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TitleA comparative study of the deformation history of auriferous quartz veins in the Archean Côté Gold deposit and the structural evolution of the spatially-related Ridout Deformation Zone, Swayze Greenstone Belt, northern Ontario
AuthorSmith, J; Lafrance, B; Kontak, D
SourceGeological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Abstracts Volume vol. 37, 2014 p. 257-258
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20130616
MeetingGeological Association of Canada - Mineralogical Association of Canada (GAC-MAC) annual joint meeting; Fredericton; CA; May 21-23, 2014
Mediapaper; on-line; digital
File formatpdf
AreaKirkland Lake; Côté Lake
Lat/Long WENS -80.5000 -80.0000 48.0000 47.7500
Subjectseconomic geology; structural geology; quartz veins; Archean; gold; mineralization; deformation; structural analyses; structural interpretations; Cote Lake gold system; Côté Gold deposit; Precambrian
ProgramTargeted Geoscience Initiative (TGI-4), Gold Ore Systems
AbstractThe Côté Gold deposit (8.3 M oz) is a low-grade high-tonnage Au (-Cu) deposit located on the southeast limb of the Swayze Greenstone Belt (SGB) in the Abitibi Subprovince. The deposit is hosted by a magmatic-hydrothermal breccia body in tonalite and diorite of the 2741 ± 1 Ma Chester Intrusive Complex (CIC). Mineralization occurs within or peripheral to the breccia as disseminations, fracture fills and stockwork, and in association with later quartz ± carbonate ± sulphide ± muscovite ± tourmaline veins with silica-sericite ± sulphide alteration haloes. These latter veins are similar in appearance to orogenic-style, quartz ± carbonate± sulphide quartz veins associated with the 600 m wide Ridout Deformation Zone (RDZ), which is located ~ 2.5 km from the deposit. In order to understand the timing relationship between the orogenic veins, the quartz veins in the Côté Gold deposit, and the RDZ, the style and kinematic significance of structures overprinting the CIC are compared to those of the RDZ. Detailed structural mapping of exposures inside the deposit envelope indicates that three deformation events affected the CIC. The first deformation event (D1) produced sinistral, north-side up, E-W trending shear zones with a strong S1 foliation. During the D2 event, S1 was crenulated during reversal of slip along the shear zones, which produced a S2 crenulation cleavage expressed as a mylonitic foliation in other parallel E-W-trending shear zones. Subsequently, a D3 dextral reactivation event produced a S3 foliation oriented anticlockwise to the margins of the shear zones. The RDZ is characterized by a strong composite S1-S2 fabric which formed during sinistral northside- up movement. These fabrics the S1-S2, are overprinted by dextral shear bands and Zshaped F3 folds with a S3 cleavage, which formed during dextral reactivation of the RDZ. Because the structural histories of the RDZ and CIC are similar and the structures overprint the Côté Gold Au-bearing quartz-carbonate ± sulfide veins, this suggests, therefore, that the veins pre-date regional deformation and may have formed shortly after the emplacement of the CIC. This latter conclusion is supported by previous Re-Os dating of molybdenite from Au-bearing quartz-carbonate veins in the deposit. Future work will focus on determining how the formation of the E-W quartz veins relate to that of the breccias that host the deposit.