The K-Ar Isochron Diagram and Ages of Illites from The Ordos Basin
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摘要: 根据伊利石40K-40Ar和40K/36Ar-40Ar/36Ar等时线图解与年龄验证了利用常规K-Ar测年法所确定的鄂尔多斯盆地的两期成岩作用时代?分析结果表明,伊利石K-Ar时钟是一个封闭体系,故能够用来确定沉积岩的成岩作用时代;常规K-Ar年龄所揭示的侏罗纪(170~160Ma)和志留—泥盆纪(420~370Ma)成岩作用时代是可靠的;K-Ar等时线图解与年龄是检验常规K-Ar测年法的有效的补充性测年手段.
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关键词:
- 伊利石 /
- K－Ar等时线图解与年龄 /
- 成岩作用时代 /
- 鄂尔多斯盆地
Abstract: The principle of K-Ar isochron method was introduced in this paper.The k-Ar isochron data of il-lites from the Ordos basin were successfully used to evaluate the two distinct diagenetic stages identifiedby conventional K-Ar dating.Both the Permian-Triassic and Cambrian-Ordovician samples yield well de-fined40K-40Ar isochrons, which indicate intercepts almost equal to zero and similar isochron ages to theconventional K-Ar ages.In addition, the Permian-Triassic samples gave also a well-defined40K/36Ar-40Ar / 36 Ar isochron, which yields an intercept of nearly the atmospheric argon ratio(295.5) and a similarisochron age to the conventional K-Ar ages.These facts indicated that the illite K-Ar clock belongs actu-ally to a closed system, and thus can validly be used to determine diagenetic ages of sedimentary rocks.The Jurassic(170～160 Ma) and Silurian-Devonian(420～370 Ma) diagenetic stages revealed by conven-tional K-Ar data were proved to be reliable.K-Ar isochron methods can supply additional information toevaluating the validity of conventional K-Ar isochron methods.It can also Provide improved constrintson interpreting K-Ar data and their geological meanings.-
Key words:
- illite /
- K-Ar isochron /
- diagenetic ages /
- Ordos basin
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