Articles | Volume 4, issue 1
https://doi.org/10.5194/gchron-4-191-2022
© Author(s) 2022. 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-4-191-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
07 Apr 2022
Research article |
| 07 Apr 2022
| 07 Apr 2022
Cosmogenic ages indicate no MIS 2 refugia in the Alexander Archipelago, Alaska
Department of Geology, University at Buffalo, Buffalo, NY 14260, USA
Jason P. Briner
Department of Geology, University at Buffalo, Buffalo, NY 14260, USA
James F. Baichtal
Tongass National Forest, Thorne Bay, AK 99919, USA
Alia J. Lesnek
School of Earth and Environmental Sciences, CUNY Queens College,
Flushing, NY 11367, USA
Joseph M. Licciardi
Department of Earth Sciences, University of New Hampshire, Durham, NH 03824, USA
Related authors
Caleb K. Walcott-George, Allie Balter-Kennedy, Jason P. Briner, Joerg M. Schaefer, and Nicolás E. Young
EGUsphere, https://doi.org/10.5194/egusphere-2024-2983, https://doi.org/10.5194/egusphere-2024-2983, 2024
Short summary
Short summary
Understanding the history and drivers of Greenland Ice Sheet change is important to forecast future ice sheet retreat. We combined geologic mapping and cosmogenic nuclide measurements to investigate how the Greenland Ice Sheet formed the landscape of Inglefield Land, northwest Greenland. We found that Inglefield Land was covered by warm- and cold-based ice during multiple glacial cycles and that much of Inglefield Land is an ancient landscape.
Karlee K. Prince, Jason P. Briner, Caleb K. Walcott, Brooke M. Chase, Andrew L. Kozlowski, Tammy M. Rittenour, and Erica P. Yang
Geochronology, 6, 409–427, https://doi.org/10.5194/gchron-6-409-2024, https://doi.org/10.5194/gchron-6-409-2024, 2024
Short summary
Short summary
We fill a spatial data gap in the ice sheet retreat history of the Laurentide Ice Sheet after the Last Glacial Maximum and investigate a hypothesis that the ice sheet re-advanced into western New York, USA, at ~13 ka. With radiocarbon and optically stimulated luminescence (OSL) dating, we find that ice began retreating from its maximum extent after 20 ka, but glacial ice persisted in glacial landforms until ~15–14 ka when they finally stabilized. We find no evidence of a re-advance at ~13 ka.
Caleb K. Walcott, Jason P. Briner, Joseph P. Tulenko, and Stuart M. Evans
Clim. Past, 20, 91–106, https://doi.org/10.5194/cp-20-91-2024, https://doi.org/10.5194/cp-20-91-2024, 2024
Short summary
Short summary
Available data suggest that Alaska was not as cold as many of the high-latitude areas of the Northern Hemisphere during the Last Ice Age. These results come from isolated climate records, climate models, and data synthesis projects. We used the extents of mountain glaciers during the Last Ice Age and Little Ice Age to show precipitation gradients across Alaska and provide temperature data from across the whole state. Our findings support a relatively warm Alaska during the Last Ice Age.
Jason P. Briner, Caleb K. Walcott, Joerg M. Schaefer, Nicolás E. Young, Joseph A. MacGregor, Kristin Poinar, Benjamin A. Keisling, Sridhar Anandakrishnan, Mary R. Albert, Tanner Kuhl, and Grant Boeckmann
The Cryosphere, 16, 3933–3948, https://doi.org/10.5194/tc-16-3933-2022, https://doi.org/10.5194/tc-16-3933-2022, 2022
Short summary
Short summary
The 7.4 m of sea level equivalent stored as Greenland ice is getting smaller every year. The uncertain trajectory of ice loss could be better understood with knowledge of the ice sheet's response to past climate change. Within the bedrock below the present-day ice sheet is an archive of past ice-sheet history. We analyze all available data from Greenland to create maps showing where on the ice sheet scientists can drill, using currently available drills, to obtain sub-ice materials.
Caleb K. Walcott-George, Allie Balter-Kennedy, Jason P. Briner, Joerg M. Schaefer, and Nicolás E. Young
EGUsphere, https://doi.org/10.5194/egusphere-2024-2983, https://doi.org/10.5194/egusphere-2024-2983, 2024
Short summary
Short summary
Understanding the history and drivers of Greenland Ice Sheet change is important to forecast future ice sheet retreat. We combined geologic mapping and cosmogenic nuclide measurements to investigate how the Greenland Ice Sheet formed the landscape of Inglefield Land, northwest Greenland. We found that Inglefield Land was covered by warm- and cold-based ice during multiple glacial cycles and that much of Inglefield Land is an ancient landscape.
