Open File Report 1991-20

Open File Report 1991-20

OFR 1991-20

Hydrochemistry of Phanerozoic Strata, Northeast Alberta: Report to Alberta Research Council

Author(s) Hitchon, B. Date 1991-12-01

The Northeast Alberta study area is defined as 55° to 58°N, and 110° to 114°W. A total of 2933 formation water analyses from the area were entered into the Alberta Geological Survey Well Data Base, verified, and subjected to a variety of electronic, manual-electronic and manual culling to leave a final data base of 525 analyses on which this study was based.

Salinity ranges from freshwater to 325,000 mg/l, and there are corresponding maximum contents of Cl (200,000 mg/l), Ca (40,000 mg/l) and Mg (8000 mg/l). Nine maps illustrate the distribution of salinity, which is essentially depth (temperature) related except where there is incursion of fresher waters from overlying aquifers. Sulfate is high (500-5500 mg/l) in aquifers in which anhydrite is present (Elk Point hydrostratigraphic unit -- Prairie Formation; Beaverhill Lake aquifer -- Fort Vermilion Formation; and Grosmont aquifer -- Hondo Formation). Formation waters in the Elk Point hydrostratigraphic unit from near the updip solution edge of the Prairie aquiclude (halite) are similar to those of saline springs in the valley of the Athabasca River, which have been shown to originate from solution of evaporites by meteoric water.

Based on the composition of their formation waters the aquifers can be combined into groups separated by aquitards, as follows: Viking aquifer (weak Joli Fou aquitard); Grand Rapids aquifer (strong, regional Clearwater aquitard); Clearwater, Wabiskaw and McMurray aquifers; Wabamun and Winterburn aquifers (weak Upper Ireton aquitard); Grosmont aquifer (strong Lower Ireton aquitard); Beaverhill Lake aquifer (significant, regional Prairie aquiclude); Elk Point hydrostratigraphic unit (mainly Keg River aquifer); Precambrian aquiclude. In summary, the formation waters of the Northeast Alberta area are an extension of those in the adjacent Peace River Arch area, exhibit similar characteristics, and have similar origins.

Hitchon, B. (1991): Hydrochemistry of Phanerozoic strata, northeast Alberta: report to Alberta Research Council; Alberta Research Council, ARC/AGS Open File Report 1991-20, 31 p.