Titanium bulk Earth composition

The constancy of refractory element ratios in the Earth s mantle, discussed before, is documented in the most primitive samples from the Earth s mantle. Figure 8 plots (modified from Jochum et ai, 1989) the PM-normalized abundances of 21 refractory elements from four fertile spinel Iherzolites. These four samples closely approach, in their bulk chemical composition, the primitive upper mantle as defined in the previous section. The patterns of most of the REEs (up to praseodymium) and of titanium, zirconium, and yttrium are essentially flat. The three... 

For most other elements there is no difference between the isotopic composition of carbonaceous chondrites and the Earth. As of early 2000s, only two exceptions, chromium and titanium, are known for these two elements very small differences in the isotopic composition between carbonaceous chondrites and the Earth were found. Bulk carbonaceous chondrites have isotope anomalies in chromium and titanium. Isotopically unusual material may have been mixed to the CC-source after proto-earth material has accumulated to larger objects. 

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