Date of Award
Union College Only
Bachelor of Science
In nature there are three major decay series that involve naturally occurring uranium and thorium as parent nuclides. Two of the three series; U-238, TH-232 and U-235; are shown in figure I. Of the three series two, U-238 and the Th-232 series, are examined in the study. This is because the amount of U-235 in nature is very small relative to the amount of U-238 and Th-232. This study is concerned with the presence of U-238 and Th-232 and their uranium, thorium and radium daughter products in the silicic intrusive rock, Storm King Granite. Uranium and thorium have large iconic radii and high coordination numbers. For this reason they are concentrated in accessory minerals rather than in normal rock forming minerals. (7) (Thurber) Since accessory minerals don’t form until the temperature and pressure are low enough uranium and thorium are concentrated in crustal rocks. The earth is generally more acidic in its crust. Correspondingly uranium and thorium are more concentrated in the more acidic rocks such as granite. (1) (Adams, Table I) Silver (5) has found the following distribution of uranium and thorium series in granite rocks can be generalized in having three types of sites.
Lawrence, James Robert, "The determination of the ratios U234/U238 and Th228/Th232 as leached from Storm King Granite" (1964). Honors Theses. 1933.