Cycles of uranium and thorium
Earth differentiation is considered to be advanced but incomplete, and to be proceeding largely through the agencies of liquid or creep convection, diffusion, and igneous intrusion. Seafloor-spreading (Fig. 3) rates up to 4.5 cm per year (Heirtzler, 1968), when compared with the proportion of uranium believed transferred to the crust, suggest that convection velocities may be greater than the transfer rate and, therefore, that uranium and thorium in convection cells may have been recycled and a proportion bled off for transfer during each cycle.
Figures & Tables
Migration of Uranium and Thorium-Exploration Significance
The uranium resource industry since the late 1960s has presented a paradox to those concerned with the growing energy shortage and the relative ability of uranium resources to respond to the need on a timely basis. This publication reviews the possible ways that uranium in the earth might be concentrated into economic deposits, and considers what industry should be able to expect from an exploration effort. Some of the chapters in this volume include: Fundamental sources of uranium and thorium; Mechanisms of uranium and thorium transfer to the crust; Shallow uranium mobilization processes; Geochemical distinction of uranium moneralization processes; and Oceanic migration history of uranium and thorium.