McFaulds Cu-Zn-Ag VMS Deposits
The McFaulds volcanogenic massive sulphide (VMS) deposits were the first discoveries in the ROF and spurred the initial staking rush in 2002-2003. Since then, ten Cu-Zn rich VMS deposits have been identified on the property, two of which (MCF No.1 and No.3) have calculated resources. In 2015 Noront acquired an 85% interest in the McFaulds property through the acquisition of Cliffs Natural Resources’ assets in the ROF. The McFaulds property is now held jointly between Noront (85%) and KWG Resources (15%).
Early exploration on the property focused on near-surface mineralization easily detected with airborne geophysics. This exploration methodology successfully identified seven Cu-Zn mineral occurrences. However, after the discovery of Eagle’s Nest and the various chromite deposits in the ROF, exploration shifted away from VMS to magmatic Ni-Cu-PGE and chromite.
Starting in late 2016, Noront renewed its interest in the area by systematically compiling and reviewing historic geological, geochemical, and geophysical datasets, including re-logging one-quarter of all historical drill holes at McFaulds and acquiring a high-resolution airborne magnetic survey which forms the basis for our current geological model. Following up on this initial work, in 2017 Noront completed ground and borehole EM surveys and executed its first ever drill program at McFaulds which led to the discovery of a new sulphide deposit, MCF No. 8, located 175m into the footwall of the high-grade MCF No.3 deposit. Subsequent drilling has identified an additional two VMS exhalative horizons, MCF No.9 and No.10.
Noront is actively exploring the area through the integration of new data from geophysical surveys and diamond drilling with historical results and a refined deposit model.
Deposit Geology & Mineralization
The McFaulds VMS deposits are situated within in a structurally controlled volcanic basin near the top of the Muketei Assemblage, stratigraphically above the ultramafic sills hosting the Ni-Cu-PGE and chromite resources and above the large Thunderbird layered ferrogabbro body (figure 1). High resolution age-dating by the OGS and GSC has determined the age of these underlying intrusive suites and the overlying volcanic succession to be virtually the same, suggesting the heat source for hydrothermal VMS mineralization at McFaulds may have been driven by cooling of these large, high-temperature magmatic bodies.
The McFaulds deposits are hosted within a northeast trending, northwest facing, folded sequence of altered felsic to intermediate tuffs and lesser flows (figure 2) deposited into an interpreted half graben based on the asymmetry of the volcanic basin. Mineralization consists dominantly of pyrite-chalcopyrite-sphalerite rich banded sulfides and stringers. Broad zones of chlorite alteration mark the exhalative horizons with intense talc-magnetite zones immediately adjacent to or within the mineralized zones at MCF No. 1 and No.3. The copper-rich nature of the mineralization along with the presence of talc-magnetite zones attest to the high-temperature nature of the VMS hydrothermal system at McFaulds.
Based on the results of our recently acquired high resolution airborne magnetic survey and in conjunction with our re-logging, 3D modelling efforts, and new drilling results, we have identified four main VMS horizons on the property (figure 2). From bottom to top these are the: i) Tamarack horizon, ii) MCF No.1, No.3, No.8, No.9, No.10 and No.6 horizon, iii) MCF No. 2 horizon, and iv) MCF No. 4 and No.5 horizon.
Vertical stacking of VMS mineralized zones over hundreds of meters as at MCF No.8, No.10, No.3 and No.4 suggest a primary volcanic structural control to the mineralization (figure 3) as seen in other VMS camps in the Superior Province, and which provides a useful exploration vector.
Since initiating our VMS strategy in the fall of 2016, our understanding of the volcanic stratigraphy and mineralizing controls on the McFaulds property has improved dramatically. Current thinking is that the plunge of the McFaulds No.8 deposit is largely controlled by syn-volcanic faults which were responsible for the formation of a 3rd order basin within which were deposited the host volcanic sediments and tuffs as portrayed in figure 4.
The McFaulds No.1, No.3 and No.8 deposits are the centerpiece of a 1,043 claim-cell property held 85% by Noront and 15% by KWG Resources. Noront continues to explore the property with the aim of defining a minimum 5-10Mt of potentially mineable copper-zinc resources to feed a central milling operation in the future.
Noront has been actively exploring the property since 2017, completing 17 drill holes totaling 8,182m coupled with 35 borehole EM surveys, 78 line-km of ground EM and 33 line-km of ground gravity surveys, in addition to 1,941 km of high resolution airborne magnetic surveying. This work has led to the discovery of three new VMS horizons, the most significant being MCF No.8, which returned 26.4m of massive sulfides grading 2.1% Cu, 3.4% Zn, 5.5g/t Ag and 0.2g/t Au in hole MCF-18-98 (figure 5) located 118m down-dip of the next closest hole MCF-18-96.
Drilling in early 2019 along strike of hole MCF-18-98 returned 20.0m of banded and stringer sulfides grading 2.0% Cu, 0.1% Zn, 4.8g/t Ag and 0.1g/t Au in hole MCF-19-102 in a sequence of strongly altered volcanic tuffs.
Assay highlights of the holes drilled by Noront to date on the McFaulds property are listed in the table below.
|Width (m)||Cu %||Zn %||Ag g/t||Au g/t|
Current resources for the McFaulds deposits (MCF No. 1 and No.3) are presented in the table below.
|McFaulds 3 Mineral Resource|
|Tonnage (tonnes)||Grade (% Cu)||Grade (% Zn)|
|Indicated Mineral Resources||802,000||3.75||1.1|
|McFaulds 1 Mineral Resource|
|Tonnage (tonnes)||Grade (% Cu)||Grade (% Zn)|
|Inferred Mineral Resources||279,000||2.13||0.58|
|A cut-off of 1.5% Cu was used. Please see the report titled “Updated Technical Report on the McFaulds Lake Project, Porcupine Mining Division, James Bay Lowland, Ontario, Canada” by Deep Search Exploration Technologies, dated August 30th, 2008 (the “Technical Report”) for details regarding the mineral resource estimates.|