THE MIDCONTINENT RIFT SYSTEM IN
IOWA
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GEOPHYSICAL SIGNATURE |
Introduction
Interpretation and modeling of geophysical data has been a primary tool in the investigation of the Midcontinent Rift System in all areas, especially in Iowa. In Iowa the MRS is overlain by 1500 to 5000 feet (450 to 1500 m) of Paleozoic and Mesozoic strata and Quaternary sediments, and only 73 wells penetrate into MRS rocks (click here for discussion MRS drill data -- here for map locating MRS drill data). Because of this lack of direct data, geophysical information, both potential field (gravity and magnetic) and seismic, have been critical to developing an understanding of the structure in Iowa. A state-wide network of gravity stations and a series of aeromagnetic surveys flown between 1958 and 1972 provided the basis for interpretation of large-scale structures. In the late 1980's a series of Petty Ray-Geosource deep reflection seismic profiles were made available to the Iowa Geological Survey for interpretations. These seismic data allowed a more detailed interpretation of the Iowa Horst and associated basins along the profiles. Anderson (1992) used the seismic data to contol gravity modeling along the lines of profile, then used the structural and stratigraphic trends from these models to develop our current understanding of the Midcontinent Rift System in Iowa.
GRAVITY ANOMALY
AEROMAGNETIC ANOMALY
SEISMIC DATA AND INTERPRETATIONS
(click here for discussion MRS seismic data and interpretations)
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