In situ Lu–Hf geochronology with LA-ICP-MS/MS analysis.
In: JAAS (Journal of Analytical Atomic Spectrometry), Jg. 38 (2023-06-01), Heft 6, S. 1285-1300
academicJournal
Zugriff:
Lu–Hf geochronology is useful for constraining the evolution of geological systems. In this study, the in situ LA-ICP-MS/MS Lu–Hf dating technique was successfully applied to Paleozoic-Precambrian xenotime, apatite and garnet. For an iCap TQ ICP-MS/MS instrument (Thermo Fisher, USA), high-purity NH 3 was more effective in the reaction than the commonly used 1 : 9 NH 3 –He mixture, and an 80% improvement in sensitivity was achieved using an N 2 flow rate of 4.0 mL min −1 . Lutetium, Yb and Hf reaction products with NH 3 were identified in the mass range from 175–300 amu. The reaction product of (176+82) Hf (expressed for 176 Hf( 14 N 1 H)( 14 N 1 H 2 )( 14 N 1 H 3 ) 3 , mass shift by +82) is measured for the separation of 176 Hf from 176 Lu and 176 Yb. Isobaric interferences 176 Lu and 176 Yb have extremely low reaction rates of ∼0.0034% and ∼0.00036% (at mass shift +82), which are only required to be corrected for the samples (e.g., xenotime) with extremely high 175 Lu/ 177 Hf and 172 Yb/ 177 Hf ratios. A matrix-induced bias of 176 Lu/ 177 Hf ratios was observed between NIST SRM 610 and the samples, which required further correction using matrix-matched reference materials. For xenotime, the accuracy of the common-Hf corrected single-spot ages is generally better than 1.5%, comparable to those obtained by in situ U–Pb analysis. The precisions of common-Hf corrected single-spot ages were in a range of 1.5–8.1% and 9.2–36.0% for xenotime and apatite samples. For garnet, the analytical uncertainties of the isochron ages are in a range of 3.5–10%, which could be further improved using a sensitivity-enhanced instrument and/or enlarged sampling volume. Our study revealed that the xenotime reference materials can be used as calibrators for apatite Lu–Hf dating. The novel in situ Lu–Hf dating technique may be especially useful for determining the age of the samples with complex temporal records or lack of traditional U-rich accessory minerals (e.g., zircon). [ABSTRACT FROM AUTHOR]
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Titel: |
In situ Lu–Hf geochronology with LA-ICP-MS/MS analysis.
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Autor/in / Beteiligte Person: | Wu, Shitou ; Wang, Hao ; Yang, Yueheng ; Niu, Junlong ; Lan, Zhongwu ; Zhang, Liangliang ; Huang, Chao ; Xie, Liewen ; Xu, Lei ; Yang, Jinhui ; Wu, Fuyuan |
Zeitschrift: | JAAS (Journal of Analytical Atomic Spectrometry), Jg. 38 (2023-06-01), Heft 6, S. 1285-1300 |
Veröffentlichung: | 2023 |
Medientyp: | academicJournal |
ISSN: | 0267-9477 (print) |
DOI: | 10.1039/d2ja00407k |
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