Articles | Volume 5, issue 1
https://doi.org/10.5194/gchron-5-35-2023
© Author(s) 2023. 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-5-35-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Short communication/technical note
| 
16 Jan 2023
Short communication/technical note |
| 16 Jan 2023
Short communication: age2exhume – a MATLAB/Python script to calculate steady-state vertical exhumation rates from thermochronometric ages and application to the Himalaya
Institute for Geosciences, University of Potsdam, Potsdam, Germany
Taylor F. Schildgen
GFZ German Research Centre for Geosciences, Potsdam, Germany
Institute for Geosciences, University of Potsdam, Potsdam, Germany
Related authors
Marion Roger, Arjan de Leeuw, Peter van der Beek, Laurent Husson, Edward R. Sobel, Johannes Glodny, and Matthias Bernet
Solid Earth, 14, 153–179, https://doi.org/10.5194/se-14-153-2023, https://doi.org/10.5194/se-14-153-2023, 2023
Short summary
Short summary
We study the construction of the Ukrainian Carpathians with LT thermochronology (AFT, AHe, and ZHe) and stratigraphic analysis. QTQt thermal models are combined with burial diagrams to retrieve the timing and magnitude of sedimentary burial, tectonic burial, and subsequent exhumation of the wedge's nappes from 34 to ∼12 Ma. Out-of-sequence thrusting and sediment recycling during wedge building are also identified. This elucidates the evolution of a typical wedge in a roll-back subduction zone.
Coline Ariagno, Caroline Le Bouteiller, Peter van der Beek, and Sébastien Klotz
Earth Surf. Dynam., 10, 81–96, https://doi.org/10.5194/esurf-10-81-2022, https://doi.org/10.5194/esurf-10-81-2022, 2022
Short summary
Short summary
The
critical zonenear the surface of the Earth is where geologic substrate, erosion, climate, and life meet and interact. This study focuses on mechanisms of physical weathering that produce loose sediment and make it available for transport. We show that the sediment export from a monitored catchment in the French Alps is modulated by frost-weathering processes and is therefore sensitive to complex modifications in a warming climate.
Xiong Ou, Anne Replumaz, and Peter van der Beek
Solid Earth, 12, 563–580, https://doi.org/10.5194/se-12-563-2021, https://doi.org/10.5194/se-12-563-2021, 2021
Short summary
Short summary
The low-relief, mean-elevation Baima Xueshan massif experienced slow exhumation at a rate of 0.01 km/Myr since at least 22 Ma and then regional rock uplift at 0.25 km/Myr since ~10 Ma. The high-relief, high-elevation Kawagebo massif shows much stronger local rock uplift related to the motion along a west-dipping thrust fault, at a rate of 0.45 km/Myr since at least 10 Ma, accelerating to 1.86 km/Myr since 1.6 Ma. Mekong River incision plays a minor role in total exhumation in both massifs.
Zoltán Erdős, Ritske S. Huismans, and Peter van der Beek
Solid Earth, 10, 391–404, https://doi.org/10.5194/se-10-391-2019, https://doi.org/10.5194/se-10-391-2019, 2019
Short summary
Short summary
We used a 2-D thermomechanical code to simulate the evolution of an orogen. Our aim was to study the interaction between tectonic and surface processes in orogenic forelands. We found that an increase in the sediment input to the foreland results in prolonged activity of the active frontal thrust. Such a scenario could occur naturally as a result of increasing relief in the orogenic hinterland or a change in climatic conditions. We compare our results with observations from the Alps.
Jean Braun, Lorenzo Gemignani, and Peter van der Beek
Earth Surf. Dynam., 6, 257–270, https://doi.org/10.5194/esurf-6-257-2018, https://doi.org/10.5194/esurf-6-257-2018, 2018
Short summary
Short summary
We present a new method to interpret a type of data that geologists obtained by dating minerals in river sand samples. We show that such data contain information about the spatial distribution of the erosion rate (wear of surface rocks by natural processes such as river incision, land sliding or weathering) in the regions neighboring the river. This is important to understand the nature and efficiency of the processes responsible for surface erosion in mountain belts.
