The Open UniversitySkip to content
 

A simple method for in situ U-Th-He dating

Vermeesch, Pieter; Sherlock, Sarah C.; Roberts, Nick M. W. and Carter, Andy (2012). A simple method for in situ U-Th-He dating. Geochimica et Cosmochimica Acta, 79 pp. 140–147.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/j.gca.2011.11.042
Google Scholar: Look up in Google Scholar

Abstract

This paper presents a significantly simplified method for in-situ U–Th–He dating removing the need to know any absolute concentrations. 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.

Item Type: Journal Article
Copyright Holders: 2011 Elsevier Ltd.
ISSN: 0016-7037
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 31700
Depositing User: Sarah Sherlock
Date Deposited: 31 Jan 2012 11:16
Last Modified: 22 Nov 2012 17:29
URI: http://oro.open.ac.uk/id/eprint/31700
Share this page:

Actions (login may be required)

View Item
Report issue / request change

Policies | Disclaimer

© The Open University   + 44 (0)870 333 4340   general-enquiries@open.ac.uk