A pull-apart basin (PAB) is a releasing zone constrained by strike–slip faults. A PAB partly appears as a unique basin type typically dominated by the basin sidewall and cross-basin faults. However, the structural characteristics of different subsidiary faults derived from strike–slip motions are currently poorly understood in PABs. Under the control of different bend strike–slip faults, this study examines the formation and evolution of PABs reconstructed from wet clay with high water content (68%) as the experimental material. It was reported that (1) a PAB shows the single asymmetric half-graben architecture in the profile and rhombus in the plane, regardless of the bend type of the strike–slip fault; (2) the subsidiary fault area density increases with increasing fault displacement in PABs and might be impacted by the nature of the wet clay; (3) as the strike–slip fault displacement increases, the subsidiary fault number initially increases and then begins to decrease with large fault formation; and (4) T-faults are the most numerous faults in PABs, followed by Riedel shear faults. R′- and P-shear faults account for a small proportion and are unstable. The proportion of Riedel shear faults gradually decreases from the underlapping strike–slip faults to the overlapping strike–slip faults, accompanied by an increase in the corresponding R′-shear faults. The primary control factor affecting the proportion of subsidiary faults is the stress component. Re-recognition of subsidiary faults in the PABs is significant for interpreting strike–slip faults and the study of hydrocarbon migration.

Horsetail faults and rotational faults, which maintain slight differences, are all important identity markers for strike-slip movement. However, it is difficult to explain why horsetail faults also appear in the extensional regime. Using the Linnan Sag as a reference, physical experiments are conducted to reproduce the formation processes of horsetail faults in the extensional regime. Characteristics of these horsetail faults include: (1) horsetail faults are the product of strain superposition during two phases of noncoaxial extension; (2) preexisting faults generated in the initial stage may reactivate by the combined elongation of dip-slip motion, followed by oblique-slip faulting at the middle-late stage, thus becoming the principal fault of the horsetail faults; this initial distance is obviously less (approximately 46%) than its distance during the middle-late stage; (3) a large number of new dip-slip faults appear at the tip of the principal fault in the middle-late stage, spatially connecting with the principal fault to form the horsetail faults; and (4) other preexisting faults that intersect the principal fault are not necessary for forming the horsetail faults but their presence may make the principal fault prone to segmentation. Therefore, although horsetail faults in the extensional and strike-slip regimes are similar in shape, their formation conditions and fault properties are very different. Understanding the characteristics of the horsetail faults in the extension regime contributes to further study related to oil and gas migration and accumulation in the Petroliferous basin.