Public health restrictions implemented in response to the COVID-19 pandemic resulted in the cancellation of the 2020 RGP field season.
The contents of this section are based on a pilot project initiated by RGP staff to test scanning and digitizing technology for drill-core applications, as an alternative to field work and unavailable OGS GeoLabs services in 2020. Two properties were chosen by RGP staff as test sites, the Eric Lake property and the Killala Lake (Madonna Diamond dyke) property. R. Wahl agreed to provide drill core that was sent to Enersoft to use with GeologicAl systems for nondestructive mineralogical and geochemical testing using core scanning technology. Preliminary results include high-resolution imagery and X-ray fluorescence (XRF) profiles for the Eric Lake property and high-resolution imagery and short-wave infrared (SWIR) images for the Killala Lake (Madonna Diamond Dyke) property. For further information about the entire core scan data set, please contact the Thunder Bay South Resident Geologist office.
Additionally, a compilation for the Dead Horse Creek property is presented from field data collected in
2018 and research in 2019–2020 by Ontario Geological Survey (RGP and ERGMS staff) and by
Dr. S. Zurevinski, Lakehead University.
Eric Lake Nickel Property
The Eric Lake property has a “bulls–eye” airborne magnetic anomaly that was identified 2 km southwest of Eric Lake, 40 km northwest of Marathon (red dot shown on Figure 30, and on the high magnetic relief on Figure 31). The Eric Lake property consists of 109 cell claims held 100% by Rudy Wahl (black outline shown on Figures 30 and 31). Access to the Eric Lake property is easily obtained via Highway 614 and Swede road. All-terrain vehicle (ATV) trails provide access to the western part of the property where the Eric Lake magnetic anomaly is located.
The Eric Lake mafic to ultramafic intrusion is hosted within the Black-Pic batholith (foliated to gneissic tonalite to granodiorite rocks) situated approximately 3 km north of the Hemlo greenstone belt within the Wawa Subprovince. Later mafic dikes, gabbroic intrusive rocks and granitoid plutons (granodiorite- granite-tonalite compositions) such as the Gowan and Fourbay Lake plutons intrude the Black-Pic batholith (Figure 30; Muir 2000).
The exploration history in the area of the Eric Lake magnetic anomaly dates back to 2000, where SouthernEra Resources Ltd, under JV with Sparton Resources Ltd., and Freewest Resources Canada Inc. carried out grassroots exploration programs for potential diamond-bearing kimberlite pipes, blows and dikes. Exploration was limited to surface work targeting pipe-like anomalies selected from regional airborne geophysical surveys. One of the targets selected was the Eric Lake magnetic anomaly, referred to as the D-001 Target. Surface work included prospecting, mapping, till and soil sampling, and follow-up ground magnetic, electromagnetic and gravity surveys. Results from electromagnetic and gravity surveys were not reported. Geochemical sampling of the “B” horizon included 15 soil samples that returned anomalous elements from the D-001 Target area and in the area to the southwest of the magnetic anomaly. Sampling returned CaO > 10%, MgO > 4%, local Ni > 20 ppm, elevated Sr > 40 ppm and elevated TiO2 > 0.01%, indicative of the presence of mafic rocks at depth. The D-001 Target was deemed of interest and a drilling program was proposed (Jones 2003).
Figure 30. Regional geological map (from Ontario Geological Survey 2011) superimposed on the total magnetic shadow field (from Ontario Geological Survey 2002) showing the location of the Eric Lake property (black outline) and the “bulls-eye” magnetic anomaly (red dot). Granitoid rocks shown in various shades of pink, metavolcanic rocks in shades of green, metasedimentary rocks in grey, gabbroic intrusive rocks in blue and Coldwell complex intrusive rocks in purple. The Eric Lake property is shown in greater detail in Figure 31.
Subsequently, Churchill Diamond Corporation drilled 1 hole (16ER-01D) into the D-001 magnetic anomaly in the area of the strongest magnetic response, to test for a potential kimberlite dike. Drill hole 16ER-01D did not intersect kimberlitic rock; however, strongly magnetic mafic to ultramafic rocks were intersected (Figure 32; Kivi 2017).
The property at that time, under option to Churchill Diamond Corporation, was returned to R. Wahl. Subsequently, R. Wahl sampled
and analysed the core for its nickel-copper-PGE potential.
