[MIS11-P17] Swelling behavior of magnesium saturated smectites
Morida Koki, Keisuke Fukushi, Hiroshi Sakuma
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.