Therefore, this system is ideal to for tracinge lithosphere forming events where extraction of a melt volume strips depletes the initially primitive mantle source of itsin Re-content and leaves behind a residue enriched in Os, with which retardsed the ingrowth of the radiogenic Os.
Moreover, due to the high concentration of Os in the residue and the typically low Os concentrations in mantle-derived melts, this system is thought to be robust during subsequent metasomatism.
This allows us to see through the veil of post-formation processes to the very beginning of continent nucleation of the lithospheric mantle.
The advent of in -situ methods for the collection of Re-Os isotope data from individual sulfides not only removes the ambiguity that is inherent in whole-r rock studies due to the usual common presence of at least two generations of sulfide within the same rock;, but it also allows for a relatively fast rapid acquisition of a large data-set compared to solution methods.
We have developed an method for preparing large numbers of sulfide grains included in kimberlite-entrained mantle xenocrysts, so that each grain can be analyhsed for major and trace elements and isotopic composition.
Combining the m Major and trace element data obtained from the same sulfide as well as fromand the host mineral provides the necessarya petrological context for the isotope data, in terms of in terms of sample populations, temperatures (e.g.
Compositions for Os range from 0.00180 (± 0.00026) to 5.13 (± 0.58).
Discussion Major- element data combined withand oxygen fugacity data suggest the presence of two distinct sulfide populations;, of which one is Fe-rich and formed at relatively oxidising conditions, the other is Ni-Co-rich and formed in a relatively reducing sourceenvironment.
Primary sulfides that can be shown to be related by igneous processes should may yield formation ages for the lithospheric mantle.
This combined with recent advances in the in -situ collection ofanalysis of Re-Os data isotopes using a multicollector-cum-ICPMS laser ablation microprobe set-up (LAM-MC-ICPMS) enables us to quickly obtain a statistically significant data -set of Re-depletion and, hence, mantle formation depletion ages from sulfides., These spectra are similar to age spectrathose obtained from U-Pb and Hf-Zr dating of zircons for in crustal formationrocks.
C., Canada We have developed an approach to prepare large numbers of sulfide samples included in kimberlite-entrained mantle xenocrysts for major and trace element and isotopic analysis.