Uranium-Bearing and Associated Minerals in Their Geochemical and Sedimentological Context, Elliot Lake, Ontario

摘要

The depositional energy environment of the Rio Algom-Denison ore reef was investigated on a regional scale using several parameters including pebble size. Regional trends of decreasing pebble size coincide with the regional direction of sediment transport. Pebble size was also used to characterize the depositional energy environment at the sample level. Quartz-pebble size and pyrite-grain size as determined from the same samples have a correlation coefficient of 0.93 which indicates that the coarse granular pyrite is detrital. Bulk chemical analyses of selected elements (U, Th, Pb, Ti, Ce, La, Y and Zr: which were chosen to reflect specific minerals (uraninite, brannerite, monazite and zircon:, showed strong correlation with quartz-pebble size of the respective samples. Electron microprobe analyses of uraninite and brannerite are reported. The uraninites have typical pegmatitic compositions. Several types of brannerite are described; the conclusion reached is that although some brannerite may be detrital, most of it formed by adsorption of uranium onto titania collectors. Redistribution of some of the uranium has not changed the placer nature of the ore reef. Genesis of individual minerals (pyrite, uraninite, brannerite, zircon and monazite: is discussed. It is concluded that the mineralogy and its geochemical expression have been controlled by processes of fluvial deposition. As a result of the regional patterns in depositional environment, the ore reef shows a broad mineralogical zoning. Fluctuations in depositional energy have also produced lithologically related mineral zoning on a smaller scale. (Atomindex citation 12:632146)