| Budget Amount *help |
¥11,960,000 (Direct Cost: ¥9,200,000、Indirect Cost: ¥2,760,000)
Fiscal Year 2016: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2015: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2014: ¥8,190,000 (Direct Cost: ¥6,300,000、Indirect Cost: ¥1,890,000)
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| Outline of Final Research Achievements |
Both geological survey in the Barberton Greenstone Belt, South Africa and laboratory experiments using a hydrothermal flow-through apparatus were conducted to investigate the origin of chromium spinel and temporal/special distributions of chromium enrichment found in a banded iron formation formed 3.2 billion years ago. The experimental results demonstrated that chromium spinel can be formed from iron and chromium hydroxides by the addition of dissolved ferrous iron under low temperature hydrothermal conditions (e.g., 150 degree Celsius). The results of geological survey showed that chromium enrichment in the banded iron formation were due to chemical processes. However, the chromium enrichments were localized in a particular geological unit and area. Important factors controlling the chemical enrichment of chromium are likely the degree of hydrothermal activity and sedimentary environments. These results suggest that a part of ocean was already oxygenated 3.2 billion years ago.
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