The mineralization within the North China Craton (NCC) is intricately linked to Mesozoic large-scale extension in eastern China and is a consequence of a unified geodynamic tectonic background. Despite previous attempts to elucidate the relationship between large-scale mineralization and magmatic activity in the NCC, a lack of systematic research has hindered the identification of connections among deposits with inconsistent metallogenic ages. This study focuses on the coal measures of the Huanghebei Coalfield (HHBC) in western Shandong, presenting a regional magmatic–hydrothermal metallogenic system with a genetic connection. It delves into the intricate interplay between the multi-mineral enrichment mechanism, metallogenic regularity, and the NCC’s destruction. The findings reveal that: (1) Various stages of magmatic intrusion during the Yanshanian period significantly influenced the Late Paleozoic coal measures in the HHBC. The coal measures exhibit distinct ranks, ranging from medium-rank bituminous C to A and high-rank anthracite C, resulting in noticeable differences in gas generation among different coal ranks. The shale between the coal seams C5 and C7 emerges as excellent with a good hydrocarbon-generating capacity during the middle-maturity stage. (2) The “Intrusion along the rock layer type” proves most conducive to shale gas enrichment, while the “laccolith type” is more favorable for shale gas enrichment compared to “dike type” intrusions, which have a limited impact on shale gas enrichment. (3) The mineralization process of CBM, shale gas, and iron ore is influenced by Yanshanian-period magma. The enrichment degree of CBM and shale gas exhibits an inverse correlation with the distance from the magmatic intrusion. Iron deposits demonstrate a close association with the magmatic intrusion, with enhanced enrichment along the rock layer. The results indicate that the destruction of the NCC triggered intense metasomatism in the deep cratonic fluids, serving as the primary driving mechanism for large-scale mineralization during the Yanshanian period. Magmatic intrusions bring hydrothermal fluids conducive to mineralization, and the heat release from these intrusions promotes thermal evolution, hydrocarbon generation, and the enrichment of organic-rich strata.

This study examines the origin, tectonic setting, and Cu–Pb–Zn polymetallic mineralization of the Yangjiayu Complex, situated on the southwestern margin of the Jiaolai Basin. We present detailed geochemical, zircon U–Pb geochronological, and Hf isotopic data for rhyolite porphyry and monzodiorite samples. Zircon U–Pb dating reveals that the emplacement of both intrusions occurred in the Early Cretaceous. While the monzodiorite (122.5 ± 0.7 Ma) is numerically slightly older than the rhyolite porphyry (121.2 ± 0.6 Ma), considering the error ranges, their ages are essentially similar. The rhyolite porphyry displays higher SiO₂ and Na₂O + K₂O contents and a lower Al₂O₃ content relative to the monzodiorite. Geochemically, both intrusions are classified as high-K calc-alkaline and peraluminous, characterized by enrichment in large-ion lithophile elements (LILEs; e.g., Ba, Rb, Pb) and light rare earth elements (LREEs), along with depletion in high-field-strength elements (HFSEs; e.g., Nb, P, Ta) and heavy rare earth elements (HREEs). The rhyolite porphyry further exhibits middle rare earth elements (MREEs; e.g., Eu, Gd, Tb, Dy) depletion. Similar zircon εHf(t) values (monzodiorite: −23.0 to −26.1; rhyolite porphyry: −23.2 to −25.0) suggest a shared source derived from partial melting of the thickened lower crustal rocks. In comparison to the monzodiorite, the rhyolite porphyry shows lower total REE contents, a more pronounced negative Eu anomaly and stronger MREE depletion, higher Rb, Th, and U concentrations, and more significant P depletion, features indicative of more extensive assimilation-fractional crystallization (AFC). These geochemical and geochronological data indicate that the Yangjiayu Complex originated within an extensional tectonic setting associated with the Early Cretaceous subduction of the Paleo-Pacific Plate underneath the Eurasian Plate. Cu–Pb–Zn mineralization, primarily localized within the monzodiorite, is interpreted to be generated by magmatic-hydrothermal fluids. Therefore, ~120 Ma dioritic intrusions within the Jiaolai Basin constitute prospective targets for (Cu)–Pb–Zn polymetallic exploration.

