The Crescent Lake Property is located approximately 235 km north-northeast of Thunder Bay and approximately 42 km east of the community of Armstrong, Ontario. The Jackfish forestry road system provides access to the property and the CN Rail mainline is accessible about 9 km to the south at Ferland Station.
Stockport's property consists of 13 unpatented claims that have a combined surface area of approximately 2576 ha. The entire property hosts Stockport's Seymour Lake lithium-berylium-tantalum (Li-Be-Ta) deposit, KM 61 molybdenum-copper-silver (Mo-Cu-Ag) deposit and four Li-bearing pegmatite occurrences that have been named the Crescent Lake Property.
In the fall of 2016, Stockport entered into an option agreement with Sovereign in regard to the Crescent Lake lithium property. Sovereign would be executing a due diligence program focused on assessing the four historic Li-pegmatite prospects (showings) located on the property. The assessment programs consisted of prospecting, geological mapping, trenching and diamond core drilling. After completion of the work programs, Sovereign opted in late November 2016 not to exercise its option to earn an interest in the Crescent Lake Property.
The four historic Li-bearing pegmatite occurrences are located northeast of the Seymour Lake pegmatites and closely follow the favourable tonalite intrusion contact zone. The four zones of interest, as identified in the Geological Survey of Ontario's mineral occurrence database, are identified as;
Each showing was opened up by surface trenching and geologically mapped and sampled in detail. This was immediately followed by a diamond drilling program consisting of 14 holes totaling 859 metres. These holes were drilled to test subsurface extensions of the trenched Li-bearing pegmatite veins.
Result highlights of the initial surface samples (grab samples) appear in Figure 2: Location of L61 Showing, Chappais Lake Showing and Selected Lithium Oxide Assay Results From Pegmatites L61, L40 and L28. This figure confirms the mineralized characteristic of the Li-bearing pegmatites.
The Stockport property area is located in the Caribou Lake Greenstone Belt that forms part of the Superior structural province's Wabigoon sub-province. Deformed and metamorphosed Archean mafic volcanic sequences of the Willet Assemblage and dacitic volcanic and sedimentary strata of the Marshall Assemblage trend northeast across the property and are intruded to the east by a large tonalite intrusion. Thin iron formation units are locally present in both the Willet and Marshall assemblages. The tonalite intrusion has historically been linked to genesis of the various Li bearing pegmatite sills and dikes that occur on the property, including the Seymour Lake deposit, and has also been linked by some to genesis of the KM 61 Mo-Cu-Ag deposit.
The Crescent Lake showings appear to occur along the northeast extension of the Seymour Lake geological trend, and appears to occur in a similar geological setting. Volcano-sedimentary country rock assemblages that comprise non-plutonic bedrock areas on the property are folded and show steeply dipping axial surfaces that strike northeast to east along the main tonalite intrusion contact zone. Shearing parallel to this northeast to east trend is described for both the Crescent Lake showings and Seymour Lake. Shallow east-dipping pegmatites were emplaced along shallow dipping faults and to a lesser degree along the steeply dipping shears, indicating that their emplacement was relatively late in the local structural sequence. Minor spatial dislocation of both the tonalite contact and adjacent host rocks appears to have taken place locally along north to northwest cross faults that are evidenced by breaks and offsets of contact trends discernible in airborne magnetometer survey results.
Large areas of unmapped volcano-sedimentary and tonalite rock are present within the limits of property and offer good potential for additional pegmatite discoveries. The extension of favorable host sequences and settings into areas currently mapped as intrusion may be an important exploration factor, since Li-pegmatites known to date on the property show spatial association with discrete magnetic marker anomalies that characterise the host rock sequence. These are apparent adjacent to the main northeast trending intrusion contact zone.
The Chappais Lake Showing is one of the 4 pegmatite dykes evaluated for lithium in the Crescent Lake Project area. The outcropping is approximately 8 m x 25 m in surface exposure and was stripped of overburden, power washed, geologically mapped and sampled. Based on the geological mapping of the showing, two lines of channel samples were cut across the pegmatite dyke. The Li2O results ranged from 0.08% to 3.15% for 11 samples. The Chappais Showing has strong spodumene mineralization occurring as large patches containing some very coarse crystals up to 50 cm long. The channel sampling did not cut through these obvious high grade areas.
The pegmatite dyke is within a granitic intrusion (tonalite), strikes in an east-west direction and dips southerly at a low angle. The true width of the dyke near surface, as indicated by drilling (CL-16-02 and 16-03), is 4.7 m and in a down dip drill hole (CL-16-10), the depth is at least 22 m.
Five drill holes were completed over the Chappais Lake Showing, some highlights were;
The L61 Showing was named from its grid location by the Dempster Exploration Company in the 1950's. The initial exploration history partially defined two pegmatite dykes, West and East, through stripping and a series of small drill holes. The two mineralized pegmatite dykes were recognized through geological mapping, and some off-setting faults in the area were noted.
The West Dyke was 1 m wide at the south end and weakly mineralized with spodumene (lithium) and at the north end of the north striking dyke was 5 m wide and contained very strong spodumene mineralization.
The East Dyke (6 m wide) is located approximately 13 m from the West Dyke and strikes parallel to it. Trench maps highlight the results of surface channel sampling and include 2.29 % Li2O over 1.0 m on the East dyke at the L61 South exposure and 2.43 Li2O over 1.0 m on the East dyke at the L61 North exposure.
Six diamond drill holes were completed on L61 South showing within both lithium bearing pegmatites dykes. Some of the highlights were;
L61 North Showing has been extensively drilled, and results of this drilling suggest that the east and west dykes may converge at depth.
The L28 Showing was named in the 1950's when it was originally discovered along with the three other occurrences on the Crescent Lake Property. The L28 outcropping is barely visible at the edge of a wet, low bog. The pegmatite dyke is within a granitic intrusion (tonalite), striking north-east and dipping southeast at a low angle.
Geological mapping was completed of the showing and channel samples were cut across the pegmatite dyke (Figure 9). The analytical results are pending. The L28 Showing has weak spodumene mineralization with some large patches containing some very coarse crystals. Trench sample highlights include sample No-1123960 that returned 1.27% Li2O over 1 m, and sample No-1123961 that returned 1.15% Li2O over 1.3 m. An extension of the L28 showing was discovered 90 meters along strike to the southeast of the originally mapped showing.
Two drill holes were completed at L28,
L28 Showing has shown enormous potential, based on these intersected mineralized pegmatite dykes, and warrants further exploration work. The limited surface exposure may not be representative of its potential.
The L40 area is located on a low sloping hillside with very little outcrop exposure. Surface work included trenching across the width of the pegmatite dyke and the taking of a large hand sample for analysis. The geological model shows a very flat lying dyke or sill that is mineralogically zoned with a coarse-grained footwall section of feldspar and quartz then grading into feldspar, quartz and muscovite with spodumene mineralization. The hanging wall contact was buried in overburden.
One drill hole was completed to test for mineralization;
The Crescent Lake Property exploration activity has been mainly focused towards Li as the main metal of interest. The property produced encouraging Ta levels of several hundred parts per million, observed during the 2016 Sovereign exploration programs. The property also has a huge potential for the discovery of new Mo-Cu mineralization similar to the KM-61 deposit.
Stockport Exploration holds a 100% interest in the the Crescent Lake Lithium Prospect in Ontario, Canada property.