Rb-Sr isotopic studies of muruntau ore deposit. Ore-bearing metasomatites

The results of Rb-Sr isotopic studies of 4 metasomatite samples of different mineral composition and geological position in terms of oreformation succession are presented: from earliest quartz-biotite metasomatite up to chlorite enriched metasomatite of regressive stage. All four isochrones are parallel within the error limit with common decline corresponding to 272.6+-3.8 m.y. The initial Sr isotope ratios in metasomaties (0.7138-0.7166) fall within the time interval characteristics to metasedimentary country rocks (273 m.y). The history of hydrothermal activity at Muruntau could be expressed as a sequence of separate activity impulses: 272.6+-3.8; 256.2+-6.4; 230.2+-3.5; 219.4+-4.2 m.y