TY - JOUR
T1 - New constraints on the 138La β-decay constant based on a geochronological study of granites from the Yilgarn Block, Western Australia
AU - Makishima, Akio
AU - Nakamura, Eizo
AU - Akimoto, Syun iti
AU - Campbell, Ian H.
AU - Hill, Robert I.
N1 - Funding Information:
Dr. Robert Hill, one of the coauthors, died during the preparation of this paper. We mourn his sudden death in this paper. We thank H. Honma, H. Kagami and K. Na-gao (ISEI, Okayama University) for supporting this work. We are also grateful to M. Yosh-ikawa for her technical help with the Rb-Sr dating, and to T. Ishikawa and others at ISEI for discussion and encouragement. We thank A. Kent (RSES, Australian National University) who helped us in sampling and separating minerals. We also thank the journal reviewers R.K. O'Nions and K.R. Ludwig for their constructive comments, especially on the statistics. This research is supported by the Monbusho (Ministry of Education, Science and Culture, Japan) International Scientific Research Program to S. Akimoto (No.
PY - 1993/2/10
Y1 - 1993/2/10
N2 - The β-decay constant of 138La has been geochronologically determined using Archean granites from the Yilgarn Block, Western Australia. RbSr and SmNd mineral isochron ages were obtained for the two granite samples, which are nearly identical with the ion microprobe UPb zircon ages. This agreement indicates that the closure date for these samples is the same, within analytical error, making them suitable for geochronological estimation of the β-decay constant for 138La. Applying a new method of Ce isotope analysis, with analytical reproducibility of ±0.008%, LaCe isotope data for the studied samples resulted in precise mineral isochrons. Based on these internal mineral isochrons and ages determined by other geological clocks, the β-decay constant for 138La was estimated to be (2.33 ± 0.24)·10-12a-1 (2σ).
AB - The β-decay constant of 138La has been geochronologically determined using Archean granites from the Yilgarn Block, Western Australia. RbSr and SmNd mineral isochron ages were obtained for the two granite samples, which are nearly identical with the ion microprobe UPb zircon ages. This agreement indicates that the closure date for these samples is the same, within analytical error, making them suitable for geochronological estimation of the β-decay constant for 138La. Applying a new method of Ce isotope analysis, with analytical reproducibility of ±0.008%, LaCe isotope data for the studied samples resulted in precise mineral isochrons. Based on these internal mineral isochrons and ages determined by other geological clocks, the β-decay constant for 138La was estimated to be (2.33 ± 0.24)·10-12a-1 (2σ).
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U2 - 10.1016/0009-2541(93)90158-F
DO - 10.1016/0009-2541(93)90158-F
M3 - Article
AN - SCOPUS:0027449525
SN - 0009-2541
VL - 104
SP - 293
EP - 300
JO - Chemical Geology
JF - Chemical Geology
IS - 1-4
ER -