CALIBRATION OF TERRESTRIAL COSMIC-RAY-PRODUCED NUCLIDES: CRONUS

Cosmic-ray-produced nuclides are extensively utilized to quantify the chronologies and process rates associated with the continuously changing features of Earth's surface. Among these cosmogenic species are the radionuclides ¹⁰Be, ¹⁴C, ²⁶Al, and ³⁶Cl, and the least abundant noble gas isotopes, ³He and ²¹Ne. As the questions probed by these techniques become more sophisticated so too must our knowledge of the factors that govern the production rates of cosmogenic nuclides. The NSF-funded CRONUS-Earth project was established to improve our understanding of the various factors that influence in-situ-cosmogenic nuclide production rates. Our approach is to utilize both geologic calibration sites and the measurement of production parameters in laboratory experiments to better constrain production rates. In the first year we collected samples from the well-dated Bonneville shorelines in Utah, Tabernacle Hill (³He, ¹⁴C, and ³⁶Cl) and Promontory Point (³He, ¹⁰Be, ¹⁴C, ²¹Ne, ²⁶Al, and ³⁶Cl), and performed neutron irradiations on specific target materials. Cl-36 and ³He has been measured in samples from Tabernacle Hill. In the second year samples were collected from well-dated Younger Dryas features in Scotland: the Isle of Skye and the Scottish Highlands. All cosmogenic nuclides are being measured in these samples.