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Orientation of olivine in dunite from elastic wave velocity measurements
Author(s) -
Sayers Colin M.
Publication year - 1987
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl014i010p01050
Subject(s) - olivine , geology , crystallite , anisotropy , mantle (geology) , seismic anisotropy , orientation (vector space) , mineralogy , distribution function , materials science , geophysics , geometry , thermodynamics , physics , mathematics , optics , metallurgy
There is a strong correlation between the measured elastic anisotropy of dunite and the preferred orientation of its main component, olivine. Olivine is a major constituent of the mantle and dunite is considered representative of upper mantle materials. In this report the measured elastic wave velocities for a dunite from Hidaka Horoman are used to determine the coefficients W 1mn of a series expansion of the crystallite orientation distribution function in generalised Legendre functions. This function gives the probability of a crystallite having a given orientation with respect to a set of axes fixed in the rock. The solution to this problem allows construction of crystallographic pole figures, which indicate a strong alignment of olivine a‐axes in agreement with the conclusions of petrofabric examination. Seismic studies of the crystallite orientation distribution function are therefore feasible and these should lead to a better understanding of the deformation processes associated with flow in the upper mantle.