An improved experimental determination of cosmogenic 10Be/21Ne and 26Al/21Ne production ratios in quartz

Abstract

The confidence in surface exposure dating and related research, such as erosion rate studies or burial dating, strongly depends on the accuracy and precision of the currently used production rates of in situ-produced cosmogenic nuclides. Reducing the uncertainties of nuclide production rates by more accurate calibrations with independently dated natural rock surfaces is crucial for further improving the quantification of earth surface processes. Here we use surface samples from the 760±2 ka old Bishop Tuff in eastern California to quantify the Ne production rate, and (3) the assumption of steady-state erosion. Other assumptions, such as the applied scaling procedure, the muon contribution to nuclide production, or the attenuation lengths of neutrons and muons in rock, do not substantially affect the results. Based on 13 samples, the following average production rate ratios and conservative uncertainty estimates are obtained for sea level, high latitude, open sky, and rock surface: 0.249±0.009 or 0.232±0.009 for 10

Neon diffusion kinetics in olivine, pyroxene and feldspar: Retentivity of cosmogenic and nucleogenic neon

“…The 21 Ne production rate in quartz is reasonably well established (Amidon et al, 2009;Balco and Shuster, 2009;Goethals et al, 2009;Kober et al, 2011), but that High-T resetting (for 10% loss) Fig. 6.…”

“…Several studies have quantified 21 Ne production rates in quartz (Niedermann, 2002;Balco and Shuster, 2009;Amidon et al, 2009;Goethals et al, 2009;Kober et al, 2011), and quantitative retention of 21 Ne in quartz at Earth surface temperatures has been clearly established by both laboratory diffusion experiments and observations of natural samples (Niedermann et al, 1994;Kober et al, 2005;Shuster and Farley, 2005). It is probably safe to assume that minerals that tightly retain He (e.g., olivine and pyroxene; Trull et al, 1991;Trull and Kurz, 1993; retain neon, although we are not aware of quantitative measurements of diffusion kinetics in these minerals or in others that are potentially useful for exposure dating (e.g., feldspars).…”

Landscape evolution of a bedrock peneplain on the southern Tibetan Plateau revealed by in situ-produced cosmogenic 10Be and 21Ne

“…The plot was generated with CosmoCalc, version 1.7 (Vermeesch, 2007), using the time-invariant scaling scheme of Stone (2000) and the following parameters: a total production rate of 4.66 at g -1 a -1 for 10 Be and 20.1 at g -1 a -1 for 21 Ne, a contribution of 2.1% from slow muons and 1.9% from fast muons to 10 Be production and of 3.6% from fast muons to 21 Ne production (cf. Goethals et al, 2009b and references therein), a 10 Be decay constant of 5.00×10 -7 a -1 (corresponding to a half-life of 1.387 Ma), the preset production rate mechanisms of CosmoCalc with three exponentials, and the default values for the attenuation lengths. Error bars represent 2σ uncertainties.…”

Multi-phased uplift of the southern margin of the Central Anatolian plateau, Turkey: A record of tectonic and upper mantle processes

“…Although seasonal snow cover can shield surfaces from cosmogenic nuclide accumulation (Schildgen et al, 2005), such effects are insignificant at low elevations of the Eastern Mediterranean. We calculated 21 Ne production rates using a value of 0.232 ± 0.009 for the ratio of 10 Be/ 21 Ne production (Goethals et al, 2009) to correspond to a 1.387 Ma 10 Be half-life (Chmeleff et al, 2010;Korschinek et al, 2010), and using the 10 Be production rates derived from the Lal (1991)/ Stone (2000) constant production rate scaling with a total reference 10 Be production rate (from spallation and muon production) of 4.58 ± 0.43 atoms/(g yr). Stepwise heating Ne data are given in Table A3, and 21 Ne ages are summarized in Table A4.…”