Denudation rates of carbonate pinnacles in Japanese karst areas: Estimates from cosmogenic Cl-36 in calcite

作者：Matsushi Yuki^*; Sasa Kimikazu; Takahashi Tsutomu; Sueki Keisuke; Nagashima Yasuo; Matsukura Yukinori

来源：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms , 2010, 268(7-8): 1205-1208.

DOI：10.1016/j.nimb.2009.10.134

• Chlorine-36
• Denudation rate
• Carbonates
• Karst
• Isotope dilution

This study attempted to quantify long-term subaerial denudation of bare carbonate rock surfaces by using in situ-produced cosmogenic Cl-36 in calcite. Carbonate samples were collected from the topmost 5 cm of exposed pinnacles at several non-glaciated karst areas in subtropical to subarctic regions in Japan. Concentrations of natural Cl and Cl-36 in calcite were determined by accelerator mass spectrometry with isotope dilution with Cl-35-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 20-60 mm 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.

• 出版日期2010-4