Articles | Volume 3, issue 2
https://doi.org/10.5194/gchron-3-433-2021
© Author(s) 2021. 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-3-433-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Confined fission-track revelation in apatite: how it works and why it matters
Richard A. Ketcham
CORRESPONDING AUTHOR
Department of Geological Sciences, Jackson School of Geoscience,
University of Texas, Austin, TX 78712, USA
Murat T. Tamer
Department of Geological Sciences, Jackson School of Geoscience,
University of Texas, Austin, TX 78712, USA
Related authors
Murat Taner Tamer, Ling Chung, Richard A. Ketcham, and Andrew J. W. Gleadow
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-26, https://doi.org/10.5194/gchron-2024-26, 2024
Preprint under review for GChron
Short summary
Short summary
We present the first new image-based study to reveal how choices made by different analysts affect the results obtained by fission-track analysis. Participants analyzed an identical image data set with varying grain quality. Experienced analysts tend to select lower rates of unsuitable grains and conduct lower rates of invalid length measurements. Fission-track studies need image data repositories, teaching modules, guidelines, an open science culture, and new approaches for calibration.
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.
David M. Whipp, Dawn A. Kellett, Isabelle Coutand, and Richard A. Ketcham
Geochronology, 4, 143–152, https://doi.org/10.5194/gchron-4-143-2022, https://doi.org/10.5194/gchron-4-143-2022, 2022
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Multi-thermochronometry, in which methods such as (U-Th)/He dating of zircon and apatite and apatite fission track dating are combined, is used to reconstruct rock thermal histories. Our ability to reconstruct thermal histories and interpret the geological significance of measured ages requires modeling. Here we use forward models to explore effects of grain size and chemistry on cooling ages and closure temperatures for the (U-Th)/He decay systems in apatite and zircon.
Emily H. G. Cooperdock, Richard A. Ketcham, and Daniel F. Stockli
Geochronology, 1, 17–41, https://doi.org/10.5194/gchron-1-17-2019, https://doi.org/10.5194/gchron-1-17-2019, 2019
Short summary
Short summary
(U–Th) / He chronometry relies on accurate grain-specific size and shape measurements. Using > 100 apatite grains to compare
assumed2-D versus
true3-D grain shapes measured by a microscope and X-ray computed tomography, respectively, we find that volume and surface area both differ by ~ 25 % between the two techniques and directly affect mass and concentration measurements. But we found a very small effect on the FT correction (2 %) and no discernible impact on mean sample age or dispersion.
Murat Taner Tamer, Ling Chung, Richard A. Ketcham, and Andrew J. W. Gleadow
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-26, https://doi.org/10.5194/gchron-2024-26, 2024
Preprint under review for GChron
Short summary
Short summary
We present the first new image-based study to reveal how choices made by different analysts affect the results obtained by fission-track analysis. Participants analyzed an identical image data set with varying grain quality. Experienced analysts tend to select lower rates of unsuitable grains and conduct lower rates of invalid length measurements. Fission-track studies need image data repositories, teaching modules, guidelines, an open science culture, and new approaches for calibration.
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
Short summary
Short summary
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.
David M. Whipp, Dawn A. Kellett, Isabelle Coutand, and Richard A. Ketcham
Geochronology, 4, 143–152, https://doi.org/10.5194/gchron-4-143-2022, https://doi.org/10.5194/gchron-4-143-2022, 2022
Short summary
Short summary
Multi-thermochronometry, in which methods such as (U-Th)/He dating of zircon and apatite and apatite fission track dating are combined, is used to reconstruct rock thermal histories. Our ability to reconstruct thermal histories and interpret the geological significance of measured ages requires modeling. Here we use forward models to explore effects of grain size and chemistry on cooling ages and closure temperatures for the (U-Th)/He decay systems in apatite and zircon.
Emily H. G. Cooperdock, Richard A. Ketcham, and Daniel F. Stockli
Geochronology, 1, 17–41, https://doi.org/10.5194/gchron-1-17-2019, https://doi.org/10.5194/gchron-1-17-2019, 2019
Short summary
Short summary
(U–Th) / He chronometry relies on accurate grain-specific size and shape measurements. Using > 100 apatite grains to compare
assumed2-D versus
true3-D grain shapes measured by a microscope and X-ray computed tomography, respectively, we find that volume and surface area both differ by ~ 25 % between the two techniques and directly affect mass and concentration measurements. But we found a very small effect on the FT correction (2 %) and no discernible impact on mean sample age or dispersion.