Alia J. Lesnek, Joseph M. Licciardi, Alan J. Hidy, and Tyler S. Anderson
Geochronology, 6, 475–489, https://doi.org/10.5194/gchron-6-475-2024, https://doi.org/10.5194/gchron-6-475-2024, 2024
Short summary
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We present an improved workflow for extracting and measuring chlorine isotopes in rocks and minerals. Experiments on seven geologic samples demonstrate that our workflow provides reliable results while offering several distinct advantages over traditional methods. Most notably, our workflow reduces the amount of isotopically enriched chlorine spike used per rock sample by up to 95 %, which will allow researchers to analyze more samples using their existing laboratory supplies.
Benjamin A. Keisling, Joerg M. Schaefer, Robert M. DeConto, Jason P. Briner, Nicolás E. Young, Caleb K. Walcott, Gisela Winckler, Allie Balter-Kennedy, and Sridhar Anandakrishnan
EGUsphere, https://doi.org/10.5194/egusphere-2024-2427, https://doi.org/10.5194/egusphere-2024-2427, 2024
Short summary
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Understanding how much the Greenland ice sheet melted in response to past warmth helps better predicting future sea-level change. Here we present a framework for using numerical ice-sheet model simulations to provide constraints on how much mass the ice sheet loses before different areas become ice-free. As observations from subglacial archives become more abundant, this framework can guide subglacial sampling efforts to gain the most robust information about past ice-sheet geometries.
Karlee K. Prince, Jason P. Briner, Caleb K. Walcott, Brooke M. Chase, Andrew L. Kozlowski, Tammy M. Rittenour, and Erica P. Yang
Geochronology, 6, 409–427, https://doi.org/10.5194/gchron-6-409-2024, https://doi.org/10.5194/gchron-6-409-2024, 2024
Short summary
Short summary
We fill a spatial data gap in the ice sheet retreat history of the Laurentide Ice Sheet after the Last Glacial Maximum and investigate a hypothesis that the ice sheet re-advanced into western New York, USA, at ~13 ka. With radiocarbon and optically stimulated luminescence (OSL) dating, we find that ice began retreating from its maximum extent after 20 ka, but glacial ice persisted in glacial landforms until ~15–14 ka when they finally stabilized. We find no evidence of a re-advance at ~13 ka.
Joseph P. Tulenko, Jason P. Briner, Nicolás E. Young, and Joerg M. Schaefer
Clim. Past, 20, 625–636, https://doi.org/10.5194/cp-20-625-2024, https://doi.org/10.5194/cp-20-625-2024, 2024
Short summary
Short summary
We take advantage of a site in Alaska – where climate records are limited and a former alpine glacier deposited a dense sequence of moraines spanning the full deglaciation – to construct a proxy summer temperature record. Building on age constraints for moraines in the valley, we reconstruct paleo-glacier surfaces and estimate the summer temperatures (relative to the Little Ice Age) for each moraine. The record suggests that the influence of North Atlantic climate forcing extended to Alaska.
Caleb K. Walcott, Jason P. Briner, Joseph P. Tulenko, and Stuart M. Evans
Clim. Past, 20, 91–106, https://doi.org/10.5194/cp-20-91-2024, https://doi.org/10.5194/cp-20-91-2024, 2024
Short summary
Short summary
Available data suggest that Alaska was not as cold as many of the high-latitude areas of the Northern Hemisphere during the Last Ice Age. These results come from isolated climate records, climate models, and data synthesis projects. We used the extents of mountain glaciers during the Last Ice Age and Little Ice Age to show precipitation gradients across Alaska and provide temperature data from across the whole state. Our findings support a relatively warm Alaska during the Last Ice Age.
Gifford H. Miller, Simon L. Pendleton, Alexandra Jahn, Yafang Zhong, John T. Andrews, Scott J. Lehman, Jason P. Briner, Jonathan H. Raberg, Helga Bueltmann, Martha Raynolds, Áslaug Geirsdóttir, and John R. Southon
Clim. Past, 19, 2341–2360, https://doi.org/10.5194/cp-19-2341-2023, https://doi.org/10.5194/cp-19-2341-2023, 2023
Short summary
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Receding Arctic ice caps reveal moss killed by earlier ice expansions; 186 moss kill dates from 71 ice caps cluster at 250–450, 850–1000 and 1240–1500 CE and continued expanding 1500–1880 CE, as recorded by regions of sparse vegetation cover, when ice caps covered > 11 000 km2 but < 100 km2 at present. The 1880 CE state approached conditions expected during the start of an ice age; climate models suggest this was only reversed by anthropogenic alterations to the planetary energy balance.
Brandon L. Graham, Jason P. Briner, Nicolás E. Young, Allie Balter-Kennedy, Michele Koppes, Joerg M. Schaefer, Kristin Poinar, and Elizabeth K. Thomas
The Cryosphere, 17, 4535–4547, https://doi.org/10.5194/tc-17-4535-2023, https://doi.org/10.5194/tc-17-4535-2023, 2023
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Glacial erosion is a fundamental process operating on Earth's surface. Two processes of glacial erosion, abrasion and plucking, are poorly understood. We reconstructed rates of abrasion and quarrying in Greenland. We derive a total glacial erosion rate of 0.26 ± 0.16 mm per year. We also learned that erosion via these two processes is about equal. Because the site is similar to many other areas covered by continental ice sheets, these results may be applied to many places on Earth.
