Finding fault in a shear zone: a magnetic and drill core study in the Valentine Lake Property, Newfoundland, Canada

• Main Authors: Flanagan, Marie, Leitch, Alison, Wall, Adam
• Format: Article in Journal/Newspaper
• Language: English
• Published: Atlantic Geoscience Society 2023
• Subjects: Canada; Découverte; Valentine; Newfoundland; Terre-Neuve
• Online Access: https://journals.lib.unb.ca/index.php/ag/article/view/32972

The Valentine Lake Property in southwestern Newfoundland has five known gold deposits over a distance of 20 km along a northeast to southwest trend and is expected to be the future site for the largest gold mine in Atlantic Canada. The property contains structurally controlled orogenic-type quartz-tourmaline-pyrite veins, which are gold-bearing, occurring along or proximal to the Valentine Lake Shear Zone. The mineralization is found mostly on the northwest side of the shear zone in intrusive rocks and is rare in the conglomerate on the southeast side. The area has many mafic dykes, which show up well when conducting a magnetic survey due to their magnetite content. These dykes, like the mineralization, occur mainly in the intrusive rocks and trend predominantly subparallel to the shear zone, and so can help indicate structure. To constrain the location of the shear zone (and hence the mineralized region) in an area where an offset was suspected, a detailed magnetic survey was conducted over a 200 m x 300 m grid comprising sixteen lines. With the collected data, residual magnetic intensity maps were created and processed. A region was identified where the pattern of linear magnetic highs weaken and appear to terminate near the suspected offset. In combination with drill core information, this location is interpreted as a fault offset of the shear zone. The loss in magnetic intensity is possibly due to alteration or thinning of the mafic dykes near the fault. La propriété du lac Valentine dans le sud-ouest de Terre-Neuve abrite cinq gîtes aurifères connus sur une distance de 20 km le long d’un axe du nord-est au sud-ouest et on anticipe qu’elle constituera l’emplacement de la plus vaste mine d’or au Canada atlantique. La propriété recèle des filons de quartz-tourmaline-pyrite orogéniques régis par la structure le long ou à proximité de la zone de cisaillement du lac Valentine. La minéralisation est principalement présente sur le flanc nord-ouest de la zone de cisaillement dans des roches intrusives et elle est ...