, ON, Canada
Affiliation: McGill University, Montreal, QC, Canada
Pages: 859-878
Published: 201509
Text Language: English
Publisher: Mineralogical Association of Canada, Ottawa, ON, Canada
References: 73
Accession Number: 2016-094381
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 7 tables, sketch map
N45°49'60" - N48°30'00", W83°40'00" - W80°19'60"
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Association of Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201646
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