REASSEMBLING IOWA: SPATIAL AND TEMPORAL EVAUATION OF THE MINERAL POTENTIAL OF THE IOWA SEGMENT OF THE MIDCONTINENT RIFT AND RELATED PLUTONS

The Iowa basement includes several terranes that are associated with nickel, copper, platinum group element deposits in other areas of the craton. These include a paleo-craton margin and an intracontinental rift. Rift related features in Iowa have received intermittent interest as exploration targets since the 1950’s when airborne geophysical surveys were undertaken. During the 1960’s several drilling programs targeted anomalies identified by these surveys, evaluating them for iron and titanium. Recent revision of isotopic ages for key basement rocks from Iowa has pushed the Yavapai boundary north, constraining the ages of the massive Northeast Iowa Intrusive Complex to Keweenawan. Insights into the magmatic processes involved in emplacement of contemporaneous Duluth Complex copper, nickel, and platinum group element deposits, combined with the new age constraints for the Iowa Complex, compels reevaluation of Iowa data. Several of the plutons in the Iowa Complex have been studied and modeled using gravity and magnetic data. One linear anomaly has been cored, penetrating 724 feet of troctolite, and modeled. The revisiting of these data and core using modern exploration modeling techniques would lead to a better understanding of the nature of the features and provide a more accurate evaluation of their mineral potential.