Kinematics, structure and relationship to metamorphism of the east‐west flow in the Sanbagawa Belt, southwest Japan

Abstract

Abstract Deformation in the Sanbagawa Belt is characterized by ductile flow in an east‐west direction sub‐parallel to its length. The east‐west flow (D 1 ) caused large‐scale recumbent folding of the metamorphic sequence in central Shikoku, which can explain the inverted thermal structure of this region. Chemical zoning of metamorphic minerals associated with D 1 microstructures also suggest that the east‐west flow developed under retrograde conditions. D 1 is therefore related to exhumation rather than subduction processes. A variety of kinematic indicators show that during the east‐west flow, deformation was partitioned into structurally continuous domains with opposed senses of shear. This suggests that bulk deformation was not simple shear but included a component of flattening.