Arcuate extension structures in kinematic analysis of regional and global tectonic settings

Resumo

Disjunctive extension structures with a regular arcuate shape in plan view are widespread in the Earth’s tectonosphere. Author analyzes and explains the features of their geometry. A study of the formation conditions of arcuate extension structures in tectonic settings of various scale and type has shown that the common cause of their curvature is kinematic asymmetry of horizontal extension, when acceleration is attained only from one of two fault limbs, which meets smaller resistance of the medium. The concave side of arc is oriented in the same direction. Data are given on kinematics of lateral motions in settings of continental rifting, gravitational collapse of orogens, and moderate extension of gravitational–tectonic nature within continental platforms. It is suggested that asymmetric extension occurs widely in the formation of arcuate structures in continents and oceans. It is shown that the effect of asymmetric extension can be considered for subduction-related island arcs in the Western Pacific.