An inter-laboratory evaluation of OD-3 zircon for use as a secondary U-Pb dating standard

作者：Iwano Hideki^*; Orihashi Yuji; Hirata Takafumi; Ogasawara Masatsugu; Danhara Tohru; Horie Kenji; Hasebe Noriko; Sueoka Shigeru; Tamura Akihiro; Hayasaka Yasutaka; Katsube Aya; Ito Hisatoshi; Tani Kenichiro; Kimura Jun Ichi; Chang Qing; Kouchi Yoshikazu; Haruta Yasuhiro; Yamamoto Koshi

来源：Island Arc, 2013, 22(3): 382-394.

DOI：10.1111/iar.12038

• Kawamoto Granodiorite
• secondary standard
• U-Pb dating
• zircon

Zircon OD-3 from the Paleogene Kawamoto Granodiorite (Mihara body) in Japan has been identified as a potential multi-grain secondary standard for U-Pb dating. We have carried out an inter-laboratory evaluation in order to evaluate possible heterogeneity amongst the OD-3 zircon grains. U-Pb ages were obtained using two analytical techniques (a sensitive high-resolution ion microprobe and a laser ablation-inductively coupled plasma-mass spectrometry) in eight laboratories. All the U-238-Pb-206 ages show good agreement, with an overall weighted average U-238-Pb-206 age of 33.0 +/- 0.1 Ma (2 sigma). The U-Pb age results revealed no significant variation or heterogeneity in the U-Pb ages of the OD-3 grains. Twelve fission-track (FT) ages from three laboratories are also reported, and have a weighted average of 32.6 +/- 0.6 Ma (2 sigma). Despite the different closure and annealing temperatures of the U-Pb and FT chronometers, respectively, the FT age is in good agreement with the U-Pb age. This suggests that the OD-3 zircon had a relatively fast cooling history and has not experienced later thermal annealing. The chronological dataset reported here clearly demonstrates that the OD-3 zircon could be a useful and reliable secondary standard for use during U-Pb dating studies of Cenozoic zircons.

• 出版日期2013-9
• 单位中国极地研究中心