Three Types of Flower Structures in a Divergent‐Wrench Fault Zone

Abstract

AbstractFlower structures are typical features of wrench fault zones. In conventional studies, two distinct kinds of flower structures have been identified based on differences in their internal structural architecture: (1) negative flower structures characterized by synforms and normal separations and (2) positive flower structures characterized by antiforms and reverse separations. In addition to negative and positive flower structures, in this study, a third kind of flower structure was identified in a divergent‐wrench fault zone, a hybrid characterized by both antiforms and normal separations. Negative flower structures widely occur in divergent‐wrench fault zones, and their presence indicates the combined effects of extensional and strike‐slip motion. In contrast, positive and hybrid flower structures occur only in fault restraining bends and step overs. A hybrid flower structure can be considered as product of a kind of structural deformation typical of divergent‐wrench zones; it is the result of the combined effects of extensional, compressional, and strike‐slip strains under a locally appropriate compressional environment. The strain situation in it represents the transition stage that in between positive and negative flower structures. Kinematic and dynamic characteristics of the hybrid flower structures indicate the salient features of structural deformation in restraining bends and step overs along divergent‐wrench faults, including the coexistence of three kinds of strains (i.e., compression, extension, and strike‐slip) and synchronous presence of compressional (i.e., typical fault‐bend fold) and extensional (normal faults) deformation in the same place. Hybrid flower structures are also favorable for the accumulation of hydrocarbons because of their special structural configuration in divergent‐wrench fault zones.