Quantifying the through-going evolution of strike-slip fault zones: Insights from analogue modeling

Large strike-slip fault zones commonly develop through-going architectures through progressive linkage of fault segments. However, quantitatively characterizing the through-going evolution of strike-slip fault zones remains challenging. Based on the pure strike-slip tectonic setting of the Tarim Basin, twelve sandbox analogue experiments were conducted to quantify the through-going process and evaluate its controlling factors, including displacement pattern, cover thickness, and displacement velocity. The results indicate that simple-shear strike-slip fault zones evolve through a progressive sequence from the en échelon stage to soft-linkage, hard-linkage, and ultimately a through-going stage. Each evolutionary stage corresponds to distinct threshold values of relative displacement (D/L). En échelon faults initiate at the base of the model during the embryonic stage and propagate upward to the surface during the soft-linkage stage when D/L ranges from 1.37% to 2.38%. Subsequently, Y-shear faults link individual fault segments during the hard-linkage stage at D/L values of 2.59%–4.81%, followed by the formation of a fully through-going fault zone at D/L values of 6.14%–7.76%. Generally, displacement threshold values increase with greater cover thickness during upward fault propagation. Threshold values also increase from bilateral codirectional displacement to unilateral displacement, and further to bilateral anti-directional displacement patterns, whereas higher displacement velocities tend to reduce the threshold values. The experimentally derived quantitative evolution is consistent with the fault segmentation and linkage mechanisms observed in strike-slip faults of the central Tarim intracratonic basin. These results demonstrate that the through-going process of pure strike-slip fault zones can quantitatively constrained by displacement, while strata thickness, displacement patterns, and displacement velocity exert significant control on the corresponding threshold values.