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This list was put together simply by full-text search of the ADMD for words such as "cosmogenic," "exposure-age," and related terms.Information in cells that are not red, yellow, or green is directly pulled from the ADMD entry.(2014) Reconstruction of changes in the Amundsen Sea and Bellingshausen Sea sector of the West Antarctic Ice Sheet since the Last Glacial Maximum. (2014) Reconstruction of ice-sheet changes in the Antarctic Peninsula since the Last Glacial Maximum. (2014) Glacial retreat in the Amundsen Sea sector, West Antarctica – first cosmogenic evidence from central Pine Island Bay and the Kohler Range. (2014) Rapid thinning of Pine Island Glacier in the early Holocene. Information in cells that are red, yellow, or green is my commentary. Total ADMD entries: 34 Data as described and easily accessible (green): 14 Data sort of accessible or accessible elsewhere if you have special knowledge (yellow): 10 Data not yet accessible in a form resembling what was described: 10 The data set consist of in-situ cosmogenic Be-10 and Al-26 surface exposure ages for subglacial erratics in the Vestfold Hills.If it has so far been possible to obtain a decent amount of the data described in the entry, typically by following links but often by more devious methods, the cell is green. Samples were collected during the 1994/95 summer season and processed at the research School of Earth Sciences, ANU.Multi-nuclide analyses from multiple labs serve as an ad hoc inter-laboratory comparison that supplements and expands on the formalized CRONUS-Earth and CRONUS-EU inter-laboratory comparisons (Blard et al., 2015; Jull et al., 2015; Vermeesch et al., 2015).Results from Cl from plagioclase mineral separates exhibits comparable reproducibility.
Both sites have well-constrained exposure histories in which factors such as potential prior exposure, erosion, and shielding are either demonstrably negligible or quantifiable.
This study was designed to combine surficial ages with a Ground Penetrating Radar data set generated by Dr. Because cosmogenic rays only penetrate 2 m in rock, freshly eroded glacial debris only begins accumulating cosmogenic nuclides after deposition from the glacier. Surface exposure ages from Hjorth Hill --------------------------------------------3He 10Be Sample moraine Lithology mineral alt (m) Age ( -1 sig) Age ( -1 sig) ...........................................(kyrs) (kyrs) GP92-641-2 RS1r basalt olivine 300 40.0 0.8 KBA89-140 RS2 basalt olivine 310 56.7 1.8 KBA89-142 RS2 basalt olivine 310 83.3 2.7 KBA89-143 RS2 granite quartz 310 28.4 0.7 38.1 2.7 KBA89-148 RS2 quartzitequartz 310 47.9 0.6 48.2 0.7 DK92-477-3 W3 basalt olivine 365 21.4 0.8 DK92-477-4-1 W3 basalt cpx 365 40.6 1.2 DK92-477-4-2 W3 basalt cpx 365 29.3 1.7 3He ages calculated using production rate of 121 and 133 at/g/yr (sealevel, high lat) for olivine and quartz respectively.
When production rates are known the concentration of cosmogenic nuclides in moraine boulders can be used to date formation of end moraines and drift sheets. 10Be ages calculated using production rate of 5.1 at/g/yr RS1r=Ross Sea Drift recessional moraine S2= older Ross Sea Drift W3= Wilson-Piedmont drift The data set description gives some information on exposure ages that were measured, but not enough information to recalculate the exposure ages with current methods.
Mariah Radue (University of Maine) will use the former ice extents during the Late Pleistocene to track the rate of deglaciation. The clock begins once the erratics are deposited by the glacial ice and exposed to cosmic rays because they begin accumulating the Be at the University of Washington’s Cosmogenic Nuclide Laboratory, they will then be sent to Lawrence-Livermore National Laboratory where the Accelerator Mass Spectrometry process is used to count the number of Beryllium isotopes for each sample, which in turn, allows us to calculate an age for the samples. Corrections can be made for shielding effects, but to introduce the least error, our field crew tried to select boulders where shielding was minimal.
Nathaniel Norris (University of Maine at Presque Isle) will use ages obtained from Holy Mountain the create a history of ice thinning during deglaciation. Radiocarbon and surface exposure-age dating techniques are tools that will allow us to assign ages to the drift deposits we mapped in the field, leading us to hypothesize the history and stability of the AIS. After each boulder was approved by the field team, a surface-slab was taken using either a small charge or a set of wedges and shims.Our production rates agree well with those of a recent calibration study from northeastern North America, but are 12–14% lower than other commonly adopted values.