: half flower structure

Until now comprehensive studies have been carried out by various researchers on the structural and geometric model of the Mosha-North Tehran fault system. As a structural lozenge with an general WNW- ESE trend, this fault system is located in the southern flank of Alborz Mountain range where is considered a part of Alpine-Himalayan orogenic belt. The mentioned system consists of Mosha fault zone to the NNE and North Tehran fault zone to the SSW which has experienced various left-lateral or right-lateral strike slip mechanisms with contractional or extensional components during the geological time. NW-striking thrusts, the Purkan- Vardij Thrust (PVT) and Emamzadeh-Davud Fault (EDF) are also considered as other remarkable structural features of the region. The studied structural zone has gone through several uplifts and subsidences from the Mesozoic to the present day. This means that in the study area, the phenomenon of inversion tectonics has occurred many times and so, extensional and contractional regimes have interchanges alternately to each other. For example, during Oligo-Miocene, due to the northwestward movement of the South Caspian Basin with respect to the Eurasia, inversion tectonics turned a transtensional (right- lateral with extensional component) environment into a transpressional (left- lateral with small contractional component) one. In this research, a new structural model has been presented, based on which the study area is formed by an interchangeable half-negative flower structure and half-positive flower structure.