Zircon U-Th-Pb Geochronology by Isotope Dilution -- Thermal Ionization Mass Spectrometry (ID-TIMS)
Zircon U-Th-Pb Geochronology by Isotope Dilution -- Thermal Ionization Mass Spectrometry (ID-TIMS)
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DOI：
10.2113/0530183
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发表时间：
2003-01
影响因子：
--
通讯作者：
R. Parrish;S. Noble
中科院分区：
文献类型：
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作者：
R. Parrish;S. Noble
ID-TIMS是同位素稀释热电离质谱法的首字母缩写。这是指将同位素示踪剂添加到溶解的样品中以制备均匀的同位素混合物，并使用热电离质谱仪测量混合物的同位素组成。该方法是同位素技术中最准确和精确的方法之一，因为它对化学产率或质谱灵敏度相对不敏感。它是一种在地球和许多其他科学领域中广泛应用的方法，涉及测量元素或同位素浓度和同位素比值。ID-TIMS技术在20世纪50年代首次应用于锆石的U-Th-Pb定年（Tilton et al. 1955，Wetherill 1956，Tilton et al. 1957），利用了20世纪40年代和50年代开发的与核能研究有关的浓缩铀同位素的普遍可用性。ID-TIMS一直是锆石年代学的主要基础，尽管其他分析方法的扩散。在过去的50年里，人们做出了许多改进，这些改进有助于该方法的成熟性和可靠性。作为一种方法，直到20世纪80年代，二次电离质谱法（安德森和Hinthorne 1972）得到进一步发展并被W.澳大利亚国立大学的Compston及其同事（Compston et al. 1984）。ANU小组开发的仪器（SHRIMP，或灵敏高分辨率离子微探针）和相关的测量协议促进了单个锆石颗粒小区域内Pb/U同位素比值的测量，它被证明是解决多组分锆石复杂年龄结构的有力工具。在20世纪90年代，激光烧蚀四极杆ICP-MS方法开始投入使用，并提供了一种替代方法，使晶粒内的U-Th-Pb同位素。
ID-TIMS is the acronym for Isotope Dilution Thermal Ionization Mass Spectrometry. This refers to the addition of an isotope tracer to a dissolved sample to make a homogeneous isotopic mixture, and the measurement of isotopic composition of the mixture using a thermal ionization mass spectrometer. The method is one of the most accurate and precise methods of isotopic techniques because it is relatively insensitive to chemical yields or mass spectrometric sensitivity. It is a method very widely applied both in earth and many other areas of science involving the measurement of element or isotope concentrations and isotopic ratios. The ID-TIMS technique was first applied to the U-Th-Pb dating of zircon in the 1950s (Tilton et al. 1955, Wetherill 1956, Tilton et al. 1957), exploiting the general availability to academia of enriched uranium isotopes developed in the 1940s and 1950s related to nuclear energy research. ID-TIMS has remained the main foundation to zircon geochronology ever since, in spite of the proliferation of other analytical methodologies. In the past 50 years, many improvements have been made and they have contributed to the maturity and reliability of the method. As a method, it was effectively unchallenged until the 1980s when secondary ionization mass spectrometry (Anderson and Hinthorne 1972) was further developed and applied to zircon geochronology by W. Compston and colleagues at the Australian National University (Compston et al. 1984). The instrument developed by the ANU group (SHRIMP, or Sensitive High Resolution Ion Microprobe) and the associated measurement protocols facilitated measurement of Pb/U isotopic ratios within a small region of a single zircon grain, and it proved to be a powerful tool to address complex age structure of multi-component zircons. In the 1990s, laser ablation quadrupole ICP-MS methods came on stream and offered an alternate way to make intra-grain U-Th-Pb isotopic …