Abstract:
Wide range of alkaline mctasomatitcs (albitized gneisses and granite-gneisses, quartz-albite-microclinc-ric-beckite-aegirine and quartz-albite-microclinc-magnctitc rocks, albititcs) was studied in the south-east part of the Main Sayan Fault zone. It is shown that process of the metasomatism took place, at 580-600 °C and pressure about 2 kbar, due to action of Na-rich fluids upon rocks of Kitoykinskaya scries. Formation of albitizcd rocks and the quartz-albite-microcline-ricbeckite-acgirinc metasomatitcs of the frontal and intermediate zones of mcta-somatic column was accompanied in the rocks by increasing of Na2O/K2O ratio and contents of Fe3+, Fc2t, Ti, Mn, with outflow of K, Ca, P, Mg, Al. The forming of albitites of the rear zone assumes inflow of Na, Ca, F, with carried out K, P, Ti. Among the trace elements the most remarkable inflow was fixed for Be, Zr, Nb, Y, and also Sn, Zn, Pb; their concentrations have increased in 2-4.5 times (up to 7 times for Be). Data on Ba, Sr, Cr, V show their distinct outflow, as compared with average contents in primary rocks. In the whole, the studied rocks arc quite similar to metasomatitcs connected with alkaline granites, which are absent in this region.