Pd-Ag chronometry of iron meteorites and the accretion and thermal history of differentiated protoplanets

• Antragsteller: Dr. Mario Fischer-Gödde
• Fachliche Zuordnung: Mineralogie, Petrologie und Geochemie
• Förderung: Förderung von 2010 bis 2014
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 182743398

Short-lived radionuclides play a pivotal role in understanding the early history of the solar system. They provide information on the sequence of several key events, including the time-scales of the condensation of the first solids and the accretion and differentiation of planetary bodies. Such age constraints are essential for understanding planet formation and for constraining the parameters that controlled the subsequent evolution of planetary bodies. For example, Hf-W dating of iron meteorites revealed that their parent bodies accreted well before the chondrite parent bodies, a result that has led to revision of almost all models of early solar system development. The Hf-W results demonstrate that iron meteorites are remnants of some of the oldest protoplanetary bodies formed in the inner solar system and as such they play a pivotal role in the understanding of the earliest stage of planet formation. This proposal aims at providing new and firm constraints on the chronology of these differentiated protoplanets. We will focus on the thermal history of iron meteorite parent bodies and aim to constrain the cooling history of the major groups of magmatic irons using the short-lived 107Pd-107Ag chronometer. One of the major expected outcomes of this study will be a refined time scale for the differentiation and cooling history of some of these early-differentiated protoplanets. The Pd-Ag isotopic study will be combined with a detailed and quantitative assessment of the Pd-Ag closure temperature. Furthermore, the initial Pd and Ag isotopic compositions, both of which are not well defined, will be determined precisely. This integrated approach will provide important new constraints on the sizes, internal structure and early history of some of the oldest protoplanetary bodies.

• DFG-Verfahren: Sachbeihilfen