The extinct radionuclide timescale of the early solar system

The tendency of iodine to be mobilised during secondary processing is refle cted both in the presence of Xe-129(XS) in secondary minerals and in the bu lk Xe-129(XS)/I ratios in meteorites. Comparison of absolute ages derived t hrough calibration of chronometers based on Xe-129, Mn-53 and Al-26 against the Pb-Pb system yields a plausible timescale for the early solar system. In this system, the earliest chondrule ages are most readily interpreted as representing formation after the beginning of parent body processing.