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Tectonic Interpretation Using Potential Field Data for the Sweetgrass Arch Area, Montana-Alberta-Saskatchewan

Jorgensen, Clark
Big Sky Geophysics, Bozeman, MT

I performed a basement tectonic interpretation for the Sweetgrass Arch area using public domain gravity and magnetic data from the USGS and GSC. This study is timely because of recent acquisition of data by the GSC and releveling of data by the USGS. The Sweetgrass Arch area’s sedimentary geology and hydrocarbon distribution are strongly influenced by the basement fault structure. Even small offsets in the basement structure can generate hydrocarbon traps by creating structural or stratigraphic traps in the overlying sediments. I map the basement geology using the geophysical data, compare it to know oil and gas pool locations, and use this information to pick prospective areas for future exploration.

Clear association between the gravity and magnetic patterns and known oil and gas pools is observed. In some cases there is a direct correlation between major faults and hydrocarbon occurrences while in other cases these faults may be used to bound areas that are prospective to exploration. Some uplifts in the basement topography are evident in the gravity data as local highs and can be used to target structural traps. The magnetic data are most effective for mapping the faults and the gravity data are most effective for mapping uplifts.