Radioactive halos as possible indicators for geochemical processes in magmatites.

Abstract

In systematic microscopic measurements completed by fission track studies the occurrence of polonium halos and polonium bands could be confirmed in biotites of different areas. The abundance of the different types of polonium halos is given by the order 210Po ) 218Po > 214po. As magmatic and often also hydrothermal mechanisms are contrary to geological evidences a supergene hypothesis has been supposed for the genesis of the polonium halos. According to this mechanism polonium isotopes are accumulated out of uranium or radium-bearing solutions which are liberated from rocks by leaching processes of percolating weathering waters. The concept of the given origin of polonium halos may be significant in discussing problems of dating, uranium prospection and the origin of secondary uranium deposits.

Modeling of colloid-associated radionuclide transport in porous groundwater aquifers at the Gorleben site, Germany.

“…According to these observations colloid-associated nuclides could be characterized by a more rapid migration in aquifer-water systems than expected from sorption data. Additionally, there is evidence in natural geochemical systems that colloidal migration of uranium and daughter species such as thorium or polonium may be important in fieldscale mobilization and accumulation processes lasting over long periods of time (Meier and Hecker, 1976;Airey and Ivanovich, 1986;Short et al, 1988;Hoocker, 1991;Payne et al, 1992;Ivanovich et al, 1992).…”