SORI93 biotite: A new mineral standard for K-Ar dating.
SORI93 biotite: A new mineral standard for K-Ar dating.
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SORI93 黑云母：K-Ar 定年的新矿物标准。
DOI：
10.2343/geochemj.32.49
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发表时间：
1998
影响因子：
0.8
通讯作者：
S. Uchiumi
中科院分区：
文献类型：
--
作者：
M. Sudo;K. Uto;Ken Anno;O. Ishizuka;S. Uchiumi
从日本群马县的梭里花岗闪长岩中制备了一种新的K-Ar定年矿物标准——SORI93黑云母。这是作为现有标准SORI黑云母的替代品，SORI黑云母根据国际标准进行了很好的校准。测定了SORI93黑云母的K2O和40Ar含量分别为8.16±0.04 (1σ) wt %和（25.0±0.1）× 10-6 (1σ) cm3STP/g。计算出的K-Ar年龄为92.6±0.6 Ma，比SORI黑云母年龄早约100万年。部分沿SORI93黑云母的解理发生高达10%的绿岩化作用。为了证明均匀性，在100mg、50mg、20mg和10mg的等份中重复分析了K2O的含量。100 mg soori93黑云母的分析结果与SORI黑云母及地球化学标准JG-1和JB-1的相对标准偏差相似。小于100mg的同分品的标准偏差约为三个标准的两倍。这种不均匀性可能是由部分绿绿化的黑云母造成的。建议使用100 mg，以保证子样品的均匀性。
A new mineral standard for K-Ar dating, SORI93 biotite, has been prepared from the Sori Granodiorite in Gunma Prefecture, Japan. This is intended as a substitute of the existing standard, SORI biotite, which is well calibrated against international standards. The K2O and radiogenic 40Ar contents for SORI93 biotite have been determined to be 8.16 ± 0.04 (1σ) wt % and (25.0 ± 0.1) × 10-6 (1σ) cm3STP/g, respectively. The calculated K-Ar age is 92.6 ± 0.6 Ma, which is about 1 million years older than that of SORI biotite. Chloritization up to 10% partly occur along cleavages of SORI93 biotite. In order to certify the homogeneity, K2O contents have been repeatedly analyzed for 100, 50, 20 and 10 mg aliquots. The analytical result of 100 mg SORI93 biotite shows a relative standard deviation similar to that of SORI biotite and the geochemical standards, JG-1 and JB-1. The standard deviations of aliquots less than 100 mg are about twice those of the three standards. This inhomogeneity may be caused by the presence of partially chloritized biotite. It is suggested to use 100 mg to ensure the homogeneity of subsamples.