The relationship between the petrology and the thorium and uranium contents of some granitic rocks
Whitfield, John M.
Doctor of Philosophy
The object of this investigation is to find large scale variations in thorium and uranium contents of granitic rocks and to link these variations to petrographic types and to geological characteristics of the plutons in which the rocks occur; in short, the object is to find the relation between the major petrogenesis of granitic rocks and their thorium and uranium contents. For this purpose representative granitic plutons from North America have been sampled. These samples have been examined petrographically and have been analyzed by gamma-ray spectrometry for thorium, uranium, and potassium. The study is predicated on the assumption that samples sufficiently representative of plutons could be obtained so that variation between hand specimens would not mask larger variations. The fact that large-scale relations are found justifies this assumption, at least in part. The material will be presented in four main parts: a review of the previous literature, the analytical method, presentation of data, and results.