Age of phlogopite deposits at Slyudyanka (39Ar-40Ar data)

Three phlogopite samples of Slyudyanka and one hyalophane sample are studied by means of 39Ar-40Ar in the stepped heating variant. Two phlogopites demonstrated an integrity of K-Ar-isotopic systems with the age of 450-480 millions of years; in two other samples (phlogopite and hyalophane) isotopic systems are weahly disturbed, the age, calculated according to them is a little lower. In terms of new and earlier obtained isotope-geochronologic data the authors came to a conclusion that representation about the Lower Paleozoic age (450-480 millions of years) of phlogopite deposits at Slyudanka, considered up to the recent time as Precambrian, is now the most applicable