⁴He/³He Methodology

Ultra-low temperature, high-resolution ⁴He/³He thermochronology provides a means to fully exploit the temporal and thermal information preserved within U-bearing accessory minerals such as apatite. With ⁴He/³He thermochronology, high resolution thermal models can be derived from a single grain from a single sample, and exceptionally high-resolution models can be extracted from a suite of samples (e.g., age-elevation transects).

Thermal models with such high-resolution and fidelity are required to address many of the geologic enigmas that are of central focus to the COOLER project. Accordingly, this component of the COOLER project aims to set up protocols for routine proton irradiations and efficient production of ⁴He/³He datasets of exceptionally high quality and resolution. The ⁴He/³He methodology is currently under development at the University of Potsdam, and will be the first laboratory of its kind in Europe.

Through a collaboration with Prof. Andrea Denker and team at the Helmholtz Zentrum Berlin (HZB), we have successfully established a new, rapid proton irradiation procedure at HZB’s proton beam facility to synthesize sufficiently high and uniform concentrations of ³He within individual apatite grains. Through this collaboration, we can significantly improve the time lag-time between collecting a sample in the field and obtaining ⁴He/³He data from our lab. The initial, proof-of-concept results of this new procedure are summarized in Colleps et al. (2024; G³).