Articles | Volume 2, issue 2
https://doi.org/10.5194/gchron-2-187-2020
© Author(s) 2020. 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-2-187-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Multimethod U–Pb baddeleyite dating: insights from the Spread Eagle Intrusive Complex and Cape St. Mary's sills, Newfoundland, Canada
Johannes E. Pohlner
CORRESPONDING AUTHOR
Institut für Geowissenschaften, Universität Heidelberg, Im
Neuenheimer Feld 234–236, 69120 Heidelberg, Germany
Unit of Earth Sciences, Department of Geosciences, University of
Fribourg, Chemin du Musée 6, 1700 Fribourg, Switzerland
Axel K. Schmitt
Institut für Geowissenschaften, Universität Heidelberg, Im
Neuenheimer Feld 234–236, 69120 Heidelberg, Germany
Kevin R. Chamberlain
Department of Geology and Geophysics, University of Wyoming, 1000 E. University Ave., Laramie, WY 82071-2000, USA
Faculty of Geology and
Geography, Tomsk State University, Tomsk 634050, Russia
Joshua H. F. L. Davies
Department of Earth and Atmospheric Sciences, Université du Québec à Montréal, 201, Avenue du Président Kennedy, H2X 3Y7,
Montréal, QC, Canada
Department of Earth Sciences, University of Geneva, Rue des
Maraîchers 13, 1205 Geneva, Switzerland
Anne Hildenbrand
Institut für Geowissenschaften, Universität Heidelberg, Im
Neuenheimer Feld 234–236, 69120 Heidelberg, Germany
Gregor Austermann
Institut für Geowissenschaften, Universität Heidelberg, Im
Neuenheimer Feld 234–236, 69120 Heidelberg, Germany
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Dawid Szymanowski, Jörn-Frederik Wotzlaw, Maria Ovtcharova, Blair Schoene, Urs Schaltegger, Mark D. Schmitz, Ryan B. Ickert, Cyril Chelle-Michou, Kevin R. Chamberlain, James L. Crowley, Joshua H. F. L. Davies, Michael P. Eddy, Sean P. Gaynor, Alexandra Käßner, Michael T. Mohr, André N. Paul, Jahan Ramezani, Simon Tapster, Marion Tichomirowa, Albrecht von Quadt, and Corey J. Wall
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We present the first community evaluation of the reproducibility of U–Pb zircon geochronology by ID-TIMS. Eleven labs in the experiment analysed aliquots of the same, homogenised, pre-spiked solution of natural zircon. This removed geological bias inherent to using natural zircon grain populations and allowed focussing the study on final lab preparation and mass spectrometry. We discuss remaining sources of inter-lab bias and propose areas of improvement of analytical methods.
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This manuscript 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 manuscript presents synthetic datasets for testing 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.
André Bahr, Monika Doubrawa, Jürgen Titschack, Gregor Austermann, Andreas Koutsodendris, Dirk Nürnberg, Ana Luiza Albuquerque, Oliver Friedrich, and Jacek Raddatz
Biogeosciences, 17, 5883–5908, https://doi.org/10.5194/bg-17-5883-2020, https://doi.org/10.5194/bg-17-5883-2020, 2020
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We explore the sensitivity of cold-water corals (CWCs) to environmental changes utilizing a multiproxy approach on a coral-bearing sediment core from off southeastern Brazil. Our results reveal that over the past 160 kyr, CWCs flourished during glacial high-northern-latitude cold events (Heinrich stadials). These periods were associated with anomalous wet phases on the continent enhancing terrigenous nutrient and organic-matter supply to the continental margin, boosting food supply to the CWCs.
Related subject area
Longlived radio-isotope systems
Interlaboratory reproducibility of ID-TIMS U–Pb geochronology evaluated with a pre-spiked natural zircon solution
µID-TIMS: spatially resolved high-precision U–Pb zircon geochronology
Geochronological and geochemical effects of zircon chemical abrasion: insights from single-crystal stepwise dissolution experiments
Chemical abrasion: the mechanics of zircon dissolution
High-precision ID-TIMS cassiterite U–Pb systematics using a low-contamination hydrothermal decomposition: implications for LA-ICP-MS and ore deposit geochronology
Highly accurate dating of micrometre-scale baddeleyite domains through combined focused ion beam extraction and U–Pb thermal ionization mass spectrometry (FIB-TIMS)
Stepwise chemical abrasion–isotope dilution–thermal ionization mass spectrometry with trace element analysis of microfractured Hadean zircon
Dawid Szymanowski, Jörn-Frederik Wotzlaw, Maria Ovtcharova, Blair Schoene, Urs Schaltegger, Mark D. Schmitz, Ryan B. Ickert, Cyril Chelle-Michou, Kevin R. Chamberlain, James L. Crowley, Joshua H. F. L. Davies, Michael P. Eddy, Sean P. Gaynor, Alexandra Käßner, Michael T. Mohr, André N. Paul, Jahan Ramezani, Simon Tapster, Marion Tichomirowa, Albrecht von Quadt, and Corey J. Wall
EGUsphere, https://doi.org/10.5194/egusphere-2025-1001, https://doi.org/10.5194/egusphere-2025-1001, 2025
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We present the first community evaluation of the reproducibility of U–Pb zircon geochronology by ID-TIMS. Eleven labs in the experiment analysed aliquots of the same, homogenised, pre-spiked solution of natural zircon. This removed geological bias inherent to using natural zircon grain populations and allowed focussing the study on final lab preparation and mass spectrometry. We discuss remaining sources of inter-lab bias and propose areas of improvement of analytical methods.
