Explained by K.J. Schulz, W.F. Cannon, P.K. Sims, and G.L. LaBerge
On the choice of deposit models
At least seven significant volcanogenic massive sulfide deposits (Flambeau, Pelican, Crandon, Bend, Lynne, Thornapple, and Catwillow) are known in the exposed northern part of the Early Proterozoic magmatic terranes of Wisconsin.
On the delineation of permissive tracts
The tract consists of that part of the Wisconsin magmatic terranes where the rocks are concealed, but lie within one km of the surface as projected by Sims (1990). This includes areas in northwestern Iowa and northeastern Nebraska, as well as areas in northern Wisconsin that are adjacent to the exposed part.
On the numerical estimates made
Because of lack of knowledge about covered parts of the Penokean orogen, the team did not make an estimate of undiscovered kuroko deposits for this tract.
Sims, P.K., 1990, Precambrian basement map of the northern midcontinent, USA: U.S. Geological Survey Miscellaneous Investigations Map I-1853-A.