2017 Fiscal Year Annual Research Report
In situ falling sphere viscometry for silicate melts down to the lower mantle: An application of the B-doped diamond heater
| Project/Area Number |
17J10966
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| Research Institution | Okayama University |
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Principal Investigator |
XIE LONGJIAN 岡山大学, 自然科学研究科, 特別研究員(DC2)
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| Project Period (FY) |
2017-04-26 – 2019-03-31
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| Keywords | viscosity / silicate melts / Magma ocean / boron doped diamond / high pressure / ultra-high temperature |
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| Outline of Annual Research Achievements |
We succeeded to extend the experimental measurements of silicate-melt viscosity up to about 30 GPa and more than 2500 K, by devising an in-situ falling sphere method coupled with boron-doped diamond heater and ultra-fast cameral (1000 f/s) in the multi-anvil apparatus. We determined viscosities of molten forsterite, enstatite and diopside from 5 to 30 GPa and at temperatures just above their liquidus. Melt viscosities of the three compositions are found very low, in the range of 0.01 to 0.1 Pa.s, at mantle pressure conditions. The extremely low viscosity implies a short life-time for the magma ocean (1-6 thousands years) and, potentially, a fractional crystallization.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
I developed the method to measure silicate melt viscosities up to 30 GPa and succeeded to measure viscosities of Fo, En and Di melt up to 30 GPa.
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| Strategy for Future Research Activity |
I will measure viscosities of melt with CaMgSi2O6 composition at 25 and 30 GPa along the liquidus curve by in situ FSM at SPring-8. I will try to optimize the cell assembly to measure the viscosity of melt with pyrolite composition up to 30 GPa. I will invest ~20 % effort on experiments. I expect ~30 % effort on the analysis of experimental results. I will compare the experimental results with MD simulation results and prepare manuscript (~50 %).
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