Thirtynine Mile Volcanic Field
[Colorado, USA]
The Thirtynine Mile uranium project is located in central Colorado and consists of 121 unpatented lode mining claims covering approximately 10 km2 (~2,460 acres). The claims are located in the Tallahassee Creek area about 130 kilometres south-west of Denver, Colorado. The project area is located along strike and down channel from the 30 million lbs Hansen uranium deposit and the 42 million lbs Taylor Ranch uranium resource. The claim area contain a part of the small but high grade historical uranium mine, the First and last Chance mine (past production – 117,000 lbs at an average grade of 6.6 lbs/tonne U3O8.
The Thirtynine Mile uranium project is strategic alliance (Geolynx Joint Venture) between the Royal–Lynx2 LLC partnership and a Colorado registered company Geomininc to explore for and develop uranium deposits in the Thirtynine Mile Volcanic Field.
REGIONAL GEOLOGY AND MINERALISATION
The mid-Tertiary Thirtynine Mile Volcanic Field of central Colorado covers some 2,000 square kilometres and is one of the most important uranium districts in the state. The basement rocks consist of Precambrian schists, gneiss, granodiorite and quartz monzonite overlain by a Tertiary sequence of volcanic and sedimentary rocks.
The oldest Tertiary rocks known in the southern part of the volcanic field are the widely scattered remnants of the Echo Park Alluvium. This unit is composed primarily of Precambrian detritus that was deposited in depressions and subsiding basins during the Eocene period.
Volcanism in the field began with the emplacement of early Oligocene rhyolitic ash-flows of the Wall Mountain Tuff. A period of erosion followed during which major palaeochannels were incised into the underlying rocks and filled by sediment of the Tallahassee Creek Conglomerate. A substantial amount of volcanic tuff, andesitic lava flows and pyroclastic material was then deposited on the Tallahassee Conglomerate during the late Eocene and Oligocene periods to form the extensive Thirtynine Mile Andesite formation.
Uranium deposits of the district are generally hosted by both the Echo Park Alluvium and the overlying Tallahassee Creek Conglomerate. The most significant resource, the Hansen deposit (30,000 million lbs @ 1.8lbs/tonne) occurs within fluvial arkosic sands of the Echo Park Alluvium and is similar to basal-type sedimentary uranium deposits. The nearby Taylor Ranch deposit possibly occurs in the same stratigraphic horizon. In contrast, most uranium mineralisation within the Tallahassee Creek Conglomerate appears stratigraphically related to altered volcanic ash near the top of the sequence. During the period 1954 to 1972 a total of approximately 500,000 lbs of U3O8 was produced from the Tallahassee Creek Conglomerate at grades between 4.4 lbs and 6.6 lbs/tonne U3O8. Eleven small old open-pit and underground uranium mines occur within the Area of Interest.
TARGET
The primary target of the GeoLynx joint venture is medium to high grade (2 to 6 lbs/tonne) large tonnage uranium deposits associated with Eocene and Oligocene aged conglomerates and other coarse sedimentary horizons within the Thirtynine Mile Volcanic Field. |
