Tectonic activity, as a key driver of long-term climate evolution, influences atmospheric CO₂ concentrations by regulating deep carbon cycling while also shaping the development and distribution of mineral systems in specific geological settings. However, the carbon cycling processes during tectonic transitions and their coupling with mineralization remain poorly constrained. The Bangong-Nujiang Suture Zone (BNSZ), a significant tectonic unit within the Tibetan Plateau, comprehensively records the tectonic evolution from oceanic subduction to post-collision. Its formation coincides with the period of declining atmospheric CO₂ concentrations during the Mesozoic, making it an ideal natural laboratory for investigating the interconnections among tectonics, the carbon cycle, and mineralization systems. This study focuses on mafic rock samples from three key tectonic periods within the BNSZ (subduction, collision, and post-collision), conducting whole-rock geochemical and Pb-Mg-Sr isotopic analyses. The results reveal a fundamental shift in the deep carbon cycling mechanism within the region corresponding to changes in tectonic stages. The primary carrier of carbon migrated transitioned from being fluid-dominated to melt-dominated. This shift not only influenced the efficiency of carbon release but also governed the migration and enrichment of ore-forming elements in associated mineralization systems. During the Early Jurassic subduction stage, carbon was primarily transported as CO₂-rich fluids, resulting in sustained but low-flux degassing. By the Early Cretaceous collision stage, carbon migration shifted to being dominated by carbonate melts, leading to pulsed, high-flux carbon release potentially. In the Late Cretaceous post-collision stage, carbon release became more diffuse, involving enhanced multi-source mixing and crustal assimilation. This mechanistic transition indicates that specific tectonic processes, such as collision, can trigger large-scale, rapid release of deep carbon and ore-forming elements. It provides a novel tectonic-mineralization coupling model for understanding global carbon cycle fluctuations, atmospheric CO₂ evolution, and the formation of large metallogenic provinces during the Mesozoic.