| In the Geza Arc of the Sanjiang metallogenic belt, southwestern China, a series of Cu–Mo–W deposits with distinct elemental associations, genetically linked to granitic magmatism, were intensively developed within a restricted area during the Late Cretaceous (ca.76–86 Ma). To unravel the deep-seated controls on their metallogenic diversity, this study focuses on two representative deposit types—the Hongshan–Hongniu Cu–Mo deposit and the Xiuwacu W–Mo deposit—and presents systematic zircon U–Pb dating, whole-rock geochemical analysis, and in-situ mineral geochemistry of their ore-forming granitic intrusions and the mafic microgranular enclaves (MMEs) within the Hongshan–Hongniu pluton.Zircon U–Pb dating indicates that the MMEs from Hongshan–Hongniu formed at 78–79 Ma, contemporaneous with regional granitic magmatism and Cu–Mo–W mineralization. Genetic analyses reveal that the ore-forming monzonitic granite porphyry at Hongshan–Hongniu originated from partial melting of a juvenile mafic lower crust generated during Late Triassic arc magmatism, and experienced periodic recharge of Late Cretaceous mantle-derived mafic magmas, as represented by the MMEs. The source characteristics—juvenile mafic lower crust—combined with mafic magma recharge, resulted in ore-forming magmas with high oxygen fugacity (mean zircon Ce??/Ce3? = 67.2), elevated chlorine (mean apatite Cl = 0.07%), and high sulfur content (mean apatite SO? = 0.06%), which significantly enhanced copper activation, transport, and precipitation.Conversely, radiogenic Sr–Nd isotopic modeling indicates that the ore-forming monzogranite at Xiuwacu was primarily derived from partial melting of the Neoproterozoic–Triassic middle–upper crust, containing 20–80% ancient crustal materials. Although the Xiuwacu intrusion experienced a degree of mafic magma injection similar to that of the Hongshan–Hongniu pluton, its magmatic system is characterized by lower oxygen fugacity (mean zircon Ce??/Ce3? = 51.9) and a F-rich, Cl-poor composition (mean apatite F = 3.86%), consistent with properties of mid-upper crustal metavolcanic-sedimentary rocks. Such magmas favor tungsten and molybdenum enrichment and mineralization after extensive fractional crystallization.The integrated petrogenetic-metallogenic model proposed here demonstrates that the diversity of Cretaceous mineralization in the Geza Arc is fundamentally controlled by a “juvenile lower and ancient upper” double-layer crustal structure. The deep mantle-derived thermal engine acted concurrently on the juvenile mafic lower crust and the ancient middle–upper crust, leading to the formation of high-fO?, Cl-rich Cu–Mo metallogenic systems and low-fO?, F-rich W–Mo systems, respectively. These insights advance the understanding of metal coupling and separation in granitic magmatic systems and provide guidance for regional mineral exploration. |