The oxygen isotope record in Murchison and other carbonaceous chondrites |
| |
Authors: | Robert N. Clayton Toshiko K. Mayeda |
| |
Affiliation: | 1. Enrico Fermi Institute, Department of Chemistry, and Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637 U.S.A.;2. Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 U.S.A. |
| |
Abstract: | The ranges of δ18O and δ17O in components of the Murchison (C2) chondrite exceed those in all other meteorites analyzed. Previous authors have proposed that C2 chondrites are the products of aqueous alteration of anhydrous silicates. A model is presented to determine whether the isotopic variations can be understood in terms of such alteration processes. The minimum number (two) of initial isotopic reservoirs is assumed. Two major stages of reservoir interaction are required: one at high temperature to produce the16O-mixing line observed for the anhydrous minerals, and another at low temperature to produce the matrix minerals. The isotopic compositions severely constrain the conditions of the low-temperature process, requiring temperatures < 20°C and volume fractions of water > 44%. Extension of the model to the data on C1 chondrites requires aqueous alteration in a warmer, wetter environment. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|