The Plasticity of Some Fine-Grained Aggregates of Olivine at High Pressure and Temperature

  1. B.E. Hobbs and
  2. H.C. Heard
  1. P. N. Chopra

Published Online: 18 MAR 2013

DOI: 10.1029/GM036p0025

Mineral and Rock Deformation: Laboratory Studies: The Paterson Volume

Mineral and Rock Deformation: Laboratory Studies: The Paterson Volume

How to Cite

Chopra, P. N. (1986) The Plasticity of Some Fine-Grained Aggregates of Olivine at High Pressure and Temperature, in Mineral and Rock Deformation: Laboratory Studies: The Paterson Volume (eds B.E. Hobbs and H.C. Heard), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM036p0025

Author Information

  1. Bureau of Mineral Resources, Geology & Geophysics, GPO Box 378, Canberra A.C.T. 2601 Australia

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1986

ISBN Information

Print ISBN: 9780875900629

Online ISBN: 9781118664353

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Keywords:

  • Rocks—Testing—Addresses, essays, lectures;
  • Rock deformation—Addresses, essays, lectures

Summary

Synthetic aggregates of San Carlos olivine with an equiaxed grain size near 10 μm prepared by isostatic hot pressing in the presence of water have been deformed under wet conditions at a confining pressure of 300 MPa in a series of constant strain rate and stress relaxation tests at 1100°, 1200° and 1300°C. Results obtained in the 1100°C constant strain rate tests suggest that the deformations were probably produced by a dislocation creep mechanism resulting in a stress exponent, n, of 3.3 and in relatively high flow stress levels when compared with coarser grained natural olivine rocks. In contrast, the flow behaviour of the fine grained aggregates at 1200° and 1300° was characterised by very low stress levels and a near Newtonian dependence of flow stress on strain rate (i.e., n=1.5), tending to suggest that these deformations were produced by some form of diffusional creep. This dichotomy in flow behaviour delineates a boundary between deformation mechanisms in polycrystalline olivine which may be of importance in understanding the deformation of the upper mantle.