Stable chromium isotopic composition of meteorites and metal-silicate experiments: implications for fractionation during core formation

摘要: We present new mass independent and dependent Cr isotope compositions for meteorites measured by double spike thermal ionisation spectrometry. Small differences in both 53Cr 54Cr relative to the Bulk Silicate Earth are reported very similar previously published values. Carbonaceous chondrites characterised an excess compared ordinary enstatite which make isotopes a useful tool distinguishing between meteoritic groups. Mass stable same samples also reported. identical within uncertainty with average δ53Cr values of −0.118±0.040‰ −0.143±0.074‰ respectively. The heaviest recorded chondrite CO carbonaceous chondrite, have relatively reduced chemical implying some fractionation related redox processes circumstellar disk. error estimate (BSE) determined spiking. lack isotopic difference chondritic material BSE provides evidence that were not fractionated during core formation on Earth. A series high-pressure experiments was carried out investigate metal silicate no demonstrable observed, consistent our data. data achondrites suggest magmatic differentiation therefore further work is required constrain mantles Vesta Mars.