Element separation chemistry and cosmogenic 10Be dating of a ferromanganese crust

Oceanic archives are contemporary witnesses of Earth’s recent astrophysical history by incorporating extraterrestrial radionuclides. VA13/2-237KD is one of the most studied ferromanganese crusts and it has been shown that the crust contains live interstellar 60Fe. Here, we have characterized a large piece of this crust with a 3D optical scan, a micro-CT scan and 3D modeling, followed by the chemical extraction of highly purified, element-specific fractions for accelerator mass spectrometry. High-accuracy cosmogenic 10Be dating of two independent drill-holes showed a time-dependent variability in growth rate across the surface of the crust. This well-characterized crust is used to search for interstellar radionuclides, such as supernova-produced 60Fe and the r-process nuclide 244Pu. Other extraterrestrial radionuclides including 26Al, 53Mn, 129I, 182Hf or 247Cm could be investigated in the future.