Twin Horsetailing Structures in the Extensional Regime based on Physical Experiment

Abstract Horsetailing is an important feature to identify the strike‐slip structure and indicates the movement mode of the fault. However, the formation mechanism of horsetailing in the extensional regime remains unclear. In this study, the formation process of horsetailing is reproduced through physical experiment, simulating the Linnan sag in the extensional regime. The results of the physical experiment demonstrates that the formation of the horsetailing in the extensional regime requires two phases of non‐coaxial stretching plus the segment of the principal fault. The stretching distance in the early phase is slightly smaller than that in the middle–late phase. The segment point of the principal fault is only the intersection of the horsetailing structure and the principal fault. The horsetailing formed in the extensional regime is different from that in the strike‐slip regime. For the formation of structure, the principal fault is dip‐slip in the early phase and then becomes an oblique‐slip in the middle–late phase, and the horsetailing is composed of the middle–late new tensile faults. The fault properties of the horsetailing in the extensional regime has important guiding significance for the longitudinal fluid migration along the fault in petroliferous basins.