Early-Archean komatiites of the Olekma granite-green-stone area and their Sm-Nd age

Geochronological investigation of the Ancient mafiteultramafite assocation rocks in the Olekma river mean stream is conducted and rare earth element (REE) content is determined by isotopic technique. The investigated komatiites are charakterized by depletion of heavy REE [(Gd/Yb)N=1.09-1.97]. According to light REE distribution the komatiites are divided into two groups: depleted [(La/Sm)N=0.59-0.78] ones, which constitute the majority and enriched [(La/Sm)N=1.34] ones. Parallel mesurements of 143Nd/144Nd isotopic relations resulted in 0.511839±7. Six sample of komatiites and tholeiite metabasalt are approximated at isochronous diagram by regression line which determines the age, which 3507±123 millions of years