Petrogenesis of the tonalitic rocks from the Soer Rondane Mountains, East Antarctica

Tonalitic rocks (ca. 1000 Ma) from the Sor Rondane Mountains, East Antarctica, are characterized by relatively high Na_2O/K_2O (0.6-24), K/Rb (76-1638), Sr/Y (5-60), and (La/Yb) N (1-29), and relatively low CaO/ Na_2O (0.4-4) and low initial ^Sr/^Sr ratio (0.7024). They are chemically similar to trondhjemites (1000 Ma) from the Lutzow-Holm Complex and to Archean tonalite-trondhjemites. Trace element modeling of the partial melting of MORB suggests that tonalitic rocks were derived by partial melting of a basaltic source material under garnet amphibolite stability P-T conditions. We suggest that a young hot subducting plate along the S0r Rondane Mountains at 1000 Ma may have reached elevated temperatures which initiated melting of the slab and generated the tonalitic rocks