|Quadrangle map, 1:250,000-scale||MZ|
|Quadrangle map, 1:63,360-scale||D-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Several lode occurrences are along the Koyukuk River southwest of Sun Mountain, in the southern Isahultila Mountains (Miller and Ferrians, 1968). Their precise locations are unknown, but are presumed to be in T. 5 N, R. 18 E. to R. 20 E., Kateel River Meridian. For this record, the site is at an elevation of about 350 feet on the north bank of the Koyukuk River north of Fry Island.|
The Koyukuk River near Sun Mountain flows along the southern foothills of the Isahultila Mountains in an area of Quaternary flood plain, colluvium, alluvium, and terrace deposits (Patton and others, 1977). The rocks in the southwestern Isahultila Mountains consists of Cretaceous pillow basalt and andesite flows; andesite tuff and volcanic conglomerate and breccia; chert and fine-grained cherty tuff; and coquinoidal limestone. The rocks are widely altered to dark green hornfels. Numerous quartz latite porphyry dikes occur throughout the Sun Mountain area (Miller and Ferrians, 1968). Cretaceous or Tertiary rhyolite tuff, with subordinate vesicular basalt flows, crop out approximately 2 miles to the south in the Takhakhdona Hills (Patton and others, 1977).Miller and Ferrians (1968) report scattered occurrences of chalcopyrite, malachite, and pyrite along the Koyukuk River in the southern Isahultila Mountains near Sun Mountain, and suggest that several massive limestone units as much as 65 feet thick are favorable hosts for ore deposits.
|Geologic map unit||(-154.954222709806, 65.7978396473269)|
|Age of mineralization||Cretaceous or younger based on the age of the host rocks.|
|Alteration of deposit||Hornfels is widespread in the southern Isahultila Mountains.|
|Workings or exploration||Only reconnaissance geologic mapping by government geologists (Miller and Ferrians, 1968).|
|Indication of production||None|
Additional commentsThis site is the Sun Mountain, U.S. BLM MILS location 0020470016 (Oddenino and others, 1995; Interagency Minerals Coordinating Group, 2004).
Interagency Minerals Coordinating Group, 2004, Alaska Mineral Locations Database [MAS (Minerals Availability System) and MILS (Mineral Industry Location System)], http://imcg.wr.usgs.gov/dem.html (select Melozitna quadrangle).
Miller, T.P., and Ferrians, O.J., Jr., 1968, Suggested areas for prospecting in the central Koyukuk River region, Alaska: U.S. Geological Survey Circular 570, 12 p.
U.S. Bureau of Mines, 1995, Minerals Availability System / Minerals Industry Location System CD-ROM MAS/MILS CD-ROM: U.S. Bureau of Mines Special Publication 95-12.
|Reporters||G.E. Graham, D.J. Szumigala (Alaska Division of Geological and Geophysical Surveys)|
|Last report date||1/19/2005|