Endogenic mantle-driven orogenesis of retreating accretionary orogens: implications for the continental growth and stabilization

Retreating accretionary orogens exhibit a paradoxical capacity to sustain crustal shortening and growth contemporaneous with dominant upper plate extension. Deciphering the dynamic coupling between mantle flow and crustal evolution is critical in understanding orogenic mechanisms within such retreating systems, with profound implications for subduction zone dynamics and continental growth processes. Here we integrate high-resolution 2D numerical simulations, with quantitative geological boundary conditions from the Paleozoic Altaides archetype, to establish an endogenic orogenic mechanism driven by slab rollback-induced mantle circulation during retreating subduction. Our models demonstrate that spontaneous mantle upwelling and convections could systematically govern (1) progressive trench-directed arc migration, (2) self-organized forearc-arc-backarc-intraplate tectonic zoning, (3) crustal thickening-extension cycles and diachronous coexistence, (4) crustal growth and stabilization through intense bimodal magmatism with juvenile isotopic signatures, all of which characterize the Altaides and other archetypal retreating accretionary orogens. This intrinsic interplay between slab rollback, mantle upwelling, and upper plate response offers a unified framework to interpret accretionary orogens via deep Earth-surface interactions. This work was financially supported by Project (JLFS/P-702/24) of Hong Kong RGC Co-funding Mechanism on Joint Laboratories with the Chinese Academy of Science, National Science Foundation of China (Grants 424B2048, 42176064), and Australian Research Council (FL160100168).