Document Type : Original Research Paper
Authors
1 M. Sc. Student, Department of Geology, Faculty of Basic Science, Islamic Azad University, Science and Research Branch, Tehran, Iran
2 Ph.D.,Geological Survey of Iran, Tehran, Iran
Abstract
In order to investigate the structural evolution and paleo-stress analysis of the study area, North of Qazvin, geometry and kinematics of faults in are measured. Following these measurements, the stress tensor and variation of stress direction in diffeerent rock units are calculated. For this purpose, 186 fault surfaces and sliken lines from 12 sites were selected and measured. The results of the dynamic analyses using Angelier’s (1991) inversion method indicate that the stress direction changed during Eocene. They also show some change in the stress field direction occurred after Eocene time. According to our dynamic analyses on the faults, we classified the tectonic events in the study area. Principal stress axes and their directions for all sites are calculated using Angelier’s software. Results of our study indicates that the main stress dominated in this area is an extension during Eocene. Analysis of the obtained data from this part of the western AlborzMountains (north Qazvin), indicates a major NE-SW extension in the Eocene volcanic and sedimentary rocks. This extension direction is also confirm by the direction of volcanic dykes which have intruded in the same period in this area.
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