The Sandaozhuang super-large W-Mo deposit is located in the southern margin of the North China Craton, within the well-known East Qinling Mo mineralization belt, and is one of the typical skarn-type W-Mo deposits in China. Based on EMPA and LA-ICP-MS analyses, major and trace elements were presented, and the mineral chemistry of magnetite at various mineralization stages was discussed. Combining field observations, petrography, and geochemical characteristics, the magnetite at the Sandaozhuang deposit can be classified into three types, namely early-magmatic-stage high-temperature magnetite (Mag1), potassic-alteration-stage magnetite (Mag2), and retrograde-alteration-stage magnetite (Mag3). The Mag1 and Mag2 magnetites primarily occurred in granites in association with potassium (K) feldspar and biotite, whereas Mag3 is associated with metallic sulfide minerals that occurred mainly in vein-like structures in skarn. The three magnetites Mag1, Mag2, and Mag3 can be distinguished as having magmatic, magmatic–hydrothermal transition, and hydrothermal origins, respectively. All three types of magnetite exhibit a depletion of high-field-strength elements (HFSEs) such as Zr, Hf, Nb, Ta, and Ti, and large-ion lithophile elements (LILEs) including Rb, K, Ba, and Sr, compared to the mean continental crust composition. Conversely, they are enriched in elements such as Sn, Mo, V, Cr, Zn, and Ga. Mag3 showed no significant depletion of Co, Ni, Cu, and Bi, indicating that the influence of coexisting sulfides on the composition of magnetite at the Sandaozhuang deposit is limited. There are systematic variations in major and trace elements from Mag1 to Mag3, which exhibited similar patterns in trace element spider and rare earth element diagrams, and Y/Ho ratio, indicating a consistent source for the three types of magnetite. The changes in V and Cr contents and (Ti + V) vs. (Al + Mn) diagram of magnetite at the Sandaozhuang deposit reflected the evolution of ore-forming fluids with an initial increase in oxygen fugacity and a subsequent decrease, as well as a gradual decrease in temperature during skarn mineralization. The early high-temperature and high-oxygen-fugacity magmatic fluids became W and Mo enriched by hydrothermal fluid interaction. The rapid change in fluid properties during the retrograde alteration stage led to the precipitation of scheelite and molybdenite.

Northwest Zhejiang area (NWZJ) is one of the important parts of the large Qingzhou-Hangzhou mineralized belt in South China formed during the Late Jurassic–Early Cretaceous period. Through the study of zircon LA-ICPMS U-Pb dating, whole-rock geochemistry, and Sr-Nd isotopes for the Wujinshan granitoid in NWZJ, two distinct S-type granitic rocks of porphyry type granodiorite and granite were identified, and the two ages of 146.4 ± 1.5 Ma for granodiorite porphyry and 141.9 ± 1.4 Ma for granite porphyries were obtained. These rocks exhibited a geochemical affinity for S-type granitoid, and the two magmatic ages indicate that these rocks were intruded in two magmatic pulses. The Late Jurassic granodiorite porphyry showed moderate SiO₂ (64.38–67.89 wt.%) with higher K₂O + Na₂O (6.22–6.78 wt.%), lower K₂O/Na₂O (0.57–0.96), moderate Zr (170–215 ppm), high Sr (302–475 ppm), and low Mg^# (31–32) contents. The Early Cretaceous granite porphyries contained high SiO₂ (69.68–74.85 wt.%), variable K₂O + Na₂O (4.60–6.99), high K₂O/Na₂O (1.72–23.53), slightly higher Zr (160–255 ppm), variable Sr (25–412 ppm), and very low to intermediate Mg^# (13–44). The granodiorites had intermediate ∑REE (149–177 ppm), while granite samples showed moderate to high ∑REE content (147–271 ppm), and both rocks showed negative Eu anomalies (0.18–0.29). We propose that these two rocks were predominantly generated by the partial melting of Mesoproterozoic metamorphic basement and underwent variable degrees of fractionation and evolution. The Late Jurassic granodiorite porphyry was formed by the partial melting of Mesoproterozoic metamorphic basement with slab-derived melts or basaltic lower crust input following fractional crystallization, while the Early Cretaceous granite porphyries were generated by the partial melting of Mesoproterozoic metamorphic basement and crystal fractionation with variable magma mixing and assimilation in the upper crust. Tectonically, the Wujinshan granitoid formed in a volcanic arc setting largely affected by the subduction and slab rollback of the paleo-Pacific Plate.

The Cretaceous marks the peak of magmatic activity in southeastern (SE) China, which is attributed to the subduction of the paleo-Pacific plate beneath the South China Block. This region constitutes a significant igneous belt along the active continental margin of the western Pacific. Despite extensive research, the origin and evolution of Cretaceous felsic volcanic rocks are still debated. This study investigates the characteristics of zircon U-Pb-Hf isotopes and trace elements, and whole-rock geochemistry of Cretaceous volcanic rocks from the Wenzhou–Taizhou region in SE Zhejiang, and discusses their spatio-temporal patterns and petrogenesis. The results indicate that rhyolitic volcanic rocks formed during the period ca. 114 Ma and 95 Ma, representing two distinct magmatic episodes spanning the transition from the late Early to early Late Cretaceous. The late Early Cretaceous and early Late Cretaceous volcanic rocks are of a hybrid crust–mantle origin, as evidenced by their distinct Nb/Ta ratios, zircon ε_Hf(t) values, and variable trace element enrichments (Ti, Hf, U, Nb, and Yb). These compositional signatures suggest partial melting of late Paleoproterozoic to early Mesoproterozoic basement materials, with increasing mantle contributions over time. Both volcanic phases exhibit elevated Nb/Yb, Th/Nb, and U/Yb ratios, indicating a subduction-modified source akin to arc magmas. Together with calculated initial melt temperatures (800 °C for Late Cretaceous) and whole-rock rare-earth elements (REEs) distribution patterns (U-shaped with δEu = 0.37–0.65, seagull-shaped with δEu = 0.19–0.62, respectively), it is suggested that both phases of the volcanic magmas were generated through water-assisted (hydrous) melting, whereas the later phase formed at relatively higher temperatures and with a diminished water contribution via dehydration melting under extensional conditions. The generation of voluminous high-silica magmas in the SE China coastal region is probably linked to the rollback and retreat of the paleo-Pacific plate.