Variations in the Style of Thrusting Geometry of Shahroud main thrust in the South-east of Alborz Mountains (North of Iran)

Abstract

Based on the synthesis of information on maps, profiles, three-dimensional diagrams, and on the structural analyses carried out on Shahroud main thrust in the South-east of Alborz Mountains, it has been specified that some fundamental variation in the geometric form of faults have occurred along this thrust zone. These severe lateral variations from west toward east of the zone under study involve changing positive flower structure into cylinder-shaped structure and ultimately forming antiformal stack along Shahroud main thrust. This intricate geometric form indicates that along with transformation of fault trend and the entrance of thrust zone into rock units with variable plasticity, principal variations have taken place in the geometry of faults, and a positive flower structure can turn into classic thrust systems such as imbricate or duplexes. Furthermore, such geometric diversity in structural styles has led to the complexity of tectonic features of the region.