The β-decay constant of 138La has been geochronologically determined using Archean granites from the Yilgarn Block, Western Australia. Rb-Sr and Sm-Nd mineral isochron ages were obtained for the two granite samples, which are nearly identical with the ion microprobe U-Pb 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%, La-Ce 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).
@article{20200502173200-701172,
author = "Makishima, Akio and Nakamura, Eizo and Akimoto, Syun-iti and Campbell, Ian H. and Hill, Robert I.",
title = "New constraints on the 138La β-decay constant based on a geochronological study of granites from the Yilgarn Block, Western Australia",
journal = "Chemical Geology",
year = "1993",
number = "1-4",
volume = "104",
pages = "293-300",
doi = "10.1016/0009-2541(93)90158-F",
}
caption | ID | assembly | stone | ||
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