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Hans G. Machel1
(1) University of Alberta, Edmonton, AB

Abstract: Indications for low-flux, tectonically induced fluid flow into the Rocky Mountain Foreland Basin, Canada

Hydrogeologic studies in the Devonian section of the Alberta Basin have shown that regional flow of formation waters and/or petroleum currently is mainly toward the north and northeast. The recharge area(s), the nature of the driving force(s), and the time since the current flow patterns have been established, are being debated.

This study traces paleo-fluid flow through the Devonian carbonate aquifers in the deep part of the Alberta Basin using the distribution and geochemical composition of sparry calcite and dolomite cements, the Sr-isotopic composition of the surrounding and interbedded shales, and of Proterozoic metasediments that make up the underlying basement and much of the adjacent Rocky Mountain Front Ranges. The data define the regional background value of the MAximum Sr Isotope Ratio of BAsinal Shale, i.e., MASIRBAS, at about 0.7120. The data further show (a) that many carbonates close to the deformed belt form sour gas pools that are hydrologically relatively isolated at present, and (b) basin-external fluids entered during the Laramide Orogeny in some pools close to the deformed belt. The fluxes and possible geothermal anomalies during injection of these external fluids appear to have been low.

These findings may have implications for petroleum exploration. A tectonic push of fluids into the foreland basin implies that these fluids may have been hotter than previously thought, and that petroliferous fluids may have been pushed in directions other that those presently established and/or recognized.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana