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John M. Stevens

Publications and source records attributed to John M. Stevens.

5 recordsLinked to original sources
USGS1956

Radiometric traverse along the Yukon River from Fort Yukon to Ruby, Alaska, 1949

In 1949, a radiometric traverse was made of rocks exposed along the banks of and near the Yukon River about Fort Yukon to Ruby, Alaska. Granitic rocks of Tertiary age and of Devonian or Carboniferous age and sandstone beds of Cretaceous age gave the highest readings obtained in the field. Other rock types examined were greenstone of Devonian or Carboniferous age and metamorphic rocks of Devonian and pre-Devonian age, sedimentary rocks, and liginite of Tertiary age, and alluvial deposits of Quaternary age. The most radioactive sample, from Melozitna River canyon, contained only 0.017 percent equivalent uranium.

Alaska↗
USGS1953

Reconnaissance for radioactive deposits in the Nixon Fork mining district, Medfra Quadrangle, central Alaska, 1949

Reconnaissance for radioactive deposits in the Nixon Fork mining district, Medfra quadrangle, central Alaska, in 1949 disclosed the occurrence of allanite in sampled containing as much as 0.05 percent equivalent uranium from the dump of the Whalen mine; the presence of radioactive parisite (a rare-earth fluocarbonate) in a highly altered limestone containing about 0.025 percent equivalent uranium near the Whalen shaft; and radioactive idocrase in samples of altered garnet rock with about 0.025 percent equivalent uranium, form the Crystal shaft of the Nixon Fork mine. This radioactivity is due mostly to thorium rather than uranium. Placer concentrates from Ruby and Eagle Creeks contain 0.078 and 0.26 percent equivalent uranium respectively, in which the radioactivity is due chiefly to uraniferous thorianite. The bedrock source of the uraniferous thorianite was not located primarily because much of the area is overlain by a relatively thick mantle of vegetation (mostly moss) which limited the effectiveness of radiometric surveying. The uraniferous thorianite is believed to occur in a restricted zone or zones at or near the contact of limestone with monzonite similar to the gold-copper ores of the district and the deposits of radioactive parisite and garnet rock at the Whelan and Crystal shafts respectively.

Alaska↗