Zones of ultramafic (picrite) and mafic (gabbro) rocks were logged and anomalous values of nickel (Ni) and chromium (Cr) are shown to be associated with the ultramafic rocks. Anomalous values of nickel and chromium associated with ultramafic rocks were encountered in at least 3 sections (Figure 32); highlights are reported as follows (from R. Wahl’s Prospecting website):
- 1373 ppm Ni and 2784 ppm Cr over 4 m
- 2112 ppm Ni and 2136 ppm Cr over 5 m
- 1814 ppm Ni and 3587 ppm Cr over 7 m
Churchill Diamond Corporation completed a VLF survey and identified a strong conductor west of the D-001 magnetic target and a weak cross-over north of the D-001magnetic target. These conductors remain untested. The OGS (2001) airborne magnetic and electromagnetic (EM) survey outlined the D-001 magnetic anomaly and several weak EM anomalies west of D-001 (Figure 33). Churchill Diamond Corporation stopped the drill hole short because the drilling program was designed to test the potential for diamond-bearing kimberlitic rocks. Although, kimberlitic rocks were not encountered, the potential for nickel with associated magmatic sulphides should be re-visited at the Eric Lake property and surrounding area.
In 2017, the Eric Lake drill core (16ER-01D) was observed by RGP staff and a sample with anomalous nickel (greater than 2000 ppm Ni) within an ultramafic unit was collected for analysis to determine the host rock and also whether nickel was associated with silicates or sulphides. Results showed that the rock was classified as a serpentinite and nickel was found
in all phases of the sample. However, higher concentrations of nickel were found in the iron oxides and sulphides (pentlandite).
In mid-July 2020, drill core (16ER-01D – 71 m) from the Eric Lake property was shipped to Enersoft in Calgary. Preliminary data presented by Enersoft’s GeologicAl system includes high-resolution imagery and XRF data,
as shown on the Core Table in Figure 34. Zoom-in capabilities on the Core Table provide better detail for rock and mineral identification (Figure 35). The XRF profiles for the anomalous zones of Ni (light blue) and Cr (pink) concur with assay results reported by R. Wahl and the associated ultramafic rocks logged by Kivi (2017; see Figure 34).
Based on results from hole 16ER-01D by Churchill Diamond Corporation that encountered ultramafic rocks with associated anomalous Ni values (greater than 2000 ppm), further exploration is recommended on the Eric Lake property and in the surrounding area. The D-001 magnetic anomaly has not been fully tested. Additionally, a strong VLF anomaly located on west flank of the magnetic anomaly, and a weak cross-over to the north magnetic anomaly (Kivi 2017) remain untested.
Another area of interest is southwest of the D-001 magnetic anomaly, where weak EM anomalies (OGS 2001) are noted and mafic intrusive rocks (diorite) are identified in Muir’s (2000) compilation and regional geology (OGS 2011; see Figure 33). Milne (1968a) identified a regional northwest-trending fault, referred to as the Pinegrove Lake Fault, that appears to cut the dioritic rocks to the southwest (see Figures 31, 33).
Geochemical results from soil sampling by SouthernEra Resources Ltd. reported anomalous values of Ni, CaO, MgO and elevated Sr and TiO2 located near the D-001 Target and to
the southwest (Jones 2003). On the adjacent property to the south, held by Hemlo Explorers Inc., 2 larger magnetic anomalies located 5 km south of D-001 are reported as oxidized intrusive rocks and are also recommended for further exploration (see Figure 33).
The low-grade nickel mineralization observed in the Eric Lake area is likened to the Crawford Ni-Co Sulphide project (Canada Nickel Company) located north of Timmins. The D-001 magnetic anomaly is smaller in size than the Crawford magnetic anomaly and there are geological differences. The Crawford Ni-Co deposit is hosted within metavolcanic rocks while the Eric Lake occurrence is hosted within gneissic tonalite to granodiorite rocks. The mineral resource estimate for the Crawford Ni-Co deposit prepared by Caracle Creek International Consulting Inc. (NI 43-101compliant) reported a measured and indicated (M&I) resource of 280 Mt at 0.31% Ni, 0.013% Co. Canada Nickel Company reported the Crawford Ni-Co deposit resource ranks as one of the 10 largest nickel sulphide resources
globally (Canada Nickel Company website, Corporate Presentation, January 2021).
On the other hand, it should be noted that Palladium One Mining Inc. recently discovered a mineralized ultramafic body at Smoke Lake, 43 km west-northwest of Eric Lake, hosted within gneissic tonalite rocks. The mineralization at Smoke Lake occurs as a consistent sheet with a possible fault near its base controlling the emplacement. Highlights from Palladium One’s Smoke Lake deposit returned grades of up to 6.6% Ni, 3.7% Cu and 1.5 g/t PGE over 3.8 m (Palladium One Mining Inc., news release, January 5, 2021).
Killala Lake (Madonna Diamond Dyke) Property
Preliminary data from core scanning on the Madonna Diamond Dyke includes high-resolution imagery and SWIR images (Figure 36). This data can be used to identify some minerals not visible to the naked eye and potentially prove to be quite useful in recognising kimberlitic indicator minerals (KIMs).