107:. Cosmogenic nuclides such as these are produced by chains of spallation reactions. The production rate for a particular nuclide is a function of geomagnetic latitude, the amount of sky that can be seen from the point that is sampled, elevation, sample depth, and density of the material in which the sample is embedded. Decay rates are given by the decay constants of the nuclides. These equations can be combined to give the total concentration of cosmogenic radionuclides in a sample as a function of age. The two most frequently measured cosmogenic nuclides are
58:. These particles interact with atoms in atmospheric gases, producing a cascade of secondary particles that may in turn interact and reduce their energies in many reactions as they pass through the atmosphere. This cascade includes a small fraction of hadrons, including neutrons. When one of these particles strikes an atom it can dislodge one or more protons and/or neutrons from that atom, producing a different element or a different
140:) is bombarded by a spallation product: oxygen of the quartz is transformed into Be and the silicon is transformed into Al. Each of these nuclides is produced at a different rate. Both can be used individually to date how long the material has been exposed at the surface. Because there are two radionuclides decaying, the ratio of
88:, solar winds, and atmospheric shielding due to air pressure variations. Rates of nuclide production must be estimated in order to date a rock sample. These rates are usually estimated empirically by comparing the concentration of nuclides produced in samples whose ages have been dated by other means, such as
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Geological calibration of spallation production rates in the CRONUS-Earth project. Borchers, Brian; Marrero, Shasta; Balco, Greg; Caffee, Marc; Goehring, Brent; Lifton, Nathaniel; Nishiizumi, Kunihiko; Phillips, Fred; Schaefer, Joerg; Stone, John. Quaternary
Geochronology Volume 31, February 2016,
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is eroding. The basic principle is that these radionuclides are produced at a known rate, and also decay at a known rate. Accordingly, by measuring the concentration of these cosmogenic nuclides in a rock sample, and accounting for the flux of the cosmic rays and the half-life of the nuclide, it is
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of these elements, and are common in crustal material, whereas the radioactive daughter nuclei are not commonly produced by other processes. As oxygen-16 is also common in the atmosphere, the contribution to the beryllium-10 concentration from material deposited rather than created
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A complete and easily accessible means of calculating surface exposure ages or erosion rates from 10Be and 26Al measurements. Balco, Greg; Stone, John O.j Lifton, Nathaniel A.; Dunaic, Tibor J.; Quaternary
Geochronology Volume 3, Issue 3, August 2008, Pages
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possible to estimate how long the sample has been exposed to the cosmic rays. The cumulative flux of cosmic rays at a particular location can be affected by several factors, including elevation, geomagnetic latitude, the varying intensity of the
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of the original element. In rock and other materials of similar density, most of the cosmic ray flux is absorbed within the first meter of exposed material in reactions that produce new isotopes called
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Nishiizumi, K.; Kohl, C. P.; Arnold, J. R.; Dorn, R.; Klein, I.; Fink, D.; Middleton, R.; Lal, D. (1993). "Role of in situ cosmogenic nuclides Be and Al in the study of diverse geomorphic processes".
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of these two nuclides can be used without any other knowledge to determine an age at which the sample was buried past the production depth (typically 2–10 meters).
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79:, scientists can date how long a particular surface has been exposed, how long a certain piece of material has been buried, or how quickly a location or
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Terrestrial in situ cosmogenic nuclides: theory and application. Gosse, J.C. and
Phillips, F.M. Quaternary Science Reviews, 20, 1475–1560, 2001.
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Schaefer, Joerg M.; Codilean, Alexandru T.; Willenbring, Jane K.; Lu, Zheng-Tian; Keisling, Benjamin; Fülöp, Réka-H.; Val, Pedro (2022-03-10).
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Schaefer, Joerg M.; Codilean, Alexandru T.; Willenbring, Jane K.; Lu, Zheng-Tian; Keisling, Benjamin; Fülöp, Réka-H.; Val, Pedro (2022-03-10).
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techniques for estimating the length of time that a rock has been exposed at or near Earth's surface. Surface exposure dating is used to date
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Geomorphology and in situ cosmogenic isotopes. Cerling, T.E. and Craig, H. Annual Review of Earth and
Planetary Sciences, 22, 273-317, 1994.
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The excess relative to natural abundance of cosmogenic nuclides in a rock sample is usually measured by means of
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nuclides are also measured to date surface rocks. This isotope may be produced by cosmic ray spallation of
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115:. These nuclides are particularly useful to geologists because they are produced when cosmic rays strike
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Stone, J; Allan, G; Fifield, L; Cresswell, R (1996). "Cosmogenic chlorine-36 from calcium spallation".
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Vanacker, V.; von
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452:Online system for exposure age calculations
489:New techniques for surface exposure dating
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98:optically stimulated luminescence
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246:Nature Reviews Methods Primers
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75:. Using certain cosmogenic
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20:Surface exposure dating
375:10.1002/esp.3290180504
86:Earth's magnetic field
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65:cosmogenic nuclides
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