Exchange Frequency of Oxygen Isotope Reservoirs in The Early Solar System

摘要

High precision Mg isotope measurements have been performed to determine radiogenic 26Mg of coarse-grained Ca-Al-rich inclusions (CAIs) in two carbonaceous chondrites by secondary ion mass spectrometry using faraday cup multi-collection system. Minerals in each CAI show individual internal isochrones of 26Al-26Mg with respect to each own oxygen isotopic composition of minerals. This indicates that 16O-rich and 16O-poor oxygen isotopic environments existed more than 0.45 Myrs in the solar nebula. The switching time scale between wO-rich and 16O-poor gaseous environments surrounding CAIs was faster than 10 kyrs.