Initial Sr-87/Sr-86 and Sm-Nd chronology of chondritic meteoritesIsotopic analyses of the Rb-Sr and Sm-Nd systems in phosphates from ordinary chondritic meteorites (Bjurbole, Mocs, Menow, Elenovka, Ambapur Nagla, and St. Severin) are presented. The Sm-Nd data yield an isochron of age 4.55 + or - 0.45 Ga and an initial Nd-143/Nd-144 consistent with that of Juvinas. Initial Sr-87/Sr-86 ratios are characteristically (possibly excepting St. Severin) elevated with respect to BABI or ALL. Considering both presently and previously reported data, elevation of initial Sr-87/Sr-86 ratios corresponding to metamorphism intervals of the order of 10 to the 8th years seems quite characteristic of chondrites of metamorphic grade 4 or higher. These formation intervals, however, do not correlate with either degree of metamorphism or with I-Xe ages, hence such data for metamorphic chronologies should be interpreted with caution.
Document ID
19890023525
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Brannon, J. C. (California Univ. La Jolla, CA, United States)
Podosek, F. A. (Washington University Saint Louis, MO, United States)
Lugmair, G. W. (California, University La Jolla, United States)