OXYGEN-ISOTOPE COMPOSITION OF MANTLE PERIDOTITE

被引：620
作者：
MATTEY, D
LOWRY, D
MACPHERSON, C
机构：
[1] Department of Geology, Royal Holloway, University of London, Egham, Surrey TW20 0EX, Egham Hill
来源：
EARTH AND PLANETARY SCIENCE LETTERS | 1994年 / 128卷 / 3-4期
基金：
英国自然环境研究理事会;
关键词：
D O I：
10.1016/0012-821X(94)90147-3
中图分类号：
P3 [地球物理学]; P59 [地球化学];
学科分类号：
0708 ; 070902 ;
摘要：
The oxygen isotopic composition of 76 samples of olivine in spinel-, garnet- and diamond-facies peridotites, and as syngenetic inclusions within diamond has been determined by laser fluorination (LF). delta(18)O(V-SMOW) values of olivine are almost invariant, averaging 5.18 +/- 0.28 parts per thousand (2 S.D.) with an overall range of 4.8-5.5 parts per thousand. Coexisting clinopyroxenes display positive Delta(18)O(cpx-olivine) fractionations averaging 0.4 parts per thousand that are consistent with isotopic equilibrium at normal mantle temperatures. The bulk compositions of spinel-, garnet- and diamond-facies mantle are similar, with a calculated bulk mantle delta(18)O of +5.5 parts per thousand. Olivine inclusions in diamonds of Archaean age yield delta(18)O values that are indistinguishable from olivine in post-Archaean mantle and the LF data do not provide evidence for gross spatial or temporal delta(18)O variation in peridotitic mantle. There is no evidence that mantle hydration processes impart distinctive oxygen isotope characteristics, other than a subtle isotopic disequilibrium disturbing pyroxenes relative to olivine.
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页码：231 / 241
页数：11
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