Oxygen isotopic heterogeneity in the Temora-2 reference zircon

Schmitt, Axel K.; Magee, C. W.; Williams, Ian S.; Holden, P.; Ireland, Trevor; DiBugnara, D.; Bodorkos, S.

doi:10.11636/record.2019.004

Cited by 6 publications

(4 citation statements)

References 6 publications

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“…Zircon reference materials Temora-2 (d 18 O = 8.2 ± 0.03‰) (Black et al, 2004), and Penglai (d 18 O = 5.31 ± 0.1‰) (Li et al, 2010) were used as a secondary reference to monitor the quality of the applied corrections. The analysis of the secondary standard Temora-2 yielded d 18 O of 8.0 ± 0.5‰, and 7.8 ± 0.4‰ (2r) in accordance with the accepted value (but see Schmitt et al (2019) for a discussion of oxygen isotopic heterogeneity in different batches of Temora-2). The analysis of the secondary standard Penglai yielded d 18 O of 5.0 ± 0.3‰ (2r) in accordance with the accepted value.…”

Section: Sims Zircon Oxygen and Pyrite Sulfur Isotope Ratiossupporting

confidence: 81%

Coupling sulfur and oxygen isotope ratios in sediment melts across the Archean-Proterozoic transition

Liebmann

Spencer

Kirkland

et al. 2021

Geochimica et Cosmochimica Acta

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The Archean-Proterozoic transition marks a time of fundamental geologic, biologic, and atmospheric changes to the Earth system, including oxygenation of the atmosphere (termed the Great Oxygenation Event; GOE), and the emergence of continents above sea level. The impacts of the GOE on Earth's surface environment are imprinted on the geologic record, including the disappearance of mass-independent fractionation of sulfur isotopes (S-MIF). Temporally overlapping geologic and geochemical observations (e.g. a change in oxygen isotope ratio of sediments and an increase in subaerial volcanism) imply the widespread subaerial emergence of continents was coeval with atmospheric oxygenation. Here we present triple sulfur isotope ratios in pyrite and oxygen isotope ratios in garnet and zircon in a global suite of Archean and Proterozoic granitoids derived from the partial melting of sedimentary protoliths. These crustal melts record an increase in average garnet and zircon d 18 O from 7.2‰ before 2.3 Ga to 10.0‰ post-2.3 Ga. Pre-2.3 Ga granitoids show small S-MIF signatures with D 33 S ranging from À0.29‰ to 0.13‰, whereas post-2.3 Ga granitoids record S-MDF (i.e. D 33 S = 0‰). The combination of sulfur and oxygen isotope signatures in the same sample with zircon U-Pb geochronology provides new insights on a potential causal link between the emergence of continents and Paleoproterozoic atmospheric oxygenation.

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Section: Sims Zircon Oxygen and Pyrite Sulfur Isotope Ratiossupporting

confidence: 81%

Coupling sulfur and oxygen isotope ratios in sediment melts across the Archean-Proterozoic transition

Liebmann

Spencer

Kirkland

et al. 2021

Geochimica et Cosmochimica Acta

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“…While the original plan was to split a single vial of TEMORA 2 zircon, a sample preparation miscommunication resulted in an entire vial being chemically abraded. Even though both the original and the replacement vials were labelled as being the older material (heavier in δ 18 O) described in Schmitt et al (2019), we suspect an old vial was refilled with more recent material with lighter δ 18 O. The Mount Painter Volcanics zircon rims showed substantially more scatter in δ 18 O composition than the reference zircons.…”

Section: Shrimp δ 18 O Discussionmentioning

confidence: 84%

“…This is probably a sample handling error. Schmitt et al (2019) show that the TEMORA 2 zircon distributed 645 by Geoscience Australia has variable δ 18 O values, which differ depending on which batch of zircon is used. While the original plan was to split a single vial of TEMORA 2 zircon, a sample preparation miscommunication resulted in an entire vial being chemically abraded.…”

Section: Shrimp δ 18 O Discussionmentioning

confidence: 95%

Effect of chemical abrasion of zircon on SHRIMP U/Pb, δ¹⁸O, Trace element, and LA-ICPMS trace element and Lu-Hf isotopic analyses