Margaux Mouchené, Peter van der Beek, Sébastien Carretier, and Frédéric Mouthereau
Earth Surf. Dynam., 5, 125–143, https://doi.org/10.5194/esurf-5-125-2017, https://doi.org/10.5194/esurf-5-125-2017, 2017
Short summary
Short summary
The Lannemezan megafan (northern Pyrenean foreland) was abandoned during the Quaternary and subsequently incised. We use numerical models to explore possible scenarios for the evolution of this megafan. We show that autogenic processes are sufficient to explain its evolution. Climate may have played a second-order role; in contrast base-level change, tectonic activity and flexural isostatic rebound do not appear to have influenced its evolution.
Marion Roger, Arjan de Leeuw, Peter van der Beek, Laurent Husson, Edward R. Sobel, Johannes Glodny, and Matthias Bernet
Solid Earth, 14, 153–179, https://doi.org/10.5194/se-14-153-2023, https://doi.org/10.5194/se-14-153-2023, 2023
Short summary
Short summary
We study the construction of the Ukrainian Carpathians with LT thermochronology (AFT, AHe, and ZHe) and stratigraphic analysis. QTQt thermal models are combined with burial diagrams to retrieve the timing and magnitude of sedimentary burial, tectonic burial, and subsequent exhumation of the wedge's nappes from 34 to ∼12 Ma. Out-of-sequence thrusting and sediment recycling during wedge building are also identified. This elucidates the evolution of a typical wedge in a roll-back subduction zone.
Coline Ariagno, Caroline Le Bouteiller, Peter van der Beek, and Sébastien Klotz
Earth Surf. Dynam., 10, 81–96, https://doi.org/10.5194/esurf-10-81-2022, https://doi.org/10.5194/esurf-10-81-2022, 2022
Short summary
Short summary
The
critical zonenear the surface of the Earth is where geologic substrate, erosion, climate, and life meet and interact. This study focuses on mechanisms of physical weathering that produce loose sediment and make it available for transport. We show that the sediment export from a monitored catchment in the French Alps is modulated by frost-weathering processes and is therefore sensitive to complex modifications in a warming climate.
Xiong Ou, Anne Replumaz, and Peter van der Beek
Solid Earth, 12, 563–580, https://doi.org/10.5194/se-12-563-2021, https://doi.org/10.5194/se-12-563-2021, 2021
Short summary
Short summary
The low-relief, mean-elevation Baima Xueshan massif experienced slow exhumation at a rate of 0.01 km/Myr since at least 22 Ma and then regional rock uplift at 0.25 km/Myr since ~10 Ma. The high-relief, high-elevation Kawagebo massif shows much stronger local rock uplift related to the motion along a west-dipping thrust fault, at a rate of 0.45 km/Myr since at least 10 Ma, accelerating to 1.86 km/Myr since 1.6 Ma. Mekong River incision plays a minor role in total exhumation in both massifs.
Sara Savi, Stefanie Tofelde, Andrew D. Wickert, Aaron Bufe, Taylor F. Schildgen, and Manfred R. Strecker
Earth Surf. Dynam., 8, 303–322, https://doi.org/10.5194/esurf-8-303-2020, https://doi.org/10.5194/esurf-8-303-2020, 2020
Short summary
Short summary
Fluvial deposits record changes in water and sediment supply. As such, they are often used to reconstruct the tectonic or climatic history of a basin. In this study we used an experimental setting to analyze how fluvial deposits register changes in water or sediment supply at a confluence zone. We provide a new conceptual framework that may help understanding the construction of these deposits under different forcings conditions, information crucial to correctly inferring the history of a basin.
Mitch K. D'Arcy, Taylor F. Schildgen, Jens M. Turowski, and Pedro DiNezio
Earth Surf. Dynam., 7, 755–771, https://doi.org/10.5194/esurf-7-755-2019, https://doi.org/10.5194/esurf-7-755-2019, 2019
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The age of formation of sedimentary deposits is often interpreted to record information about past environmental changes. Here, we show that the timing of abandonment of surfaces also provides valuable information. We derive a new set of equations that can be used to estimate when a sedimentary surface was abandoned based on what is known about its activity from surface dating. Estimates of abandonment age can benefit a variety of geomorphic analyses, which we illustrate with a case study.
Stefanie Tofelde, Sara Savi, Andrew D. Wickert, Aaron Bufe, and Taylor F. Schildgen
Earth Surf. Dynam., 7, 609–631, https://doi.org/10.5194/esurf-7-609-2019, https://doi.org/10.5194/esurf-7-609-2019, 2019
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We performed seven physical experiments to explore terrace formation and sediment export from a braided alluvial river system that is perturbed by changes in water discharge, sediment supply, or base level. Each perturbation differently affects (1) the geometry of terraces and channels, (2) the timing of terrace formation, and (3) the transient response of sediment discharge. Our findings provide guidelines for interpreting fill terraces and sediment export from fluvial systems.