Jason P. Briner, Caleb K. Walcott, Joerg M. Schaefer, Nicolás E. Young, Joseph A. MacGregor, Kristin Poinar, Benjamin A. Keisling, Sridhar Anandakrishnan, Mary R. Albert, Tanner Kuhl, and Grant Boeckmann
The Cryosphere, 16, 3933–3948, https://doi.org/10.5194/tc-16-3933-2022, https://doi.org/10.5194/tc-16-3933-2022, 2022
Short summary
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The 7.4 m of sea level equivalent stored as Greenland ice is getting smaller every year. The uncertain trajectory of ice loss could be better understood with knowledge of the ice sheet's response to past climate change. Within the bedrock below the present-day ice sheet is an archive of past ice-sheet history. We analyze all available data from Greenland to create maps showing where on the ice sheet scientists can drill, using currently available drills, to obtain sub-ice materials.
Joshua K. Cuzzone, Nicolás E. Young, Mathieu Morlighem, Jason P. Briner, and Nicole-Jeanne Schlegel
The Cryosphere, 16, 2355–2372, https://doi.org/10.5194/tc-16-2355-2022, https://doi.org/10.5194/tc-16-2355-2022, 2022
Short summary
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We use an ice sheet model to determine what influenced the Greenland Ice Sheet to retreat across a portion of southwestern Greenland during the Holocene (about the last 12 000 years). Our simulations, constrained by observations from geologic markers, show that atmospheric warming and ice melt primarily caused the ice sheet to retreat rapidly across this domain. We find, however, that iceberg calving at the interface where the ice meets the ocean significantly influenced ice mass change.
Douglas P. Steen, Joseph S. Stoner, Jason P. Briner, and Darrell S. Kaufman
Geochronology Discuss., https://doi.org/10.5194/gchron-2021-19, https://doi.org/10.5194/gchron-2021-19, 2021
Publication in GChron not foreseen
Short summary
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Paleomagnetic data from Cascade Lake (Brooks Range, Alaska) extend the radiometric-based age model of the sedimentary sequence extending back 21 kyr. Correlated ages based on prominent features in paleomagnetic secular variations (PSV) diverge from the radiometric ages in the upper 1.6 m, by up to about 2000 years at around 4 ka. Four late Holocene cryptotephra in this section support the PSV chronology and suggest the influence of hard water or aged organic material.
Svend Funder, Anita H. L. Sørensen, Nicolaj K. Larsen, Anders A. Bjørk, Jason P. Briner, Jesper Olsen, Anders Schomacker, Laura B. Levy, and Kurt H. Kjær
Clim. Past, 17, 587–601, https://doi.org/10.5194/cp-17-587-2021, https://doi.org/10.5194/cp-17-587-2021, 2021
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Cosmogenic 10Be exposure dates from outlying islets along 300 km of the SW Greenland coast indicate that, although affected by inherited 10Be, the ice margin here was retreating during the Younger Dryas. These results seem to be corroborated by recent studies elsewhere in Greenland. The apparent mismatch between temperatures and ice margin behaviour may be explained by the advection of warm water to the ice margin on the shelf and by increased seasonality, both caused by a weakened AMOC.
Nicolás E. Young, Alia J. Lesnek, Josh K. Cuzzone, Jason P. Briner, Jessica A. Badgeley, Alexandra Balter-Kennedy, Brandon L. Graham, Allison Cluett, Jennifer L. Lamp, Roseanne Schwartz, Thibaut Tuna, Edouard Bard, Marc W. Caffee, Susan R. H. Zimmerman, and Joerg M. Schaefer
Clim. Past, 17, 419–450, https://doi.org/10.5194/cp-17-419-2021, https://doi.org/10.5194/cp-17-419-2021, 2021
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Retreat of the Greenland Ice Sheet (GrIS) margin is exposing a bedrock landscape that holds clues regarding the timing and extent of past ice-sheet minima. We present cosmogenic nuclide measurements from recently deglaciated bedrock surfaces (the last few decades), combined with a refined chronology of southwestern Greenland deglaciation and model simulations of GrIS change. Results suggest that inland retreat of the southwestern GrIS margin was likely minimal in the middle to late Holocene.
Joseph P. Tulenko, William Caffee, Avriel D. Schweinsberg, Jason P. Briner, and Eric M. Leonard
Geochronology, 2, 245–255, https://doi.org/10.5194/gchron-2-245-2020, https://doi.org/10.5194/gchron-2-245-2020, 2020
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We investigate the timing and rate of retreat for three alpine glaciers in the southern Rocky Mountains to test whether they followed the pattern of global climate change or were majorly influenced by regional forcing mechanisms. We find that the latter is most likely for these glaciers. Our conclusions are based on a new 10Be chronology of alpine glacier retreat. We quantify retreat rates for each valley using the BACON program in R, which may be of interest for the audience of Geochronology.
