Western Alaska Range PCD

Region Alaska, Alaska
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Permissive geology, substantial ARDF occurrences with porphyry copper characteristics.
Identified resources Identified resources of copper, gold, molybdenum, PGE, rhenium, and silver.
Production None recorded.
Status Current and past exploration.
Estimated resources Pebble: 5,942 Mt at 0.42% Cu, 0.025% MoS2, 0.35 g/t Au, 140 Moz Ag, 1.2 million kg Re, and 907,000 oz Pd; Whistler: 79.2 Mt at 0.17% Cu and 0.51 g/t Au; Kijik: 91 Mt at 0.3% Cu and 0.17% MoS2; 38 Porphyry: 500 Mt at 0.32% Cu and 0.33 g/t Au; 52 Porphyry: 150 Mt at 0.35% Cu; Island Mountain: 31.1 Mt at 0.06% Cu and 0.49 g/t Au.
Geologic maps No modern mapping better than 1:250,000 scale.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Calc-alkaline diorite porphyry, granodiorite porphyry, dacite porphyry, breccia pipes, and associated coeval andesite volcanic rocks. Arc magmas span the Early Cretaceous through the Paleocene.
Deposits Pebble, Whistler, Kijik, 38 porphyry 52 porphyry, Island Mountain.
Evidence from mineral occurrences Numerous ARDF occurrences, including Pebble, Whistler, Island Mountain, etc.
Geochemical evidence Mo, Cu, Ag, Au, Pb, Zn.
Geophysical evidence Detailed aeromagnetic data shows strong magnetic highs associated with batholiths exhibiting strong spatial proximity to known porphyry systems, and potential concealed porphyry systems.
Evidence from other sources Favorable calc-alkaline felsic to intermediate arc rocks associated with a minimum of three arc cycles, and possibly as many as 5, with locally reactive host rocks.
Cover thickness and description Parts of Pebble are covered by as much as 1,000 m of post-mineral cover, and Pebble itself is tilted by as much as 25ยบ post-mineral-suggestive of further concealed and tilted, and/or dismembered porphyry systems.
Authors Douglas C. Kreiner, James V. Jones III, Melanie B. Werdon.
New data needs New mapping, geophysics, updated geochemical sampling.
Geologic mapping and modeling needs Mapping at 1:100,000 scale or better.
Geophysical survey and modeling needs Aeromagnetics and radiometrics collected at Rank 2.
Digital elevation data needs IfSAR coverage is complete over entire focus area.