Zoltán Erdős, Ritske S. Huismans, and Peter van der Beek
Solid Earth, 10, 391–404, https://doi.org/10.5194/se-10-391-2019, https://doi.org/10.5194/se-10-391-2019, 2019
Short summary
Short summary
We used a 2-D thermomechanical code to simulate the evolution of an orogen. Our aim was to study the interaction between tectonic and surface processes in orogenic forelands. We found that an increase in the sediment input to the foreland results in prolonged activity of the active frontal thrust. Such a scenario could occur naturally as a result of increasing relief in the orogenic hinterland or a change in climatic conditions. We compare our results with observations from the Alps.
Andrew D. Wickert and Taylor F. Schildgen
Earth Surf. Dynam., 7, 17–43, https://doi.org/10.5194/esurf-7-17-2019, https://doi.org/10.5194/esurf-7-17-2019, 2019
Short summary
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Rivers can raise or lower their beds by depositing or eroding sediments. We combine equations for flow, channel/valley geometry, and gravel transport to learn how climate and tectonics shape down-valley profiles of river-bed elevation. Rivers steepen when they receive more sediment (relative to water) and become straighter with tectonic uplift. Weathering and breakdown of gravel is needed to produce gradually widening river channels with concave-up profiles that are often observed in the field.
Jean Braun, Lorenzo Gemignani, and Peter van der Beek
Earth Surf. Dynam., 6, 257–270, https://doi.org/10.5194/esurf-6-257-2018, https://doi.org/10.5194/esurf-6-257-2018, 2018
Short summary
Short summary
We present a new method to interpret a type of data that geologists obtained by dating minerals in river sand samples. We show that such data contain information about the spatial distribution of the erosion rate (wear of surface rocks by natural processes such as river incision, land sliding or weathering) in the regions neighboring the river. This is important to understand the nature and efficiency of the processes responsible for surface erosion in mountain belts.
Sara Savi, Stefanie Tofelde, Hella Wittmann, Fabiana Castino, and Taylor Schildgen
Earth Surf. Dynam. Discuss., https://doi.org/10.5194/esurf-2017-30, https://doi.org/10.5194/esurf-2017-30, 2017
Preprint withdrawn
Short summary
Short summary
When using cosmogenic nuclides to determine exposure ages or denudation rates in rapidly evolving landscapes, challenges arise related to the small number of nuclides that have accumulated in surface materials. Here we describe an approach that defines a lower threshold above which samples with low 10Be content can be statistically distinguished from laboratory blanks. This in turn dictates the meaning and reliability of the samples and their possible use.
Margaux Mouchené, Peter van der Beek, Sébastien Carretier, and Frédéric Mouthereau
Earth Surf. Dynam., 5, 125–143, https://doi.org/10.5194/esurf-5-125-2017, https://doi.org/10.5194/esurf-5-125-2017, 2017
Short summary
Short summary
The Lannemezan megafan (northern Pyrenean foreland) was abandoned during the Quaternary and subsequently incised. We use numerical models to explore possible scenarios for the evolution of this megafan. We show that autogenic processes are sufficient to explain its evolution. Climate may have played a second-order role; in contrast base-level change, tectonic activity and flexural isostatic rebound do not appear to have influenced its evolution.
Related subject area
Geochronological data analysis/statistics/modelling
Technical note: colab_zirc_dims: a Google Colab-compatible toolset for automated and semi-automated measurement of mineral grains in laser ablation–inductively coupled plasma–mass spectrometry images using deep learning models
Calculation of uncertainty in the (U–Th) ∕ He system
Bayesian age–depth modelling applied to varve and radiometric dating to optimize the transfer of an existing high-resolution chronology to a new composite sediment profile from Holzmaar (West Eifel Volcanic Field, Germany)
U and Th content in magnetite and Al spinel obtained by wet chemistry and laser ablation methods: implication for (U–Th) ∕ He thermochronometer
In situ LA-ICPMS U–Pb dating of sulfates: applicability of carbonate reference materials as matrix-matched standards
An algorithm for U–Pb geochronology by secondary ion mass spectrometry
Technical note: Rapid phase identification of apatite and zircon grains for geochronology using X-ray micro-computed tomography
Simulating sedimentary burial cycles – Part 2: Elemental-based multikinetic apatite fission-track interpretation and modelling techniques illustrated using examples from northern Yukon
sandbox – creating and analysing synthetic sediment sections with R
Improving age–depth relationships by using the LANDO (“Linked age and depth modeling”) model ensemble
How many grains are needed for quantifying catchment erosion from tracer thermochronology?
