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TitleThe Point Rousse listvenites, Baie Verte, Newfoundland: altered ultramafic rocks with potential for gold mineralization?
AuthorEscayola, M P; Proenza, J A; van Staal, C R; Rogers, N; Skulski, T
SourceNewfoundland and Labrador Mineral Development Division, Current Activities 2009 p. 1-12 (Open Access)
LinksOnline - En ligne (PDF, 2.4 MB)
Alt SeriesEarth Sciences Sector, Contribution Series 20090231
PublisherGeological Survey of Canada
File formatpdf
ProvinceNewfoundland and Labrador
NTS2E/13; 2L/04; 12H/16; 12I/01
AreaBaie Verte
Lat/Long WENS -56.5000 -55.5000 50.2500 49.7500
Subjectsigneous and metamorphic petrology; geochemistry; tectonics; alteration; ultramafic rocks; mineralization; gold; hydrothermal alteration; obduction; deformation; ophiolites; chlorite; mineral assemblages; breccias; major element geochemistry; talc; carbonates; sulphides; spinel; petrogenesis; listvenites; Silurian; Ordovician
Illustrationslocation maps; photographs; photomicrographs; tables; plots
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010, Appalachian TGI-3
AbstractThe Point Rousse listvenites in northern Newfoundland are potential sites of gold mineralization, interpreted to have formed during obduction-related deformation and accompanying hydrothermal alteration of ultramafic rocks of the Baie Verte ophiolite belt in Newfoundland. These unusual rocks have much in common with those from other altered serpentinite-associated gold deposits. Mineralized listvenites display widely varying morphologies and metallic mineral assemblages, but all examples are intimately related to fault zones that bound slices and blocks of carbonatized ophiolite.
Several stages of hydrothermal alteration have been recognised in the Point Rousse listvenites. The hydrothermal mineral assemblages were controlled largely by temperature, XCO2, and oxygen and sulphur fugacity. The transformation of the rocks to talc-carbonate schists (listvenites) by Ca-CO2-S and As rich solutions liberated large quantities of silica that were subsequently mobilized and re-deposited to form silicified rocks and quartz vein networks.
Highly magnesian chlorites found in the listvenites have estimated formation temperatures of circa 200°C, which are consistent with the presence of pyrite and millerite in listvenites and birbirites (silicified ultramafic rocks). Gold present in trace amounts in some of the sulphides in the ultramafic-mafic rocks appears to have been mobilized and deposited during hydrothermal alteration, over several deformational stages. The Point Rousse listvenites and their associated Au mineralization are a subject of interest for future research, and also for mineral exploration in the area.