GCHRON - recent papers
https://gchron.copernicus.org/articles/
Combined list of the recent articles of the journal Geochronology and the recent discussion forum Geochronology DiscussionsMinimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MS
https://doi.org/10.5194/gchron-6-89-2024
<b>Minimizing the effects of Pb loss in detrital and igneous U–Pb zircon geochronology by CA-LA-ICP-MS</b><br>
Erin E. Donaghy, Michael P. Eddy, Federico Moreno, and Mauricio Ibañez-Mejia<br>
Geochronology, 6, 89–106, https://doi.org/10.5194/gchron-6-89-2024, 2024<br>
Chemical abrasion (CA) is a technique that reduces or eliminates the effects of Pb loss in zircon U–Pb geochronology. However, CA has yet to be applied to large-n detrital zircon (DZ) analyses. We show that CA does not negatively impact or systematically bias U–Pb dates, improves the resolution of age populations defined by 206Pb/238U dates, and increases the percentage of concordant analyses in age populations defined by 207Pb/206Pb dates.
2024-03-27T13:36:57+01:00Bayesian integration of astrochronology and radioisotope geochronology
https://doi.org/10.5194/gchron-6-107-2024
<b>Bayesian integration of astrochronology and radioisotope geochronology</b><br>
Robin B. Trayler, Stephen R. Meyers, Bradley B. Sageman, and Mark D. Schmitz<br>
Geochronology, 6, 107–123, https://doi.org/10.5194/gchron-6-107-2024, 2024<br>
Developing models that relate stratigraphic position to time are important because they allow the rock record to be understood in terms of absolute time, allowing global comparisons. We developed a novel method for developing these models (called age–depth models) that uses two different types of chronologic information, dated rocks, and records of variations in the Earth's orbit (astrochronology). The resulting models are very precise, which can improve understanding of past climates.
2024-03-27T13:36:57+01:00Technical note: RA138 Calcite U-Pb LA-ICP-MS primary reference material
https://doi.org/10.5194/gchron-2024-7
<b>Technical note: RA138 Calcite U-Pb LA-ICP-MS primary reference material</b><br>
Marcel Guillong, Elias Samankassou, Inigo A. Müller, Dawid Szymanowski, Nathan Looser, Lorenzo Tavazzani, Óscar Merino-Tomé, Juan R. Bahamonde, Yannick Buret, and Maria Ovtcharova<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-7,2024<br>
<b>Preprint under review for GChron</b> (discussion: open, 0 comments)<br>
RA138 is a new reference material for U-Pb dating of carbonate samples via LA-ICP-MS. RA138 exhibits variable U/Pb ratios and consistent U content, resulting in a precise isochron with low uncertainty. ID-TIMS analyses fix a reference age of 321.99 ± 0.65 Ma. The observed systematic uncertainty challenges previous estimates. This research advances our ability to date carbonate samples accurately, providing deeper insights into geological processes and historical timelines.
2024-03-06T13:36:57+01:00Short communication: Synchrotron-based elemental mapping of single grains to investigate variable infrared-radiofluorescence emissions for luminescence dating
https://doi.org/10.5194/gchron-6-77-2024
<b>Short communication: Synchrotron-based elemental mapping of single grains to investigate variable infrared-radiofluorescence emissions for luminescence dating</b><br>
Mariana Sontag-González, Raju Kumar, Jean-Luc Schwenninger, Juergen Thieme, Sebastian Kreutzer, and Marine Frouin<br>
Geochronology, 6, 77–88, https://doi.org/10.5194/gchron-6-77-2024, 2024<br>
This is a preliminary study using a synchrotron light source to generate elemental maps, incorporating oxidation states, with a spatial resolution of <1 µm for individual grains within the K-feldspar density fraction. The elemental fingerprint characterizing grains with a signal suitable for infrared radiofluorescence dating reveals high levels of K, Pb, and Ba coupled with low levels of Fe and Ca. In contrast, grains exhibiting higher proportions of Fe and Ca produce an odd signal shape.