Sava Markovic, Jörn-Frederik Wotzlaw, Dawid Szymanowski, Joakim Reuteler, Peng Zeng, and Cyril Chelle-Michou
Geochronology, 6, 621–638, https://doi.org/10.5194/gchron-6-621-2024, https://doi.org/10.5194/gchron-6-621-2024, 2024
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We present a pioneering method for high-precision U–Pb dating of individual growth zones in zircon. These micrometer zones in single grains can record key geological processes from magma priming prior to eruptions to planetary formation, yet dating them at high precision has so far been technically challenging. Our method employs two cutting-edge microbeam techniques to microsample these growth zones for high-precision dating, allowing us to tackle a number of outstanding research questions.
Alyssa J. McKanna, Blair Schoene, and Dawid Szymanowski
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Acid leaching is used to remove radiation-damaged portions of zircon crystals prior to U–Pb dating to improve the accuracy of datasets. We test how the temperature and duration of acid leaching affect geochronological and geochemical outcomes. We build a framework that relates radiation damage, zircon solubility, and Pb loss.
Alyssa J. McKanna, Isabel Koran, Blair Schoene, and Richard A. Ketcham
Geochronology, 5, 127–151, https://doi.org/10.5194/gchron-5-127-2023, https://doi.org/10.5194/gchron-5-127-2023, 2023
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Acid leaching is commonly used to remove damaged portions of zircon crystals prior to U–Pb dating. However, a basic understanding of the microstructural processes that occur during leaching is lacking. We present the first 3D view of zircon dissolution based on X-ray computed tomography data acquired before and after acid leaching. These data are paired with images of etched grain surfaces and Raman spectral data. We also reveal exciting opportunities for imaging radiation damage zoning in 3D.
Simon Tapster and Joshua W. G. Bright
Geochronology, 2, 425–441, https://doi.org/10.5194/gchron-2-425-2020, https://doi.org/10.5194/gchron-2-425-2020, 2020
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Cassiterite is the primary tin ore mineral and is associated with other elements needed for green technology. The mineral is deposited from hydrothermal fluids released from magmas. Because it is extremely acid resistant, there has been difficulty dissolving the mineral for isotopic analysis. To improve the understanding of the timing and models of formation processes, we use a novel method to dissolve and extract radiogenic isotopes of the uranium-to-lead decay scheme from cassiterite.
Lee F. White, Kimberly T. Tait, Sandra L. Kamo, Desmond E. Moser, and James R. Darling
Geochronology, 2, 177–186, https://doi.org/10.5194/gchron-2-177-2020, https://doi.org/10.5194/gchron-2-177-2020, 2020
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The generation of highly precise and accurate ages requires crushing of the original sample so that individual mineral grains may be separated out for dating. Here, we use a focused ion beam to extract grains directly from a subset of a sample, effectively performing microsurgery to isolate individual crystals from the rock itself. This approach opens the door to high-precision dating for a variety of precious planetary materials that have previously been challenging to date.
C. Brenhin Keller, Patrick Boehnke, Blair Schoene, and T. Mark Harrison
Geochronology, 1, 85–97, https://doi.org/10.5194/gchron-1-85-2019, https://doi.org/10.5194/gchron-1-85-2019, 2019
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The oldest known minerals on Earth are Hadean (> 4.0 Ga) zircons from the Jack Hills, Australia. We present the first application to such Hadean zircons of stepwise chemical abrasion–isotope dilution–thermal ionization mass spectrometry with trace element analysis (stepwise CA-ID-TIMS-TEA). We examine the evolution in the U–Pb age and trace element chemistry of zircon domains accessed by successive chemical abrasion steps in the context of the geologic history of the Jack Hills zircons.
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Short summary
Baddeleyite is commonly used for U–Pb dating, but textural complexities, alteration features and discordance often make age interpretation difficult. Based on this case study, we discuss strategies for obtaining more accurate baddeleyite ages by high-precision and high spatial resolution methods, including analytical challenges and discordance interpretation. An evaluation of microtextures allows us to distinguish among seven different types of baddeleyite–zircon intergrowths.
Baddeleyite is commonly used for U–Pb dating, but textural complexities, alteration features...