Goldscmidt2019, Barcelona, August 20, 2019 In-situ experiments of aqueous alteration of amorphous silicates in the system MgO-SiO2 Yohei IGAMI1, Akira TSUCHIYAMA2, Tomoya YAMAZAKI3, Yuki KIMURA3 1 Nagoya University 2 Ritsumeikan University and Guangzhou Institute of Geochemistry, CAS 3 Hokkaido University

Motivation Aqueous alteration of amorphous silicates plays an important role in the evolution of the early Solar System. However, we do not know how the alteration begins, in particular, the first reaction of amorphous silicates with water. In-situ experiments of aqueous alteration of amorphous silicates 　　 in the system MgO-SiO2 as one of the most simplest using TEM and XRD ・ Implication to meteorites Slide-3:   X-ray CT is a method to obtain internal structures of samples non-destructively. 3-D structures can be obtained by stacking successive CT slice images. Using synchrotron radiation gives 3-D images with high spatial resolution and quantitative CT image brightness. We have developed an X-ray microtomographic system at SPring-8, a SR facility in Japan.

Analyses under dry condition Experiments In-situ TEM Starting materials: TEM imaging http://www.protochips.com/products/poseidon/ TEM holder for In-situ liquid analysis e- JEOL JEM2100F am-Fo (Mg2SiO4) 200nm 100nm XRD holder for In-situ wet analysis In-situ XRD X-ray Diffraction X-ray Rigaku SmartLab am-En (MgSiO3) Slide-3:   X-ray CT is a method to obtain internal structures of samples non-destructively. 3-D structures can be obtained by stacking successive CT slice images. Using synchrotron radiation gives 3-D images with high spatial resolution and quantitative CT image brightness. We have developed an X-ray microtomographic system at SPring-8, a SR facility in Japan. Drying in vacuum Analyses under dry condition

In-situ TEM 0:31 19:13 am-Fo (Mg2SiO4) Drying am-En (MgSiO3) Starting 　　material 200 nm Drying am-En (MgSiO3) Dehydration Starting 　　material 500 nm 0:31 19:13 19:13 200 nm 0:31 BL47XUの装置の細かな使用目的。それがどのような装置なのか。 （はやぶさ２の大目標はこれの前に示しているはず）

In-situ XRD am-Fo (Mg2SiO4) am-En (MgSiO3) 5.7 h 0.1 h dry 3.0 h 9.4 h 12.4 h 15.4 h 18.4 h 21.4 h 23.4 h 26.4 h 30.6 h 33.6 h 36.6 h 42.6 h 45.0 h Wet condition 48.0 h Intensity / a.u. 5.8 h 3.1 h 8.8 h 11.8 h 14.8 h 18.0 h 21.0 h 24.0 h 27.3 h 30.8 h 33.8 h 36.8 h 42.0 h Peak shift of amorphous silicates Formation of M-S-H (magnesium silicate hydrate) BL47XUの装置の細かな使用目的。それがどのような装置なのか。 （はやぶさ２の大目標はこれの前に示しているはず）

Aqueous alteration processes Hydration of am by diffusion of H+, OH- (H2O) Dissolution (MgO>SiO2) am-Fo/En particle (dry) H2O-saturated Mg-poor am M-S-H Dry/Mg-poor am Drying Dehydration BL47XUの装置の細かな使用目的。それがどのような装置なのか。 （はやぶさ２の大目標はこれの前に示しているはず）

Comparison with meteorites 500 nm 2.6 Å 1.5 Å Run product after drying (am Fo) Primitive carbonaceous chondrite (Paris meteorite: Leroux et al., 2105) BL47XUの装置の細かな使用目的。それがどのような装置なのか。 （はやぶさ２の大目標はこれの前に示しているはず） Hydration of amorphous silicates followed by the formation of M–S–H also occurred in carbonaceous chondrites.