2024-03-05T13:36:57+01:00U and Th zonation in apatite observed by synchrotron X–ray fluorescence tomography and implications for the (U–Th)/He system
https://doi.org/10.5194/gchron-2024-8
<b>U and Th zonation in apatite observed by synchrotron X–ray fluorescence tomography and implications for the (U–Th)/He system</b><br>
Francis J. Sousa, Stephen E. Cox, E. Troy Rasbury, Sidney R. Hemming, Antonio Lanzirotti, and Matthew Newville<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-8,2024<br>
<b>Preprint under review for GChron</b> (discussion: open, 2 comments)<br>
We have discovered a new way of measuring the three-dimensional distribution of radioactive elements in individual crystals by shining a very bright light on apatite crystals at the Advanced Photon Source at Argonne National Laboratory. This allows us to learn about the rates and timing of geologic processes, and to help resolve problems that previously were unsolvable because we had no way to make this type of measurement.
2024-02-29T13:36:57+01:00Short communication: Cosmogenic noble gas depletion in soils by wildfire heating
https://doi.org/10.5194/gchron-6-71-2024
<b>Short communication: Cosmogenic noble gas depletion in soils by wildfire heating</b><br>
Greg Balco, Alan J. Hidy, William T. Struble, and Joshua J. Roering<br>
Geochronology, 6, 71–76, https://doi.org/10.5194/gchron-6-71-2024, 2024<br>
We describe a new method of reconstructing the long-term, pre-observational frequency and/or intensity of wildfires in forested landscapes using trace concentrations of the noble gases helium and neon that are formed in soil mineral grains by cosmic-ray bombardment of the Earth's surface.
2024-02-21T13:36:57+01:00Short communication: Inverse correlation between radiation damage and fission-track etching time on monazite
https://doi.org/10.5194/gchron-2024-2
<b>Short communication: Inverse correlation between radiation damage and fission-track etching time on monazite</b><br>
Toru Nakajima, Shoma Fukuda, Shigeru Sueoka, Sota Niki, Tetsuo Kawakami, Tohru Danhara, and Takahiro Tagami<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-2,2024<br>
<b>Preprint under review for GChron</b> (discussion: open, 1 comment)<br>
Establishing an etching procedure for the monazite fission track (MFT) is essential for MFT dating. In this short communication, we have investigated the parameters governing the etching rate of MFT, in particular 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 MFT of young monazite, advocating the importance of a revision of etching methods.
2024-02-21T13:36:57+01:00A method for quantifying the time of cooling in thermochronometric inversions
https://doi.org/10.5194/gchron-2024-3
<b>A method for quantifying the time of cooling in thermochronometric inversions</b><br>
Kalin T. McDannell and C. Brenhin Keller<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-3,2024<br>
<b>Preprint under review for GChron</b> (discussion: open, 0 comments)<br>
We introduce a new statistical method for determining the time of "peak cooling" in thermochronological inversions. Specifically, we focus on the time-temperature paths that intersect the half-maximum cooling isotherm, signifying the zenith or most rapid cooling within a defined interval. The resultant interpolated time distribution provides a systematic metric, particularly applicable for evaluating model cooling characterized by relatively smooth histories featuring a single inflection point.
2024-02-16T13:36:57+01:00(anchored) isochrons in IsoplotR
https://doi.org/10.5194/gchron-2024-5
<b>(anchored) isochrons in IsoplotR</b><br>
Pieter Vermeesch<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-5,2024<br>
<b>Preprint under review for GChron</b> (discussion: final response, 2 comments)<br>
The age of some geological materials can be estimated from the ratio of certain radiogenic 'daughter' isotopes to their radioactive 'parent'. However, in many cases, the age estimation process is complicated by the presence of an inherited component of nonradiogenic daughter isotopes. This paper presents an improved algorithm to estimate the radiogenic and non-radiogenic components, either separately or jointly.
2024-02-14T13:36:57+01:00Technical note: a new analytical protocol for apatite (U-Th)/He and trace element analysis (incorporating a continuous ramped heating measurement system for the He)
https://doi.org/10.5194/gchron-2024-6
<b>Technical note: a new analytical protocol for apatite (U-Th)/He and trace element analysis (incorporating a continuous ramped heating measurement system for the He)</b><br>
Alexis Derycke, Nathan Cogné, Dominique Bavay, David Vilbert, Lionel Dutruch, Sebastien Ternois, Gilles Ruffet, Marc Jolivet, and Kerry Gallagher<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-6,2024<br>
<b>Preprint under review for GChron</b> (discussion: final response, 6 comments)<br>
This note details a development of the (U-Th)/He method for dating apatite crystals in low-temperature thermochronology. Our innovation simplifies analysis protocols for gases (He) and crystals (U, Th, etc.), aiming to expedite data production and enhance study reliability.
