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Comparison of experimental and natural boudinage

Published online by Cambridge University Press:  01 May 2009

R. Sen
Affiliation:
Hindusthan Zinc LimitedUdaipurRajasthanIndia
A. D. Mukherjee
Affiliation:
Department of Geological SciencesJadavpur UniversityCalcutta-32India

Summary

Strain distribution inside an elliptical shaped boudin under normal compressive stress is calculated by photo-elastic methods following Frocht (1966). The strain magnitude varies horizontally within the boudin and the value increases gradually from the central part of the body to the margin. The magnitude is nearly constant along the vertical central part of the boudin. Around the margin, inside the body, it shows an average value of the vertical and horizontal stress magnitudes. No actual change in the direction of shearing stress in different parts within the boudin is noted, hence no directional change of strain. Petrofabric diagrams of different parts of natural boudins showing the quartz (0001) plots, indicate no variation in the pattern of orientation in different parts of the body. However, the elongation ratio of quartz grains shows a correspondent increase with the increment of stress magnitude as noted in the experiments.

Type
Articles
Copyright
Copyright © Cambridge University Press 1975

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