Comparison of TIMS (U-Pb) and laser ablation microprobe ICP-MS (Pb) techniques for age determination of detrital zircons from Paleoproterozoic metasedimentary rocks from northeastern Laurentia, Canada, with tectonic implications
Comparison of TIMS (U-Pb) and laser ablation microprobe ICP-MS (Pb) techniques for age determination of detrital zircons from Paleoproterozoic metasedimentary rocks from northeastern Laurentia, Canada, with tectonic implications
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TIMS (U-Pb) 和激光烧蚀微探针 ICP-MS (Pb) 技术对加拿大劳伦西亚东北部古元古代变沉积岩碎屑锆石年龄测定的比较及其构造意义
DOI：
10.1016/0009-2541(96)00030-7
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
G. Gauthier
中科院分区：
文献类型：
--
作者：
D. J. Scott;G. Gauthier
采用热电离质谱(TIMS)和激光烧蚀微探针电感耦合等离子体四极质谱(LAM-ICPMS)对加拿大劳伦蒂省古元古代四个变质沉积岩样品的碎屑锆石颗粒年龄进行了分析，并对两种方法进行了比较。TIMS的结果更精确(年龄的±0.1%)，在一致性分析的情况下比LAM-ICPMS分析更准确(±L-2%的精度)，但两种方法显示的每个样本的年龄分布相似。作为补充技术，TIMS和LAM-ICPMS分析相结合，提供了有关硅质碎屑岩来源的快速、准确和准确的信息，为解释造山带沉积层序的构造意义提供了强有力的工具。拉玛群的底部不整合地位于奈恩克拉通上，只含有太古宙碎屑，碎屑锆石年龄与奈恩克拉通中的年代单位非常接近。湖港群在构造上与拉埃克拉通有关，沉积于1934年±2 Ma至1834±2 Ma之间，仅含古元古代碎屑，20%的分析颗粒为∼2.3Ga，与部分碎屑来自拉埃克拉通的解释一致。Tasiuyak副片麻岩沉积于1940±2 Ma至1895±2 Ma之间，构造交错于Rae和Nain克拉通之间，分析的两个样品中的大部分颗粒为&Gt；2.1Ga，表明相邻的Rae和Nain克拉通都不是这种碎屑的重要源区。这与Tasiuyak副片麻岩的解释是一致的，它是一个轴向馈送的增生杂岩，而不是与Rae或Nain克拉通有关的边缘序列。
Ages of detrital zircon grains from four samples of Paleoproterozoic metasedimentary rocks from northeastern Laurentia, Canada, analysed by thermal ionisation mass spectrometry (TIMS) and laser-ablation microprobe inductively-coupled plasma quadrupole mass spectrometry (LAM-ICP-MS), are presented and the methods compared. The TIMS results are more precise (±0.1% of age) and in the case of concordant analyses more accurate than the LAM-ICP-MS analyses (± l-2% precision), but both methods show a similar distribution of ages from each sample. Used as complimentary techniques, the combination of TIMS and LAM-ICP-MS analyses yield rapid, precise, and accurate information on the provenance of siliciclastic rocks, offering a powerful tool for the interpretation of the tectonic significance of sedimentary sequences in orogenic belts. The base of the Ramah Group, which sits unconformably on the Nain craton, contains exclusively Archean detritus, with detrital zircon ages corresponding closely to those of dated units in the Nain craton. The Lake Harbour Group, tectonically associated with the Rae craton, was deposited between 1934 ± 2 and 1834 ± 2 Ma and contains exclusively Paleoproterozoic detritus; 20% of the analysed grains are ∼ 2.3 Ga, consistent with an interpretation that the source of some of the detritus was the Rae craton. The Tasiuyak paragneiss, tectonically interleaved between the Rae and Nain cratons, was deposited between 1940 ± 2 and 1895 ± 2 Ma; most of the analysed grains in the two samples examined are > 2.1 Ga, suggesting that neither the adjacent Rae nor Nain cratons were important source areas for this detritus. This is consistent with an interpretation of the Tasiuyak paragneiss as an axially-fed accretionary complex rather than a marginal sequence associated with either the Rae or Nain cratons.