Applying the Landsat Images and Geomagnetic Data on Investigation of Fault Lineaments and their Origin Analysis in the Lurestam Region, Zagros Fold Belt

The Lurestan Subzone, is located on the Northwest Zagros Folded Belt. The sedimentary cover of this fold belt, such as the other parts of Zagros Fold-Thrust Belt, is affected by reactivation of subsurface structures through post Miocene Zagros Orogeny. Among the main structural problems in the Lurestan subzone is the disaffiliation between surface deformation and faults. In this study, by means of ETM+ satellite images and based on surface deformations like curved, truncated and offset structures (i.e., bending of fold axial traces), the fault Lineament which are related to the activity of subsurface or conceal faults are mapped. These lineaments, besides the NW- trending which is related to thrust fault corresponding with the Zagros Fold-Thrust belt, have two general orientations. The first set, that is N-trending and shows right-lateral offset; and the second set, that is NE-trending Indicate left lateral separation. Since these lineaments are the surface aspects of subsurface structures, comparison of them with subsurface data like focal mechanism of earthquake and geomagnetic Lineaments have also used for analyzing the origin of these lineaments. The most adoption belonged to the NW-trending fault lineaments. Moreover adaption of some earthquake mechanism in Lurestan subzone with detected fault lineaments in this study shows that they have a basement origin and are formed through reactivation of basement fault during the convergence of Arabian Plate and Central Iran. The other fault lineaments which do not correspond to the basement faults are proposed as the younger order of the fault reactivation on the covering surface. The detachment layers within the sedimentary cover of the Zagros do not allow the basement faults reactivation reach to surface. The most abundant of the occurred earthquakes in Lurestan subzone are in Balarud and Mountain Front Faults. The similarities on trend of these faults with focal mechanism of earthquakes confirm that these two zones are the main basement zones in Lurestan Region