The geometrical investigation of Tafresh fractures with emphasis on joint studies

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Research Paper 01/06/2015
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The geometrical investigation of Tafresh fractures with emphasis on joint studies

Pegah Shahverdi, Alireza Farokhnia, Ali Sorbi
J. Bio. Env. Sci.6( 6), 540-551, June 2015.
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Studied area, is an ancient structure of Central Iran which is located between the central Zagros and Alborz. Numerous fractures can be seen in the Tafresh area. Base on studying on this area, fractures of Tafresh was affected by a major fracture process zone in central Iran and the southern part of Alborz. Although many researchers have been done over the Tafresh area, but due to the complexity of the geological and specific conditions of topography, Geometric studying of joints and fractures of tafresh has not completely done. This paper examines the fracture based on geometry and kinematics and spatial distribution of folds and joints using joint study techniques. Fieldwork was done, at 36 Stations – 498 joints – and during 35 days, using Clark compass. At each station bedding, Attitude, spacing, opening, filling, shape and dimensions of the joint sets plus their relationship to one another and other structures such as faults and folds were done using the selection method (Nickelsen and Hough, 1967) and directory (Davis 1984), Which are fast with measuring and statistical calculations. Joint sets were classified based on the concentrations of the poles to the joint surfaces. The analysis shows that joint sets J1 are main stress on the Tafresh zone and J2 and J3 joint sets show the sheer stresses. The main stress tends the northeast of the area that is perpendicular to the main fault of Tafresh. The statistical analyses show three categories of joint set (J1,J2 & J3) in the region in which J1 is main stress on the Tafresh Zone and J2, J3 joint sets are the sheer stresses.


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