Constraints from cosmogenic nuclides on the glaciation and erosion history of Dove Bugt, northeast Greenland

2020 ◽  
Vol 132 (11-12) ◽  
pp. 2282-2294 ◽  
Author(s):  
Daniel Søndergaard Skov ◽  
J.L. Andersen ◽  
J. Olsen ◽  
B.H. Jacobsen ◽  
M.F. Knudsen ◽  
...  
Keyword(s):  
Ice Cover ◽  
High Elevation ◽  
Cosmogenic Nuclide ◽  
Erosion History ◽  
Minimum Age ◽  
History Of ◽  
Subglacial Topography ◽  
Ice Sheet Dynamics ◽  
Cosmogenic 10Be ◽  
Exposure Ages

Abstract The intricate interplay between subglacial topography and ice-sheet dynamics is key to the evolution of large ice sheets, but in Greenland as elsewhere the effects of long-term glacial history on landscape evolution remain poorly constrained. Here we measure abundances of cosmogenic 10Be and 26Al in bedrock and transported boulders to unveil the glaciation and erosion history of Dove Bugt, northeast Greenland. In agreement with studies of west Greenland, we find that apparent exposure ages increase with elevation from 9 ka to 13 ka in low-lying valleys to 21 ka to 204 ka on high-elevation, blockfield-covered plateaus. We employ a Markov chain Monte Carlo inversion framework to constrain the probability of various erosion histories, and we quantify the residence time of samples within the upper 2 m of the bedrock subsurface—a measure defined as the cosmogenic nuclide memory. This cosmogenic nuclide memory exceeds 600 ka on the highest plateaus but is limited to less than 500 ka in most other high-elevation samples and to less than 100 ka at low-elevations. Our results define maximum limits for the fraction of ice cover during the past 1 Ma to ∼70% on the Store Koldewey peaks and ∼90% farther inland at Pusterdal, respectively. Minimum limits to ice cover, however, cannot be reliably constrained by the data. Finally, we propose that limited erosion on the highest plateaus of Store Koldewey since 0.6–1.0 Ma indicates a minimum age for fjord-plateau formation within this area of northeast Greenland.

Cosmogenic 10Be exposure dating of glacial erratics on Horseshoe Island in western Antarctic Peninsula confirms rapid deglaciation in the Early Holocene

2019 ◽  
Vol 31 (6) ◽  
pp. 319-331 ◽  
Author(s):  
Attila Çiner ◽  
Cengiz Yildirim ◽  
M. Akif Sarikaya ◽  
Yeong Bae Seong ◽  
Byung Yong Yu
Keyword(s):  
Antarctic Peninsula ◽  
Late Quaternary ◽  
Western Antarctic Peninsula ◽  
Sea Levels ◽  
Exposure Dating ◽  
Ice Stream ◽  
Marguerite Bay ◽  
History Of ◽  
Cosmogenic 10Be ◽  
Exposure Ages

AbstractThe rapid warming observed in the western Antarctic Peninsula gives rise to a fast disintegration of ice shelves and thinning and retreat of marine-terminating continental glaciers, which is likely to raise global sea levels in the near future. In order to understand the contemporary changes in context and to provide constraints for hindcasting models, it is important to understand the Late Quaternary history of the region. Here, we build on previous work on the deglacial history of the western Antarctic Peninsula and we present four new cosmogenic 10Be exposure ages from Horseshoe Island in Marguerite Bay, which has been suggested as a former location of very fast ice stream retreat. Four samples collected from erratic pink granite boulders at an altitude of ~80 m above sea level yielded ages that range between 12.9 ± 1.1 ka and 9.4 ± 0.8 ka. As in other studies on Antarctic erratics, we have chosen to report the youngest erratic age (9.4 ± 0.8 ka) as the true age of deglaciation, which confirms a rapid thinning of the Marguerite Trough Ice Stream at the onset of Holocene. This result is consistent with other cosmogenic age data and other proxies (marine and lacustrine 14C and optically stimulated luminescence) reported from nearby areas.

