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TitleStratigraphy and hydrothermal alteration of the Ming Cu-Au volcanogenic massive-sulphide deposit, Baie Verte Peninsula, Newfoundland
AuthorPilote, J -L; Piercey, S J; Mercier-Langevin, P
SourceGeological Survey of Canada, Current Research (Online) no. 2014-7, 2014, 21 pages, (Open Access)
PublisherNatural Resources Canada
Mediaon-line; digital
File formatpdf
ProvinceNewfoundland and Labrador
AreaBaie Verte Peninsula
Lat/Long WENS-56.1397 -56.0217 49.9317 49.8658
Subjectseconomic geology; stratigraphy; alteration; hydrothermal alteration; stratigraphic analyses; stratigraphic correlations; mineral occurrences; mineral deposits; mineralization; copper; gold; zinc; volcanogenic deposits; sulphides; sulphide deposits; deformation; Ming Mine; Rambler Mining Camp; Pacquet Harbour Group; Paleozoic; Ordovician
Illustrationslocation maps; stratigraphic columns; photographs; photomicrographs; cross-sections
ProgramVolcanogenic Massive Sulfide Ore Systems, Targeted Geoscience Initiative (TGI-4)
Released2015 01 08
AbstractThe Cambro-Ordovician bimodal-mafic Ming Cu-Au-(Zn-Ag) volcanogenic massive-sulphide deposit is a type example of an Appalachian precious metal-enriched volcanogenic massive-sulphide deposit. The footwall of the deposit comprises at least three distinct felsic volcanic and volcaniclastic units. The immediate hanging wall is lithologically heterogeneous, comprising a highly silicified volcaniclastic rock and a magnetite-rich volcanogenic siltstone. Three generations of mafic to intermediate sills and dykes intrude the deposit and have distinctive lithogeochemical signatures; they are interpreted to be genetically related to the mafic rocks in the ophiolitic cover sequence that overlies the deposit.
The Ming deposit has distinct hydrothermal alteration mineral assemblages including: chlorite-quartz-epidote, sericite-quartz-green mica, quartz-pyrite, and Mn-garnet-calcite. Other minor secondary phases include biotite, tremolite, and magnetite. A Cu-rich zone consisting primarily of chalcopyrite, pyrrhotite, and pyrite with minor Bi-Te sulphosalt minerals and sphalerite in a strongly chlorite-quartz-epidote-altered felsic volcanic rock occurs 50 m to 100 m below the main sulphide lens, and represents the high-temperature discharge zone of the Ming hydrothermal system. An overprint of metamorphic biotite is ubiquitous throughout the felsic footwall rocks and represents metamorphosed K-Fe-(Mg) alteration to upper greenschist facies.
Despite local remobilization of the sulphide minerals due to deformation and metamorphism, the relationship between the host rocks, the alteration assemblages and their spatial distribution, and the ore strongly favour a syngenetic origin for the sulphide zones and their base and precious metals, suggesting intrinsically precious metal-enriched volcanogenic massive-sulphide ore-forming fluids at the Ming mine.
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. The Ming base (Cu, Zn, Pb) and precious (Au and Ag) metal-rich deposit, which is part of the Rambler mining district located in Newfoundland, is associated with a series of altered volcanic and volcaniclastic units that were emplaced at the early Ordovician, about 487 million years ago, controlling the formation and location of the ore lenses. The specific environment, different alteration assemblages and ore lenses and metal zonations defined in this study can be used to vector towards prospective environments at depth. Overprinting tectonic events controls the actual geometry of the deposit but primary characteristics are largely preserved, facilitating exploration in such environments.