Variation of effective seismic velocities of minerals with pressure and its use in velocity prediction |
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| Authors: | Jeremy Hall F M Al-Haddad |
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| Institution: | Department of Geology, University of Glasgow, Glasgow G12 8QQ |
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| Abstract: | summary . Regression analyses of P -wave velocity measurements on rocks at variable confining pressure yield'effective'mineral velocities which can be used in conjunction with geological data to predict the variation of velocity with depth in major units of continental crustal layering. Such prediction equations are more reliable than those based on density, mean atomic weight, or single-crystal data from the literature, because they take into direct account the effects of cracks on velocity. This is particularly important in the upper crust where many cracks are likely to be partly open: a by-product of the technique is the statistical relationship of cracks and alteration to minerals present in the samples. The technique is demonstrated in measurements of Vp to 3 kbar in rocks sampled in the vicinity of the Lewisian Units Seismic Traverse, in north-west Scotland. |
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