Japan Geoscience Union Meeting 2015

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Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS24] Gas hydrates in environmental-resource sciences

Thu. May 28, 2015 9:00 AM - 10:45 AM 102B (1F)

Convener:*Hitoshi Tomaru(Department of Earth Sciences, Chiba University), Akihiro Hachikubo(Environmental and Energy Resources Research Center, Kitami Institute of Technology), Sumito Morita(Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology), Chair:Akihiro Hachikubo(Environmental and Energy Resources Research Center, Kitami Institute of Technology)

9:45 AM - 10:00 AM

[MIS24-09] Cross section observation of shallow gas hydrates by Raman imaging

*Atsushi TANI1, Keisuke KURUMI1, Akihiro HIRUTA2, Ryo MATSUMOTO2 (1.Osaka Univ., Sci., 2.Meiji Univ. GHLAB)

Keywords:shallow gas hydrates, imaging, Raman, X-CT, dissociation

Natural gas hydrate, an inclusion compound of natural gas in water cages, is found in deep-sea sediments and permafrost region. In eastern margin of Japan Sea, shallow gas hydrates have been found and recovered by piston coring (Matsumoto et al., 2011; Lu et al., 2011). X-CT observation of the shallow gas hydrates revealed that icy materials divided into two regions (darker and lighter regions) by CT-values (Tani et al., 2013). Since CT-values of ice and natural gas hydrate are close each other due to similar X-ray linear attenuation coefficients, it is difficult to specify which region is gas hydrate only by CT images. In this study, cross section of the shallow gas hydrate was observed by Raman imaging to understand the differences of the darker and lighter regions in CT-values. The sample recovered from the eastern margin of Japan Sea in UT13 cruise was measured by X-CT first and then broken into two pieces. The cross section was measured by Raman imaging. The results indicate that pieces of natural gas hydrate with a few mm in diameter are scattered in the sample. Comparison between Raman images and CT images reveals that the lighter region of icy materials in CT images is natural gas hydrate and the darker region is ice. This study was supported by 2014 development and promotion program of methane hydrate.