Jacob Downs, Jesse Johnson, Jason Briner, Nicolás Young, Alia Lesnek, and Josh Cuzzone
The Cryosphere, 14, 1121–1137, https://doi.org/10.5194/tc-14-1121-2020, https://doi.org/10.5194/tc-14-1121-2020, 2020
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We use an inverse modeling approach based on the unscented transform (UT) and a new reconstruction of Holocene ice sheet retreat in western central Greenland to infer precipitation changes throughout the Holocene. Our results indicate that warming during the Holocene Thermal Maximum (HTM) was linked to elevated snowfall that slowed retreat despite high temperatures. We also find that the UT provides a computationally inexpensive approach to Bayesian inversion and uncertainty quantification.
Joshua K. Cuzzone, Nicole-Jeanne Schlegel, Mathieu Morlighem, Eric Larour, Jason P. Briner, Helene Seroussi, and Lambert Caron
The Cryosphere, 13, 879–893, https://doi.org/10.5194/tc-13-879-2019, https://doi.org/10.5194/tc-13-879-2019, 2019
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We present ice sheet modeling results of ice retreat over southwestern Greenland during the last 12 000 years, and we also test the impact that model horizontal resolution has on differences in the simulated spatial retreat and its associated rate. Results indicate that model resolution plays a minor role in simulated retreat in areas where bed topography is not complex but plays an important role in areas where bed topography is complex (such as fjords).
Related subject area
Cosmogenic nuclide dating
Technical note: Altitude scaling of 36Cl production from Fe
Production rate calibration for cosmogenic 10Be in pyroxene by applying a rapid fusion method to 10Be-saturated samples from the Transantarctic Mountains, Antarctica
Technical note: Optimizing the in situ cosmogenic 36Cl extraction and measurement workflow for geologic applications
Cosmogenic 3He chronology of postglacial lava flows at Mt Ruapehu, Aotearoa / New Zealand
Last ice sheet recession and landscape emergence above sea level in east-central Sweden, evaluated using in situ cosmogenic 14C from quartz
Cosmogenic 21Ne exposure ages on late Pleistocene moraines in Lassen Volcanic National Park, California, USA
Regional 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
Short communication: Cosmogenic noble gas depletion in soils by wildfire heating
Early Holocene ice retreat from Isle Royale in the Laurentian Great Lakes constrained with 10Be exposure-age dating
Technical note: Studying lithium metaborate fluxes and extraction protocols with a new, fully automated in situ cosmogenic 14C processing system at PRIME Lab
Cosmogenic 10Be in pyroxene: laboratory progress, production rate systematics, and application of the 10Be–3He nuclide pair in the Antarctic Dry Valleys
Technical note: A software framework for calculating compositionally dependent in situ 14C production rates
10Be age control of glaciation in the Beartooth Mountains, USA, from the latest Pleistocene through the Holocene
Constraining the aggradation mode of Pleistocene river deposits based on cosmogenic radionuclide depth profiling and numerical modelling
Technical note: Evaluating a geographical information system (GIS)-based approach for determining topographic shielding factors in cosmic-ray exposure dating
Combined linear-regression and Monte Carlo approach to modeling exposure age depth profiles
Cosmogenic nuclide weathering biases: corrections and potential for denudation and weathering rate measurements
Cosmogenic nuclide and solute flux data from central Cuban rivers emphasize the importance of both physical and chemical mass loss from tropical landscapes
Technical note: Accelerator mass spectrometry of 10Be and 26Al at low nuclide concentrations
Reconciling the apparent absence of a Last Glacial Maximum alpine glacial advance, Yukon Territory, Canada, through cosmogenic beryllium-10 and carbon-14 measurements
In situ-produced cosmogenic krypton in zircon and its potential for Earth surface applications
Cosmogenic nuclide exposure age scatter records glacial history and processes in McMurdo Sound, Antarctica
Technical Note: Noble gas extraction procedure and performance of the Cologne Helix MC Plus multi-collector noble gas mass spectrometer for cosmogenic neon isotope analysis
Exposure dating of detrital magnetite using 3He enabled by microCT and calibration of the cosmogenic 3He production rate in magnetite
Calibrating a long-term meteoric 10Be delivery rate into eroding western US glacial deposits by comparing meteoric and in situ produced 10Be depth profiles
Delayed and rapid deglaciation of alpine valleys in the Sawatch Range, southern Rocky Mountains, USA
Technical note: A prototype transparent-middle-layer data management and analysis infrastructure for cosmogenic-nuclide exposure dating
Isolation of quartz for cosmogenic in situ 14C analysis
Chlorine-36∕beryllium-10 burial dating of alluvial fan sediments associated with the Mission Creek strand of the San Andreas Fault system, California, USA
Angus K. Moore and Darryl E. Granger
Geochronology, 6, 541–552, https://doi.org/10.5194/gchron-6-541-2024, https://doi.org/10.5194/gchron-6-541-2024, 2024
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Cosmogenic nuclide geochronology requires accurately scaling production rates with altitude. The energy spectrum of cosmic radiation changes with altitude, and reactions that are sensitive to different energies may have different scaling behavior. Here, we model the altitude scaling of 36Cl production from Fe and evaluate this model against calibration data. The data are broadly consistent with the prediction of larger-altitude scaling factors for 36Cl from Fe than for other reactions.