2024-02-14T13:36:57+01:00Short Communication: Nanoscale heterogeneity of U and Pb in baddeleyite – implications for nanogeochronology and 238U series alpha recoil effects
https://doi.org/10.5194/gchron-2024-4
<b>Short Communication: Nanoscale heterogeneity of U and Pb in baddeleyite – implications for nanogeochronology and 238U series alpha recoil effects</b><br>
Steven Denyszyn, Donald W. Davis, and Denis Fougerouse<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-4,2024<br>
<b>Preprint under review for GChron</b> (discussion: open, 1 comment)<br>
Decay of U to Pb in the mineral baddeleyite is used for precisely dating mafic rocks, but some daughter Pb atoms can be ejected out of the crystal, resulting in an age that appears too young. Atom Probe Tomography was used to map the distribution of U and Pb atoms in 3 dimensions within a baddeleyite crystal and estimate the average distance that Pb atoms are displaced by decay of U. This allows us to correct the measured age on a baddeleyite crystal knowing its size and shape.
2024-02-09T13:36:57+01:00The daughter-parent plot: a tool for analyzing thermochronological data
https://doi.org/10.5194/gchron-2024-1
<b>The daughter-parent plot: a tool for analyzing thermochronological data</b><br>
Birk Härtel and Eva Enkelmann<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-1,2024<br>
<b>Revised manuscript under review for GChron</b> (discussion: final response, 6 comments)<br>
We present a new data analysis workflow for thermochronological data based on plots of radiogenic daughter vs. radioactive parent concentration. The daughter-parent relationship helps to identify the sources of age variation. Our workflow classifies the daughter-parent relationship and provides further suggestions, e.g., if a dataset can be described by a sample age and which type of sample age to report.
2024-01-25T13:36:57+01:00Modeling apparent Pb loss in zircon U–Pb geochronology
https://doi.org/10.5194/gchron-6-37-2024
<b>Modeling apparent Pb loss in zircon U–Pb geochronology</b><br>
Glenn R. Sharman and Matthew A. Malkowski<br>
Geochronology, 6, 37–51, https://doi.org/10.5194/gchron-6-37-2024, 2024<br>
The mineral zircon is widely used to determine the age of rocks based on the radioactive decay of U to Pb, but the measured U–Pb date can be too young if the zircon loses Pb. We present a method for estimating the distribution of apparent Pb loss by mathematical convolution. Applying this approach to 10 samples illustrates contrasting patterns of apparent Pb loss. This study highlights the importance of quantifying Pb loss to better understand its potential effects on zircon U–Pb dates.
2024-01-19T13:36:57+01:00Insight into the dynamics of a long-runout mass movement using single-grain feldspar luminescence in the Pokhara Valley, Nepal
https://doi.org/10.5194/gchron-6-53-2024
<b>Insight into the dynamics of a long-runout mass movement using single-grain feldspar luminescence in the Pokhara Valley, Nepal</b><br>
Anna-Maartje de Boer, Wolfgang Schwanghart, Jürgen Mey, Basanta Raj Adhikari, and Tony Reimann<br>
Geochronology, 6, 53–70, https://doi.org/10.5194/gchron-6-53-2024, 2024<br>
This study tested the application of single-grain feldspar luminescence for dating and reconstructing sediment dynamics of an extreme mass movement event in the Himalayan mountain range. Our analysis revealed that feldspar signals can be used to estimate the age range of the deposits if the youngest subpopulation from a sample is retrieved. The absence of clear spatial relationships with our bleaching proxies suggests that sediments were transported under extremely limited light exposure.
2024-01-19T13:36:57+01:00Calibration methods for laser ablation Rb–Sr geochronology: comparisons and recommendation based on NIST glass and natural reference materials
https://doi.org/10.5194/gchron-6-21-2024
<b>Calibration methods for laser ablation Rb–Sr geochronology: comparisons and recommendation based on NIST glass and natural reference materials</b><br>
Stijn Glorie, Sarah E. Gilbert, Martin Hand, and Jarred C. Lloyd<br>
Geochronology, 6, 21–36, https://doi.org/10.5194/gchron-6-21-2024, 2024<br>
Radiometric dating methods, involving laser ablation as the sample introduction, require robust calibrations to reference materials with similar ablation properties to the analysed samples. In the case of the rubidium–strontium dating method, calibrations are often conducted to nano powder with different ablation characteristics than the crystalline minerals. We describe the limitations of this approach and recommend an alternative calibration method involving natural minerals.
