Partition coefficient basaltic andesite

Table 4.2 Usts partition coefficients" jfof dace elements betwe a range of rock-foi ing minerals and andesitic liquids (57-63 wt % StOj in the TAS classification). A summary of the REE values is given in Figure 4,9. Many published sources of partition Coefficients treat andesites and basalts together and a comparison of Figures 4.1 and 4.2 shows that the partition coefficients for the REE are similar in basaltic and andesitic liquids. Values for garnet, the pyroxenes and the value for Eu in plagioclase, however, are higher in andesites than in basalts. REE partition coefficients for hornblende are higher in andesites than basalts, but are comparable between andesites and basaltic andesites. Values for the REE in the pyroxenes vary between published sources this may in part be due to compositional effects.

Nicholls I. A. and Harris K. L. (1980) Experimental rare earth element partition coefficients for garnet, clinopyroxene and amphibole coexisting with andesitic and basaltic liquids. Geochim. Cosmochim. Acta 34, 331-340. 

Partition In Table 4.1 partition coefficients are listed for trace elements in minerals In coejficients in equilibrium with basaltic and basaltic andesite liquids. Following the TAS basalts and classification these are liquids with silica contents in the range 45 57 wt %. A basaltic andesites summary of the REE partition coefficients is presented in Figure 4.8 as a plot of partition coefficient vs atomic number. The compilation in Table 4.1 is based upon a variety of published sources from experimental and phenocryst/matrix data. Averages are arithmetic means. 

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