Late Quaternary glacial and climate history of the Pamir Mountains derived from cosmogenic 10Be exposure ages

2005 ◽  
Vol 64 (2) ◽  
pp. 212-220 ◽  
Author(s):  
Roland Zech ◽  
Uwe Abramowski ◽  
Bruno Glaser ◽  
Pjotr Sosin ◽  
Peter W. Kubik ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Late Quaternary ◽  
Limited Extent ◽  
Climate History ◽  
Pamir Mountains ◽  
History Of ◽  
Cosmogenic 10Be ◽  
Exposure Ages ◽  
Glacial Advance

AbstractMoraines southwest of Lake Yashilkul, Pamir, Tajikistan, were dated using 10Be exposure ages of boulder surfaces. We found evidence for (1) an extensive glaciation ∼60,000 yr ago; (2) a less extensive glacial advance, which deposited a characteristic hummocky moraine lobe with exposure ages ranging from ∼11,000 to 47,000 yr, probably deposited at or before 47,000 yr ago; and (3) lateral moraines with exposure ages of ∼40,000 yr, 27,000 yr and 19,000 yr, respectively. Increasing aridity in the Pamir is most likely responsible for the progressively limited extent of the glaciers during the Late Pleistocene.

Cosmogenic nuclide exposure ages and glacial history of late Quaternary Ross Sea drift in McMurdo Sound, Antarctica

1995 ◽  
Vol 131 (1-2) ◽  
pp. 41-56 ◽  
Author(s):  
Edward J. Brook ◽  
Mark D. Kurz ◽  
Robert P. Ackert ◽  
Grant Raisbeck ◽  
Françoise Yiou
Keyword(s):  
Ross Sea ◽  
Late Quaternary ◽  
Glacial History ◽  
Mcmurdo Sound ◽  
Cosmogenic Nuclide ◽  
History Of ◽  
Exposure Ages

Slow regolith degradation without creep determined by cosmogenic nuclide measurements in Arena Valley, Antarctica

2008 ◽  
Vol 69 (2) ◽  
pp. 242-249 ◽  
Author(s):  
Jaakko Putkonen ◽  
Greg Balco ◽  
Daniel Morgan
Keyword(s):  
Indirect Evidence ◽  
Soil Surface ◽  
Ice Cover ◽  
Surface Erosion ◽  
Dry Valleys ◽  
Cosmogenic Nuclide ◽  
Exposure Age ◽  
Excellent Preservation ◽  
Exposure Ages ◽  
Landslide Deposit

Estimates of regolith degradation in the McMurdo Dry Valleys of Antarctica are currently based on indirect evidence and ancient ashes at or near the soil surface that suggest excellent preservation of surfaces. On the other hand, the existing cosmogenic-nuclide surface exposure ages from many parts of the Dry Valleys are younger than the age of surface deposits inferred from stratigraphic relations. This suggests some combination of surface erosion or past ice cover, both of which would reduce the apparent exposure age. This paper quantifies the regolith degradation and/or past ice cover by measuring10Be and26Al from a landslide deposit that contains 11.3 Ma volcanic ash. The surface sample yields an apparent exposure age of only 0.4 Ma. However, measurements of the subsurface nuclide concentrations show that the deposit has not been shielded by ice, and that the age of the ash does not conflict with the apparent exposure age when slow degradation of the deposit (2 m Ma−1) is taken into account. Soil creep, which is a common degradational process in a wide variety of environments, is non-existent at this field site, which likely reflects the persistent lack of bio- and cryoturbation.

