Reconnaissance for radioactive deposits in east-central Alaska, 1949

Abstract

In the summer of 1949, several mines and prospects in the Fairbanks and Livengood quadrangles, east-central Alaska, were examined for the possible presence of radioactive materials. Also tested were metamorphic and sedimentary rocks of pre-Cambrian and Paleozoic age crossed by the Elliott Highway, which extends from Fox, near Fairbanks, northwestward about 70 miles to the town of Livengood. Nuggets consisting chiefly of native bismuth and containing as much as 0.1 percent equivalent uranium had been found previously in a placer on Fish Creek several miles downstream from the reported bismuth-bearing lode on Melba Creek, but none of the lodes tested in 1949 exhibited radioactivity in excess of 0. 003 percent equivalent uranium. The greatest radioactivity found in the rocks along the Elliott Highway was in an iron-stained pre-Cambrian schist and in a carbonaceous(?) shale of Middle Devonian or Carboniferous age. Respective samples of these rocks contain 0. 003 and 0.004 percent equivalent uranium. A possible local bedrock source for the euxenite-polycrase mineral found in a placer concentrate containing about 0.04 percent equivalent uranium was sought in the watershed of Goodluck Creek, near Livengood. The bedrock source of this mineral could not be located and it is believed that the source could be outside of the Goodluck watershed because drainage changes during Quaternary time may well have introduced gravels from nearby areas.