Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Determination of the shape factor variation spectrum with the classification of Paleostress ellipsoids in the southern part of Central Alborz

Document Type : Original Research Paper

Authors
1 Department of Geology, Faculty of Sciences, University of Tehran, Tehran, Iran
2 Institute of Earth Techniques & Scientific Researches, Tehran, Iran
3 Geological Survey of Iran, Tehran, Iran
Abstract
Shear planes, containing slickenside lineations were analysed statistically in 28 localities. The sampling sites were selected on the basis of Post-Eocene fault activations. The sites cover an area of 750 square kilometers of the southern part of the Central Alborz. Different methods of shape factor determination were tested. The results demonstrated that plotting 3-D unscaled Mohr diagram is the most reliable method. Variation in A-spectrum in the studied area proved to be of type II, i.e geometrically type flattened (0 < R< 1).
The R- value of equivalent ellipsoid represents the whole ellipsoids can be replaced by an ellipsoid similar to that causing conjugate faults. Variation in R- spectrum also supports the slip-tendency model to be low and high in Mobarak Abad and Tochal area respectively.
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Volume 9, 35-36
Spring & Summer 2000, Vol. 9, No. 35-36
Autumn 2000
Pages 18-27