Cosmogenic Nuclides

2020 ◽  
Author(s):  
Rainer Wieler
Keyword(s):  
Noble Gas ◽  
Cosmic Ray ◽  
Parent Body ◽  
Cosmogenic Nuclides ◽  
Cosmogenic Nuclide ◽  
Production Models ◽  
History Of ◽  
Noble Gas Isotopes ◽  
Exposure Ages

Cosmogenic nuclides are produced by the interaction of energetic elementary particles of galactic (or solar) cosmic radiation and their secondaries with atomic nuclei in extraterrestrial or terrestrial material. Cosmogenic nuclides usually are observable only for some noble gas isotopes, whose natural abundances in the targets of interest are exceedingly low; some radioactive isotopes with half-lives mostly in the million-year range; and a few stable nuclides of elements, such as Gd and Sm, whose abundance is sizably modified by reactions with low energy secondary cosmic ray neutrons. In solid matter, the mean attenuation length of galactic cosmic ray protons is on the order of 50 cm. Therefore, cosmogenic nuclides are a major tool in studying the history of small objects in space and of matter near the surfaces of larger parent bodies. A classical application is to measure “exposure ages” of meteorites, namely the time they spent as a small body in interplanetary space. In some cases, also the previous history of the future meteorite in its parent-body regolith can be constrained. Such information helps to understand delivery mechanisms of meteorites from their parent asteroids or parent planets and to constrain the number of ejection events responsible for the collected meteorites. Cosmogenic nuclides in lunar samples from known depths of up to ~2 m serve to study the deposition and mixing history of the lunar regolith over hundreds of millions of years, as well as to calibrate nuclide production models. Present and future sample return missions rely on cosmogenic nuclide measurements as important tools to constrain the sample’s exposure history or loss rates of their parent body surfaces to space. The first data from cosmogenic noble gas isotopes measured on the surface of Mars demonstrate that the exposure and erosional history of planetary bodies can be obtained by in-situ analyses. For the foreseeable future, exposure ages of presolar grains in meteorites are presumably the only means to quantitatively constrain their presolar history. In some cases, irradiation effects of energetic particles from the early sun can be detected in early solar system condensates, confirming that the early sun was likely much more active than today, as expected from observations of young stars. The ever-increasing precision of isotope analyses also reveals tiny isotopic anomalies induced by cosmic-ray effects in several elements of interest in cosmochemistry, which need to be recognized and corrected for. Cosmogenic nuclide studies rely on the knowledge of their production rates, which depend on the elemental composition of a sample and its “shielding” during irradiation, that is, its position within an irradiated object and for meteorites their preatmospheric size. The physics of cosmogenic nuclide production is basically well understood and has led to sophisticated production models. They are most successful if a sample’s shielding can be constrained by the analyses of several cosmogenic nuclides with different depth dependencies of their production rates. Cosmogenic nuclides are also an important tool in Earth Sciences. The foremost example is 14C produced in the atmosphere and incorporated into organic material, which is used for dating. Cosmogenic radionuclides and noble gases produced in-situ in near surface samples, mostly by secondary cosmic-ray neutrons, are an important tool in quantitative geomorphology and related fields.

Reconstructing the erosion history of glaciated passive margins: applications of in situ produced cosmogenic nuclide techniques

2002 ◽  
Vol 196 (1) ◽  
pp. 153-168 ◽  
Author(s):  
Arjen P. Stroeven ◽  
Derek Fabel ◽  
Jon Harbor ◽  
Clas Hättestrand ◽  
Johan Kleman
Keyword(s):  
Passive Margins ◽  
Cosmogenic Nuclide ◽  
Erosion History ◽  
History Of

scholarly journals Deglaciation of the Cordillera of Western Canada at the end of the Pleistocene

2017 ◽  
Vol 43 (2) ◽  
pp. 449 ◽  
Author(s):  
J.J. Clague
Keyword(s):  
British Columbia ◽  
Ice Sheet ◽  
Ice Cover ◽  
High Elevation ◽  
Coast Mountains ◽  
Western Margin ◽  
Warming Climate ◽  
Glacier Ice ◽  
Cordilleran Ice Sheet ◽  
Exposure Ages

