|Title||Epidote-amphibole and accessory phase mineral chemistry as a vector to low-sulphide platinum group element mineralization, Sudbury: laser ablation ICP-MS trace element study of hydrothermal
|Download||Download (whole publication) |
|Licence||Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences.|
|Author||Ames, D E; Tuba,
|Source||Targeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models; by Ames, D E (ed.); Houlé, M G (ed.); Geological Survey of Canada, Open File 7856, 2015 p.
269-286, https://doi.org/10.4095/296695 Open Access|
|Publisher||Natural Resources Canada|
|Related||This publication is contained in Targeted Geoscience
Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models |
|Lat/Long WENS|| -82.0000 -80.0000 47.0000 46.0000|
|Subjects||metallic minerals; igneous and metamorphic petrology; geochemistry; epidote; amphibole; platinum; mineralization; ore mineral genesis; metallogeny; hydrothermal alteration; mass spectrometer analysis;
trace element geochemistry; Superior Province; Sudbury Igneous Complex|
|Program||Targeted Geoscience Initiative (TGI-4) Mafic-Ultramafic Ore Systems|
|Released||2015 06 22|
|Abstract||In Sudbury, one of the world's largest Ni-Cu-Co mineral districts, geophysical methods have been successfully employed for detecting traditional contact and offset types of Ni-Cu-PGE ore for over a
century. Recent discoveries of low- to no-sulphide, high-PGE tenor orebodies, defined in 2005 in the footwall environment to the Sudbury Igneous Complex (SIC), caused a shift in exploration focus to the detection of these precious metal-rich
resources. These high-grade orebodies are hosted in randomly distributed impactderived breccia (Sudbury breccia) entirely within Archean and Proterozoic country rocks and comprise two footwall styles: a) high-sulphide vein-style Cu-PGE ores (i.e.
Strathcona, McCreedy East 153 chalcopyrite veins) with a widely recognized magmatic-hydrothermal origin and b) low-sulphide disseminations, blebs and stringers with high PGE tenor and dominated by silicate assemblages of hydrothermal origin. This
second, low- to no-sulphide, high-PGE footwall ore-style is a challenge to detect in the field with traditional geophysical methods used for magmatic deposits due to the absence of chalcopyrite or sulphide minerals, resulting in a need for
development of non-conventional exploration techniques.|
Proper classification is important for guiding future exploration for the low-sulphide metal-rich deposits in the footwall to the Sudbury Igneous Complex. Key hydrothermal alteration
assemblages with distinct trace element signatures may aid the development of discriminant mineral chemistry diagrams to yield criteria that help find these high-grade PGE hydrothermal footwall ores. The aim of this study was to establish typical
element-associations and behaviours for the paragenetically different hydrothermal assemblages produced during the diverse post-impact magmatic-hydrothermal history of the footwall and hanging-wall units of the Sudbury structure to detect a unique
signature for alteration related to the high-tenor PGE mineralization. Factors affecting the trace element distribution patterns in epidote, amphibole, titanite, and allanite are examined, including the element partitioning between coeval minerals,
the crystal structural control, and the effect of country rocks on the fluid-rock interaction, and detection of pathfinder elements. As and Zn in epidote and amphibole are host-rock dependant. The pathfinder elements Ni, Pb, Sn, and Co in epidote and
amphibole are the most reliable elements to distinctly fingerprint the PGE mineralizing alteration in the footwall. However, mineral-pair partitioning of elements between epidote-amphibole-titanite and allanite indicate that single mineral phases or
elements should not be used.
|Summary||(Plain Language Summary, not published)|
The Targeted Geoscience Initiative (TGI-4) is a collaborative federal geoscience program that provides industry with the next generation of geoscience
knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. This volume summarizes 22 research activities completed under the TGI-4 Ni-Cu-PGE-Cr ore systems project that focused on
revised and new geologic models for Ni-Cu-PGE, PGE-Cu and Cr deposits, innovative techniques for determining potential fertility of intrusion (Ni-Cu-PGE), and defining pathfinders for Ni-Cu-PGE mineralization.