Evaluation of K-Ar and 40Ar/39Ar Dating and Q Value
详细信息
- 责任者：Quan Wuxun (Laboratory of Orogenic Belts and Crustal Evolution ; School of Earth and Space Sciences ; Peking University ; Beijing 100871 ; China) ; Ji Jianqing
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(8)
- 关键词：钾—氩计时 ; K-Ar dating ; 氩—氩计时 ; Ar-Ar dating
- 页码：p.2803-2810
- 图表：7 illus., 9 refs.
- 分类号：1300
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
ary" name="EnDivSummary">Reasonable application of K-Ar and 40Ar/39Ar dating result should be based on a proper assessment of dating precision. To assess the reliability and accuracy of final results,researchers used to calculate statistic errors and error propagation. MSWD and Probability are proposed to involve systematic (external) and statistic (instrumental) errors at the same time,thus are widely applied for considering the relation of instrument and sample. This fact indicates that K-Ar and 40Ar/39Ar dating results could be affected by both instrument and sample. Based on the theory and process of K-Ar and 40Ar/39Ar dating,this paper assesses error propagation of each testing step and their effect to the final results numerically. Parameters Q1 and Q2 are proposed to represent related properties of samples that may affect the final results. Q1 defines the relativity of K content, 36Ar content and initial 40Ar/36Ar value of sample. Q1 is crucial factor to affect the value of error propagation index. Q2 defines the relativity of K content, 36Ar content and error of initial 40Ar/36Ar of sample. Q2 is proposed to assess the accuracy of isochron age and estimate whether samples started isochron clock in the exactly same geological time and on the same initial 40Ar/36Ar ratio without isotope diffusion and exchange after isotope system closure. According to parameter Q1 and Q2 ,we can tell whether errors of final results are caused mostly by instruments or by samples. Obviously,properties of instruments and samples should be assessed from different aspects before dating as suggested here. Well designed testing process is the key to getting high precision K-Ar and 40Ar/39Ar dating results.
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