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Okuchi, Takuo*; Tomioka, Naotaka*; Purevjav, N.*; Shibata, Kaoru
Journal of Applied Crystallography, 51, p.1564 - 1570, 2018/12
Times Cited Count:2 Percentile:21.21(Chemistry, Multidisciplinary)It is demonstrated that quasielastic neutron scattering (QENS) is a novel and effective method to analyse atomic scale hydrogen transport processes occurring within a mineral crystal lattice. The method was previously characterized as sensitive for analysing the transport frequency and distance of highly diffusive hydrogen atoms or water molecules in condensed matter. Here are shown the results of its application to analyse the transport of much slower hydrogen atoms which are bonded into a crystal lattice as hydroxyls. Two types of hydrogen transport process were observed in brucite, Mg(OH) : a jump within a single two-dimensional layer of the hydrogen lattice and a jump into the next nearest layer of it. These transport processes observed within the prototypical structure of brucite have direct implications for hydrogen transport phenomena occurring within various types of oxides and minerals having layered structures.
Tonai, Satoshi*; Ito, Shun*; Hashimoto, Yoshitaka*; Tamura, Hajimu; Tomioka, Naotaka*
Journal of Structural Geology, 89, p.19 - 29, 2016/08
Times Cited Count:14 Percentile:46.73(Geosciences, Multidisciplinary)We used the K-Ar ages of clay-sized mineral grains to investigate the timing of activity on the fossil seismogenic Minami-Awa Fault. The K-Ar ages from matrix shale of the mlange range from 85 to 48 Ma and decrease with decreasing amount of detrital mica. In contrast, the K-Ar ages of an ultracataclasite within the fault core are significantly younger, ranging from 29 to 23 Ma, and are unrelated to grain size. This indicates that Ar diffused completely from the ultracataclasite between 29 and 23 Ma. The diffusion of Ar in the ultracataclasite was probably caused by frictional heating or high-temperature fluid migration that occurred when the fault was reactivated. The results indicate that seismogenic faults that separate tectonic mlange from coherent strata in accretionary complex may slip, not only during accretion, but also long after accretion.
Tomioka, Naotaka*; Okuchi, Takuo*; Purevjav, N.*; Abe, Jun*; Harjo, S.
Physics and Chemistry of Minerals, 43(4), p.267 - 275, 2016/04
Times Cited Count:7 Percentile:25.75(Materials Science, Multidisciplinary)