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Figure 1 shows the mantle age spectra obtained from the sulfides compared to known crust formation and tectonic events in the Slave craton. & Makovicky, M, 1996, Partitioning of nickel, copper, iridium, rhenium, platinum, and palladium between monosulfide solid solution and sulfide liquid: Effects of composition and temperature, Geochim. The isochron age coincides with a period of crust formation between 3.3 and 3.4 Ga in the western craton, a continental complex. 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.Re-Os isotope data were collected for 40 of the Fe-rich mss and 4 of the Ni-Co-rich mss. Compositions for Os range from 0.00180 (± 0.00026) to 5.13 (± 0.58). Major- element contents of sulfides and host olivine, orthopyroxene and clinopyroxene were collected using the CAMECA Camebax SX50 electron microprobe.
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.
A number of samples, however, have very high Pd relative to for their (high) Ir abundances, which is not consistent with a onesingle-stage formation of these sulfides and indicates that the trace element budget has been disturbed.
The same is true for samples with highly radiogenic Os isotopic compositions that are not supported by their sufficiently high Re/Os to produce the radiogenic signature.
Comparison of mantle Re-Os age spectra to crustal formation ages can provide constraints for the interpretation of geophysical data (e.g.
seismic reflection profiles) and the mapping of lithospheric terrane boundaries in the lateral dimension.
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Re-Os isotopic ratios were analysed by a LAM coupled to the a Nu instrument Plasma multi-collector ICPMS.