Summary:
The Project is located in the Churchrock sub-district of the greater Grants Mineral Belt uranium district of northwestern New Mexico.
Local Geology
The exposed stratigraphy in the Churchrock area includes marine and non-marine sediments of Late Cretaceous age (Mancos Shale, Dakota Sandstone), unconformably overlying the continental-fluvial sediments of the Jurassic Morrison Formation, the principal host of uranium mineralization. The deposits dip generally from one to three degrees north towards the San Juan Basin.
Property Geology
Dakota Sandstone (Early Cretaceous)
The lower Dakota (Kd) Sandstone consists of a well-sorted fine-grained quartzose sandstone, deposited in a mostly marine, shoreface environment. In the subsurface at the Project, the lower portion of the Dakota Sandstone is approximately 75 ft thick.
Morrison Formation (Late Jurassic)
Brushy Basin Member
In the Churchrock area, the Brushy Basin Member is typically from 50 ft to 75 ft thick, depending on the level of erosion prior to deposition of the overlying Dakota Sandstone. The Brushy Basin (Jmb) is mostly shales/mudstones of greenish-grey to red-brown colour with a sandstone submember (Poison Canyon) that is mineralized locally. The Poison Canyon sub-member was not differentiated from the encompassing Brushy Basin Member in this report.
Westwater Canyon Member
In the Churchrock area, the bulk of the uranium mineralization is located in the sandstones of the Westwater (Jmw) Canyon Member. Eight informal sandstones, A to H in descending order, make up the Westwater Canyon, separated by thin shales/mudstones. The sands are yellowgrey to pale red and the shales are typically greenish-grey. In the Project area, the Westwater is approximately 325 ft thick, depending on the paleotopography and the amount of subsequent erosion.
Mineralization
The typical mineralized rock in the Churchrock sub-district, as well as the Ambrosia Lake and Jackpile districts, occurs as uranium-humate cemented sandstone. The uranium mineralization consists largely of unidentifiable organic-uranium oxide complexes that are light grey-brown to black.
For this report, the uranium mineralization is defined by each host sand unit: Dakota, Brushy Basin, and Westwater sands A to H. It is generally confined to the individual sand units except where intervening shales/mudstones are absent and the sand units are merged. Although not extensively studied in the Churchrock area, the mineralization is likely predominantly coffinite (uranium silicate mineral) with lesser amounts of uraninite and unidentifiable organic-uranium oxide complexes. Regionally, gangue mineralization includes varying amounts of vanadium, molybdenum, copper, selenium, and arsenic. The mineralization coats and fills the intergranular spaces of the host sandstones. Of note is the lack of organic carbon in the Churchrock deposits, unlike the primary-trend type and redistributed deposits further east in the Ambrosia Lake area.
The primary mineralization control is the presence of a quartz-rich, arkosic, fluviatile sandstone in the Morrison Formation. This type of sandstone is the primary host rock in the Churchrock sub-district, although some deposits were produced from Cretaceous Dakota Sandstone, a quartz-sandstone. The presence of carbonaceous matter as humate pods is important. Detrital plant fragments are less common in the Churchrock sub-district than in the Ambrosia Lake subdistrict. The presence of pyrite and bleaching alteration is important. Sedimentary features may exhibit control on a small scale. Alteration bleaching forms a halo that encloses mineralization, up-dip to the deposit. The bleaching caused by the removal of reddish ferric-iron pigmentation imparts a light-grey colour to the sandstone, and a greenish rim on red-cored claystone cobbles or galls (Fitch, 2005).
Deposit Types
The mineralized deposits in the Churchrock sub-district are sandstone-type uranium deposits. These types of deposits are irregular in shape, roughly tabular and elongated, and range from pods a few feet in thickness, length and width, to extensive bodies of mineralization tens of feet thick, several hundreds to thousands of feet long, and several tens to hundreds of feet wide. The deposits are roughly parallel to the enclosing beds, but may cut across bedding where interbedded shales/mudstones are absent and the sand units are merged.
Two types of uranium deposits occur in the Grants Mineral Belt, primary trend deposits and post-faulting, or redistributed, secondary deposits. The primary trend mineralization, located predominantly further east near Ambrosia Lake, was controlled by humic acids (humates) which acted as the reductants to precipitate the uranium from groundwater. In the Churchrock area, the secondary deposits predominate, having likely formed from remobilization and destruction of nearby primary trend deposits likely of non-humate origin. These secondary deposits at the Project are tabular in shape, and many formed into “roll-fronts”, similar in shape to the Wyoming-type uranium roll fronts that are mined by ISR methods in Wyoming, Nebraska, and Texas. Roll-front mineralization is distributed across a regional interface of oxidized and reduced groundwater environments, known as the redox front.