9:30 AM - 3:00 PM
[R3P-13] Melting relations of the Fe-Ni-S-C system and the formation of superdeep diamonds
Keywords:superdeep diamond, mantle transition zone, the Fe-Ni-S-C system
We have performed high-pressure and high-temperature quench experiments of the Fe-Ni-S-C system at 15 GPa to investigate diamond formation in the mantle transition zone. Diamonds can coexist with Fe-Ni-S-C melt above 1400 K at 15 GPa. Taking into consideration the carbon abundance of the mantle and geotherm, diamonds can be crystallized from the liquid alloy by supersaturation when sulfur abundance in the liquid ranges from 5 to 15 wt.%. On the other hand, the diamonds cannot form within the top of subducting slab, due to its lower temperature.