As a key microcontinental block/terrane in the southernmost Central Asian Orogenic Belt (CAOB), the Early Paleozoic magmatism genesis and tectonic evolution of the Dunhuang block remain poorly constrained. This gap hinders a comprehensive understanding of the ocean- continent subduction- accretionary evolution of the southern Paleo- Asian Ocean (PAO) and the recycling of deep materials. In this study, we identify Silurian quartz diorites from the Changshaliang area in the eastern Danghe reservoir, located in the central Dunhuang block, NW China. Petrological analysis, zircon U- Pb dating, whole- rock geochemistry, and Hf- in- zircon isotopic data were carried out on the Changshaliang quartz monzodiorite. Zircon U- Pb dating reveals that the quartz diorites were crystallized at ca. 428~426 Ma. Whole- rock geochemical analyses show a high- K calc- alkaline metaluminous series, characterized by sodium- rich composition (K2O/Na2O=0. 84~0. 99), high Al2O3 (16. 5%~17. 0%) and Mg# (51. 5~53. 0), and low A/CNK ratios (0. 96~1. 00). Hf- in- zircon isotopes display a wide range of negative εHf(t) values (12. 0 to 2. 2) and Paleoproterozoic two- stage model ages (2136~1525 Ma). These geochemical and isotopic characteristics suggest that the Changshaliang quartz monzodiorites originated through melting of a mantle wedge that had been metasomatized by subduction- related sediment melts, which subsequently triggered remelting of Paleoproterozoic lower crustal materials. Our findings, combined with existing research results, indicate that the Dunhuang block was strongly involved in the Early Paleozoic orogenic events along the southern CAOB. These processes contributed to a significant crustal modification and reactivation, generating multi- stage magmatism with diverse compositions. The block was situated in an active continental margin arc environment during this period, with continuous subduction of the Paleo- Asian Ocean beneath the Dunhuang block.