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Hafnium Isotope Characteristics of Palaeoarchaean Zircon OG 1/ OGC from the Owens Gully Diorite, Pilbara Craton, Western Australia
Author(s) -
Kemp Anthony I. S.,
Vervoort Jeffrey D.,
Bjorkman Katarina E.,
Iaccheri Linda M.
Publication year - 2017
Publication title -
geostandards and geoanalytical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.037
H-Index - 73
eISSN - 1751-908X
pISSN - 1639-4488
DOI - 10.1111/ggr.12182
Subject(s) - zircon , diorite , archean , geology , isotope , geochemistry , craton , laser ablation , chemistry , analytical chemistry (journal) , mineralogy , environmental chemistry , laser , tectonics , physics , paleontology , quantum mechanics , optics
We report Hf isotope data for 3467 Ma igneous zircons from the Owens Gully Diorite of the Pilbara Craton. These zircons, designated OG 1 or OGC , have simple, well‐defined U‐Pb age systematics. Measurements obtained by single crystal dissolution yield a moderate range in 176 Hf/ 177 Hf (mean 0.280633 ± 34) and 176 Lu/ 177 Hf (mean 0.00119) that translate into initial (3467 Ma) 176 Hf/ 177 Hf values that are equivalent within measurement uncertainty (mean 0.280554 ± 7, ε Hf = +0.6 ± 0.2, 2 s ). Laser ablation analysis yielded clustered initial 176 Hf/ 177 Hf ratios (mean 0.280560 ± 20, 2 s ) indistinguishable from those obtained by solution analysis. The antiquity and moderately high 176 Lu/ 177 Hf of these zircons result in significant corrections for radiogenic ingrowth of 176 Hf (to 6 ε Hf units). Depth profiling by concurrent Pb‐Hf isotope determination reveals trends to lower 207 Pb/ 206 Pb in several crystals, although these are not accompanied by shifts in 176 Hf/ 177 Hf. We conclude that zircons from the Owens Gully Diorite are homogeneous for Hf isotopes at the scale of sampling and within the uncertainty limits of the measurement techniques employed. Zircon OG 1/ OGC would appear to be an ideal quality monitor for laser ablation Hf isotope determination in ancient zircons, and for laser ablation techniques where Hf isotope and age information are determined concurrently or simultaneously.