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Oxygen isotopic record of silicate alteration in the Shergotty-Nakhla-Chassigny meteorite Lafayette
- Source :
- Meteoritics & Planetary Science. 33:775-784
- Publication Year :
- 1998
- Publisher :
- Wiley, 1998.
-
Abstract
- — Samples from a suite of Shergotty—Nakhla—Chassigny (SNC) meteorites were analyzed for their O isotopic ratios by a modified version of the laser fluorination technique. Measured isotopic ratios (17O/16O and 18O/16O) from bulk samples of the Shergottites, EETA79001, Shergotty and Zagami; the Nakhlite Lafayette; and Chassigny are similar to those reported in the literature, as are those from olivine and pyroxene mineral separates from Lafayette. Iddingsite, a preterrestrial alteration product of Lafayette, was measured for the first time as a separate phase. Oxygen isotopic ratios increase with the percentage of iddingsite in a sample to a maximum δ18O of 14.4% for a ∼90% separate. Based on these measurements, end-member iddingsite has a δ18O of 15.6%, which places it among other 18O-enriched secondary phases (carbonate and silica) observed in SNC meteorites. The relatively large difference in δ18O between iddingsite and the olivine and pyroxene it replaces (∼11%) is typical of low-temperature alteration products. A range of crustal fluid δ18O values can be interpreted from the δ18O for end-member iddingsite, assuming isotopic equilibrium was achieved during low-temperature hydrous alteration (
Details
- ISSN :
- 19455100 and 10869379
- Volume :
- 33
- Database :
- OpenAIRE
- Journal :
- Meteoritics & Planetary Science
- Accession number :
- edsair.doi...........b22e14b1270416c8a81d965fe4b035fc