Chemical abrasion applied to LA-ICP-MS U-Pb zircon geochronology

Crowley, Quentin G. and Heron, Kyle and Riggs, Nancy Rosalind and Kamber, Balz and Chew, David and McConnell, Brian and Benn, Keith (2014) Chemical abrasion applied to LA-ICP-MS U-Pb zircon geochronology. Minerals, 4 (2). pp. 503-518. ISSN 2075-163X

Preview

Text Crowley_Q_etal_2014_chemical_abrasion_zircon_geochronology.pdf Available under License Creative Commons Attribution. Download (3MB) | Preview

Abstract

Zircon (ZrSiO4) is the most commonly used mineral in U-Pb geochronology. Although it has proven to be a robust chronometer, it can suffer from Pb-loss or elevated common Pb, both of which impede precision and accuracy of age determinations. Chemical abrasion of zircon involves thermal annealing followed by relatively low temperature partial dissolution in HF acid. It was specifically developed to minimize or eliminate the effects of Pb-loss prior to analysis using Thermal Ionization Mass Spectrometry (TIMS). Here we test the application of chemical abrasion to Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) by analyzing zircons from both untreated and chemically abraded samples. Rates of ablation for high alpha-dose non-treated zircons are up to 25% faster than chemically abraded equivalents. Ablation of 91500 zircon reference material demonstrates a ca. 3% greater down-hole fractionation of Pb-206/U-238 for non-treated zircons. These disparities necessitate using chemical abrasion for both primary reference material and unknowns to avoid applying an incorrect laser induced fractionation correction. All treated samples display a marked increase in the degree of concordance and/or lowering of common Pb, thereby illustrating the effectiveness of chemical abrasion to LA-ICP-MS U-Pb zircon geochronology.

Item Type:	Article
ID number or DOI:	10.3390/min4020503
Keywords:	Abrasion (Engineering); accuracy; ages; chemical abrasion; Chronometers; complex; diffusion; Dissolution (Chemistry); geological time; hf; laser ablation inductively coupled plasma mass spectrometry; Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS); Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS); lead; natural zircon; Pb-loss; ROBUST control; systematics; th-pb; trace-element; U-Pb geochronology; U–Pb geochronology; Zircon
Subjects:	Q Science > QE Geology
NAU Depositing Author Academic Status:	Faculty/Staff
Department/Unit:	College of Engineering, Forestry, and Natural Science > School of Earth Sciences and Environmental Sustainability
Date Deposited:	10 Nov 2015 17:06
URI:	http://openknowledge.nau.edu/id/eprint/1047

Actions (login required)

IR Staff Record View

Downloads