Kooymans,

Magee Jr.,

Waltenberg

et al. 2023

Preprint

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Abstract. Chemical abrasion improves the U/Pb systematics of SHRIMP analyses of reference zircons, while leaving other isotopic systems largely unchanged. SHRIMP 206Pb/238U ages of chemically abraded reference materials TEMORA 2, 91500, QGNG, and OG1 are precise to within 0.25 to 0.4 %, and are within uncertainty of chemically abraded TIMS reference ages, while SHRIMP 206Pb/238U ages of untreated zircons are within uncertainty of TIMS ages of zircons which are untreated by chemical abrasion. Chemically abraded and untreated zircons appear to cross-calibrate within uncertainty using all but one possible permutations of reference materials, provided that the corresponding chemically abraded or untreated reference age is used for the appropriate material. In the case of reference zircons QGNG and OG1, which are slightly discordant, the SHRIMP U-Pb ages of chemically abraded and untreated material differ beyond their respective 95 % confidence intervals. SHRIMP U/Pb analysis of chemically abraded zircons with multiple growth stages are more difficult to interpret. Treated igneous rims on zircons from the S-type Mount Painter Volcanics are much lower in common Pb than the rims on untreated zircons. However, the analyses of chemically abraded material show excess scatter. Chemical abrasion also changes the relative abundance of the ages of zircon cores inherited from the sedimentary protolith, presumably due to some populations being more likely to survive the chemical abrasion process than others. We consider these results from inherited S-type zircon cores to be indicative of results for detrital zircons from unmelted sediments. Trace element, δ18O, and εHf analyses were also performed on these zircons. None of these systems showed substantial changes as a result of chemical abrasion. The most discordant reference material, OG1, showed a loss of OH as a result of chemical abrasion, presumably due to dissolution of hydrous metamict domains, or thermal dehydration during the annealing step of chemical abrasion. In no case did zircons gain fluorine due to exchange of lattice-bound substituted OH or other anions with fluorine during the HF partial dissolution phase of the chemical abrasion process. As the OG1, QGNG, and TEMORA 2 zircons are known to be compositionally inhomogenous in trace element composition, spot-to-spot differences dominated the trace element results. Even the 91500 megacrystic zircon exhibited substantial chip-to-chip variation. The LREE in chemically abraded OG1 and TEMORA 2 were lower than in the untreated samples. Ti and phosphorus saturation ((Y+REE)/P) were generally unchanged in all samples.

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“…Of these zircons, Temora 2 exists in a number of mounts already and is widely used as a geochronological reference material. One potential limitation for Temora 2 is whether it can be differentiated from Temora 1 (Black et al , ) and Temora 3 (Allen and Campbell , Hervé et al ) in existing mounts where some confusion might exist regarding provenance of the Temora grains used (Schmitt et al ).…”

Section: Discussionmentioning

confidence: 99%

High‐Precision, High‐Accuracy Oxygen Isotope Measurements of Zircon Reference Materials with the SHRIMP‐SI

Ávila

Ireland

Holden

et al. 2019

Geostandard Geoanalytic Res

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Analytical protocols for SHRIMP‐SI oxygen isotope analysis (δ18O) of a suite of zircon reference materials (RMs) are presented. Data reduction involved a robust estimate of uncertainties associated with the individual spot as well as for groups where the spot data are combined. The repeatability of δ18O measurements is dependent on both the analytical conditions and the choice of the primary reference material. Under optimised conditions, repeatability was often better than 0.4‰ (2s) allowing sample uncertainties to be obtained to better than 0.2‰ (at 95% confidence limit). Single spot uncertainty combined the within‐spot precision with the scatter associated with repeated measurements of the primary zircon reference material during a measurement session. The uncertainty for individual spots measured under optimised conditions was between 0.3 and 0.4‰ (at 95% confidence). The analytical protocols described were used to assess a variety of zircon RMs that have been used for geochronology and for which laser fluorination oxygen isotope data are available (Temora 2, FC1, R33, QGNG and Plešovice), as well as zircons that have been used as RMs for trace element or other types of determination (Mud Tank, Monastery, 91500, AS57, AS3, KIM‐5, OG1, SL13, CZ3 and several other Sri Lankan zircons). Repeated analyses over nine sessions and seven different mounts show agreement within analytical uncertainty for Temora 2, FC1, R33, QGNG, Plešovice and 91500, when normalised to Mud Tank. For existing ion microprobe mounts with these materials, an appropriate δ18O can be determined. However, care should be taken when using zircons from the Duluth Complex (i.e., FC1, AS57 and AS3) as reference materials as our data indicated an excess scatter on δ18O values associated with low‐U zircon grains.

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Oxygen isotopic heterogeneity in the Temora-2 reference zircon

Abstract: Geoscience Australia acknowledges the traditional custodians of the country where this work was undertaken. We also acknowledge the support provided by individuals and communities to access the country, especially in remote and rural Australia.

Cited by 6 publications

References 6 publications

Coupling sulfur and oxygen isotope ratios in sediment melts across the Archean-Proterozoic transition

Coupling sulfur and oxygen isotope ratios in sediment melts across the Archean-Proterozoic transition

Effect of chemical abrasion of zircon on SHRIMP U/Pb, δ¹⁸O, Trace element, and LA-ICPMS trace element and Lu-Hf isotopic analyses

High‐Precision, High‐Accuracy Oxygen Isotope Measurements of Zircon Reference Materials with the SHRIMP‐SI

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Oxygen isotopic heterogeneity in the Temora-2 reference zircon

Abstract: Geoscience Australia acknowledges the traditional custodians of the country where this work was undertaken. We also acknowledge the support provided by individuals and communities to access the country, especially in remote and rural Australia.

Cited by 6 publications

References 6 publications

Coupling sulfur and oxygen isotope ratios in sediment melts across the Archean-Proterozoic transition

Coupling sulfur and oxygen isotope ratios in sediment melts across the Archean-Proterozoic transition

Effect of chemical abrasion of zircon on SHRIMP U/Pb, δ18O, Trace element, and LA-ICPMS trace element and Lu-Hf isotopic analyses

High‐Precision, High‐Accuracy Oxygen Isotope Measurements of Zircon Reference Materials with the SHRIMP‐SI

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Product

Resources

About

Effect of chemical abrasion of zircon on SHRIMP U/Pb, δ¹⁸O, Trace element, and LA-ICPMS trace element and Lu-Hf isotopic analyses