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.
- Northeastern portion of the Athabasca Basin near Stony Rapids, SK
- Black Lake consists of twelve claims totaling 30,381 hectares (75,073 acres)
- Black Lake is currently held as a joint venture between UEX and Orano Canada Inc. (“Orano”). As of June 30, 2017, Black Lake was held 90.92% by UEX and 9.08% by Orano
- ALX can earn up to a 75% participating interest in the joint venture from UEX by issuing up to 12.0 million common shares to UEX and spending up to $6.0 million on exploration over an approximate 4-year period
- ALX will act as operator of exploration at Black Lake
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.