Drilling by UEX at Black Lake to date has intersected unconformity-style mineralization in the northern Black Lake property along a strike length of more than 1.7 kilometres along and adjacent to the Eastern Fault Zone of the Platt Creek Fault system. Mineralization comprises (i) unconformity-style mineralization straddling the unconformity in the footwall of the Eastern Fault Zone, and (ii) mineralization directly along the fault where it intersects the unconformity, with best intercepts developed where a small basement wedge is present.
The Company has planned a radon and helium survey at Black Lake while snow cover remains and the low-lying swamps in the northern part of the Project are still frozen. C.O. Geosciences Inc. of St-Lazare, Quebec has developed for ALX a new technique of augering into frozen swamps to collect sediment samples for analysis.
Approximately 160 radon and helium sample sites are planned on a grid established in the northernmost area of the Project located above the main conductive system. Historical drilling bracketing the survey area has intersected faulted and fractured rocks, which are more likely to allow the escape of radon, helium, and other gases known to be emitted by uranium mineralization. Anomalous uranium mineralization was intersected in Eldorado Nuclear Ltd. 1980 drill hole RL-4B and in two drill holes completed by ALX in 2017 (BL-155 and BL-156) at the edges of the 2019 survey area, which has received sparse drill testing in relatively shallow sandstone cover (225 to 250 metres to basement).
On July 9, 2018, The Company reported the final geochemical results from the 2017 fall diamond drilling program at Black Lake. Two of the five holes, BL-155 and BL-156, which both intersected narrow intervals of uranium mineralization, returned values of 0.06% U3O8 over 0.15 metres from 316.69 to 316.84 m in hole BL-155 and 0.03% U3O8 over 0.07 metres from 272.77 to 272.84 m in hole BL-156 corresponding to pitchblende veinlets observed in the drill core. Large graphite-rich fault zones, varying from 34 to 68 metres thick with local strongly graphitic to carbonaceous breccias were intersected in holes BL-152, BL-153 and BL-156. These graphitic fault zones are enriched in uranium pathfinder elements such as nickel (up to 401 ppm Ni), copper (up to 1,420 ppm Cu), cobalt (up to 81 ppm Co) and boron (up to 195 ppm B). All five holes intersected graphitic fault zones, which were the target of the 2017 program. Sandstone alteration observed included dravite veining, siderite and minor pyrite, and basement alteration included hematization, chloritization, saussuritization and carbonate veining.
Downhole radiometric probing of holes BL-155 and BL-156 recorded peaks of 2677 and 1144 counts per second (cps), respectively, with a Mount Sopris Model 2PGA‑1000 downhole probe, which coincided with the observed veinlets of pitchblende. Core samples are being submitted to the Saskatchewan Research Council in Saskatoon, Saskatchewan, and geochemical results will be released when received, compiled and interpreted.
A leading-edge borehole induced polarization (IP) resistivity geophysical survey using a Dias system was carried out on two of the 2017 drill holes and one historical drill hole to provide a 3-D view of the sub-surface to depths of over 500 metres, and up to 200 metres around each drill hole. This new technique employs a conductive downhole probe combined with a traditional induced polarization surface array to better define the character of the known conductors and locate possible alteration zones in the vicinity of those conductors.
ALX plans to integrate the results of the downhole surveys with the recently-completed ZTEM™ airborne survey to develop additional targets at Black Lake. These results combined with geological and geochemical data collected from the 2017 drill program will provide valuable information for future exploration programs.
In 2004, UEX intersected a significant intersection of uranium mineralization in drill hole BL-18 (0.69% U3O8 over 4.4 metres, including 1.09% U3O8 over 1.5 metres) which sparked an extensive amount of exploration work in the northern Athabasca Basin by UEX and other uranium exploration companies. Other mineralized holes were drilled at Black Lake over the next several years (see Table 1 below), but despite the series of uranium occurrences, no new uranium deposit was discovered.
Table 1. Black Lake Historical Mineralized Uranium Intersections
| Hole No. | Year | Grade (% U3O8 ) | From (metres) | To (metres) | Interval (metres) |
|---|---|---|---|---|---|
| BL-018 | 2004 | 0.69 | 310.50 | 314.90 | 4.40 |
| including |
|
1.09 | 312.80 | 314.30 | 1.50 |
| BL-023 | 2005 | 0.28 | 307.90 | 308.00 | 0.10 |
| BL-032 | 2005 | 0.16 | 313.90 | 315.30 | 1.40 |
| BL-056 | 2005 | 0.26 | 319.90 | 322.50 | 2.60 |
| BL-064 | 2005 | 0.54 | 338.75 | 340.75 | 2.00 |
| BL-082 | 2006 | 0.50 | 273.45 | 276.75 | 3.30 |
| including |
|
1.60 | 274.45 | 275.15 | 0.70 |
| BL-110 | 2006 | 0.79 | 309.73 | 312.55 | 2.82 |
| including |
|
1.57 | 311.25 | 312.55 | 1.30 |
| BL-137 | 2007 | 0.24 | 275.40 | 278.40 | 3.00 |
| BL-140 | 2007 | 0.67 | 274.10 | 277.10 | 3.00 |
| including |
|
1.58 | 274.40 | 275.40 | 1.00 |
The mineralized intervals listed in Table 1 were encountered at the unconformity between the overlying Athabasca sandstones and underlying basement rocks at downhole depths between 274.10 and 340.75 metres. Historical work in the northern part of the Project has demonstrated the potential for a polymetallic mineralizing system in relatively shallow sandstone cover that ranges from approximately 225 to 300 metres. A predecessor company of UEX re-sampled historical drill hole RL-4B drilled by Eldorado Uranium in 1980, which returned values of 171.6 parts per million (“ppm”) uranium, 0.207% cobalt and 256 ppm nickel over 0.75 metres from 251.00 to 251.75 metres in basement rocks, approximately 25 metres below the unconformity.