Marie Bergelin, Greg Balco, Lee B. Corbett, and Paul R. Bierman
Geochronology, 6, 491–502, https://doi.org/10.5194/gchron-6-491-2024, https://doi.org/10.5194/gchron-6-491-2024, 2024
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Cosmogenic nuclides, such as 10Be, are rare isotopes produced in rocks when exposed at Earth's surface and are valuable for understanding surface processes and landscape evolution. However, 10Be is usually measured in quartz minerals. Here we present advances in efficiently extracting and measuring 10Be in the pyroxene mineral. These measurements expand the use of 10Be as a dating tool for new rock types and provide opportunities to understand landscape processes in areas that lack quartz.
Alia J. Lesnek, Joseph M. Licciardi, Alan J. Hidy, and Tyler S. Anderson
Geochronology, 6, 475–489, https://doi.org/10.5194/gchron-6-475-2024, https://doi.org/10.5194/gchron-6-475-2024, 2024
Short summary
Short summary
We present an improved workflow for extracting and measuring chlorine isotopes in rocks and minerals. Experiments on seven geologic samples demonstrate that our workflow provides reliable results while offering several distinct advantages over traditional methods. Most notably, our workflow reduces the amount of isotopically enriched chlorine spike used per rock sample by up to 95 %, which will allow researchers to analyze more samples using their existing laboratory supplies.
Pedro Doll, Shaun Robert Eaves, Ben Matthew Kennedy, Pierre-Henri Blard, Alexander Robert Lee Nichols, Graham Sloan Leonard, Dougal Bruce Townsend, Jim William Cole, Chris Edward Conway, Sacha Baldwin, Gabriel Fénisse, Laurent Zimmermann, and Bouchaïb Tibari
Geochronology, 6, 365–395, https://doi.org/10.5194/gchron-6-365-2024, https://doi.org/10.5194/gchron-6-365-2024, 2024
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In this study, we use cosmogenic-sourced 3He to determine the eruption ages of 23 lava flows at Mt Ruapehu, Aotearoa New Zealand, and we show how this method can help overcome challenges associated with traditional dating methods in young lavas. Comparison with other methods demonstrates the accuracy of our data and the method's reliability. The new eruption ages allowed us to identify periods of quasi-simultaneous activity from different volcanic vents during the last 20 000 years.
Bradley W. Goodfellow, Arjen P. Stroeven, Nathaniel A. Lifton, Jakob Heyman, Alexander Lewerentz, Kristina Hippe, Jens-Ove Näslund, and Marc W. Caffee
Geochronology, 6, 291–302, https://doi.org/10.5194/gchron-6-291-2024, https://doi.org/10.5194/gchron-6-291-2024, 2024
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Carbon-14 produced in quartz (half-life of 5700 ± 30 years) provides a new tool to date exposure of bedrock surfaces. Samples from 10 exposed bedrock surfaces in east-central Sweden give dates consistent with the timing of both landscape emergence above sea level through postglacial rebound and retreat of the last ice sheet shown in previous reconstructions. Carbon-14 in quartz can therefore be used for dating in landscapes where isotopes with longer half-lives give complex exposure results.
Joseph P. Tulenko, Greg Balco, Michael A. Clynne, and L. J. Patrick Muffler
Geochronology Discuss., https://doi.org/10.5194/gchron-2024-18, https://doi.org/10.5194/gchron-2024-18, 2024
Revised manuscript accepted for GChron
Short summary
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Cosmogenic nuclide exposure dating is an exceptional tool for reconstructing glacier histories, but reconstructions based on common target nuclides (e.g., 10Be) can be costly and time consuming to generate. Here, we present a low-cost proof-of-concept 21Ne exposure age chronology from Lassen Volcanic National Park, CA, USA that broadly agrees with nearby 10Be chronologies but at lower precision.
