Preliminary report on uranium and thorium content of intrusive rocks in northeastern Washington and northern Idaho
This study delineates favorable areas for uranium resources in northeastern Washington and northern Idaho by identifying granitic rocks with relatively large amounts of uranium and (or) thorium. Results are based on analysis of 344 rock samples. Uranium analyses obtained by gamma-ray spectrometric data correlate closely with fluorometric determinations. On the basis of cumulative frequency distribution curves, more than 8 ppM equivalent uranium and more than 20 ppM equivalent thorium are considered anomalous for granitic rocks in northeastern Washington and northern Idaho. Granitic rocks anomalously high in uranium and (or) thorium are concentrated in two northeast-trending belts. The most prominent, the Midnite-Hall Mountain belt, includes the Midnite and Sherwood uranium mines, and two lesser but productive areas farther north. This belt follows the contact between Precambrian and Paleozoic rocks, which is also the locus of the Kootenai arc fold belt. The second belt of anomalously radioactive granitic rocks is along the Republic graben, a prominent linear structure in an area with no recorded uranium production. Anomalously radioactive granitic rocks are generally massive quartz monzonite, alaskite, or pegmatite, which contain abundant quartz and potash feldspar. They are also characterized by pink potash feldspar, commonly as large phenocrysts, and by the presence of muscovite. Several uranium and thorium minerals have been identified in these rocks. The two belts of anomalously radioactive plutons are considered favorable for uranium resources. Deposits could occur in the intrusive rocks themselves or in favorable environments in adjacent rocks. 13 figs., 2 tables.
- Research Organization:
- Bendix Field Engineering Corp., Grand Junction, CO (USA)
- DOE Contract Number:
- EY-76-C-13-1664
- OSTI ID:
- 6553719
- Report Number(s):
- GJBX-89(77)R; TRN: 79-000009
- Country of Publication:
- United States
- Language:
- English
Similar Records
RECONNAISSANCE FOR RADIOACTIVE MINERALS IN WASHINGTON, IDAHO, AND WESTERN MONTANA 1952-1955
Petrology and radiogeology of the Stripa pluton