Preliminary study on sample-preparation for Re-Os isotopic dating of pyrite
Preliminary study on sample-preparation for Re-Os isotopic dating of pyrite
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发表时间：
2012
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通讯作者：
L. Ying-ying
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作者：
L. Ying-ying
对黄铁矿样品进行了不同温度、不同酸、不同时间的消解条件下的Re-Os同位素测年试验，结果表明：消解温度和不同酸介质对Re测年结果无影响，但对Os测年结果有显著影响，当消解温度为120~150 ℃时，Os测年结果远低于真实值;这可能是由于190 Os掺入与样品中Os的同位素不平衡所致，当温度为180 ℃、200 ℃和220 ℃时，用硝酸或反王水作溶样介质，在不同温度下测定的Re值在误差范围内基本一致，在120 ℃和150 ℃下，反王水消解比HNO_3消解更接近真实值，在180 ~ 220 ℃范围内，无论消解酸是哪种，Os的含量在误差范围内基本相似。c（Fe 3+）对Re阴离子交换效率的影响实验表明，随着c（Fe 3+）的增加，Re的回收率急剧下降，当黄铁矿样品量为3g时，稀释至40 mL，Re的回收率较好。
Different digestion conditions,including temperature,acids and time,were tested for Re-Os isotopic dating of pyrite.The results show that the digestion temperature and different acids medium have no effect on Re results but have significant effect on Os.The results of Os are much lower than the true values,when digestion temperature at 120~150 ℃,this may probably due to isotope disequilibrium between 190Os spike and Os in samples.When temperature at 180 ℃,200 ℃ and 220 ℃,the results are basically the same and in agreement with the true values.Re results are similar to each other within error using HNO3 or inverse aqua regia as digestion medium at different temperatures,whereas Os concentrations are much closer to the true values under inverse aqua regia digestion than HNO3 digestion at 120 ℃ and 150 ℃.Os concentrations are similar to each other within error from 180 ℃ to 220 ℃,irrespective of the digestion acids.Coincident Re,187Os contents have been obtained by digesting with inverse aqua regia at 200 ℃ for 5 h,8 h,12 h and 18 h,indicating that good results can be obtained for a relatively short time of digestion.The experiments of c(Fe3+) on anion-exchange efficiency of Re show that the recovery of Re decrease sharply with increasing c(Fe3+).When the sampling weight of pyrite reaches three grams,diluting the solution to 40 mL will get a good recovery of Re.