Analysis of experimental data on the diffusion coefficients of Fe, Mn, Mg, and Ca in garnets

Experimental data on the diffusion coefficients of Fe, Mn, Mg, and Ca in garnets are generalized. Frequency factors (cm2/s), activation energies (cal/mole), and activation volumes (cm3/mole) are optimized. Based on the compensation law, the dependences of diffusion coefficients on pressure (kbar) and temperature (K) have been derived:D˜Fe=1.0·10−3exp[−(61450+23.9·8·P)/(RT)],D˜Mn=2.3·10−6exp[−(44600+23.9·6·P)/(RT)],D˜Mg=4.9·10−3exp[−(65900+23.9·9.2·P)/(RT)],D˜Ca=4.1·10−5exp[−(62450+23.9·11.2·P)/(RT)].