From objective and scope: The objective of this report us to provide a descriptive body of knowledge on Cordilleran metamorphic core complexes including their lithologic and structural characteristics, distribution within the Cordillera, and their evolutionary history and tectonic setting. We also examine the occurrence of uranium in the context of possibility for uranium concentration.

From introduction: The emanation method of uranium exploration consists of measuring the abundance of one or more uranium decay products at some distance from the orebody itself. The halo of decay products expands the exploration target and improves the chances of detection. This method assumes that indicator nuclides migrate away from the ore by some physio-chemical mechanism such as diffusion or solution in groundwater. The indicators must remain at detectable concentrations and be distinguishable from background levels. This study is concerned with gas-phase transport of Rn-222, Xe-133, and He-4 away from uranium ore deposits. The first of these indicator nuclides, Rn-222, is a member of the uranium series decay chain (Table 1) and has a 3.82 day half-life. The second, Xe-133,. is a spontaneous fission product which has a half-life of 5.26 days. Finally, He-4 is a stable nuclide created from alpha particles emitted by various members of the uranium, actinium, and thorium decay series.

Supplementary data containing analyses of the way that radiogenic gases affect soil samples to accompany a modeling study on the use of gaseous RN-222, XE-133, and HE-4 for uranium exploration.