Vertical distribution of 10Be, 26Al, and 36Cl in the surface soil layer of weathered granite at Abukuma, Japan

The northern Abukuma region of Japan is thickly covered by weathered Mesozoic granite. We investigated the vertical distribution of radionuclides (Be-10, Al-26, and Cl-36) produced by cosmic irradiation of weathered granitic soil collected from this region at a sampling site located 496 m above sea level, at 37 degrees 30'52.6 " N, 140 degrees 40'13.2 " E. We mechanically and chemically separated quartz particles from the weathered granitic soil, and purified them. We also analyzed the vertical distribution of Al-26, Be-10, and Cl-36 and estimated a long term averaged erosion rates of 0.019 +/- 0.001 mm/y from Al-26, 0.017 +/- 0.001 mm/y from Be-10, and similar to 0.01 +/- 0.001 mm/y from Cl-36. These cosmogenic erosion rates are comparable to the rate estimated from a geomorphological evolution model and with the observed sedimentary deposition rate at Abukuma. (C) 2009 Elsevier B.V. All rights reserved.