Legault, Jean M. (Geotech Lt.) | Lymburner, Josh (Crone Geophysics & Exploration Ltd.) | Ralph, Kevin (Crone Geophysics & Exploration Ltd.) | Wood, Peter (Zenyatta Ventures Ltd.) | Orta, Marta (Geotech Ltd.) | Prikhodko, Alexander (Geotech Ltd.) | Bournas, Nasreddine (Geotech Ltd.)
On January 19TH, 2012, Zenyatta Ventures Ltd. (Zenyatta) announced the discovery of a very rare type of hydrothermal graphite deposit on its Albany Project. The discovery was based on drill testing of anomalies identified by airborne electromagnetic survey flown in 2010 by Geotech Ltd. using its prototype VTEMMAX time-domain EM system. Crone Geophysics & Exploration Ltd. (Crone) was contracted by Zenyatta to perform surface time-domain EM (TDEM) surveys on the Property during February and March 2013. Crone targeted the drill-confirmed East and West graphitic breccia pipes using an in-loop and out-of-loop configuration to couple with their top and steeply dipping edges, respectively, and successfully outlined their lateral extents.
While conducting an exploration program targeting nickel (Ni), copper (Cu), and platinum group metals (PGMs) Zenyatta made the discovery of a very rare type of hydrothermal graphite deposit in 2011 on their Albany Graphite Project located 30km north of the Trans-Canada Highway near Hearst Ontario. The Albany Project area had been largely unexplored in the past as a result of swamp and the younger Phanerozoic (460-360 Ma) cover rocks, up to 200m thick, overlying the prospective Archean rocks. However, recent advances in airborne electromagnetic (EM) technology had allowed deeper penetration/resolution through the Fe-deficient shallow marine carbonate/clastic sediments to target favourable geological and structural settings within the underlying Archean rocks (see Zenyatta website www.zenyatta.ca).
This case study describes the airborne time-domain EM (TDEM) and magnetic geophysical survey results from 2010 that lead to the discovery and the subsequent ground follow up in 2013 using surface TDEM that better characterized the two graphite deposits (East Pipe and West Pipe) at Albany.
Geology and Exploration
The Albany graphite deposit is located in the Superior Province of the Canadian Shield, at the terrane boundary between the Quetico Subprovince to the north and the Marmion Subprovince to the south (Ross and Masun, 2014). The geology of the survey area consists of Precambrian paragnelsslC granitoids and migmatltlc metasediments to the south and metamorphosed tonalite to granodiorite to the north. These rocks have been intruded by a younger alkalic intrusive complex (Figure 1).