A simple method for in-situ U-Th-He dating
Vermeesch, Pieter and Sherlock, S.C. and Roberts, N.M.W. and Carter, Andrew (2012) A simple method for in-situ U-Th-He dating. Geochimica et Cosmochimica Acta 79 , ISSN 0016-7037.
Abstract
This paper presents a significantly simplified method for in-situ U-Th-He dating removing the need to know any absolute concentrations or ablation pit volumes. This is done by calculating the normalised U, Th, and He concentrations of a conventionally dated calibration standard from its measured Th/U ratio and known U-Th-He age, and scaling these concentrations to the raw U, Th, and He signals of the sample. The Th/U ratio of the standard can be determined from its measured 208Pb/206Pb ratio, removing the need to use NIST glass as a reference material. We introduce an LA-ICP-MS-based method to correct for variable ablation depths between the standard and the unknown, using the strength of the ablated 29Si signal. Finally, we propose a pseudo-depth profile method to assess the effects of compositional zoning on the accuracy of in-situ U-Th-He data. The effectiveness of the proposed method has been demonstrated on three samples of gem-quality Sri Lanka zircon, which yield ages that are in agreement with previously published conventional U-Th-He measurements.
Metadata
| Item Type: | Article |
|---|---|
| School: | Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences |
| Depositing User: | Administrator |
| Date Deposited: | 09 Dec 2011 09:25 |
| Last Modified: | 02 Aug 2023 16:56 |
| URI: | https://eprints.bbk.ac.uk/id/eprint/4497 |
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