To investigate the petrogenesis and tectonic setting of the Dianzhong Formation volcanic rocks in the Shiquanhe area, we present detailed zircon U- Pb geochronology, whole- rock geochemistry, and Lu- Hf isotopic data for volcanic rocks from the Dianzhong Formation (Linzizong Group). The results reveal zircon U- Pb ages of 57. 1±0. 8 Ma and 55. 8±0. 7 Ma, demonstrating that these volcanic rocks, previously assigned to the Tuocheng Formation (Zenong Group), should be reclassified as the Paleocene Dianzhong Formation. Geochemical analyses indicate the samples are peraluminous, high- K calc- alkaline series characterized by high SiO2 and low TiO2 contents, along with low MgO, Cr, and Ni concentrations and low Mg# values (mean=22). These rocks show distinct enrichment in large ion lithophile elements (LILE; e. g. , K, Rb and Pb), coupled with depletion in high field strength elements (HFSE; e. g. , Nb, Ta, Ti and P), indicative of an arc magmatic affinity. The fractionation of light and heavy rare earth elements is obvious, with relative enrichment in LREE and significant negative Eu, Ba, and Sr anomalies, indicative of extensive fractional crystallization processes. Zircon Hf isotopes yield εHf(t) values ranging from +2. 61 to +9. 51, with two- stage model ages (TDMC) between 965 and 514 Ma, indicating derivation from the remelting of juvenile crustal material. These data suggest that following the initial India- Asia continental collision (~70 Ma), continued rollback of the Neo- Tethyan slab resulted in the formation of the Dianzhong Formation volcanics. The subsequent slab breakoff at ~56 Ma triggered the large- scale Nianbo and Pana Formation volcanism, which lasted until about 40 Ma.