Sequence stratigraphy and its use for uranium exploration in the western Athabasca Basin of Alberta and Saskatchewan

Eighty-nine cores were logged on a metre-by-metre basis in the western Athabasca Basin of Alberta and Saskatchewan. Seven third-order sequences, ranging from several tens to hundreds of metres in thickness, were positively identified. These include from base to top: the Fair Point, Shea Creek, Lower Manitou Falls, Upper Manitou Falls, Lower Wolverine Point, Upper Wolverine Point and Locker Lake-Otherside sequences. Above the Fair Point Sequence, a highly erosive boundary containing localized paleosols separates two unique depositional basins. The older Jackfish Basin consists entirely of coarser fluvial clastic sediments of the Fair Point Sequence. The overlying William River Basin consists of the relatively finer-grained and dominantly fluvial clastics of all of the remaining sequences.

The basal Shea Creek, Lower Manitou Falls and Upper Manitou Falls sequences are entirely fluvial and were probably restricted to near the present-day margins of the Athabasca Basin. Their general coarsening-upward stacking pattern and limited lateral distribution suggest a normal regression under relatively low change in rates of accommodation. In contrast, the overlying Lower and Upper Wolverine Point sequences were probably more widespread beyond the present-day margins of the Athabasca Basin. This fining-upward succession represents deposition under relatively higher change in rates of accommodation, as deposits retrograded from entirely fluvial to fluvial-lacustrine. The uppermost Locker Lake-Otherside sequence, although not complete, represents a late normal regression where relative change in rates of accommodation are overtaken by rates of sediment supply. Changes in sequence thickness and basal lithology appear to be linked to faulting within the basin. If such is the case then this can be used to predict where fault zones occur in the western Athabasca Basin, and indicate potential uranium mineralized zones.