This study focuses on the igneous rocks in the Bogda area along the southern margin of the Junggar Basin. Through geochemical analysis and zircon U-Pb dating, we reveal distinct differences in lithology and distribution of Late Carboniferous and Early Permian volcanic rocks between the northern and southern flanks of the Bogda Mountains. The findings suggest that the Late Carboniferous was characterized by post-collisional extension, while the Early Permian experienced intense extensional activity caused by lithospheric delamination. Late Carboniferous-Early Permian mafic rocks in the Bogda region exhibit significant depletion in high-field-strength elements (HFSE) such as Nb and Ta, slight depletion in Ti, and minor enrichment in Zr. The Nb/Ta and Zr/Hf ratios closely resemble primitive mantle values, reflecting typical mantle-derived magmatic characteristics. This suggests that crustal contamination was limited, while lithospheric contamination played a more dominant role. Late Carboniferous basalts show greater depletion in large-ion lithophile elements (LILE) and higher Mg# compared with Early Permian basalts. The Zr-TiO_₂ tectonic discrimination diagrams indicate that Late Carboniferous basalts exhibit MORB-like affinities, whereas Early Permian basalts are more enriched in large-ion lithophile elements and rare earth elements, showing intraplate basalt characteristics, indicating divergent dynamic mechanisms between the two stages. Following the closure of the North Tianshan Ocean in the Late Carboniferous, due to slab breakoff, post-collisional extension prevailed under a weakly extensional tectonic regime. By the Early Permian, the post-collisional extensional regime changed, and delamination of the subducted slab occurred beneath the Bogda area. With the influx of abundant slab-derived fluids, trace elements were progressively enriched in some mafic rocks, and geochemical indices of certain mafic rocks exhibited intraplate basalt characteristics. The two episodes of extension with contrasting dynamic mechanisms during the Late Carboniferous and Early Permian in the Bogda area impose important constraints on the nature of the southern margin of the Junggar Basin.