Planetesimal accretion timescales inferred from Hf-W chronometry

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Determining the timescales of planetary accretion in the inner solar system is critical to understanding planet formation and for constraining the parameters that controlled the subsequent evolution of planets. Short-lived nuclides are well suited for obtaining such age constraints and the 182Hf–182W chronometer has proven particularly useful for providing the timescales of the chemical differentiation of asteroids and terrestrial planets. The major aim of this research project will be to obtain highly precise Hf–W ages for ureilites and enstatite chondrites and to constrain the accretion timescales of their parent bodies. Both ureilites and enstatite chondrites have formed in distinct regions of the solar nebula, where accretion may have been rapid. As such, knowing the accretion timescales of these meteorite parent bodies is essential for understanding planetary accretion in the inner solar system. However, information on the ages of ureilites and enstatite chondrites are scarce and their accretion timescales are not known. The chronological work on ureilites and enstatite chondrites will be complemented by Hf–W dating of Ca-Al-rich inclusions with the aim to better constrain the initial Hf and W isotopic compositions of the solar system. These parameters are critical for a precise determination of Hf–W ages of meteoritic materials but are currently not known sufficiently precise.