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The Wulong deposit is a large gold deposit in the Liaodong peninsula (North China Craton). Silicic and pyrite alterations are well-developed in the deposit and closely related to mineralization. The least altered and silicified microdiorite samples were selected for major and trace element analyses to reveal the elemental migration/enrichment. Pyrites of stage 1 (Py1) were selected for backscattered electron (BSE) imaging and LA-ICP-MS trace element analyses to reveal their possible metallogenic link. Mass balance calculation showed that Al2O3, CaO, Fe2O3, K2O, SiO2, Ag, As, Cu, and Pb were brought in, whereas MgO, Na2O, FeO, Cr, Zn, and Ni were leached out during silicification. LA-ICP-MS trace element analyses show that Py1 has higher Au and Zn contents than Py2 and Py3, Py2 has higher Au and Cu contents than Py1 and Py3, and Py3 has higher Pb, Cu, and As contents than Py1 and Py2. During the process of silicification and pyritization, the depleted H+ concentration and HS− concentration in the ore-forming fluids led to instability of the Au(HS)2− complexes and led to gold precipitation. The depleted sulfur and the reduced temperature during the precipitated of bismuthinite also led to instability of the Au(HS)2− complexes and gold precipitation. [ABSTRACT FROM AUTHOR]

Late Mesozoic granitoids are widely emplaced in the Qinling Orogen on the southern margin of North China Craton (NCC), and can provide important clues on the Late Mesozoic regional geodynamic setting. The Late Jurassic Laoniushan granitic pluton is located in the western end of the southern NCC margin. Zircon U–Pb dating for the granodiorite, quartz diorite, and biotite monzogranite of the pluton yielded 152.5 ± 1.6 Ma, 148.7 ± 1.2 Ma, and 149–146 Ma, respectively. Compilation of the single zircon ages revealed magmatic peaks at ca. 146, 152, and 163 Ma, suggesting multiphase Late Jurassic magmatism. These granitoids are high‐K calc‐alkaline, I‐type, and metaluminous to weakly peraluminous. The rocks show chondrite‐normalised LREE enrichments, HREE depletions and flat HREE patterns, together with (slightly) negative Eu, Nb, Ta, P, and Ti anomalies. The Laoniushan granodiorite and biotite monzogranite have similar REE patterns to the quartz diorite, but the former two have much smaller Eu anomalies than the latter. The negative zircon εHf(t) (−32.6 to −13.7), εNd(t) (−20.7 to −14.3) and crustal‐like whole‐rock trace‐elemental ratios (e.g., Nb/Ta, Th/U, Nb/U, and Ce/Pb), together with the low Mg (MgO = 0.18–2.02 wt%, Mg# = 20–34), Cr (7.00–39.0 ppm), and Ni (0.80–4.00 ppm) contents, suggests that the Late Jurassic granitoids were probably derived from the partial melting of ancient crustal rocks with minor mantle‐derived input. The granodiorite and quartz diorite have similar average εHf(t) (−26.5 and −26.7, respectively), εNd(t) (−20.5 and −20.2, respectively), TDM2(Hf) (2880 and 2885 Ma, respectively) and TDM2(Nd; 2607 and 2578 Ma, respectively), whereas the biotite monzogranite has higher average εHf(t) (−17.1) and εNd(t) (−15.3), and younger TDM2(Hf) (2281 Ma) and TDM2(Nd) (2176 Ma). This suggests that the biotite monzogranite has different magma sources and shallower magma formation depths compared to the granodiorite and quartz diorite. The latter two were likely formed by the partial melting of continental crustal rocks (notably the Taihua Group basement rocks), which was triggered by mantle underplating led by asthenospheric upwelling. The Late Jurassic Laoniushan granitoids may have formed in an extensional setting caused by the Palaeo‐Pacific Plate subduction beneath Eastern China. Commencement of Late Jurassic Laoniushan granitic magmatism likely marked the incipient of lithospheric thinning along the southern NCC margin. Considering also the regional geological evolution, we conclude that although the Laoniushan pluton exhibits spatial–temporal relationships with the nearby Mo (–U) and REE deposits, there is still no unambiguous metallogenic link with these deposits. [ABSTRACT FROM AUTHOR]

