Application of cosmogenic super(10)Be to dating soils on the raisedcoral reef terraces of Kikai Island, southwest Japan

摘要

super(10)Be concentrations of six soils on the raised coral reef terraces of Kikai Island, southwest Japan range from 0.80 to 7.17x10 super(9) atoms g super(-1). The annual deposition rate of super(10)Be from the atmosphere to Kikai Island from 2000 to 2002 ranges from 2.0 to 3.5x10 super(6) atoms cm super(-2) year super(-1), with a mean of 2.8 plus or minus 0.7x10 super(6) atoms cm super(-2) year super(-1). Minimum absolute ages, calculated from the inventory of meteoric super(10)Be in the soils and the annual deposition rate of super(10)Be, are: Initial Rendzina-like soil, 8 ka; Rendzina-like soil, 18 ka; Brown Rendzina-like soil, 56 ka; Terra fusca-like soil, 127 ka; Terra rossa-like soil, 136 ka; and Intergrade between Terra rossa-like and Red-Yellow soil, 102 ka. Therefore, it was concluded that soil formation during the first [not, vert, similar]60, 000 years would be as Rendzina-like soils and more than [not, vert, similar]100, 000 years would be required for Red-Yellow soils to develop on raised coral reef terraces under subtropical humid climatic conditions.