| Basis for focus area |
Data-driven prospectivity ranking of watersheds (HUCs; Karl and others, 2016) shows that the focus area includes 12,260 km2 with a total of 14 HUCs that have high prospectivity. Scores within high prospectivity HUC's are dominated by sediment geochemistry (ranges from 55-85% of total score) followed by Igneous and Lithology scores. Barker (1983) reports on rare-metal occurrences associated with Old Crow batholith highlights known or suspected potential. |
| Identified resources |
None. |
| Production |
None recorded. |
| Status |
Unknown. |
| Estimated resources |
Unknown. |
| Geologic maps |
There are no suitable geologic maps at 1:63,360 scale or better. |
| Geophysical data |
Rank 2 aeromagnetic survey funded by U.S. Geological Survey Mineral Resource Program, flown in 2016 by DGGS. Currently in preparation for publication by DGGS; inadequate aeroradiometric coverage. |
| Favorable rocks and structures |
Carboniferous Old Crow peralkaline granite and monzonite batholith covers most of the areas highlighted by the high prospectivity HUCs. Total lithology and igneous scores range from 0-2. |
| Deposits |
None. |
| Evidence from mineral occurrences |
Known placer ARDF occurrences for REE are associated with drainage basins draining the Old Crow batholith; ARDF scores range from 0-2. |
| Geochemical evidence |
Sediment scores range from 5-6, and pan concentrates are rare in the region, but range from 0-2. |
| Geophysical evidence |
Aeroradiometric scores range from 0-1. |
| Evidence from other sources |
Barker (1983) report on rare-element potential of the region highlights favorable geology including rock geochemistry. |
| Comments |
This is a poorly mapped, geologic hole in the understanding of Alaska and contains a known peralkaline intrusive complex with REE-bearing minerals hosted in quartz veins and associated sparse placer workings suggesting upside prospectivity. Commodities include arsenic, phosphate, uranium, xenotime, uranophane, arsenuranylite, and metatorbernite. |
| Cover thickness and description |
Unknown. |
| Authors |
Douglas C. Kreiner, James V. Jones III, Melanie B. Werdon. |
| New data needs |
New mapping, geophysics, and updated geochemical sampling. |
| Geologic mapping and modeling needs |
Framework geology-includes lithology, structure, and hydrothermal alteration. There is no detailed mapping in the region. Particular attention paid to characterizing key structures (i.e., Porcupine Shear Zone), which may play a role in fluid plumbing. Host rock mapping-Selwyn basin stratigraphy present, is there potential for Carlin-like gold systems as in the eastern portions of the Selwyn basin? Igneous phases identified and quantified geochemically-what are the key alkaline phases associated with REE mineralization at Old Crow, are there other magmatic hydrothermal systems? Isotopic data (Hf, Pb) to test crustal character and terrane affinity. |
| Geophysical survey and modeling needs |
Targeted EM for lithologic and structural mapping under cover. |
| Digital elevation data needs |
IfSAR coverage is complete over entire focus area. |
