| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Tatsuhiko IFREE, JAMSTEC, Technical Researcher, 固体地球統合フロンティア研究システム, 技術研究員 (90271709)
KAWAHATA Hotaka Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 産業技術総合研究所, 主任研究官
OKADA Hisatake Faculty of Science, Hokkaido University, Professor, 大学院・理学研究科, 教授 (80111334)
AMAMIYA Masami JEOL, Inc., Researcher, 技術統括部, 主任研究員
HASEGAWA Masami Faculty of Science, Kanazawa University, Assistant, 理学部地球学科, 助手 (50272943)
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| Research Abstract |
In this study, we have developed a non-destructive fluorescence X-ray sediment core scanner, named "TATSCAN-F1", with JEOL Co. for research of unsolved several year to decadal time-scale climatic changes recorded in sedimentary records. The "TATSCAN-F1" is based on energy-dispersive fluorescence X-ray analysis system, which is for non-destructive, continuous, qualitative, and quantitative 2-dimensional elemental measurement for marine sediment core and terrestrial sheet and slab samples. The instrument has a resolution of micron meter on the surface of sediment core and sedimentary rock. Maximum sample size is in the range of 250 mm long, 200 mm wide, and 100 mm thickness. Line and mapping scanning for surface of sample is able to do in about 0.03mm of minimum measurement step. The instrument has an automated focusing sensor for X-ray detector, small windows of measurement (0.1mm, 0.4mm, 1.9mm in diameter), and high resolution CCD video camera for checking measurement point. Continuous
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and quantitative data sets which are measured by "TATSCAN-F1" are unable us for statistical and spectral analysis to discuss preciously about periodicity and modulation of amplitude of climatic variations. In this study, using the "TATSCAN-F1", we have analyzed Archean banded iron formation (BIF) from Australia, Late Cretaceous black shale (OAE-1B) from south France, and Holocene sediment core from Lake Abashiri in Hokkaido. Alternation of Si-rich layer and Fe-rich layer are clearly detected by line analysis for BIF sample. By mapping analysis, it is clear that P is rich in Si-layer, and Na, Mg, Ca, Mn, Rb, and Sr are rich in Fe-layer. For OAE black shale, variations of Ca and Al in 0.1 mm thickness are definitely detected, which are corresponded to foraminifer-rich lamina and clay-rich lamina. For Holocene Abashiri lake sediment, Si peaks in several mm to 10 mm thickness on Al background variation are detected. These peaks are corresponded to annual variation of spring diatom blooming in the lake, because sedimentation rate is estimated as 6 mm /year in average. From these results, "TATSCAN-F1" has great opportunity to open a way to study high frequency-variation recorded in sediment core and sedimentary rocks. Less
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