Paleostress analysis of Mansour-Abad area (southeast Rafsanjan - Kerman Province) using Multiple Inversion Method
Subject Areas :لیلا عبادی 1 , سید احمد علوی 2 , محمدرضا قاسمی 3
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Abstract :
This study uses multiple inversion method to analyze slip data on shear planes and faults containing slickenlines in different rock units, and evaluates paleostress field in Mansour-Abad area. It was gathered the required kinematic data in 18 stations according to the stratigraphic age of the rock units. It was used the most important shear sense indicators, including mineral steps, Riedel shears and tension fractures. According to the multiple inversion method, which calculates stress tensor from the inhomogeneous fault data (data without any knowledge of stress field orientation or fault classification), four parameters of stress ellipsoid shape and axes were analyzed. It was found 3 different phases of compression, extension-shear and shear- compression using the phase separation in this method. The maximum principal stress orientation in different locations changes from N24˚ to N162˚ between Cretaceous and Neogene, while the minimum principal stress orientation changes from N79˚ to N116˚. The NW-SE strike of the reverse faults indicates that these faults developed during the activity of compressional phase. During the extensional-shear phase of the activity, local sedimentation occurred in the area. Late shear deformation of area, and change in stress field orientation, resulted in a block rotation between the fractures. Further increase in the rotation caused the fractures to increase in size, and provide space for intrusion of the magma.