Felix Martin Hofmann, Claire Rambeau, Lukas Gegg, Melanie Schulz, Martin Steiner, Alexander Fülling, Laëtitia Léanni, Frank Preusser, and ASTER Team
Geochronology, 6, 147–174, https://doi.org/10.5194/gchron-6-147-2024, https://doi.org/10.5194/gchron-6-147-2024, 2024
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We determined 10Be concentrations in moraine boulder surfaces in the southern Black Forest, SW Germany. We applied three independent dating methods to younger lake sediments. With the aid of independent age datasets, we calculated the growth of 10Be concentrations in moraine boulder surfaces.
Greg Balco, Alan J. Hidy, William T. Struble, and Joshua J. Roering
Geochronology, 6, 71–76, https://doi.org/10.5194/gchron-6-71-2024, https://doi.org/10.5194/gchron-6-71-2024, 2024
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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.
Eric W. Portenga, David J. Ullman, Lee B. Corbett, Paul R. Bierman, and Marc W. Caffee
Geochronology, 5, 413–431, https://doi.org/10.5194/gchron-5-413-2023, https://doi.org/10.5194/gchron-5-413-2023, 2023
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New exposure ages of glacial erratics on moraines on Isle Royale – the largest island in North America's Lake Superior – show that the Laurentide Ice Sheet did not retreat from the island nor the south shores of Lake Superior until the early Holocene, which is later than previously thought. These new ages unify regional ice retreat histories from the mainland, the Lake Superior lake-bottom stratigraphy, underwater moraines, and meltwater drainage pathways through the Laurentian Great Lakes.
Nathaniel Lifton, Jim Wilson, and Allie Koester
Geochronology, 5, 361–375, https://doi.org/10.5194/gchron-5-361-2023, https://doi.org/10.5194/gchron-5-361-2023, 2023
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We describe a new, fully automated extraction system for in situ 14C at PRIME Lab that incorporates more reliable components and designs than our original systems. We use a LiBO2 flux to dissolve a quartz sample in oxygen after removing contaminant 14C with a lower-temperature combustion step. Experiments with new Pt/Rh sample boats demonstrated reduced procedural blanks, and analyses of well-characterized intercomparison materials tested the effects of process variables on 14C yields.
Allie Balter-Kennedy, Joerg M. Schaefer, Roseanne Schwartz, Jennifer L. Lamp, Laura Penrose, Jennifer Middleton, Jean Hanley, Bouchaïb Tibari, Pierre-Henri Blard, Gisela Winckler, Alan J. Hidy, and Greg Balco
Geochronology, 5, 301–321, https://doi.org/10.5194/gchron-5-301-2023, https://doi.org/10.5194/gchron-5-301-2023, 2023
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Cosmogenic nuclides like 10Be are rare isotopes created in rocks exposed at the Earth’s surface and can be used to understand glacier histories and landscape evolution. 10Be is usually measured in the mineral quartz. Here, we show that 10Be can be reliably measured in the mineral pyroxene. We use the measurements to determine exposure ages and understand landscape processes in rocks from Antarctica that do not have quartz, expanding the use of this method to new rock types.
Alexandria J. Koester and Nathaniel A. Lifton
Geochronology, 5, 21–33, https://doi.org/10.5194/gchron-5-21-2023, https://doi.org/10.5194/gchron-5-21-2023, 2023
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In situ 14C’s short half-life (5.7 kyr) is unique among cosmogenic nuclides, making it sensitive to complex exposure and burial histories since 25 ka. Current extraction methods focus on quartz, but the ability to extract it from other minerals would expand applications. We developed MATLAB® scripts to calculate in situ 14C production rates from a broad range of mineral compositions. Results confirm O, Si, Al, and Mg as key targets but also find significant production from Na for the first time.
Aaron M. Barth, Elizabeth G. Ceperley, Claire Vavrus, Shaun A. Marcott, Jeremy D. Shakun, and Marc W. Caffee
Geochronology, 4, 731–743, https://doi.org/10.5194/gchron-4-731-2022, https://doi.org/10.5194/gchron-4-731-2022, 2022
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Deposits left behind by past glacial activity provide insight into the previous size and behavior of glaciers and act as another line of evidence for past climate. Here we present new age control for glacial deposits in the mountains of Montana and Wyoming, United States. While some deposits indicate glacial activity within the last 2000 years, others are shown to be older than previously thought, thus redefining the extent of regional Holocene glaciation.
Nathan Vandermaelen, Koen Beerten, François Clapuyt, Marcus Christl, and Veerle Vanacker
Geochronology, 4, 713–730, https://doi.org/10.5194/gchron-4-713-2022, https://doi.org/10.5194/gchron-4-713-2022, 2022
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We constrained deposition phases of fluvial sediments (NE Belgium) over the last 1 Myr with analysis and modelling of rare isotopes accumulation within sediments, occurring as a function of time and inverse function of depth. They allowed the determination of three superposed deposition phases and intercalated non-deposition periods of ~ 40 kyr each. These phases correspond to 20 % of the sediment age, which highlights the importance of considering deposition phase when dating fluvial sediments.
