Articles | Volume 7, issue 3
https://doi.org/10.5194/gchron-7-309-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gchron-7-309-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
06 Aug 2025
Research article |
| 06 Aug 2025
| 06 Aug 2025
Zircon micro-inclusions as an obstacle for in situ garnet U–Pb geochronology: an example from the As Sifah eclogite locality, Oman
Jesse B. Walters
CORRESPONDING AUTHOR
NAWI Graz Geocenter, Department of Earth Sciences, University of Graz, Graz, 8010, Austria
Department of Geosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Joshua M. Garber
Department of Geosciences, The Pennsylvania State University, University Park, PA 16802, USA
Aratz Beranoaguirre
Department of Geosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Leo J. Millonig
Department of Geosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Axel Gerdes
Department of Geosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Tobias Grützner
Department of Geosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Horst R. Marschall
Department of Geosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
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Geochronology, 7, 369–385, https://doi.org/10.5194/gchron-7-369-2025, https://doi.org/10.5194/gchron-7-369-2025, 2025
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This article presents a new method to date geological events affecting sedimentary rocks. This method relies on the potential for the zircon U-Pb system to be disturbed during fluid-flow, alteration, and metamorphic events in sedimentary rocks. This article presents synthetic datasets for benchmarking the accuracy and precision of the discordance dating method, as well as data from detrital zircons found in the contact metamorphic aureole surround the Alta stock.
Sune G. Nielsen, Frieder Klein, Horst R. Marschall, Philip A. E. Pogge von Strandmann, and Maureen Auro
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Magnesium isotope ratios of arc lavas have been proposed as a proxy for serpentinite subduction, but uncertainties remain regarding their utility. Here we show that bulk serpentinite Mg isotope ratios are identical to the mantle, whereas the serpentinite mineral brucite is enriched in heavy Mg isotopes. Thus, Mg isotope ratios may only be used as serpentinite subduction proxies if brucite is preferentially mobilized from the slab at pressures and temperatures within the arc magma source region.
Benedikt Ritter, Richard Albert, Aleksandr Rakipov, Frederik M. Van der Wateren, Tibor J. Dunai, and Axel Gerdes
Geochronology, 5, 433–450, https://doi.org/10.5194/gchron-5-433-2023, https://doi.org/10.5194/gchron-5-433-2023, 2023
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Chronological information on the evolution of the Namib Desert is scarce. We used U–Pb dating of silcretes formed by pressure solution during calcrete formation to track paleoclimate variability since the Late Miocene. Calcrete formation took place during the Pliocene with an abrupt cessation at 2.9 Ma. The end took place due to deep canyon incision which we dated using TCN exposure dating. With our data we correct and contribute to the Neogene history of the Namib Desert and its evolution.
Aratz Beranoaguirre, Iuliana Vasiliev, and Axel Gerdes
Geochronology, 4, 601–616, https://doi.org/10.5194/gchron-4-601-2022, https://doi.org/10.5194/gchron-4-601-2022, 2022
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U–Pb dating by the in situ laser ablation mass spectrometry (LA-ICPMS) technique requires reference materials of the same nature as the samples to be analysed. Here, we have explored the suitability of using carbonate materials as a reference for sulfates, since there is no sulfate reference material. The results we obtained are satisfactory, and thus, from now on, the sulfates can also be analysed.
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We develop in situ-produced terrestrial cosmogenic krypton as a new tool to date and quantify Earth surface processes, the motivation being the availability of six stable isotopes and one radioactive isotope (81Kr, half-life 229 kyr) and of an extremely weathering-resistant target mineral (zircon). We provide proof of principle that terrestrial Krit can be quantified and used to unravel Earth surface processes.
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We have measured the chemical composition of the carbonate shells of the parasitic foraminifera Hyrrokkin sarcophaga in order to test if it is influenced by the host organism (bivalve or coral). We find that both the chemical and isotopic composition is influenced by the host organism. For example strontium is enriched in foraminifera that grew on corals, whose skeleton is built from aragonite, which is naturally enriched in strontium compared to the bivalves' calcite shell.
Eric Salomon, Atle Rotevatn, Thomas Berg Kristensen, Sten-Andreas Grundvåg, Gijs Allard Henstra, Anna Nele Meckler, Richard Albert, and Axel Gerdes
Solid Earth, 11, 1987–2013, https://doi.org/10.5194/se-11-1987-2020, https://doi.org/10.5194/se-11-1987-2020, 2020
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This study focuses on the impact of major rift border faults on fluid circulation and hanging wall sediment diagenesis by investigating a well-exposed example in NE Greenland using field observations, U–Pb calcite dating, clumped isotope, and minor element analyses. We show that fault-proximal sediments became calcite cemented quickly after deposition to form a near-impermeable barrier along the fault, which has important implications for border fault zone evolution and reservoir assessments.
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Short summary
Garnet U–Pb dating is useful for dating geologic events. However, contamination by U-rich minerals included in garnet is a risk. Inclusions are often spotted by high-U spikes or large errors in the age. We dated garnets in metamorphic rocks and calculated ages 10–15 Myr older than expected, reflecting contamination by the mineral zircon. We provide recommendations for identifying contamination and suggest that the bulk dating of zircon inclusions in garnet may also provide valuable information.
Garnet U–Pb dating is useful for dating geologic events. However, contamination by U-rich...
