The use of in-situ cosmogenic 21Ne in studies on long-term landscape development

Abstract

Cosmogenic Ne isotopes are stable and are routinely used for constraining the timing of events and the rate of surface change beyond the limit that can be studied with the radionuclides 10 Be, 26 Al and 36 Cl. In addition to quartz it can be used in a range of other minerals. Analysis typically requires significantly less material than for cosmogenic 10 Be and 26 Al opening up the technique for small samples, for example, individual pebbles in river sediments. Analysis is easier and faster than for the radionuclides, not least because Ne measurements do not require significant chemical procedures. However, the presence of other sources of Ne in minerals tends to restrict the use of cosmogenic 21 Ne to old landscapes and long exposure durations. In this review we briefly outline the background to cosmogenic Ne production in rocks and minerals at the Earth's surface, then documents the key uses of the technique by highlighting some earlier studies, and finishes with a short perspective on the future of the technique.

Inter-laboratory redetermination of the atmospheric 22Ne/20Ne

“…The weighted mean air 22 Ne/ 20 Ne from the four laboratories are statistically indistinguishable, yielding a global value of 0.10195 ± 0.00004 (0.04% 1σ) (Figure 1). This new value is consistent with the long-established air 22 Ne/ 20 Ne [2] yet nearly 20 times more precise (Figure 1).…”

“…Consequently, accurate and precise knowledge of the isotope composition of air-derived noble gases is essential. Neon isotopes are exceptional tracer of Earth history [1] and are highly prized chronometer of Earth surface processes [2]. The widely accepted value of atmospheric 22 Ne/ 20 Ne (0.1020 ± 0.0008, 1 σ) was established over half a century ago [3].…”

The formation of NeH+ in static vacuum mass spectrometers and re-determination of 21Ne/20Ne of air

“…Cosmogenic 21 Ne produced in rocks in the upper few centimeters of Earth surface is now widely used to unravel long-term landscape development, particularly in arid regions that are sensitive to climate change (Ma and Stuart, 2018). The recently developed (U+Th)/ 21 Ne chronometer is finding use for determining the timing of Earth processes that have hitherto proved difficult to date (Gautheron et al, 2006).…”

Detrital cosmogenic 21Ne records decoupling of source-to-sink signals by sediment storage and recycling in Miocene to present rivers of the Great Plains, Nebraska, USA

“…The stable cosmogenic nuclides 3 He (Margerison et al 2005) and 21 Ne (Ma and Stuart, 2017) do not decay after production, and so their measured concentrations record (minimum) surface exposure times of several million years, or erosion rates of less than 0.05 m/Myr. In the case of detrital material, the cosmogenic 21 Ne in quartz-rich pebbles from rivers can be used to quantify the spatial distribution of sediment production across a catchment (e.g., Codilean et al 2008).…”