Porcupine River REE

Region Alaska, Alaska
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

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.