A compiled geological, geochemical, and metallogenic study of a magmatic nickel-copper sulphide occurrence at the Cirque Property, Nain Plutonic Suite, Northern Labrador

• Main Author: Dwyer, Berni Lori
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2001
• Subjects: Nain; Okak; Okak Bay
• Online Access: https://research.library.mun.ca/6593/; https://research.library.mun.ca/6593/1/BerniLoriDwyer.pdf; https://research.library.mun.ca/6593/3/BerniLoriDwyer.pdf

Located approximately 40 kilometers south of Okak Bay, the Cirque property lies within an area spanning 40 km long by 5-10 km wide that contains several localized, magmatic Ni-Cu sulphide occurrences. With the exception of the OKG prospect located approximately 35 km north of the Cirque prospect, most of the magmatic Ni-Cu sulphide occurrences are hosted within Mesoproterozoic varieties of leucotroctolite, leuconorite, leucogabbro, and anorthosite of the Nain Plutonic Suite. -- The Cirque property (LBN, Licence #1764M), so named because the gossan lies within a 1 km wide cirque, consists dominantly of massive and layered anorthosite and lesser amounts of leuconorite/leucogabbro and leucotroctolite. Outcrop exposure has defined the mineralized zone to strike approximatelyl km northwest and dip to the west Ground and borehole geophysical surveys have defined a corresponding narrow zone (250 to 300 m wide) plunging steeply to the southeast. Six drill holes at the top and two of six drill holes at the base of the cirque have intersected sulphide zones of variable widths and textures. Mineralization consists of massive, net, and disseminated pyrrhotite with minor chalcopyrite. Trace pentlandite occur as fine flame-lamellae within massive pyrrhotite. -- Overall, the metal contents in all of the holes are low (average Ni/Cu = ≤ 1, Pd and Pt values <50 ppb). The best intersection is from borehole LBN-4 (390.35m): 0.28% Ni, 0.44% Cu, and 0.12% Co over 5.1 m. Localized, elevated Cu values were intersected in several boreholes but were not extensive; the greatest is 3.9% Cu over 20 cm in a 1.5 cm wide sulphide vein @ 923.92 m in borehole LBN-8. Values from neighbouring properties to the north (Canadian States Resources; Licence #1514M) and west (Noranda Mining and Exploration Ltd.; Licence #915M) are anomalous; highest values from grab samples are 0.36-0.85% Ni and 1.8% Ni, respectively. -- Sulphide mineralization at the Cirque gossan consists of thin, irregular lenses and stringers, steeply dipping to the west and ...