Cretaceous mafic magmatic enclaves and host granites in the Luanchuan ore cluster, East Qinling, China: Insights into Mo mineralisation and tectonic evolution

• The Shibaogou MMEs in Luanchuan Mo cluster are dated at ca. 144 Ma. • Mixing mafic and granitic magma and post-injection modifications lead to the formation of MMEs. • A reduced influx of Mo-bearing ore-forming materials and low mineralisation potential can be attested by MMEs. The genesis of mafic magmatic enclaves (MMEs) remains a topic of scientific discussion, particularly regarding their relationship to the mineralising potential of granites. This research presents geochemical, isotopic, and geochronological analyses of MMEs from the Shibaogou pluton in the Luanchuan Mo cluster within the East Qinling Mo metallogenic belt of central China. Our findings indicate that the MMEs, primarily quartz diorite, formed at ca. 144 Ma. These MMEs represent mafic magma derived from the mantle, which was injected into the molten felsic magma and subsequently underwent hybridisation with the host granites. The Shibaogou pluton is characterised by high-K calc-alkaline I-type granites, which originated from the partial melting of basaltic lower crustal rocks followed by fractional crystallisation. In the Luanchuan ore cluster, the Late Mesozoic granitic plutons with a higher abundance of MMEs are associated with increased erosion and reduced input of Mo-bearing ore-forming materials. This observation indicates a decreased exploration potential for granitic intrusions in the region. The log f O 2 values of the MMEs from the Shibaogou pluton range from −25.6 to −6.5, consistent with those of their host granites. However, these values are lower than those observed in the Mo mineralised granitic plutons of the northern Nannihu ore filed, indicating a lower mineralising potential for the Shibaogou pluton in the Luanchuan area. The formation of the Shibaogou MMEs is attributed to asthenospheric upwelling and the underplating of lithospheric mantle-derived magma, while the host granites formed through the partial melting of basaltic lower crust. Additionally, the formation of both the MMEs and their host granites reveals a Late Mesozoic tectonic transition from a syn -collisional compressional to a within-plate extensional setting. The limited exposure of mafic-dioritic rocks, including MMEs, in the Luanchuan area reflects the restricted nature of asthenospheric upwelling. This study underscores the importance of MMEs in evaluating the exploration and mineralising potential of granitic intrusions.