Japan Geoscience Union Meeting 2019

Presentation information

[J] Poster

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS11] Aqua planetology

Tue. May 28, 2019 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:Yasuhito Sekine(Earth-Life Science Insitute, Tokyo Institute of Technology), Tomohiro Usui(Earth-Life Science Institute, Tokyo Institute of Technology), Keisuke Fukushi(Institute of Nature & Environmental Technology, Kanazawa University), Takazo Shibuya(Japan Agency for Marine-Earth Science and Technology)

[MIS11-P17] Swelling behavior of magnesium saturated smectites

Morida Koki, Keisuke Fukushi, Hiroshi Sakuma

*Koki Morida1 (1.Kanazawa University)

Smectite belongs to clay minerals formed in the presence of liquid water. Smectites are composed of 2:1 layer with tetrahedral sheet and octahedral sheet. Smectites are categorized to di-octahedral type (e.g., nontronite and montmorillonite) and tri-octahedral type (e.g. saponite). The interlayer between the sheets is occupied by hydrated cations. The interlayer cations are usually Na+, K+, Mg2+, Ca2+. The distances of interlayer (basal spacing) depend on type of interlayer cations and relative humidity (RH). The basal spacing can change from 9 to 15Å as function of amount of RH. At 0% of RH, basal spacings are around 10Å when interlayer cation is Na+ or K+. That is 12Å when interlayer cation is Ca2+. On the other hand, the basal spacings ranges from 11 to 14Å when interlayer cation is Mg2+ (Sato et al, 1992; Morodome and Kawamura 2009).

Curiosity rover sent to the Gale crater on mars examines the possibility of existence of life and habitable environment (Vaniman et al, 2014). Water is essential for life. Therefore, in order to estimate possibility of life, it is important to know water quality. Gale crater is thought to be an ancient lake. Curiosity obtained the lacustrine sediment samples and analyzed the mineralogical and geochemical characteristics of the sediments. From the CheMin-XRD analyses, smectites were discovered in JohnKlein and Cumberland sites. The smectites are presumed to be saponite (Vaniman et al, 2014; Bristow et al, 2015). The basal spacing in Cumberland’s saponite exhibited 13.2Å at RH0%. Now it has been under debates whether the interlayer cation in Cumberland’s saponite is MgOH+ or Mg2+ ion.

Suquet et al, 1975 showed that basal spacing of Mg2+ saturated saponite is 11.4Åat RH0%. Therefore, Vaniman et al. 2014 and Bristow et al, 2015 presumed that the interlayer cation in Cumberland’s saponite is MgOH+ ion. However, basal spacing of some other Mg2+ saturated smectites exhibited above 13.2Å. This study experimentally assess the basal spacing of smectites including saponite under several atomospheric compositions with N2, air or CO2.