2024-01-17T13:36:57+01:00Geochronological and geochemical effects of zircon chemical abrasion: insights from single-crystal stepwise dissolution experiments
https://doi.org/10.5194/gchron-6-1-2024
<b>Geochronological and geochemical effects of zircon chemical abrasion: insights from single-crystal stepwise dissolution experiments</b><br>
Alyssa J. McKanna, Blair Schoene, and Dawid Szymanowski<br>
Geochronology, 6, 1–20, https://doi.org/10.5194/gchron-6-1-2024, 2024<br>
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.
2024-01-09T13:36:57+01:00Local Beryllium-10 production rate for the mid-elevation mountainous regions in Central Europe, deduced from a multi-method study of moraines and lake sediments in the Black Forest
https://doi.org/10.5194/gchron-2023-27
<b>Local Beryllium-10 production rate for the mid-elevation mountainous regions in Central Europe, deduced from a multi-method study of moraines and lake sediments in the Black Forest</b><br>
Felix Martin Hofmann, Claire Rambeau, Lukas Gegg, Melanie Schulz, Martin Steiner, Alexander Fülling, Laëtitia Léanni, Frank Preusser, and the ASTER Team<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2023-27,2024<br>
<b>Revised manuscript under review for GChron</b> (discussion: final response, 4 comments)<br>
We present a new 10Be production rate for the mid-elevation mountain ranges of central Europe. Beryllium-10 surface exposure dating of moraines and radiocarbon dating of presumably younger lake sediments allowed for determining the accumulation rate of 10Be in the surfaces of large boulders on moraines. The accumulation of 10Be was slower at most European reference sites. The estimated rate will not only be useful for future age determinations but also for revising existing age estimates.
2024-01-09T13:36:57+01:00The marine reservoir age of Greenland coastal waters
https://doi.org/10.5194/gchron-5-451-2023
<b>The marine reservoir age of Greenland coastal waters</b><br>
Christof Pearce, Karen Søby Özdemir, Ronja Forchhammer Mathiasen, Henrieka Detlef, and Jesper Olsen<br>
Geochronology, 5, 451–465, https://doi.org/10.5194/gchron-5-451-2023, 2023<br>
Reliable chronologies lie at the base of paleoclimatological reconstructions. When working with marine sediment cores, the most common dating tool for recent sediments is radiocarbon, but this requires calibration to convert it to calendar ages. This calibration requires knowledge of the marine radiocarbon reservoir age, and this is known to vary in space and time. In this study we provide 92 new radiocarbon measurements to improve our knowledge of the reservoir age around Greenland.
2023-12-19T13:36:57+01:00Towards the construction of regional marine radiocarbon calibration curves: an unsupervised machine learning approach
https://doi.org/10.5194/gchron-2023-26
<b>Towards the construction of regional marine radiocarbon calibration curves: an unsupervised machine learning approach</b><br>
Ana-Cristina Marza, Laurie Menviel, and Luke Cameron Skinner<br>
Geochronology Discuss., https://doi.org/10.5194/gchron-2023-26,2023<br>
<b>Revised manuscript has not been submitted</b> (discussion: closed, 3 comments)<br>
Radiocarbon serves as powerful dating tool, but there remain significant challenges in the calibration of marine radiocarbon dates. This is because the whole surface ocean cannot be represented by a single calibration curve. Here we use climate model outputs to assess a novel method for developing regional marine calibration curves. Our results are encouraging, particularly for the high latitude regions, and point a way forward for solving the marine radiocarbon age calibration problem.
2023-12-18T13:36:57+01:00Late Neogene terrestrial climate reconstruction of the central Namib Desert derived by the combination of U–Pb silcrete and terrestrial cosmogenic nuclide exposure dating
https://doi.org/10.5194/gchron-5-433-2023
<b>Late Neogene terrestrial climate reconstruction of the central Namib Desert derived by the combination of U–Pb silcrete and terrestrial cosmogenic nuclide exposure dating</b><br>
Benedikt Ritter, Richard Albert, Aleksandr Rakipov, Frederik M. Van der Wateren, Tibor J. Dunai, and Axel Gerdes<br>
Geochronology, 5, 433–450, https://doi.org/10.5194/gchron-5-433-2023, 2023<br>
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.
2023-12-01T13:36:57+01:00