Pressure-temperature-time path discontinuity in the Main Central thrust zone, central Nepal

Metapelites collected in central Nepal reveal a discontinuity in metamorphi c pressure-temperature-time (P-T-t) paths near the base of the Main Central thrust zone, despite an absence of obvious structural breaks. Garnets in t he structurally lowest rocks grew with increasing T and P (loading), wherea s garnets 1-3 km upsection grew with increasing T, but decreasing P (exhuma tion), Monazite grains in structurally lower rocks yield ion-microprobe Th- Pb ages of 8-9 Ma, Structurally higher monazite grains range from 10 to 22 Ma, The P-T-t paths confirm previous interpretations that footwall metamorp hism in part resulted from thrust reactivation ca, 8 Ma, but also reflect t hermal relaxation following older (20 Ma or older) thrust movement. The Mai n Central thrust zone formed during pulses of movement that resulted in pro gressive transfer of material from the lower to upper plate.