(U–Th)/He lab

The (U-Th-Sm)/He lab is equipped with an Alphachron automated system for helium measurement. We routinely measure 2 laser pans of 24 aliquots each in automatic mode in 1 week. We collaborate with PD Dr. Johannes Glodny in section 3.1 at the GFZ-Potsdam; he is responsible for sample dissolution and analysis of U, Th and Sm using ICP-MS. At present, we analyze both apatites and zircons.

To test the reproducibility of our analyses, we have analyzed numerous aliquots of Durango apatite, which has an age of 31.0 ± 2.0 Ma (mean of 24 (U-Th)/He ages (some without Sm); McDowell et al. 2005) or 31.4 ± 0.2 Ma (⁴⁰Ar/³⁹Ar; McDowell et al. 2005). From 72 aliquots, we have obtained a mean age of 32.5 ± 2.0 Ma (2σ analytical error). If we discard 6 obvious outliers, we obtain an age of 30.8 ± 1.6 Ma (2σ, N = 66).

For picking single crystals for analysis, we have a high resolution binocular microscope equipped with a digital camera.