Felix Martin Hofmann
Geochronology, 4, 691–712, https://doi.org/10.5194/gchron-4-691-2022, https://doi.org/10.5194/gchron-4-691-2022, 2022
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If topographical obstructions are present in the surroundings of sampling sites, exposure ages of rock surfaces need to be corrected. A toolbox for the ESRI ArcGIS software allows for quantifying topographic shielding with a digital elevation model, but it has only been validated with few field data. In this study, the output of the toolbox is evaluated with a more extensive dataset. If suitable elevation data are chosen, the toolbox provides a sound approach to determine topographic shielding.
Yiran Wang and Michael E. Oskin
Geochronology, 4, 533–549, https://doi.org/10.5194/gchron-4-533-2022, https://doi.org/10.5194/gchron-4-533-2022, 2022
Short summary
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When first introduced together with the depth profile technique to determine the surface exposure age, the linear inversion approach has suffered with the drawbacks of not incorporating erosion and muons into calculation. In this paper, we increase the accuracy and applicability of the linear inversion approach by fully considering surface erosion, muogenic production, and radioactive decay, while maintaining its advantage of being straightforward to determine an exposure age.
Richard F. Ott, Sean F. Gallen, and Darryl E. Granger
Geochronology, 4, 455–470, https://doi.org/10.5194/gchron-4-455-2022, https://doi.org/10.5194/gchron-4-455-2022, 2022
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Cosmogenic nuclides are a tool to quantify denudation – the total removal of mass from near the Earth's surface. Chemical weathering can introduce biases to cosmogenic-nuclide-based denudation rates measurements. Here, we investigate the effects of weathering on cosmogenic nuclides and develop tools to correct for this influence. Our results highlight which additional measurements are required to determine accurate denudation rates in regions where weathering is not negligible.
Mae Kate Campbell, Paul R. Bierman, Amanda H. Schmidt, Rita Sibello Hernández, Alejandro García-Moya, Lee B. Corbett, Alan J. Hidy, Héctor Cartas Águila, Aniel Guillén Arruebarrena, Greg Balco, David Dethier, and Marc Caffee
Geochronology, 4, 435–453, https://doi.org/10.5194/gchron-4-435-2022, https://doi.org/10.5194/gchron-4-435-2022, 2022
Short summary
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We used cosmogenic radionuclides in detrital river sediment to measure erosion rates of watersheds in central Cuba; erosion rates are lower than rock dissolution rates in lowland watersheds. Data from two different cosmogenic nuclides suggest that some basins may have a mixed layer deeper than is typically modeled and could have experienced significant burial after or during exposure. We conclude that significant mass loss may occur at depth through chemical weathering processes.
Klaus M. Wilcken, Alexandru T. Codilean, Réka-H. Fülöp, Steven Kotevski, Anna H. Rood, Dylan H. Rood, Alexander J. Seal, and Krista Simon
Geochronology, 4, 339–352, https://doi.org/10.5194/gchron-4-339-2022, https://doi.org/10.5194/gchron-4-339-2022, 2022
Short summary
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Cosmogenic nuclides are now widely applied in the Earth sciences; however, more recent applications often push the analytical limits of the technique. Our study presents a comprehensive method for analysis of cosmogenic 10Be and 26Al samples down to isotope concentrations of a few thousand atoms per gram of sample, which opens the door to new and more varied applications of cosmogenic nuclide analysis.
Brent M. Goehring, Brian Menounos, Gerald Osborn, Adam Hawkins, and Brent Ward
Geochronology, 4, 311–322, https://doi.org/10.5194/gchron-4-311-2022, https://doi.org/10.5194/gchron-4-311-2022, 2022
Short summary
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We explored surface exposure dating with two nuclides to date two sets of moraines from the Yukon Territory and explain the reasoning for the observed ages. Results suggest multiple processes, including preservation of nuclides from a prior exposure period, and later erosion of the moraines is required to explain the data. Our results only allow for the older moraines to date to Marine Isotope Stage 3 or 4 and the younger moraines to date to the very earliest Holocene.
Tibor János Dunai, Steven Andrew Binnie, and Axel Gerdes
Geochronology, 4, 65–85, https://doi.org/10.5194/gchron-4-65-2022, https://doi.org/10.5194/gchron-4-65-2022, 2022
Short summary
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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.
Andrew J. Christ, Paul R. Bierman, Jennifer L. Lamp, Joerg M. Schaefer, and Gisela Winckler
Geochronology, 3, 505–523, https://doi.org/10.5194/gchron-3-505-2021, https://doi.org/10.5194/gchron-3-505-2021, 2021
Short summary
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Cosmogenic nuclide surface exposure dating is commonly used to constrain the timing of past glacier extents. However, Antarctic exposure age datasets are often scattered and difficult to interpret. We compile new and existing exposure ages of a glacial deposit with independently known age constraints and identify surface processes that increase or reduce the likelihood of exposure age scatter. Then we present new data for a previously unmapped and undated older deposit from the same region.
