Dr. Yanhao Lin [Vrije Universiteit Amsterdam, The Netherlands]

Title: Fate of Lunar Water

Time: 15:30-16:30, Friday, July 27, 2018

Place: Conference room 410, HPSTAR (Shanghai)

Host: Ho-Kwang Mao

Polycom: 02120004

Abstract:

The Moon is thought to have been covered initially by a deep magma ocean, its gradual solidification leading to the formation of the plagioclase-rich highland crust. We performed a high-pressure, high-temperature experimental study of lunar mineralogical and geochemical evolution during magma ocean solidification that yields constraints on the presence of water in the earliest lunar interior. Using the relationship between magma water content and the resulting crustal thickness in the experiments, and considering uncertainties in initial lunar magma ocean depth, we estimate that the Moon may have contained at least 270 to 1,650 ppm water at the time of magma ocean crystallization, suggesting the Earth–Moon system was water-rich from the start.

Afterwards, we performed a series of experiments to determine the water partition coefficient between plagioclase and co-existing silicate melt under lunar magma ocean (LMO) conditions. Using our newly calibrated partition coefficient in combination with the published water contents of lunar plagioclase, we conclude that ~100 ppm H2O may have been present in the residual magma when 95 % of the initial LMO had crystallized. This is significantly lower than the water content of the residual LMO calculated from crystallization of a closed-system LMO with the initial LMO water content constrained by laboratory high-pressure experiments. This indicates >99 % hydrogen degassing may have occurred during LMO crystallization, suggesting a highly dynamic early volatile cycle on the Moon.

Biography of the Speaker:

2014 – 2018 PhD - Planetary Science, VU University Amsterdam,

Netherlands (Advisor: Prof. Wim van Westrenen)

2011 – 2014 Master - Geology, China University of Geosciences, China

(Advisors: Profs. Zeming Zhang and Nengsong Chen)

2007 – 2011 Bachelor of Science - Geology, China University of Geosciences, China