A new chronology of the early solar system

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Recent analytical advances in isotope geochemistry have started to lead to a fundamental revision of our understanding of early solar system chronology. Classical models regarded chondritic meteorites as the oldest and most primitive solar system matter, building planets and planetesimals. Many planetesimals subsequently differentiated and developed metal cores and silicate mantles. Combined Hf-W, U-Pb and Al-Mg chronology now suggests that iron meteorites are remnants of even older planetesimals and that some of the material that makes up chondritic meteorites is reprocessed material from these early formed planetesimals. In two related projects we will evaluate the newly proposed chronological scheme by (1) dating of early solar system materials with different chronometers (i.e., Hf-W) and (2) by assessing homogenisation processes in the early solar system through 180Ta and 180W measurements. Both isotopes are very rare and extremely sensitive to nucleosynthetic conditions. Hence, sufficiently precise measurements were nearly impossible in the past. A prerequisite for resolving these key issues is the availability of a state of the art mass spectrometer (new generation Multicollector ICPMS) for the relevant analyses. No such instrument is currently used for research in cosmochemistry at a German university or research institution.