Comparison of isotope data obtained with Sm-Nd and Re-Os methods for minerals and rocks from the Ozernoe ore occurrence, Salla-Kuolajarvi belt

Sm-Nd isochrone, drawn for rock-forming and sulfide minerals from the Ozernoe ore occurrence, indicates albitite age of 1,759 ± 11 Ma. It shows synchronous formation mineralization, fully corresponds to earlier defined rutile in (1,757 7 Ma U-Pb, n = 3, MSWD 0.2), Rb-Sr isochrone 1,754 39 biotite, apatite, albite, WR. Recently published Re-Os ages molybdenite 1,872 23 chalcopyrite 1,891 230 indicate more ancient mineralization. These figures are conflict with minerals, methods. The possibility use Salla-Kuolajarvi belt rock dating has been considered, low reliability method it shown. reasons following: 1) extremely uneven distribution Re molybdenite, where content varies 1 wt.% even within one same grain, 2) openness system after crystallization, is mobylized partly removed mineral zone hypergenesis. Removal promotes erroneous molybdenite. According equations radioactive decay, would be 110-130 bigger if 5-6 % taken away. conclusion that must studied detail, proved homogenous unaltered, before used dating. In other case results will not reliable.