Background

Cosmogenic nuclides are rare isotopes that are produced by the interaction of atoms with cosmic rays, which are charged particles that impinge the Earth with high kinetic energy. Most of these particles originate from supernovae within our galaxy. When cosmic rays enter the Earth’s atmosphere, they collide with nitrogen and oxygen atoms, from which they produce meteoric cosmogenic nuclides such as ¹⁴C and ¹⁰Be, for example. A cascade of secondary cosmic rays eventually reaches and penetrates the upper few meters of the Earth surface, where they produce in situ cosmogenic nuclides such as ¹⁰Be, ¹⁴C, ²⁶Al, or ³⁶Cl, for example. The above-mentioned nuclides are radioactive, with various half-lives and they lend themselves for dating landforms and for quantifying erosion and weathering rates. We continuously expand the use of cosmogenic nuclides for constraining the dynamic response of the Earth surface to changes in climate, biota, and tectonics. We work mostly with in situ produced ¹⁰Be and ²⁶Al, and with meteoric ¹⁰Be. Whereas in situ¹⁰Be requires quartz grains, and is thus not applicable to quartz-free rocks like basalt or limestone, meteoric ¹⁰Be can be applied to any rock type. We are currently developing meteoric cosmogenic nuclide methods for quantifying weathering and denudation rates in quartz-free rocks such as basalt and carbonate, because they are key components in the long-term CO₂ cycle.

Scientific key questions

• How can we precisely quantify denudation rates with cosmogenic nuclides in different landscapes, such as in large depositional basins or rapidly uplifting mountain ranges?

• How can we use the combination of in situ and meteoric cosmogenic nuclides in a single soil profile to improve their production rate estimates?

• How can we expand meteoric cosmogenic nuclide methods in carbonate landscapes to constrain deep weathering, soil and sediment erosion, and secondary carbonate formation?