Related subject area
Fission track
Short communication: Inverse correlation between radiation damage and fission-track etching time on monazite
Short communication: Experimental factors affecting fission-track counts in apatite
Deconvolution of fission-track length distributions and its application to dating and separating pre- and post-depositional components
AI-Track-tive: open-source software for automated recognition and counting of surface semi-tracks using computer vision (artificial intelligence)
Thermal annealing of implanted 252Cf fission tracks in monazite
Technical note: Nikon–TRACKFlow, a new versatile microscope system for fission track analysis
Toru Nakajima, Shoma Fukuda, Shigeru Sueoka, Sota Niki, Tetsuo Kawakami, Tohru Danhara, and Takahiro Tagami
Geochronology, 6, 313–323, https://doi.org/10.5194/gchron-6-313-2024, https://doi.org/10.5194/gchron-6-313-2024, 2024
Short summary
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Establishing an etching procedure for monazite fission tracks (MFTs) is essential for MFT dating. In this short communication, we investigated the parameters governing the etching rate of MFTs, particularly the effect of radiation damage. Our results show an inverse relationship between MFT etching time and the degree of radiation damage. We show that existing etching recipes may not sufficiently etch MFTs in young monazite, advocating the importance of revising etching methods.
Carolin Aslanian, Raymond Jonckheere, Bastian Wauschkuhn, and Lothar Ratschbacher
Geochronology, 4, 109–119, https://doi.org/10.5194/gchron-4-109-2022, https://doi.org/10.5194/gchron-4-109-2022, 2022
Short summary
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Fission tracks are damage trails from uranium fission in minerals, whose ages and thermal histories are deduced from their number and length. A mineral is etched for observing the tracks with a microscope. We show that the etching and observation conditions affect the track count and explain it in the framework of a recent etch model. We conclude that established solutions do not secure that the ages and thermal histories inferred from track counts and measurements are accurate.
Peter Klint Jensen and Kirsten Hansen
Geochronology, 3, 561–575, https://doi.org/10.5194/gchron-3-561-2021, https://doi.org/10.5194/gchron-3-561-2021, 2021
Short summary
Short summary
Fission tracks are generated in minerals due to spontaneous fission of uranium-238. The initial track length decreases with time due to recrystallization. The age of a track can be calculated by counting the number of the shorter tracks per volume and including the decay constant. However, the theoretical order of the track length versus time is disrupted by uncertainties. We shown how the order can be re-established. The age of tectonic events such as uplift and burial can then be determined.
Simon Nachtergaele and Johan De Grave
Geochronology, 3, 383–394, https://doi.org/10.5194/gchron-3-383-2021, https://doi.org/10.5194/gchron-3-383-2021, 2021
Short summary
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Artificial intelligence techniques are capable of automatically detecting fission tracks in minerals. The AI-Track-tive software presented here can be used to automatically determine fission track densities for apatite fission track dating studies. Apatite fission track dating is mainly applied to tectonic research on exhumation rates in orogens. Time-consuming manual track counting can be replaced by deep neural networks capable of automatically finding the large majority of tracks.
Sean Jones, Andrew Gleadow, and Barry Kohn
Geochronology, 3, 89–102, https://doi.org/10.5194/gchron-3-89-2021, https://doi.org/10.5194/gchron-3-89-2021, 2021
Short summary
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We present the results of a series of experiments that constrain the temperature sensitivity of fission tracks in monazite over geological time. It is concluded that over a heating duration of 10 million years, the estimated closure temperature is < 50 °C and perhaps not much above ambient surface temperatures. Monazite fission track thermochronology has the potential to understand the thermal history and constrain the timing of geological processes in the Earth’s upper crust (< 1–2 km).
Gerben Van Ranst, Philippe Baert, Ana Clara Fernandes, and Johan De Grave
Geochronology, 2, 93–99, https://doi.org/10.5194/gchron-2-93-2020, https://doi.org/10.5194/gchron-2-93-2020, 2020
Short summary
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Nikon–TRACKFlow is a new system with dedicated modules for automated microscope control and imaging for fission track laboratories. It is based on the Nikon Eclipse Ni-E motorised upright microscope and embedded within Nikon NIS-Elements software. The system decouples image acquisition from analysis based on a number of automated user-friendly designs and protocols. Nikon–TRACKFlow aims to grow towards a high-throughput imaging system for Earth Sciences and other material-oriented sciences.
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Short summary
We introduce a new model of how etching reveals damage tracks left by fissioning atoms, which accounts for variable along-track etching rates. This complete characterization explains many observations, including community difficulty in obtaining consistent track length measurements. It also provides a quantitative basis for optimizing etching procedures, discerning more about how radiation damage anneals, and ultimately deriving more reproducible fission-track ages and thermal histories.
We introduce a new model of how etching reveals damage tracks left by fissioning atoms, which...