The origin of short-lived nuclides in the early solar system: implications for the assembly of terrestrial bodies

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Short-lived isotope systems play a critical role in constraining the timescales of early solar system processes. They also potentially finger-print the stellar sources of material in the solar nebular and provide a mechanism for nebular collapse. In all these respects the constraints provided by the very short lived 26Al and 60Fe (with half-lives 0.75 and 1.5My respectively) are key. Furthermore, as major, refractory elements, these extinct isotopes once constituted an essential part of the accreting terrestrial planets and provided a significant early heat source to drive planetary differentiation. Recent work in the Fe-Ni system yield tantalising data, but highlight perennial problems in deconvolving time from initial heterogeneity when interpretting these short-lived systems. In this proposal we will explicitly address these issues by combining new high precision techniques in analysis of Fe-Ni, Al-Mg and U-Pb on same meteoritical objects (CAI and chondrules). We will thus determine the initial 60Fe and 26Al for samples absolutely dated by U-Pb and examine if this differs between meteorites groups. This will allow us to determine the magnitude of any nebular heterogeneity, assess its causes and robustly re-evaluate the chronology of the early solar system.