ORE POTENTIAL OF PRECAMBRIAN UNCONFORMITY ZONES IN STRATABOUND BASINSOF THE ALDAN SHIELD, RUSSIA

The paper describes features of the geological structure and ore poten tial of regional structural-stratigraphic unconformities in Archean an d Proterozoic assemblages in the eastern part of the Aldan Shield. In this region, molybdenum, uranium, vanadium, and silver occurrences, as well as ore deposits, are recognized along unconformities of Late Pro terozoic age and are related to large-scale alteration haloes (argilli zation) of quartz and white mica with carbonate and graphite. The argi llization haloes penetrate the overlying sedimentary rocks where anoma lous concentrations of Ba, chalcophile (Cu, Pb, Zn, and Ag), siderophi le (Ni, Co), and lithophyllic (Cr, V, Mn, and Ti) elements are associa ted with the haloes. A spatial association exists between alteration h aloes and major faults in the crystalline basement, and between altera tion haloes and Late Proterozoic alkaline basaltic dikes.