Nearly all of what is now British Columbia and adjacent areas were covered by an ice sheet at the maximum of the Last Glaciation (MIS 2) about 18,000 years ago. By 11,000 years ago, the Cordilleran Ice Sheet had disappeared, a victim of warming climate, eustatic sea-level rise along its western margin, and perhaps a reduction in precipitation. Deglaciation proceeded by frontal retreat at the periphery of the ice sheet and by downwasting, complex frontal retreat, and localized stagnation in its interior areas. The chronology of deglaciation is constrained, albeit with inherent dating errors, by AMS radiocarbon and 10Be surface exposure ages. High-elevation sites at the western margin of the British Columbia Interior Plateau, east of the Coast Mountains, became ice-free between about 15,000 and 12,000 years ago. Ice cover in the southern Coast Mountains was sufficiently extensive during the Younger Dryas Chronozone (12,900-11,700 years ago) that glaciers advanced into low-lying areas north and east of Vancouver. At the same time, however, a labyrinth of dead or dying tongues of glacier ice covered some interior valleys. By 11,000 years ago, ice cover in the Canadian Cordillera was no more extensive than it is today.

Felsenmeer persistence under non-erosive ice in the Torngat and Kaumajet mountains, Quebec and Labrador, as determined by soil weathering and cosmogenic nuclide exposure dating

2004 ◽  
Vol 41 (1) ◽  
pp. 19-38 ◽  
Author(s):  
Geneviève C Marquette ◽  
James T Gray ◽  
John C Gosse ◽  
François Courchesne ◽  
Lisa Stockli ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
High Elevation ◽  
Secondary Minerals ◽  
Soil Weathering ◽  
Exposure Dating ◽  
Cosmogenic Nuclide ◽  
Late Wisconsinan ◽  
Exposure Ages ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Soil analyses and terrestrial cosmogenic nuclide exposure dating are combined and a conceptual model proposed to explain altitudinal weathering contrasts in high-latitude highlands. We show that summits in the Torngat and Kaumajet mountains were covered by ice during the Last Glacial Maximum, and that their felsenmeer cover probably survived multiple glaciation events. For similar lithologies, soils on felsenmeer covered summits are signigicantly more weathered than those below the felsenmeer limit, displaying higher concentrations of crystalline iron, amorphous aluminium, and silicium extracted with oxalate. Secondary minerals such as gibbsite and kaolinite occur in felsenmeer soils, whereas those formed in till lacked these secondary minerals. 10Be and 26Al exposure ages for nine of ten samples, from high-elevation tors and autochthonous felsenmeer blocks, range from 73 ± 6 to 157 ± 15 ka. By contrast, ages of 11.4 ± 1.0 and 11.7 ± 1.0 ka are measured for bedrock in the much lower Saglek zone, indicating extensive (>3 m) glacial erosion of this zone during Late Wisconsinan glaciation. 26Al/10Be ratios demonstrate that exposure of the high-elevation surfaces was interrupted during at least one cosmic ray shielding event by either ice or till cover. In either case, Late Wisconsinan glaciers could not have extensively eroded these surfaces. Five erratics dated above the Saglek zone, including one in the felsenmeer zone, have exposure ages ranging from 11.6 ± 1.0 to 13.6 ± 0.7 ka. This indicates that valley and high-elevation ice persisted through the Younger Dryas Chron and provides further evidence that the highlands were not nunataks during the Late Wisconsinan period.

scholarly journals Exposure-age data from across Antarctica reveal mid-Miocene establishment of polar desert climate

Geology ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 91-95
Author(s):  
Perry Spector ◽  
Greg Balco
Keyword(s):  
Liquid Water ◽  
High Elevation ◽  
Polar Desert ◽  
Cosmogenic Nuclide ◽  
Erosion Processes ◽  
Exposure Age ◽  
Antarctic Continent ◽  
The Antarctic ◽  
Exposure Ages ◽  
Desert Climate

Abstract High-elevation rock surfaces in Antarctica have some of the oldest cosmogenic-nuclide exposure ages on Earth, dating back to the Miocene. A compilation of all available 3He, 10Be, and 21Ne exposure-age data from the Antarctic continent shows that exposure histories recorded by these surfaces extend back to, but not before, the mid-Miocene cooling at 14–15 Ma. At high elevation, this cooling entailed a transition between a climate in which liquid water and biota were present and could contribute to surface weathering and erosion, and a polar desert climate in which virtually all weathering and erosion processes had been shut off. This climate appears to have continued uninterrupted between the mid-Miocene and the present.

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