Comment on the Joint determination of 40K decay constants and 40Ar */ 40K for the Fish Canyon sanid
Comment on the Joint determination of 40K decay constants and 40Ar */ 40K for the Fish Canyon sanid
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评鱼峡谷 sanid 40K 衰变常数和 40Ar */ 40K 联合测定
DOI：
10.1016/j.gca.2011.06.022
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发表时间：
2010
影响因子：
5
通讯作者：
Hopp J.
中科院分区：
文献类型：
--
作者：
Schwarz W.H;Kossert K;Trieloff M;Hopp J.
从Begemann et al.（2001），几位作者（参见例如，Min等人，2000; Nägler和Villa，2000; Grau Malonda和Grau Carles，2002; Kwon等人，2002; Trieloff等人，2003; Kossert和Günther，2004; Krumrei等人，2006; Mundil等人，2006;施瓦茨和Trieloff，2007 a，B; Renne等人，2010年）的贡献讨论是否-如果是，以何种方式-用于K-Ar和Ar-Ar定年的Steiger和Jäger（1977）的约定常数需要重新评估。最近，Renne et al.（2010）提出了对40 K衰变常数和通过电子俘获双衰变为40 Ar和通过硼氢化物衰变为40 Ca的分支比的新评估。他们的结果部分基于Grau Malonda和Grau Carles（2002）以及Kossert和Günther（2004）的两个液体闪烁计数（LSC）实验的40 K衰变常数值。在这两项研究中，一个重要但容易被忽略的点是，LSC测量中计算的总衰变常数取决于特定采用的分支比Pb/Pec，该分支比是bcl 2衰变到40 Ca和电子捕获的概率（ec，包括两种可能的衰变，电子捕获到基态和电子捕获后c发射）到40 Ar（89.14/10.86%，Kossert和Günther，2004; 89.3/10.7%，Grau Malonda和Grau Carles，2002）和0.01167（2）%的特定40 K/K比率（Garner等人，1975年）。当采用不同的分支和40 K/K比进行计算时，由LSC获得的总衰变常数的结果发生变化，因为LSC实验的计数效率对于ec分支明显低于对于β分支（约为100%）。0.13对0.997）。这种内在依赖性如图1所示：例如，当使用相同的40 K/K比0.01167时，ec分支的概率相对降低约1%，导致总衰减常数降低约0.1%。因此，第2.4节中关于Grau Malonda和Grau Carles（2002年）以及Kossert和Günther（2004年）的活动数据的陈述以及Renne等人得出的组合衰变常数。（2010）以及第5356页上的句子：“相反，建议在相反的意义上错误校准kb，与先前讨论的LSC数据一致，该数据表明ktot的值（5.555 10 10 a1）比Steiger和Jäger（1977）推荐的值（5.543 10 10 a1）大0.22%”是不正确的。由Kossert和Günther（2004）计算的衰变常数为5.554 10 10 a 1（t½= 1.248（3）Ga），将减少到约1.248（3）Ga。当使用Steiger和Jäger（1977）推荐的89.52/10.48%衰变分支时，下降到约10.52/10.48%。当使用Renne等人计算的分支比时，（2010）（89.63/10.37%），见图1。这两个值将显着低于结果的5.5492 10 10 a1的Renne等人。（2010年）。基于Grau Malonda和Grau Carles（2002）的LSC结果，可以得出类似的考虑。本文阐述了通过Kossert和Günther（2004）以及Renne等人的不同方法获得的总衰变常数值之间的差异。（2010）可能是由于不正确的40 K/K比率，这也会改变Kossert和Günther（2004）的40 K衰变常数，或者可能是Renne等人提出的值校准不足的结果。2010年，由于以下原因。地质年代学的重要组成部分-0016-7037/$-见前页© 2011 Elsevier Ltd.保留所有权利。doi：10.1016/j. gca. 2011.06. 022
Since the call by Begemann et al.(2001), several authors (see eg, Min et al., 2000; Nägler and Villa, 2000; Grau Malonda and Grau Carles, 2002; Kwon et al., 2002; Trieloff et al., 2003; Kossert and Günther, 2004; Krumrei et al., 2006; Mundil et al., 2006; Schwarz and Trieloff, 2007a, b; Renne et al., 2010) have contributed to the discussion of whether–and if so, in which way–the convention of constants used for K–Ar and Ar–Ar dating by Steiger and Jäger (1977) needs to be reevaluated. Recently, Renne et al.