The Xinqiao Cu-S polymetallic deposit is located in the Tongling ore concentration area of the Middle-Lower Yangtze River metallogenic belt. The orebodies consist of skarn orebodies and stratiform sulfide orebodies, but the genetic link between them remains controversial. In this study, magnetite was used as a proxy to systematically constrain the hydrothermal evolution from the intrusion to the contact zone and further to the stratiform orebodies. A representative drill hole (E603) was logged, and samples were systematically collected from the Jitou pluton outward to the contact zone. Composite samples from the 8–28 m interval were crushed and prepared as resin mounts for integrated TIMA automated mineralogy, BSE textural observation, and in situ LA-ICP-MS trace element analysis. Five types of magnetite (Mt1 to Mt5) were systematically identified. Mt1 occurs as inclusions within feldspar in the quartz monzodiorite. It exhibits typical magmatic magnetite characteristics and contains grid-like ilmenite exsolution, indicating crystallization during the late magmatic stage. Mt2 is distributed in the interstices of magmatic minerals, commonly showing hematitization and replacement of ilmenite exsolution lamellae by titanite. Its trace element geochemistry displays magmatic–hydrothermal transitional features. Mt3–Mt5 in the skarn and stratiform orebodies are paragenetic with retrograde alteration minerals (e.g., epidote, chlorite, and actinolite) and sulfides, and are characterized by low Ti, Al, and V contents and high Mg, Mn, and Sn contents, indicating a hydrothermal origin. From Mt3 to Mt5, (Ti + V) and (Al + Mn) decrease, while Zn and Mn increase, accompanied by a decrease in the (Si + Al)/(Mg + Mn) ratio. This reflects a trend of decreasing fluid temperature and progressively enhanced wall-rock buffering. The Mg-in-magnetite geothermometer yields relatively consistent results for Mt1–Mt3, but anomalously high temperatures for Mt4–Mt5. This suggests that the elevated Mg activity in the fluid, caused by reaction with carbonate wall rocks, can significantly influence the calculated temperatures. Therefore, this geothermometer should be used cautiously for magnetite in the outer skarn zone and interpreted in combination with other temperature constraints. The textures, paragenetic mineral assemblages, and trace element characteristics of magnetite collectively reveal a continuous mineralization process linking the skarn and stratiform orebodies at Xinqiao, providing robust mineralogical and geochemical evidence for the contribution of Yanshanian magmatic–hydrothermal activity to the stratiform mineralization.

Quantifying gold occurrence in low-grade ores is challenging because gold minerals are sparse and fine-grained, limiting their detection in conventional polished sections. This study developed an integrated geometallurgical workflow using the Shaxi porphyry Cu–Au deposit in the Middle–Lower Yangtze River Metallogenic Belt as a case study. Representative ores containing 0.282 g/t Au were subjected to gravity pre-concentration and Superpanner enrichment, followed by resin-mount preparation. TIMA Integrated Mineral Analyzer (TIMA) analysis, electron probe microanalysis (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were combined with mineral mass-balance calculations to characterize gold mineralogy, grain size, liberation, and distribution among mineral hosts. Visible gold accounts for 98.78% of the total gold, whereas submicroscopic gold in sulfides contributes only 1.22% and is hosted predominantly by pyrite. The identified gold minerals are dominated by native gold, with minor electrum and calaverite, and gold grains predominantly range from 15 to 40 μm. At a grind size of 80% passing 150 μm, most gold can be liberated, with an estimated maximum theoretical flotation recovery of 86.53% under the assumed recovery conditions. The workflow links the characterization of discrete gold minerals with the quantification of submicroscopic gold, providing mineralogical constraints for processing low-grade porphyry Cu–Au ores. Its extension to cobalt and other critical metals warrants further evaluation, particularly where discrete mineral phases can be concentrated.