Short communication: Inverse isochron regression for Re–Os, K–Ca and other chronometers
Technical note: Analytical protocols and performance for apatite and zircon (U–Th) ∕ He analysis on quadrupole and magnetic sector mass spectrometer systems between 2007 and 2020
Simulating sedimentary burial cycles – Part 1: Investigating the role of apatite fission track annealing kinetics using synthetic data
The closure temperature(s) of zircon Raman dating
On the treatment of discordant detrital zircon U–Pb data
An evaluation of Deccan Traps eruption rates using geochronologic data
geoChronR – an R package to model, analyze, and visualize age-uncertain data
Development of a multi-method chronology spanning the Last Glacial Interval from Orakei maar lake, Auckland, New Zealand
Robust isochron calculation
Resolving the timescales of magmatic and hydrothermal processes associated with porphyry deposit formation using zircon U–Pb petrochronology
Seasonal deposition processes and chronology of a varved Holocene lake sediment record from Chatyr Kol lake (Kyrgyz Republic)
Unifying the U–Pb and Th–Pb methods: joint isochron regression and common Pb correction
Exploring the advantages and limitations of in situ U–Pb carbonate geochronology using speleothems
Michael C. Sitar and Ryan J. Leary
Geochronology, 5, 109–126, https://doi.org/10.5194/gchron-5-109-2023, https://doi.org/10.5194/gchron-5-109-2023, 2023
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We developed code to automatically and semi-automatically measure dimensions of detrital mineral grains in reflected-light images saved at laser ablation–inductively coupled plasma–mass spectrometry facilities that use Chromium targeting software. Our code uses trained deep learning models to segment grain images with greater accuracy than is achievable using other segmentation techniques. We implement our code in Jupyter notebooks which can also be run online via Google Colab.
Peter E. Martin, James R. Metcalf, and Rebecca M. Flowers
Geochronology, 5, 91–107, https://doi.org/10.5194/gchron-5-91-2023, https://doi.org/10.5194/gchron-5-91-2023, 2023
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There is currently no standardized method of performing uncertainty propagation in the (U–Th) / He system, causing data interpretation difficulties. We present two methods of uncertainty propagation and describe free, open-source software (HeCalc) to apply them. Compilation of real data using only analytical uncertainty as well as 2 % and 5 % uncertainties in FT yields respective median relative date uncertainties of 2.9 %, 3.3 %, and 5.0 % for apatites and 1.7 %, 3.3 %, and 5.0 % for zircons.
Stella Birlo, Wojciech Tylmann, and Bernd Zolitschka
Geochronology, 5, 65–90, https://doi.org/10.5194/gchron-5-65-2023, https://doi.org/10.5194/gchron-5-65-2023, 2023
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Sediment cores from the volcanic lake Holzmaar provide a very precise chronology based on tree-ring-like annual laminations or varves. We statistically combine this varve chronology with radiometric dating and tested three different methods to upgrade the age–depth model. However, only one of the three methods tested improved the dating accuracy considerably. With this work, an overview of different age integration methods is discussed and made available for increased future demands.
Marianna Corre, Arnaud Agranier, Martine Lanson, Cécile Gautheron, Fabrice Brunet, and Stéphane Schwartz
Geochronology, 4, 665–681, https://doi.org/10.5194/gchron-4-665-2022, https://doi.org/10.5194/gchron-4-665-2022, 2022
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This study is focused on the accurate measurement of U and Th by wet chemistry and laser ablation methods to improve (U–Th)/He dating of magnetite and spinel. The low U–Th content and the lack of specific U–Th standards significantly limit the accuracy of (U–Th)/He dating. Obtained U–Th results on natural and synthetic magnetite and aluminous spinel samples analyzed by wet chemistry methods and LA-ICP-MS sampling have important implications for the (U–Th)/He method and dates interpretation.
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.
