26Al- 10Be- 21Ne burial dating

Cosmogenic-nuclide burial dating relies on a pair of cosmic-ray-produced nuclides that are produced in the same rock or mineral target at a fixed ratio, but have different half-lives. For example, ²⁶Al and ¹⁰Be are produced in quartz at ²⁶Al: ¹⁰Be = 6.75:1. If a sample of quartz is exposed at the surface for a time, ²⁶Al and ¹⁰Be concentrations reflect this ratio; if it is then buried below the penetration depth of cosmic rays, production stops and both nuclides decay. The half-life of ²⁶Al is half that of ¹⁰Be, so the ²⁶Al/ ¹⁰Be ratio decreases over time and can be used to date the burial event. Because quartz derived from surface erosion and then buried by sediment accumulation is common, the method is widely applicable for dating Plio-Pleistocene clastic sediments. All (terrestrial) applications of burial dating so far have used the ²⁶Al- ¹⁰Be pair. Here we show that coupling cosmogenic ²¹Ne, which is also produced in quartz, with ²⁶Al or ¹⁰Be should improve upon both the age range and accuracy of ²⁶Al- ¹⁰Be burial dating. We establish the feasibility of this approach by ²¹Ne measurements at two sites that have already been dated using ²⁶Al- ¹⁰Be burial dating. Burial ages from all three nuclide pairs agree at both sites, which shows that currently accepted values for decay constants and production ratios are internally consistent. Thus, it is possible at present to increase the useful range of cosmogenic-nuclide burial dating by incorporating ²¹Ne. Fully realizing the potential improvements in accuracy would benefit from additional estimates of ²¹Ne/ ²⁶Al and ²¹Ne/ ¹⁰Be production ratios that are independent of the ²⁶Al and ¹⁰Be decay constants.