Nome belt

Region Alaska, Alaska
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Prospectivity analyses highlight this belt as being favorable for volcanogenic seafloor systems. However occurrences in ARDF have also been interpreted as basin-brine path systems based on a lack of association with volcanic rocks and sulfur isotope studies of barite and sulfide sulfur. This focus area is included here because it meets the criteria based on lithology, geochemistry and ARDF occurrences and a significant belt of high prospectivity drainage basins defined by Karl and others (2016).
Identified resources None.
Production None recorded.
Status Past exploration including drilling at the Aurora prospect.
Estimated resources None.
Geologic maps Statewide geologic map database; Wilson, Hults and others (2015), scale 1:1,584,000.
Geophysical data Mostly (>90%) inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Original work interpreted host lithology as metavolcanic rocks consisting of rhyolites. Subsequent work has now interpreted lithology as part of the Nome Complex consisting of pelitic, calcareous, and graphitic schist with the absence of identified volcanic rocks.
Deposits None.
Evidence from mineral occurrences ARDF occurrences.
Geochemical evidence Sediment and soil anomalies in pathfinder elements including Cu, Ag, Pb, Zn, Cd, or Co. Additional geochemical evidence comes from pan concentrates containing anglesite, cerussite, chalcopyrite, copper sulfide/oxide, galena, or sphalerite. Heavy mineral concentrates containing Cu, Pb, Zn or Ag.
Geophysical evidence No data.
Evidence from other sources Significant portion of the focus area (30-50%) covered by drainage basins exhibiting high prospectivity potential in Karl and others (2016).
Comments As noted elsewhere, ARDF occurrences in this focus area are enigmatic with conflicting interpretation as related to both basin-brine path and volcanogenic seafloor systems. Rocks in the belt have been subjected to blue-schist metamorphic grades and retrograded to green schist assemblages-further complicating the interpretation of regional geology. Sulfur isotopes (sulfate in barite) suggest a marine origin for Mississippian-Devonian seawater and sulfide sulfur of marine origin (Slack and others, 2014).
Cover thickness and description Unknown.
Authors Douglas C. Kreiner, James V. Jones, III.
New data needs New geologic mapping, geophysical surveys and well-constrained geochemical sampling.
Geologic mapping and modeling needs Mapping at 1:100,000 scale or better.
Geophysical survey and modeling needs Rank 1 or 2 aeromagnetics over the entire belt.
Digital elevation data needs IfSAR coverage is complete over entire focus area.