The K-Ar Isochron Diagram and Ages of Illites from The Ordos Basin
-
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.
-
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
-
[1] (1) Hunziker, J C, Po tassium argon dating.In: JaegerE and Hun-ziker, JC, eds, Lectures in isotope g eology, Berlin, Springer-V erlag, 1979, 52～76.
(2) Faure, G, Principles of isotope g eology: New York, John Wiley& Sons Inc, 1986, 388.
(3) 赵孟为, Hans Ahrendt, klaus wemmer.K-Ar测年法在确定沉积岩成岩时代中的应用 - 以鄂尔多斯盆地为例: 沉积学报,1996, 14(3): 11～21.
(4) McDougall I, et al.Exsess radilgenic argon in yung subaerialbasalts from Auckland volcanic field, New Zealand: GeochimCosmochim Acta, 1969, 33: 1485～1520.
(5) Happer, C T, Graphical Solutions to the problem of radiogenicargon -40 loss from metamo rphic minerals: Eclogae g eol.,Helv.1970, 63: 119～140.
(6) Hayatsu, A and Carmichael, CM.K-Ar isochron method andinitial argon ratios: Earth Plenet.Sci.Lett, 1970, 8: 71～76.
(7) Shafiqullah, M and Damon.P E, Evaluation of K-Ar isochronmethods: Geochim Acta, 1974, 33: 1341～1358.
(8) Hunziker, J C.The evolution of illite to muscovite: An ex ampleof the behavoir of isotopes in low-g rade metamorphic terrains:Chem.Geol.1986, 57: 31～40.
(9) Clauer, N and Chaudhuri, S.Clays in crustal environments,Isotope dating and tracing: Spring er - Verlan, Berlin, 1995, 359.
(10) Zhao, M-W.Beitraege zur thermischen Geschichte,den Palae-ofluidsystemen und der Diag enese des Ordos Beckens(China):Goettinger Arb.Geol.Palaeont., 1994, 62: 1～97.
(11) 赵孟为等.鄂尔多斯盆地志留— 泥盆纪和侏罗纪热事件: 首次伊利石 K - Ar 年龄证据: 地质学报, 1996, 70(2): 186～194.
(12) Zhao, M-W, et al.Thermal and tectonic history of the Ordosbasin, China: Evidence from apatite fission track analysis,vitri-nite reflectance and K-Ar dating: AAPG Bull, 1996, 80: 1110 ～1134. -
点击查看大图
计量
- 文章访问数: 611
- HTML全文浏览量: 50
- PDF下载量: 563
- 被引次数: 0
下载:
