New Data on the Age of Ozernoe Polymetallic Deposit (Western Transbaikal)

The article presents the results of biostratigraphic and U-Pb geochronological (detrital zircons) studies of the volcanic-terrigenous lacustrine member of the upper subformation of the Lower Paleozoic Oldyndinskaya Formation, which contains pyrite-polymetallic ores of the Ozernoye deposit (Kurbino-Eravninsky ore region, Western Transbaikalia). The first, second and “crystal tuff” productive horizons of the first ore-bearing level of the ozernaya member were studied. It is represented by an alternation of tuffs, calcareous, siliceous, carbonaceous tuffites, pelitomorphic limestones, limestone gravelstones with interlayers and lenses of mine-ralized tuff-conglobreccia and layers of banded siderite pyrite ores. For the first time, bryozoans, algae, and palynoflora were found in calcareous tuffaceous siltstones and limestones of the second and “crystalline tuff” productive horizons. These data indicate the Early Carboniferous, Tournaisian time of sediment accumulation. The results of U-Pb geochronological studies of detrital zircons from the mineralized tuff-conglobreccia of the third productive horizon limit the lower limit of the rock formation time as not older than the Late Cambrian.