| Basis for focus area |
PGE enrichment in the Sonju Lake Intrusion (Beaver Bay Complex) and rocks along the eastern side of the South Kawishiwi intrusion (Duluth Complex) ; Potato River Intrusion in the Mellen Complex has a similar magmatic style. Intrusions part of the 1.1 Ga Midcontinent Rift System. |
| Identified resources |
Unknown. |
| Production |
Unknown. |
| Status |
Sonju Lake intrusion (Minnesota) had reconnaissance exploration by Franconia Minerals; currently inactive. No exploration in the Potato River complex (Wisconsin). |
| Estimated resources |
Unknown. |
| Geologic maps |
Sonju Lake Intrusion: Miller, Brown and others (1993), scale 1:24,000; Potato River Intrusion: Cannon and others (1996), scale 1:100,000. |
| Geophysical data |
Adequate aeromagnetic coverage; inadequate aeroradiometric coverage. |
| Favorable rocks and structures |
Tholeiitic layered intrusions in the Duluth (Layered Series at Duluth-DLS) and Beaver Bay (Sonju Lake Intrusion) Complexes; Potato River Intrusion (part of Mellen Complex) in Wisconsin has similarities. |
| Deposits |
No data. |
| Evidence from mineral occurrences |
No data. |
| Geochemical evidence |
Multiple geochemical analyses through Sonju Lake Intrusion reported in Miller (1999). |
| Geophysical evidence |
No data. |
| Evidence from other sources |
No data. |
| Comments |
Deposit type compared to Skaergaard Intrusion; tholeiitic composition somewhat unusual for this type of deposit. |
| Cover thickness and description |
Thin glacial cover. |
| Authors |
Laurel G. Woodruff. |
| New data needs |
New mapping, high resolution geophysics. |
| Geologic mapping and modeling needs |
Mapping at 1:24,000 scale over Sonju Lake Intrusion; mapping over Potato River Intrusion of 1:100,000 scale. |
| Geophysical survey and modeling needs |
Need rank 1 aeromagnetic data in Minnesota and Wisconsin. |
| Digital elevation data needs |
Lidar in progress. |