(2010) presented a new evaluation of the 40K decay constant and the branching ratio for the dual decay into 40Ar by electron capture and 40Ca by bÀ decay. Their results are partially based on values for the 40K decay constant from two liquid scintillation counting (LSC) experiments of Grau Malonda and Grau Carles (2002) and Kossert and Günther (2004). An important–though easily overseen–point in these two studies is that the calculated total decay constant in LSC measurements depends on a specifically adopted branching ratio Pb/Pec of the probabilities for bÀ decay to 40Ca and electron capture (ec, including both possible decays, electron capture to the ground state and electron capture followed by c emission) to 40Ar (89.14/10.86%, Kossert and Günther, 2004; 89.3/10.7%, Grau Malonda and Grau Carles, 2002) and a certain 40K/K ratio of 0.01167 (2)%(Garner et al., 1975). The result of the total decay constant obtained by LSC changes when different branching and 40K/K ratio (s) are adopted for calculations, since the counting efficiency of LSC experiments is significantly lower for the ec branch than for the beta branch (approx. 0.13 against 0.997). This intrinsic dependency is shown in Fig. 1: for example, a relative decrease in the probability for the ec branch of about 1% leads to a total decay constant that is lower by about 0.1%, when using the same 40K/K ratio of 0.01167. Therefore, the statements in Section 2.4 about the activity data from Grau Malonda and Grau Carles (2002) and Kossert and Günther (2004) and the resulting combined decay constant in Renne et al.(2010) as well as the sentence on page 5356:“Rather, miscalibration of kb in the opposite sense is suggested, consistent with the previously discussed LSC data which indicate a $0.22% larger value (5.555 Â 10À10 aÀ1) of ktot than that (5.543 Â 10À10 aÀ1) recommended by Steiger and Jäger (1977)” are not correct. The decay constant calculated by Kossert and Günther (2004) of 5.554 Â 10À10 aÀ1 (t½= 1.248 (3) Ga) would decrease to approx. 5.534 Â 10À10 aÀ1, when using the decay branches of 89.52/10.48% recommended by Steiger and Jäger (1977) and down to approx. 5.528 Â 10À10 aÀ1 when using the branching ratio evaluated by Renne et al.(2010)(89.63/10.37%), see Fig. 1. Both values would be significantly lower, than the result of 5.5492 Â 10À10 aÀ1 of Renne et al.(2010). A similar consideration based on the LSC result from Grau Malonda and Grau Carles (2002) can be drawn. The discrepancy elucidated here between values for the total decay constant obtained by the different methods of Kossert and Günther (2004) and Renne et al.(2010) might be due to an incorrect 40K/K ratio, which would also change the 40K decay constant from Kossert and Günther (2004), or it could be a consequence of insufficient calibration of the value presented by Renne et al.(2010) for the following reason. An important part of the geochronologi-0016-7037/$-see front matter© 2011 Elsevier Ltd. All rights reserved. doi: 10.1016/j. gca. 2011.06. 022
对格陵兰岛南部 Ilímaussaq 杂岩体进行 40Ar / 39Ar 和 U / Pb 同位素研究：对 40K 衰变常数和过碱性杂岩岩浆活动持续时间的影响
影响因子：
3.9
作者：
Thomas V. Krumrei;I. Villa;M. Marks;G. Markl
通讯作者：
G. Markl
LSC测量的半衰期为40K。
DOI：
10.1016/j.apradiso.2003.11.059
发表时间：
2004
期刊：
Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine
影响因子：
--
作者：
K. Kossert;E. Günther
通讯作者：
E. Günther
影响因子：
5.3
作者：
GOPEL, C;MANHES, G;ALLEGRE, CJ
通讯作者：
ALLEGRE, CJ