Autor: Kubik, Peter W.; Ivy-Ochs Susan, Masarik, Jozef; Frank, Martin; Schlüchter, Christian
Názov: ¹⁰Be and ²⁶Al production rates deduced from an instantaneous event within the dendro-calibration curve, the landslide of Köfels, Ötz Valley, Austria
Typ: publication
Dátum: 1998
Jazyk: en
Poznámka:
Abstrakt:
Surface exposure dating requires the knowledge of cosmogenic nuclide production rates. When determining time-inte-grated
production rates the exposure ages of the calibration samples need to be accurately known. The landslide of Köfels
(Austria) is very well suited for this purpose. It is the largest landslide in the crystalline Alps of Austria dating back to
7800 ± 100 years BC (AMS ¹⁴C dating of buried wood), which is well within the ¹⁴C dendro calibration curve. Exposed
quartz veins were sampled from the tops of large boulders from the toe of the landslide for analysis of ¹⁰Be and ²⁶Al. To
calculate sea level, high geomagnetic latitude (≧60°), open sky radionuclide production rates, corrections were applied for
altitude and latitude, for shielding by surrounding mountains, for sample geometry, vegetation and snow cover, and for
sample thickness. The production rates for an exposure age of 10,000 years are 5.75 ± 0.24 ¹⁰Be atoms/yr g SiO₂ and
37.4 ± 1.9 ²⁶Al atoms/yr g SiO₂. A ²⁶Al/¹⁰Be ratio of 6.52 ± 0.43 can be calculated. The influence of the geomagnetic
field on these production rates has been estimated using two different geomagnetic field records. Our production rates
should be a good approximation for the use of surface exposure dating between about 5000 and 13,000 years BP.
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