Supra-canonical 26Al/27Al and the residence time of CAls in the solar protoplanetary disk

The canonical initial Al-26/At-27 ratio of 4.5 x 10(-5) has been a fiducial marker for the beginning of the solar system. Laser ablation and whole-rock multiple-collector inductively coupled plasma-source mass spectrometry magnesium isotope analyses of calcium- and aluminum-rich inclusions (CAIs) from CV3 meteorites demonstrate that some CAIs had initial Al-26/Al-27 values at least 25% greater than canonical and that the canonical initial Al-26/Al-27 cannot mark the beginning of solar system formation. Using rates of Mg diffusion in minerals, we find that the canonical initial Al-26/Al-27 is instead the culmination of thousands of brief high-temperature events incurred by CAIs during a 10(5)-year residence time in the solar protoplanetary disk.