Uranium Distribution in Ore-Bearing Rocks of the Malinov Deposit: Evidence from Fission Radiography

Application of f-radiography for the study of ore-bearing rocks of the Malinov uranium deposit revealed the following specific features: (1) occurrence of uranium in both authigenic and terrigenous components; (2) important role of fine–dispersed (mineral-free) mode of uranium occurrence; and (3) participation of different-aged epigenetic processes in the ore formation. The sequence of ore formation and transformation in this deposit is similar to that in the Semizbai deposit. Therefore, they can be united into a single subtype of Mesozoic infiltration deposits in western Siberia.     

On the Return of Comet Grigg–Skjellerup

Comet Grigg–Skjellerup must return to its perihelion on November 29, 2002. Before that, it will pass by Jupiter at a distance of 0.5 AU. A simulation of the meteor swarm that is related to this comet in origin has been made for 19 perihelia since 1907. Particles ejected from the nucleus at velocities ±40 m/s in the direction perpendicular to its radius vector are concentrated around the comet and do not approach the Earth, while for particles ejected at velocities ±60 m/s, conditions for the encounter with Jupiter are different; they approach Jupiter to a distance of 0.1 AU, then pass near the Earth's orbit at a distance of 0.01 AU. However, these particles have substantially different radiant coordinates and hardly form a flow of sufficient density.