Influence of Pre‐Existing Weak Zones During Continental Compression: Insights From Centrifuge Models

Pre‐existing heterogeneities in the crust exert a fundamental control on continental compressive deformation and mountain building, although many aspects of their role remain poorly quantified and not yet fully understood. Here, we present centrifuge models that simulate the occurrence of a pre‐existing weak heterogeneity in the lower crust (WLC) and isolate the effects of its width, interface dip orientation (i.e., inwardand outward‐dipping) and friction conditions under orthogonal compression. All models with a built‐in WLC produced a central uplift that localized strain at its interfaces, absent in a homogeneous reference model. Narrow WLCs promote folding and generate high‐relief uplifts, whereas wider weakness zones favor horizontal translation and faulting, forming broader and lower topography. WLCs with outward‐dipping boundaries enhanced vertical thickening and uplift, while inward‐dipping WLC boundaries promoted back‐thrusting and subdued relief. Reduced friction at the WLC boundaries facilitated localized deformation at its interfaces, horizontal translation and reduced overall uplift. These results refine previous analog and numerical studies by clarifying how the geometry of a pre‐existing WLC governs strain redistribution and uplift style during shortening. These experimental results are compared with exemplificative natural examples, such as the Central Qiangtang terrane in Tibet and the High Atlas in Morocco.