Dislocations in Spinel and Garnet High-Pressure Polymorphs of Olivine and Pyroxene: Implications for Mantle Rheology

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Science  04 Jan 1980:
Vol. 207, Issue 4426, pp. 66-68
DOI: 10.1126/science.207.4426.66


The meteorite Tenham was observed by transmission electron microscopy and ringwoodite and majorite, the high-pressure polymorphs of olivine and pyroxene, were identified. Ringwoodite contains antiphase boundaries and straight dislocations that are probably dissociated. Mantle flow of spinel might proceed by pure climb, and whole-mantle convection may be possible if the grain size is small enough.