ISOTOPICALLY DISTINCT RESERVOIRS IN THE SOLAR NEBULA - ISOTOPE ANOMALIES IN VIGARANO METEORITE INCLUSIONS

The isotopic compositions of Mg, Ca, Ti, Cr, Zn, Sr, Ba, Nd, and Sm we re measured in four relatively unaltered refractory inclusions from th e Vigarano carbonaceous chondrite meteorite. Three of the inclusions ( USNM 1623-2, 1623-3, and 1623-8) show similar Mg, Ca, Ti, and Cr isoto pic compositions to those found in most inclusions in the Allende carb onaceous chondrite. This indicates that these Vigarano inclusions samp led the same isotopic reservoirs as the majority of the Allende inclus ions and that isotope signatures in the latter were not significantly modified by the secondary alteration that permeates most Allende inclu sions. In contrast, inclusion 1623-5 has large deficits in Mg-26, Ca-4 8, and Ti-50 and small but distinct Cr-54, Zn-66, Sr-84, Ba-135, Ba-13 7, and Sm-144 anomalies. The magnitudes of these unusual anomalies in the refractory elements are within analytical uncertainty of those fou nd in the Allende ''FUN'' inclusion C1, yet 1623-5 has a very differen t bulk chemical composition from C1. The fact that 1623-5 and C1 have identical isotopic anomalies yet have significantly distinct major and trace element contents provide convincing evidence for the presence o f isotopically distinct reservoirs in the early solar system.