Benedikt Ritter, Andreas Vogt, and Tibor J. Dunai
Geochronology, 3, 421–431, https://doi.org/10.5194/gchron-3-421-2021, https://doi.org/10.5194/gchron-3-421-2021, 2021
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We describe the design and performance of a new noble gas mass laboratory dedicated to the development of and application to cosmogenic nuclides at the University of Cologne (Germany). At the core of the laboratory are a state-of-the-art high-mass-resolution multicollector Helix MCPlus (Thermo-Fisher) noble gas mass spectrometer and a novel custom-designed automated extraction line, including a laser-powered extraction furnace. Performance was tested with intercomparison (CREU-1) material.
Florian Hofmann, Emily H. G. Cooperdock, A. Joshua West, Dominic Hildebrandt, Kathrin Strößner, and Kenneth A. Farley
Geochronology, 3, 395–414, https://doi.org/10.5194/gchron-3-395-2021, https://doi.org/10.5194/gchron-3-395-2021, 2021
Short summary
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We use microCT scanning to improve the quality of 3He exposure ages measured in detrital magnetite. We show that the presence of inclusions can significantly increase the measured amount of 3He and thereby the exposure age. By prescreening magnetite with microCT and analyzing only inclusion-free grains, this problem can be avoided. We also calibrate the cosmogenic 3He production rate in magnetite relative to 10Be in quartz, which can be used for similar studies in the future.
Travis Clow, Jane K. Willenbring, Mirjam Schaller, Joel D. Blum, Marcus Christl, Peter W. Kubik, and Friedhelm von Blanckenburg
Geochronology, 2, 411–423, https://doi.org/10.5194/gchron-2-411-2020, https://doi.org/10.5194/gchron-2-411-2020, 2020
Short summary
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Meteoric beryllium-10 concentrations in soil profiles have great capacity to quantify Earth surface processes, such as erosion rates and landform ages. However, determining these requires an accurate estimate of the delivery rate of this isotope to local sites. Here, we present a new method to constrain the long-term delivery rate to an eroding western US site, compare it against existing delivery rate estimates (revealing considerable disagreement between methods), and suggest best practices.
Joseph P. Tulenko, William Caffee, Avriel D. Schweinsberg, Jason P. Briner, and Eric M. Leonard
Geochronology, 2, 245–255, https://doi.org/10.5194/gchron-2-245-2020, https://doi.org/10.5194/gchron-2-245-2020, 2020
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We investigate the timing and rate of retreat for three alpine glaciers in the southern Rocky Mountains to test whether they followed the pattern of global climate change or were majorly influenced by regional forcing mechanisms. We find that the latter is most likely for these glaciers. Our conclusions are based on a new 10Be chronology of alpine glacier retreat. We quantify retreat rates for each valley using the BACON program in R, which may be of interest for the audience of Geochronology.
Greg Balco
Geochronology, 2, 169–175, https://doi.org/10.5194/gchron-2-169-2020, https://doi.org/10.5194/gchron-2-169-2020, 2020
Short summary
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Geologic dating methods generally do not directly measure ages. Instead, interpreting a geochemical measurement as an age requires a middle layer of calculations and supporting data, and the fact that this layer continually improves is an obstacle to synoptic analysis of geochronological data. This paper describes a prototype data management and analysis system that addresses this obstacle by making the middle-layer calculations transparent and dynamic to the user.
Keir A. Nichols and Brent M. Goehring
Geochronology, 1, 43–52, https://doi.org/10.5194/gchron-1-43-2019, https://doi.org/10.5194/gchron-1-43-2019, 2019
Short summary
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We describe observations of anomalously high measurements of C-14 made from geologic material. We undertake a systematic investigation to identify the source of contamination, which we hypothesise is sourced from a commonly used method that is used prior to sample analysis. We find that the method does introduce modern carbon to samples and elevates C-14 measurements. We describe a standard procedure that effectively removes contamination from the aforementioned method.
Greg Balco, Kimberly Blisniuk, and Alan Hidy
Geochronology, 1, 1–16, https://doi.org/10.5194/gchron-1-1-2019, https://doi.org/10.5194/gchron-1-1-2019, 2019
Short summary
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This article applies a new geochemical dating method to determine the age of sedimentary deposits useful in reconstructing slip rates on a major fault system.
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Short summary
We present a record of ice retreat from the northern Alexander Archipelago, Alaska. During the last ice age (~ 26 000–19 000 years ago), these islands were covered by the Cordilleran Ice Sheet. We tested whether islands were ice-free during the last ice age for human migrants moving from Asia to the Americas. We found that these islands became ice-free between ~ 15 100 years ago and ~ 16 000 years ago, and thus these islands were not suitable for human habitation during the last ice age.
We present a record of ice retreat from the northern Alexander Archipelago, Alaska. During the...
