Autor: Masarik, Jozef; Frank, Martin; Schäfer, Jörg M.; Wieler, Rainer
Názov: Correction of in situ cosmogenic nuclide production rates for geomagnetic field intensity variations during the past 800,000 years
Typ: publication
Dátum: 2001
Jazyk: en
Poznámka:
Abstrakt:
We present integrated relative production rates for cosmogenic nuclides
in rock surfaces, which take into account reported variations of the
geomagnetic field intensity during the past 800,000 yr.
The calculations are based on the model simulating cosmic ray particle
interactions with the Earth s atmosphere given by Masarik and Beer
[“Simulation of particle fluxes and cosmogenic nuclide production in
the Earth's atmosphere”, J. Geophys. Res. 104(D10), 12099 12111,
1999]. Corrections are nearly independent on altitude between sea level
and at least 5000 m. The correction factors are essentially identical
for all stable and radioactive cosmogenic nuclides with half-lives
longer than a few hundred thousand years. At the equator, integrated
production rates for exposure ages between ∼40,000 to 800,000 yr are
10 to 12% higher than the present-day values, whereas at latitudes
>40°, geomagnetic field intensity variations have hardly influenced in
situ cosmogenic nuclide production. Correction factors for in situ
¹⁴C production rates differ from those of longer-lived nuclides. They
are always smaller than ∼2% because the magnetic field intensity
remained rather constant during the past ∼10 kyr, when the major
fraction of the ¹⁴C extant today was produced.
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