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| Titel |
Long-term low latitude and high elevation cosmogenic 3He production rate inferred from a new calibration site in hyperarid Northern Chile |
| VerfasserIn |
Romain Delunel, Pierre-Henri Blard, Léo Martin, Sebastien Nomade, Fritz Schlunegger |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126332
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| Publikation (Nr.) |
 EGU/EGU2016-6040.pdf |
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| Zusammenfassung |
| The rates at which the cosmogenic nuclides are produced at the surface of the Earth are
usually inferred from independently dated geological calibration sites. Despite available
calibration sites for cosmogenic 3He are relatively abundant, they are clustered both in space
(mid to high latitudes) and time (ca. 5-20 ka), which prevents qualitative assessments
and further developments of production models used to convert cosmogenic 3He
concentrations into exposure ages and/or denudation rates. Accordingly, more low
latitude calibration sites with exposure durations significantly longer than 20 ka are
required.
Here we present the results from a new geological calibration site located in northern
Chile were several samples have been collected on the surface of a well-preserved lava flow
for both 40Ar/39Ar dating and cosmogenic 3He analyzes. Cosmogenic 3He concentrations
were converted to a sea level high latitude (SLHL) reference position using the eruption age
determined for the lava flow from the Ar measurements, together with scaling frameworks
that include varying combinations of geographic spatialization schemes, atmosphere
models and geomagnetic field reconstructions. The inferred SLHL cosmogenic 3He
production rates are consistent with the most recent estimates available from the
literature and thus attest to the robustness of both the most widely used and recently
developed scaling models. Finally, we use the same scaling frameworks to re-evaluate
the mean global-scale cosmogenic 3He production rate in olivine and pyroxene
minerals using an updated compilation of previously published calibration datasets. |
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