(U–Th)/He lab

The (U-Th-Sm)/He laboratory is equipped with an automated Alphachron system for helium measurements. Two laser pans with 24 aliquots each are routinely measured in automatic mode within one week. Sample dissolution and the analysis of U, Th, and Sm by ICP-MS are carried out in collaboration with Section 3.1 of the GFZ Potsdam. Currently, both apatite and zircon samples are being analyzed.

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.