Surface exposure cosmogenic nuclide dating

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Assuming a constant rate of production, the number of atoms of Be-10 and Al-26 that accumulate in a rock surface will be proportional to the length of time the rocks were exposed to cosmic ray bombardment and the respective rates of radioactive decay for each isotope.An age determined by measurement of the amount of each nuclide would be an estimate of the age of the surface exposure, that is, the surface could have been exposed for much longer than the minimum calculated age.Ages of rock avalanche deposits throughout Norway cluster in the first few thousand years after deglaciation, however ages throughout the entire Holocene have also been obtained.The principles of dating sliding surfaces are more explained in the publication on the Oppstadhornet slide on Otrøya. 16.6 to 14.2 kyrs ago and past long-term displacement rates are in the order of 2 mm/yr.Depending or rock and landform weathering rates, landforms ranging in age from a few hundred years to tens of millions of years can be dated.

The basic principle is that these radionuclides are produced at a known rate, and also decay at a known rate.Concern about methodological uncertainties, such as those associated with the production rates, the site latitude and altitude scaling factors, as well as the effect of past changes in the Earth’s magnetic field, has led to the establishment of an international consortium made up of CRONUS-Earth ( and CRONUS-EU (Analysis of artificial targets and samples from natural sites with independent age control are underway to refine production rates.It was discovered about a decade ago that cosmic ray interaction with silica and oxygen in quartz produced measurable amounts of the isotopes Beryllium-10 and Aluminium-26.Researchers suggested that the accumulation of these isotopes within a rock surface could be used to establish how long that surface was exposed to the atmosphere.

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