Cosmochronology is the scientific attempt to determine the age and earliest evolution of the solar system. This can be done by investigating meteorites, which, in most cases, are remnants of asteroidal parent bodies which themselves were processed (e.g. melted, metamorphosed) within the first million years of the 4.56 Byr old solar system. One of the most useful tools to obtain a reasonable time resolution during age dating of early solar system events are short-lived radionuclide systems. By measuring the amount of radiogenic "daughter" isotopes produced by radioactive decay from a short-lived (now extinct) “mother” isotope with a known half-life, cosmochemists can establish a “relative age” for the parental material. This relative age can then be anchored onto an absolute time-scale (established by long-lived chronometry).
One of the most fundamental processes in the early solar system are asteroidal differentiation processes (e.g. melting of asteroids and subsequent formation of asteroidal cores, mantles and crusts). Illuminating the chronology of such asteroidal differentiation processes is therefore one of the major goals of cosmochronology. In the last decade the application of the short-lived 182Hf-182W chronometer (T1/2 = 8.9 Myr) to early solar system materials, especially iron meteorites, provided firm constraints on the timing of core formation (i.e. metal-segregation) and silicate melting as well as metamorphism inside asteroidal parent bodies.
The GeoCosmoChron Division of the Department of Lithospheric Research is equipped with all the necessary facilities to enable 182Hf-182W dating of all kinds of meteorites. Further cosmochemical applications at the Department include the investigation of
- cosmic-ray exposure effects on meteorites (using isotopes with high thermal neutron capture cross sections; e.g., 149Sm),
- solar system homogenization (using p-process isotopes) and
- the 187Re-187Os systematic of meteorites.
Contact: Toni Schulz