| Budget Amount *help |
¥14,820,000 (Direct Cost: ¥11,400,000、Indirect Cost: ¥3,420,000)
Fiscal Year 2009: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2008: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2007: ¥7,020,000 (Direct Cost: ¥5,400,000、Indirect Cost: ¥1,620,000)
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| Research Abstract |
This study attempted to quantify long-term subaerial denudation of bare carbonate rock surfaces by using in situ-produced cosmogenic ^<36>Cl in calcite. Carbonate samples were collected from the topmost 5cm of exposed pinnacles at several non-glaciated karst areas in subtropical to subarctic regions in Japan. Concentrations of natural Cl and ^<36>Cl in calcite were determined by accelerator mass spectrometry with isotope dilution with ^<35>Cl-enriched carrier spike. The nuclide concentrations were of the order of 10^5-10^6 atom g^<-1>, and converted to total denudation rates averaged over a 10^5 yr-timescale of chemical and physical processes acting on the karst surfaces. The denudation rates were 20-60mm kyr<-1>, being lowest in the central part of Japan. This tendency indicates the alternation of relative importance of chemical (dissolution) and physical (frost shattering) processes in denudation, depending on site-specific factors such as mean temperature, annual precipitation, and freeze-thawing intensity.
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