Table S6: Eclogite-melt distribution coefficients (= [C(eclogite)]/[C(melt)]) Measured Estimated Klemme Xiong Xiong Kessel Salters Kelemen Kelemen Element (rutile) (6 GPa) (rutile) Cs 0.0085 0.0084 0.0047 Rb 0.0018 0.025 0.024 0.01 Ba 0.00078 0.03 0.029 0.0065 0.00076 0.02 0.02 Th 0.0037 0.046 0.046 0.0041 0.015 0.013 0.012 U 0.0068 0.068 0.067 0.006 0.042 0.019 0.019 Nb 0.013 0.035 0.97 0.0056 0.019 0.038 0.34 K 0.003 0.0064 0.0063 0.02 0.02 La 0.014 0.029 0.029 0.0049 0.064 0.063 Ce 0.028 0.046 0.045 0.0063 0.025 0.15 0.15 Pb 0.16 0.0093 0.007 0.043 0.042 Pr 0.051 0.3 0.29 Nd 0.15 0.15 0.038 0.063 0.56 0.56 Zr 0.28 0.57 0.61 0.11 0.24 3.1 3.5 Sr 0.035 0.021 0.02 0.0081 0.046 0.046 Sm 0.22 0.68 0.68 0.14 0.16 3.2 3.1 Eu 0.25 4.4 4.3 Gd 0.53 0.47 6.2 6.2 Tb 3.9 3.9 8.7 8.6 Dy 1.4 9.9 9.8 Ti 0.27 0.47 1.3 0.16 7.4 8.4 Y 1.97 9.7 9.6 0.78 1.2 15 15 Er 2.7 1.3 12 12 Yb 22 22 3.9 3.2 15 15 References: Klemme et al., 2002; Xiong, 2006; Kessel et al., 2005b; Salters et al., 2002; Kelemen et al., 2003b 'Measured' distribution coefficients are based on experiments on eclogitic compositions. 'Estimated' distribution coefficients are based on experiments on non-eclogitic compositions, theory or data for similar elements' Eclogites were assumed to contain 60 % garnet and 40 % clinopyroxene ('rutile' indicates 1 % rutile). The 6 Gpa data from Kessel et al., 2005b are for an aqueous supercritical phase.