Pieter Vermeesch
Geochronology, 4, 561–576, https://doi.org/10.5194/gchron-4-561-2022, https://doi.org/10.5194/gchron-4-561-2022, 2022
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Secondary ion mass spectrometry (SIMS) is the oldest and most sensitive analytical technique for in situ U–Pb geochronology. This paper introduces a new algorithm for SIMS data reduction that treats data as
compositional data, which means that the relative abundances of 204Pb, 206Pb, 207Pb, and 238Pb are processed within a tetrahedral data space or
simplex. The new method is implemented in an eponymous computer programme that is compatible with the two dominant types of SIMS instruments.
Emily H. G. Cooperdock, Florian Hofmann, Ryley M. C. Tibbetts, Anahi Carrera, Aya Takase, and Aaron J. Celestian
Geochronology, 4, 501–515, https://doi.org/10.5194/gchron-4-501-2022, https://doi.org/10.5194/gchron-4-501-2022, 2022
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Apatite and zircon are the most widely used minerals for dating rocks, but they can be difficult to identify in some crushed rock samples. Incorrect mineral identification results in wasted analytical resources and inaccurate data. We show how X-ray computed tomography can be used to efficiently and accurately distinguish apatite from zircon based on density variations, and provide non-destructive 3D grain-specific size, shape, and inclusion information for improved data quality.
Dale R. Issler, Kalin T. McDannell, Paul B. O'Sullivan, and Larry S. Lane
Geochronology, 4, 373–397, https://doi.org/10.5194/gchron-4-373-2022, https://doi.org/10.5194/gchron-4-373-2022, 2022
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Phanerozoic sedimentary rocks of northern Canada have compositionally heterogeneous detrital apatite with high age dispersion caused by differential thermal annealing. Discrete apatite fission track kinetic populations with variable annealing temperatures are defined using elemental data but are poorly resolved using conventional parameters. Inverse thermal modelling of samples from northern Yukon reveals a record of multiple heating–cooling cycles consistent with geological constraints.
Michael Dietze, Sebastian Kreutzer, Margret C. Fuchs, and Sascha Meszner
Geochronology, 4, 323–338, https://doi.org/10.5194/gchron-4-323-2022, https://doi.org/10.5194/gchron-4-323-2022, 2022
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The R package sandbox is a collection of functions that allow the creation, sampling and analysis of fully virtual sediment sections, like having a virtual twin of real-world deposits. This article introduces the concept, features, and workflows required to use sandbox. It shows how a real-world sediment section can be mapped into the model and subsequently addresses a series of theoretical and practical questions, exploiting the flexibility of the model framework.
Gregor Pfalz, Bernhard Diekmann, Johann-Christoph Freytag, Liudmila Syrykh, Dmitry A. Subetto, and Boris K. Biskaborn
Geochronology, 4, 269–295, https://doi.org/10.5194/gchron-4-269-2022, https://doi.org/10.5194/gchron-4-269-2022, 2022
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We use age–depth modeling systems to understand the relationship between age and depth in lake sediment cores. However, depending on which modeling system we use, the model results may vary. We provide a tool to link different modeling systems in an interactive computational environment and make their results comparable. We demonstrate the power of our tool by highlighting three case studies in which we test our application for single-sediment cores and a collection of multiple sediment cores.
Andrea Madella, Christoph Glotzbach, and Todd A. Ehlers
Geochronology, 4, 177–190, https://doi.org/10.5194/gchron-4-177-2022, https://doi.org/10.5194/gchron-4-177-2022, 2022
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Cooling ages date the time at which minerals cross a certain isotherm on the way up to Earth's surface. Such ages can be measured from bedrock material and river sand. If spatial variations in bedrock ages are known in a river catchment, the spatial distribution of erosion can be inferred from the distribution of the ages measured from the river sand grains. Here we develop a new tool to help such analyses, with particular emphasis on quantifying uncertainties due to sample size.
Yang Li and Pieter Vermeesch
Geochronology, 3, 415–420, https://doi.org/10.5194/gchron-3-415-2021, https://doi.org/10.5194/gchron-3-415-2021, 2021
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A conventional isochron is a straight-line fit to two sets of isotopic ratios, D/d and P/d, where P is the radioactive parent, D is the radiogenic daughter, and d is a second isotope of the daughter element. The slope of this line is proportional to the age of the system. An inverse isochron is a linear fit through d/D and P/D. The horizontal intercept of this line is inversely proportional to the age. The latter approach is preferred when d<D, which is the case in Re–Os and K–Ca geochronology.
