The genesis and tectonic setting of Late Triassic volcanic rocks in the Ganzi–Litang ophiolitic mélange belt have long been a subject of contention. To elucidate these ambiguities, comprehensive petrological, geochemical, zircon U-Pb geochronological, and Sr-Nd isotopic analyses were conducted on the Luexigou basalts in the Litang area. This investigation has newly delineated a typical volcano-sedimentary sequence indicative of a mid-ocean ridge, with basalts dated to 215 ± 3 Ma. These basalts exhibit geochemical characteristics akin to E-MORB, displaying relatively flat distribution patterns for rare earth elements and trace elements. They are notably depleted in highfield-strength elements (such as Nb and Ta), similar to volcanic arc basalts. This depletion suggests their classification as SSZ-type basalts. The (⁸⁷Sr/⁸⁶Sr)i ratios (0.7054–0.7055) and ε_Nd(t) values (-13.31–-9.18) suggest these rocks were derived from partial melting of spinel peridotite mantle that had been metasomatized by subducted sediments. In light of these geochemical signatures and recent research advancements, we propose the presence of two distinct mantle sources in the Ganzi–Litang Ocean. During the Carboniferous to Early Triassic extension phase, basalts formed by the subduction of the Paleo-Tethyan Ocean exhibit N-MORB characteristics. Conversely, in the Middle to Late Triassic subduction phase, basalts exhibiting E-MORB characteristics were influenced by intra-oceanic subduction processes within the Ganzi–Litang Ocean, associated with the development of a back-arc basin.