| Basis for focus area |
Small oxide-rich ultramafic intrusions cut troctolite and anorthosite have been encountered along the western margin of the Duluth Complex. These Ti-Fe± PGM±V oxide-bearing ultramafic intrusions are related to the 1.1 Ga Midcontinent Rift System. |
| Identified resources |
Identified titanium resources. |
| Production |
No known production. |
| Status |
Reporting-code-compliant resources established at two sites (Longnose and Titac/Section 34) by Cardero Resources. Resource estimate at Water Hen and bulk sampling conducted at Longnose. |
| Estimated resources |
Longnose 58 Mt @16.6% TiO2; Titac 45.1 Mt @ 15.0% TiO2; Water Hen 62 Mt @14% TiO2; deposits have potential for V (http://files.dnr.state.mn.us/lands_minerals/mcc_docs/2016_explore_titanium.pdf). |
| Geologic maps |
Miller and others (2001), scale 1:200,000 and 1:500,000. |
| Geophysical data |
Adequate aeromagnetic coverage; inadequate aeroradiometric coverage. |
| Favorable rocks and structures |
Small late oxide-rich plugs related to faults and large xenoliths of iron-formation. |
| Deposits |
Longnose (MRDS dep_id: 10082830), Section 34 deposit (Titac) (MRDS dep_id: 10111326), Waterhen (MRDS dep_id: 10082834). |
| Evidence from mineral occurrences |
MRDS. |
| Geochemical evidence |
No data. |
| Geophysical evidence |
Sharp small round features in aeromagnetic data. |
| Evidence from other sources |
Thirteen aeromagnetic/conductive features drilled as contact-type Cu-Ni targets have intercepted Ti-Fe ± PGM ± V oxide-bearing ultramafic intrusions. |
| Comments |
Oxide is intergrown coarse-grained ilmenite and titanomagnetite; very low in coproducts such as U, Th, Zr, and REE. |
| Cover thickness and description |
Thin to variable (10m +/-10m), 30m encountered in some drill holes near Duluth. |
| Authors |
Laurel G. Woodruff, George Hudak, David Dahl, Amy Block. |
| New data needs |
Two deposits (Longnose, Titac) have reasonable geological, geochemical, and mineralogical data. Fundamental geologic, geochemical, mineral chemical, structural data need further work in other occurrences. |
| Geologic mapping and modeling needs |
more detailed geologic mapping (1:24,000) in areas of known VMS deposits may be a good place to start, especially if supported by high-quality geophysics and lidar. |
| Geophysical survey and modeling needs |
Rank 1 aeromagnetic and radiometric data, gravity data, electromagnetic data would all be very helpful. |
| Digital elevation data needs |
Lidar variable; adequate, inadequate, and in progress. |
