Open File Report 2009-12

Open File Report 2009-12

OFR 2009-12

Sandstone-Hosted Uranium in Southern Alberta: 2007 and 2008 Study Results

Author(s) Matveeva, T.M. Kafle, B. Date 2010-02-16

This report publishes the results of field observations and analysis of the well-log database. Studies of mineralization in the Willow Creek Formation are continuing and will be published in the next report.

Alberta Geological Survey completed field programs in June 2007 and October 2008 near Cardston, Taber and Fort McLeod. We described outcrops of Upper Cretaceous and Tertiary formations in the field, took radioactivity measurements onsite, and collected 122 samples for determination of multiple elements. Representative thin sections were prepared and detailed petrographic descriptions, including point counts, were made. We conducted a radiometric survey along the St. Mary, Waterton and Oldman rivers. The most notable result of the 2007 and 2008 field programs is the discovery of a new radioactive occurrence, consisting of anomalous uranium content (158 ppm) in the siltstones of the Willow Creek Formation along the Oldman River.

An automated evaluation of tens of thousands of digital logs from oil and gas wells, and subsequent detailed analysis of 1800 well logs, outlined areas for future assessment. We selected anomalous gamma-ray intervals in the upper 550 m for determination of rock type and formation. Eighty-two per cent of the high-gamma intervals occur within shaly units with a high organic content (e.g., Base of Fish Scales and Second White Specks formations). Clusters of wells with high gamma readings in sandstone occur in NTS areas 82O, 83G, 84D and 83O. In the Claresholm area, multiple wells with high gamma readings in sandstones of the Willow Creek and St. Mary River formations occur within the upper 500 m. We studied cuttings from these wells to determine rock type and possible source rock for the radioactive anomaly. However, due to very small sample size, sample dilution and washout of the fine fraction from drill cuttings, we were unable to identify the source rock of the radioactive intervals.

During 2007, several mineral-assessment reports from junior exploration companies became public. These reports contain detailed information on airborne radiometric and electromagnetic surveys in southern Alberta, drilling results for two separate projects, radon-cup surveys, outcrop sampling, studies of oil and gas well logs, and other exploration programs performed in southern Alberta during 2005-2007. The first detailed, high-resolution magnetic and radiometric airborne survey was flown in the area in order to identify potential uranium exploration targets. The best drilling intersection occurred on the Whiskey Gap project: a uranium content of 136 ppm over 0.3 m was associated with elevated concentrations of copper, antimony and selenium.