Table 1 Median values of key elemental concentrations and ratios for TTGs and selected modeled melts.

See tables S4, S6, S7, and S9 for details.

K2O (wt %)Rb (ppm)Sr (ppm)Y (ppm)Sr/YNb (ppm)Nb/TaMg#
TTGs derived from different depths
LP TTG1.6768.127714.020.58.0010.637.7
MP TTG1.5352.04437.6157.65.0010.941.5
HP TTG1.5240.05763.831302.4113.342.5
Eoarchean TTGs
Acasta (group 2)1.7643.82418.0037.19.1018.442.0
Selected modeled TTG melts of Archean arc-like basalts [X(H2O) = 2.5 wt %]
T = 820°C, P = 0.6 GPa1.1129.321814.015.68.5418.830.2
T = 820°C, P = 1.0 GPa1.2433.63049.9430.56.4018.133.6
T = 820°C, P = 1.4 GPa1.2733.14305.8573.53.3516.737.8
T = 820°C, P = 1.9 GPa1.4334.06164.531362.3216.047.5