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TitleMulti-stage hydrothermal processes involved in "low-sulfide" Cu(-Ni) -PGE mineralization in the footwall of the Sudbury Igneous Complex (Canada): Amy Lake PGE zone, East Range
AuthorTuba, G; Molnár, F; Ames, D EORCID logo; Péntek, A; Watkinson, D H; Jones, P C
SourceMineralium Deposita vol. 49, issue 1, 2014 p. 7-47,
Alt SeriesEarth Sciences Sector, Contribution Series 20140499
PublisherSpringer Nature
Mediapaper; digital; on-line
File formatpdf
AreaSudbury; Amy Lake
Lat/Long WENS -81.5000 -80.5000 46.7500 46.2500
Subjectseconomic geology; geochemistry; igneous and metamorphic petrology; metallic minerals; breccia deposits; hydrothermal alteration; trace element geochemistry; stable isotope studies; shearing; sulphide deposits; magmatic deposits; ultramafic rocks; mineral deposits; chalcopyrite; cubanite; pentlandite
Illustrationstables; graphs; photographs; photomicrographs; location maps; geological sketch maps; ternary diagrams; geochemical plots
ProgramTargeted Geoscience Initiative (TGI-4) Mafic-Ultramafic Ore Systems
Released2013 05 09
AbstractThe Amy Lake PGE zone is a "low-sulfide-type" Cu-(Ni-)PGE mineralization in the East Range footwall of the 1.85 Ga Sudbury Igneous Complex occurring in a 100-m-wide Sudbury Breccia belt that coincides with an impact-related major fracture zone (Bay Fault zone). Detailed hydrothermal alteration mapping, fluid inclusion, trace element, and stable isotope studies revealed a complex alteration and mineralization history in a multi-source, multi-stage Sudbury-related hydrothermal system. The two major stages of syn-Sudbury hydrothermal activity are characterized by similarly high-salinity, high-temperature fluids that are (1) locally derived from footwall granophyre bodies, and typified with high Ni/Cu and PGE/S ratios and high REE contents (magmatic-hydrothermal stage), and (2) a more voluminous Cu-Ni-PGE-rich fluid flux probably originated from the Sudbury Igneous Complex/footwall contact (hydrothermal stage). The second hydrothermal flux was introduced by brittle fractures in the area and resulted in a complex zonation of alteration assemblages and mineralization governed by local footwall composition. The Sudbury-related hydrothermal event was overprinted by shear-related epidote veining and calcite-chlorite replacement, both regionally present in the Sudbury structure. Based on analogies, the most important factors involved in the formation of hydrothermal low-sulfide mineralization are proposed to be (1) accumulation of PGE-enriched fluids, (2) large-scale brittle structures as conduits to these fluids, and (3) adequate host rock composition as a chemical trap resulting in sulfide and PGM precipitation. In environments meeting these criteria, hydrothermal PGE mineralization is known to have formed not only in the Sudbury footwall but also from mafic-ultramafic intrusions associated with primary magmatic PGE from several locations around the world.

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