Cécile Gautheron, Rosella Pinna-Jamme, Alexis Derycke, Floriane Ahadi, Caroline Sanchez, Frédéric Haurine, Gael Monvoisin, Damien Barbosa, Guillaume Delpech, Joseph Maltese, Philippe Sarda, and Laurent Tassan-Got
Geochronology, 3, 351–370, https://doi.org/10.5194/gchron-3-351-2021, https://doi.org/10.5194/gchron-3-351-2021, 2021
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Apatite and zircon (U–Th) / He thermochronology is now a mainstream tool to reconstruct Earth's evolution through the history of cooling and exhumation over the first dozen kilometers. The geological implications of these data rely on the precision of measurements of He, U, Th, and Sm contents in crystals. This technical note documents the methods for He thermochronology developed at the GEOPS laboratory, Paris-Saclay University, that allow (U–Th) / He data to be obtained with precision.
Kalin T. McDannell and Dale R. Issler
Geochronology, 3, 321–335, https://doi.org/10.5194/gchron-3-321-2021, https://doi.org/10.5194/gchron-3-321-2021, 2021
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We generated a synthetic dataset applying published kinetic models and distinct annealing kinetics for the apatite fission track and (U–Th)/He methods using a predetermined thermal history. We then tested how well the true thermal history could be recovered under different data interpretation schemes and geologic constraint assumptions using the Bayesian QTQt software. Our results demonstrate that multikinetic data increase time–temperature resolution and can constrain complex thermal histories.
Birk Härtel, Raymond Jonckheere, Bastian Wauschkuhn, and Lothar Ratschbacher
Geochronology, 3, 259–272, https://doi.org/10.5194/gchron-3-259-2021, https://doi.org/10.5194/gchron-3-259-2021, 2021
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We carried out thermal annealing experiments between 500 and 1000 °C to determine the closure temperature of radiation-damage annealing in zircon (ZrSiO4). Our results show that the different Raman bands of zircon respond differently to annealing. The repair is highest for the external rotation Raman band near 356.6 cm−1. The closure temperature estimates range from 250 to 370 °C for different bands. The differences in closure temperatures offer the prospect of multi-T zircon Raman dating.
Pieter Vermeesch
Geochronology, 3, 247–257, https://doi.org/10.5194/gchron-3-247-2021, https://doi.org/10.5194/gchron-3-247-2021, 2021
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This paper shows that the current practice of filtering discordant U–Pb data based on the relative difference between the 206Pb/238U and 207Pb/206Pb ages is just one of several possible approaches to the problem and demonstrably not the best one. An alternative approach is to define discordance in terms of isotopic composition, as a log ratio distance between the measurement and the concordia line. Application to real data indicates that this reduces the positive bias of filtered age spectra.
Blair Schoene, Michael P. Eddy, C. Brenhin Keller, and Kyle M. Samperton
Geochronology, 3, 181–198, https://doi.org/10.5194/gchron-3-181-2021, https://doi.org/10.5194/gchron-3-181-2021, 2021
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We compare two published U–Pb and 40Ar / 39Ar geochronologic datasets to produce eruption rate models for the Deccan Traps large igneous province. Applying the same approach to each dataset, the resulting models agree well, but the higher-precision U–Pb dataset results in a more detailed eruption model than the lower-precision 40Ar / 39Ar data. We explore sources of geologic uncertainty and reiterate the importance of systematic uncertainties in comparing U–Pb and 40Ar / 39Ar datasets.
Nicholas P. McKay, Julien Emile-Geay, and Deborah Khider
Geochronology, 3, 149–169, https://doi.org/10.5194/gchron-3-149-2021, https://doi.org/10.5194/gchron-3-149-2021, 2021
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This paper describes geoChronR, an R package that streamlines the process of quantifying age uncertainties, propagating uncertainties through several common analyses, and visualizing the results. In addition to describing the structure and underlying theory of the package, we present five real-world use cases that illustrate common workflows in geoChronR. geoChronR is built on the Linked PaleoData framework, is open and extensible, and we welcome feedback and contributions from the community.
