Calcium isotopic compositions of chondrites

摘要: Abstract We report mass-dependent and mass-independent Ca isotopic variations in nine chondrites from three groups: carbonaceous, ordinary enstatite chondrites. There is about 0.25‰ per amu, i.e., ∼1‰ 44Ca/40Ca, variation chondrites: carbonaceous have the lightest isotopes, modeled bulk Earth like are between. The correlations between chemical may reflect variable contributions different endmembers, including refractory inclusions, chondrite groups. In detail, share similar characteristics, but very compositions. At ±1 ±2 e-unit levels, respectively, there no measurable 40Ca or 43Ca anomaly Carbonaceous show several e-units of 48Ca excess. That is, exhibits both chondrites, to O isotopes. positively correlated with 50Ti anomaly, does not form simple correlation 54Cr implying multiple supernova sources for these neutron-rich isotopes Solar System. Finally, all meteorites negative Δ17O either deficits (differentiated meteorites) excess (carbonaceous chondrites), that Sun a probably also characterized by compared Earth. CAIs cannot be taken as representative initial compositions elements Earth–Moon system.