@article{oai:u-ryukyu.repo.nii.ac.jp:02006873,
 author = {Taira, Hatsuo and 平良, 初男},
 issue = {12},
 journal = {琉球大学理工学部紀要. 理学編, Bulletin of Science & Engineering Division, University of Ryukyus. Mathematics & natural sciences},
 month = {Apr},
 note = {The exponential decrease in the ionium /thorium (Th^230/Th^232) ratios with depth indicates that the assumptions of the method are in conformity with nature. The utilization of both extraction and ion exchage techniques shows good agreement in the measured ionium/thorium (Th^230/Th^232) ratios but better recovery of the thorium isotopes is obtained for the ion exchange technique.\nThe ionium/thorium (Th^230/Th^232)  ratios depend upon geographical locations and on sedimentary materials in the ocean. The surface values of the ionium/tnorium (Th^230/Th^232)  ratios are smaller for those areas receiving large amounts of land derived solid phase, and higher for carbonate materials.The rate of accumulation in the Mid-Pacific is 0.8mm/10^2 years and in the Arctic Ocean is 9.2mm/10^3 years on a gross basis. The deposits near coastal areas show a rapid accumulation rate due to the large amount of land-derived solid phase in these regions.\nThis paper is a part of a thesis submitted to the Department of Chemistry at the University of Hawaii on January, 1967., 紀要論文},
 pages = {11--30},
 title = {A Study of the Io/Th (Th^230/Th^232) Chronology of Some Marine Sediments Using Solid-state Detectors},
 year = {1969}
}