Leonie Peti, Kathryn E. Fitzsimmons, Jenni L. Hopkins, Andreas Nilsson, Toshiyuki Fujioka, David Fink, Charles Mifsud, Marcus Christl, Raimund Muscheler, and Paul C. Augustinus
Geochronology, 2, 367–410, https://doi.org/10.5194/gchron-2-367-2020, https://doi.org/10.5194/gchron-2-367-2020, 2020
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Orakei Basin – a former maar lake in Auckland, New Zealand – provides an outstanding sediment record over the last ca. 130 000 years, but an age model is required to allow the reconstruction of climate change and volcanic eruptions contained in the sequence. To construct a relationship between depth in the sediment core and age of deposition, we combined tephrochronology, radiocarbon dating, luminescence dating, and the relative intensity of the paleomagnetic field in a Bayesian age–depth model.
Roger Powell, Eleanor C. R. Green, Estephany Marillo Sialer, and Jon Woodhead
Geochronology, 2, 325–342, https://doi.org/10.5194/gchron-2-325-2020, https://doi.org/10.5194/gchron-2-325-2020, 2020
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The standard approach to isochron calculation assumes that the distribution of uncertainties on the data arising from isotopic analysis is strictly Gaussian. This excludes datasets that have more scatter, even though many appear to have age significance. Our new approach requires only that the central part of the uncertainty distribution of the data defines a "spine" in the trend of the data. A robust statistics approach is used to locate the spine, and an implementation in Python is given.
Simon J. E. Large, Jörn-Frederik Wotzlaw, Marcel Guillong, Albrecht von Quadt, and Christoph A. Heinrich
Geochronology, 2, 209–230, https://doi.org/10.5194/gchron-2-209-2020, https://doi.org/10.5194/gchron-2-209-2020, 2020
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The integration of zircon geochemistry and U–Pb geochronology (petrochronology) allows us to improve our understanding of magmatic processes. Here we could reconstruct the ~300 kyr evolution of the magma reservoir that sourced the magmas, fluids and metals to form the Batu Hijau porphyry Cu–Au deposit. The application of in situ LA-ICP-MS and high-precision CA–ID–TIMS geochronology to the same zircons further allowed an assessment of the strengths and limitations of the different techniques.
Julia Kalanke, Jens Mingram, Stefan Lauterbach, Ryskul Usubaliev, Rik Tjallingii, and Achim Brauer
Geochronology, 2, 133–154, https://doi.org/10.5194/gchron-2-133-2020, https://doi.org/10.5194/gchron-2-133-2020, 2020
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Our study presents the first seasonally laminated (varved) sediment record covering almost the entire Holocene in high mountainous arid Central Asia. The established floating varve chronology is confirmed by two terrestrial radiocarbon dates, whereby aquatic radiocarbon dates reveal decreasing reservoir ages up core. Changes in seasonal deposition characteristics are attributed to changes in runoff and precipitation and/or to evaporative summer conditions.
Pieter Vermeesch
Geochronology, 2, 119–131, https://doi.org/10.5194/gchron-2-119-2020, https://doi.org/10.5194/gchron-2-119-2020, 2020
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The U–Pb method is one of the most powerful and versatile methods in the geochronological toolbox. With two isotopes of uranium decaying to two different isotopes of lead, the U–Pb method offers an internal quality control that is absent from most other geochronological techniques. U-bearing minerals often contain significant amounts of Th, which decays to a third Pb isotope. This paper presents an algorithm to jointly process all three chronometers at once.
Jon Woodhead and Joseph Petrus
Geochronology, 1, 69–84, https://doi.org/10.5194/gchron-1-69-2019, https://doi.org/10.5194/gchron-1-69-2019, 2019
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Recently developed methods for in situ U–Pb age determination in carbonates have found widespread application, but the benefits and limitations of the method over bulk analysis approaches have yet to be fully explored. Here we use speleothems – cave carbonates such as stalagmites and flowstones – to investigate the utility of these in situ dating methodologies for challenging matrices with low U and Pb contents and predominantly late Cenozoic ages.
Cited articles
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Short summary
Thermochronometric data can provide unique insights into the patterns of rock exhumation and the driving mechanisms of landscape evolution. Several well-established thermal models allow for a detailed exploration of how cooling rates evolved in a limited area or along a transect, but more regional analyses have been challenging. We present age2exhume, a thermal model that can be used to rapidly provide a synoptic overview of exhumation rates from large regional thermochronologic datasets.
Thermochronometric data can provide unique insights into the patterns of rock exhumation and the...