Black Lake is staked over the Platt Creek Fault, a major NNE-trending fault parallel to the Black Lake Fault. Shear zones and faults of this style are frequently host to unconformity-type uranium deposits in the Athabasca Basin. The Project is underlain by 250 to 600 metres of Proterozoic sandstone of the Athabasca Group that dips shallowly to the south. The sandstone unconformably overlies Archean-aged basement rocks of the Tantato Domain, which comprise metavolcanic units, graphite-bearing metasedimentary gneiss, mafic sills and granites that have been affected by amphibolite to granulite facies metamorphism. Basement rocks trend mainly northeast, and are affected by tight, megascopic folds. Post-Athabasca faults also strike mainly to the northeast, and include the Platt Creek Fault, which extends through the project area northward into older syn-metamorphic shear zones.
Exploration to date has been principally directed towards the testing of a southeast-dipping reverse fault, termed the “Eastern Fault”, a subparallel strand of the Platt Creek Fault system, and associated graphitic gneiss units which are defined by electromagnetic (“EM”) conductors. Competency contrast between soft chloritized amphibolites or graphitic pelites and the siliceous leucocratic granitic gneiss favours the development of ductile to brittle shear zones. Reactivation of these shears may result in post-sandstone faulting. Locally multiple stages of post-sandstone faulting or branching of the same fault have resulted in more widespread fracturing and desilicification of sandstone and clay alteration of basement rocks along the fault in the vicinity of the unconformity, conditions prospective for uranium deposits. Dravite (Mg-tourmaline), siderite and less commonly pyrite veining are present in the sandstone column particularly in the northern Black Lake property, which are alteration assemblages that are often spatially associated with uranium mineralization.
Black Lake was initially explored in the 1970s following the discovery of radioactive boulders identified in till. EM surveys carried out initially by Eldorado Nuclear Ltd. during 1979 to 1980, and then subsequently by Cameco Corporation in 2000, identified well-defined north-northeast trending conductors now known to be associated with the Platt Creek Fault and its principal eastern strand along the east side of the conductive package, the Eastern Fault Zone.
After evaluating drill core from previous operators which intersected above background, low-grade mineralization near the unconformity, and on the basis of the strength of the Platt Creek Fault conductors, UEX commenced systematic testing for uranium mineralization on the Black Lake property in 2003.
During the 2004 summer program, hole BL-18 encountered unconformity-type uranium mineralization at a vertical depth of 310.5 metres grading 0.69% U3O8 over 4.4 metres between 310.5 and 314.9 metres, including 1.09% U3O8 over 1.5 metres between 312.8 and 314.3 metres. The mineralization occurs at the base of the Athabasca sandstone column straddling the unconformity. Also associated with the BL-18 intercept are highly anomalous concentrations of arsenic, copper, lead and nickel, which are typically associated with unconformity-style mineralization in other parts of the Athabasca Basin. On the basis of the BL-18 intersection, UEX increased its exploration activities in the project area, testing the Eastern Fault Zone and associated graphitic package primarily in the northern portion of the Black Lake property.
Subsequent drilling in 2005 and 2006 intersected additional uranium mineralization adjacent to the BL-18 intercept, defining a flat-lying pod of mineralization over several tens of metres which is developed along the unconformity in the footwall of the Eastern Fault Zone. In addition, significant uranium mineralization was encountered in two holes along the Eastern Fault Zone at, or immediately below, the Athabasca unconformity. In hole BL-56, located approximately 200 metres south of hole BL-18, mineralization was intersected from 319.9 to 322.5 metres, grading 0.26% U3O8 over 2.9 metres. Hole BL-64, located approximately 600 metres south of BL‑18, intersected unconformity-style uranium mineralization, similar to that found in hole BL-18, from 338.75 to 340.75 metres, grading 0.54% U3O8 over 2.0 metres.
Several holes drilled in 2006 and 2007 along the Eastern Fault Zone intersected a small overthrust wedge of graphitic gneiss on Athabasca sandstone associated with a major reverse fault where uranium mineralization is developed. In the Athabasca Basin, the presence of such a basement “wedge” is considered an important geological feature for potential uranium deposition, having formed a structural trap for mineralizing hydrothermal fluids. The uranium mineralization in these drill holes occurs along and immediately beneath the wedge where the Eastern Fault Zone intersects the Athabasca unconformity. Drilling intercepts in this area include 0.50% U3O8 over 3.3 metres from 273.45 to 276.75 metres, including 1.60% U3O8 over 0.7 metres in drill hole BL-082, 0.24% U3O8 over 3.0 metres from 275.4 to 278.4 metres, including 0.56% U3O8 over 1.0 metres in drill hole BL-137, and 0.67% U3O8 over 3.0 metres from 274.1 to 277.1 metres, including 1.58% U3O8 over 1.0 metre in drill hole BL-140.