The Eastern Tianshan Orogen (Xinjiang, NW China) in the Central Asian Orogenic Belt (CAOB) is featured by its many Carboniferous-Triassic mafic-ultramafic intrusions and associated magmatic Fe-Ti-V oxide mineralization. In this study, we present the first systematic data comparison on the age and whole-rock geochemistry of the ore-forming mafic-ultramafic complexes at Yaxi, Niumaoquan, Xiangshanxi, and Weiya. Our new age dating on the Yaxi complex indicates that the mineralized gabbro (zircon SHRIMP U-Pb dated 297.3 ± 4.9 Ma) formed in the latest Carboniferous-Early Permian, similar to the diorite (LA-ICP-MS zircon U-Pb dated 308.3 ± 8.6 Ma) and granodiorite (LA-ICP-MS zircon U-Pb dated 304.9 ± 1.7 Ma). The Yaxi complex is the oldest late Palaeozoic mafic-ultramafic intrusion reported so far in the Eastern Tianshan. The mineralized gabbro at Yaxi contains higher average Fe2O3T (20.83 wt.%), TiO2 (5.91 wt.%), and V (523 ppm) contents than its ore-barren counterpart (7.45 wt.%, 0.99 wt.%, and 133 ppm, respectively). These Eastern Tianshan mafic rocks are mildly large ion lithophile element (LILE) enriched and high field-strength element (HFSE) depleted, and with LREE/HREE enrichment (Yaxi: (La/Yb)N = 2.7 ~ 5.37) and subtle positive Eu anomalies (Yaxi: Eu/Eu* = 0.94 to 3.31). This suggests that the Eastern Tianshan mafic-ultramafic magmas were likely derived from an arc/subduction-modified magma source. The E-W trending crustal-scale faults (e.g. the Aqikkuduk fault) may have acted as magma conduits and controlled the magma emplacement. The spatial-temporal distribution of the Eastern Tianshan Fe-Ti-V ore-forming mafic-ultramafic complexes and their petrologic and geochemical features suggest that the latest Carboniferous-Early Permian magmatic phase was likely emplaced in a collision-related compression setting following the Junggar Ocean closure, whereas the late Early Permian phase may have been related to a post-collisional orogenic setting. [ABSTRACT FROM AUTHOR]

Multiphase Late Mesozoic magmatism is clearly recorded at the Xiaokelehe porphyry Cu Mo deposit in NE China, including the syn -ore granodiorite porphyry, and post-ore diorite, gabbro, monzonite (porphyry), and granite porphyry. In this study, we present new geological, LA-ICP-MS zircon U Pb geochronological and geochemical data on these intrusive units to unravel the tectonic evolution of the Late Mesozoic Great Xing'an Range (GXR). Zircon U Pb dating indicates that the multiphase magmatism extended from the Late Jurassic to Early Cretaceous, i.e., 149.4 ± 4.0 Ma (diorite), 148.9 ± 1.4 Ma (granodiorite porphyry), 146.9 ± 4.1 Ma (monzonite), 140.6 ± 3.8 Ma (gabbro), and 139.9 ± 4.3 Ma (monzonite porphyry). Geochemical data indicate that the syn -ore granodiorite porphyry is adakie-like, featured by relatively LILE-enrichments (Rb, Ba, K, Pb, LREEs), high Sr contents (1065–1130 ppm), and elevated Sr/Y (129.9–171.8) and (La/Yb) N (35.12–47.07) ratios, but with HFSE-depletions (Nb, Ta, Ti, HREEs), low Y (6.2–8.7 ppm) and Yb (0.48–0.67) contents. The granodiorite porphyry has relatively higher Mg# values (41–47), depletion of Nb and Ta, low Cr (29.0–31.0 ppm) and Ni contents (9.4–12.6 ppm), as well as enriched Sr Nd isotope features, indicating that the granodiorite porphyry was derived from an enriched mantle (garnet-bearing) refertilized by subduction-related melts in a post-collision setting, and the magmas were subsequently fractionated during their ascent. The diorite and gabbro may have also derived from the refertilized lithospheric mantle (but without garnet), whereas the monzonite and its porphyry were derived from the lower crust at >40 and < 40 km depths, respectively. Meanwhile, fractionation and crustal assimilation have been important for the diorite, gabbro, and monzonite (porphyry) formation. Combined our study with published ones, we concluded that: (1) the Mongol-Okhotsk Ocean was finally closed in the GXR before the Late Jurassic; and (2) Late Mesozoic magmatism and porphyry Cu Mo mineralization in the GXR likely occurred in the compressive-to-extensional transition after the collision between the Mongol-SinoKorea and Siberia plates. Unlabelled Image • Multiphase magmatism identified in the Xiaokelehe Cu Mo deposit. • Intrusions at Xiaokelehe occurred from Late Jurassic to Early Cretaceous. • Granodiorite porphyry is derived from partial melting of an enriched mantle. • Magmatism and mineralization formed in post-collisional environment. [ABSTRACT FROM AUTHOR]