Use of Image Analysis in the Measurement of Finite Strain by the Normalized Fry Method: Geological Implications for the ‘Zone Houillère’ (Briançonnais Zone, French Alps)

L. Ailleres, M. Champenois, J. Macaudiere* and J.M. Bertrand
C.R.P.G.-C.N.R.S., 15 rue N-D des Pauvres, B.P. 20, 54501 Vandoeuvre les Nancy, France.
*Alternative address: E.N.S.G., 94 ave De Lattre De Tassigny, BP 452, 54501 Nancy, France.

Abstract: Image analysis techniques are used to quantify finite strain in microconglomerates from the ‘Zone Houillère’ (Briançonnais Zone, French Alps) using the normalized Fry method. Two different techniques have been developed to extract the necessary parameters from quartz grains: the first uses an interactive videographic image analyser linked to a digitizer, and the second uses a semi-automatic image analyser algorithm working on numeric images. Comparison between these two techniques allows the data provided by the latter to be validated. Semi-automated image analysis is then employed to compute the characteristics of the finite strain ellipse as defined by the normalized Fry method. This has been tested on natural and simulated fabrics and gives accurate results. Finally, these techniques have been applied to samples from the French Alps, in an attempt to correlate the regional pattern of finite strain with deep seismic reflectors. This paper presents the preliminary results using finite strain data determined by image analysis processing.

Keywords: image analysis • finite strain • normalized Fry method • French Alps

Mineralogical Magazine; June 1995 v. 59; no. 395; p. 179-187; DOI: 10.1180/minmag.1995.059.395.02
© 1995, The Mineralogical Society
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