Measurement of in situ-produced cosmogenic nuclides in fine-grained quartz from shale

In situ-produced ¹⁰Be in quartz is widely used to constrain exposure ages and denudation rates, traditionally measured in sand-sized grains. Here we report a new method for isolating fine-grained quartz from shale and demonstrate its reliability for grain sizes down to single microns. Sequential dissolution tests and analyses of grain size separates show that meteoric ¹⁰Be is eliminated and that recoil losses during cosmogenic nuclide production are balanced by implantation from other mineral grains. High-temperature combustion leads to diffusion of meteoric ¹⁰Be into fine-grained quartz and must be used with caution.