HR: 1340h
AN: V23B-1426    [Abstracts]
TI: Results from the (U-Th)/He dating systems in Japan Atomic Energy Agency
AU: * Yamada, K
EM: yamada.kunimi@jaea.go.jp
AF: Japan Atomic Energy Agency, Tono Geoscience Center, 959-31 Jorinji, Izumicho, Toki-shi, Gih 509-5102, Japan
AU: Hanamuro, T
AF: Japan Atomic Energy Agency, Tono Geoscience Center, 959-31 Jorinji, Izumicho, Toki-shi, Gih 509-5102, Japan
AU: Tagami, T
AF: Kyoto University, Building #1, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto-shi, Kyo 606- 8502, Japan
AU: Yamada, R
AF: National Research Institute for Earth Science and Disaster Prevention, 3-1, Tennodai, Tsukuba-shi, Iba 305-0006, Japan
AU: Umeda, K
AF: Japan Atomic Energy Agency, Tono Geoscience Center, 959-31 Jorinji, Izumicho, Toki-shi, Gih 509-5102, Japan
AB: Japan Atomic Energy Agency (JAEA) has jointly set up the lab of the (U-Th)/He dating in cooperation with Kyoto University and National Research Institute for Earth Science and Disaster Prevention. We use the MM5400 rare gas mass spectrometer and the SPQ9000 ICP quadrupole mass spectrometer, belonging to JAEA, and built a new vacuum heater using infrared laser to extract helium. HF decomposes zircon after the alkali-fusion method using XRF bead sampler and LiBO3 in the preparation of ICP solution. Helium is quantified using sensitivity method. Uranium and thorium are using standard addition method. Quantifications of uranium-238 and thorium-232 are only need for parent isotopes to date samples because they are expected that the state of secular equilibrium becomes established and samarium does not compose the samples. At the present stage, we calibrate our systems by dating some standards, such as zircon from the Fish Canyon Tuff and apatite from the Durango, those are the international age standard, and apatite and zircon from the Tanzawa Tonalite Complex, that was dated in Yamada's PhD thesis, as a working standard. We report the results and detailed views of the dating systems.
DE: 1094 Instruments and techniques
DE: 1115 Radioisotope geochronology
DE: 1140 Thermochronology
DE: 1194 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting