Precise Re-Os dating of molybdenite using Carius tube, NTIMS and ICPMS

The technique described in this paper represents isotope dilution, the digestion in reverse aqua regia in Carius tube at 230 °C, purifying Os using normal distillation and microdistillation, purifying Re using acetone extraction and anion exchange chromatography, isotopes ratio determination using NTIMS. We have used this technique to analyze for repeatedly a molybdenite HLP powder as a reference standard. Seventeen samples from twelve small bottles were analyzed over a period of six months. The average Re-Os age was 221.3 ± 0.3 Ma with 95% confidence limit. Median age and mean absolute deviation were 221.34 ± 0.12 Ma. Using improved ICPMS and modified procedure, we also got good Re-Os age 222.0 ± 1.4 Ma with 95% confidence limit for same HLP above. The 187Re-1870s isochrone age of molybdenite is 322.7 ± 2.5 Ma with 95 % confident Limit, MSWD 0.51 and correlation constant 0.99999 for the molybdenite of porphyry copper deposit in East Tianshan, Xinjiang Province.