Oxygen bulk Earth composition

For this review the Earth s composition will be considered to be more similar to carbonaceous chondrites and somewhat less like the high-iron end-members of the ordinary or enstatite chondrites, especially with regard to the most abundant elements (iron, oxygen, silicon, and magnesium) and their ratios. However, before reaching any firm conclusions about this assumption, we need to develop a compositional model for the Earth that can be compared with different chondritic compositions. To do this we need to (i) classify the elements in terms of their properties in the nebula and the Earth and (2) establish the absolute abundances of the refractory and volatile elements in the mantle and bulk Earth. 

In contrast to their rather low dissolved concentrations in seawater, some of the trace metals, e g., iron and aluminum, along with oxygen and silicon, comprise the bulk of Earth s crust. Some trace elements are micronutrients and, hence, have the potential to control plankton species composition and productivity. This provides a connection in the crustal-ocean-atmosphere fectory to the carbon cycle and global climate. 

Bulk meteorites, the Moon and Mars lie within a few percentile above or below the terrestrial fractionation line on a three-oxygen isotope plot (see Fig. 3.1). Therefore, the oxygen isotope composition of the Sun has been assnmed to be the same as that of the Earth. This view has changed with the suggestion of Clayton (2002) that the Sun and the initial composition of the solar system are 0-rich com-... 

Figure 1. Oxygen three-isotope diagram showing isotopic compositions of minerals from Allende CAIs (CCAM = carbonaceous chondrite anhydrous minerals). The other line, labelled TF (terrestrial fractionation) is the locus of data points for terrestrial rocks and waters (data not shown). The bulk oxygen isotopic composition of the Earth is indicated by point E the expected oxygen isotopic composition of the Sun is indicated by point S. The S-notation on the...

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