The Zaozigou Au-Sb deposit has been controversial in its genesis and remains one of the most difficult ore systems to fully understand in West Qinling. The mineralization shows a broad spatial association with Triassic dikes and sills, which were previously thought to be genetically related to mineralization. Our U-Pb zircon dating in this contribution indicates that the ore-hosting porphyritic dacites were formed at 246.1 ± 5.2 Ma and 248.1 ± 3.8 Ma. The magmatic zircons yield ε_Hf(t) values ranging from −12.5 to −8.9, with corresponding two-stage model ages of 2.08 to 1.83 Ga. The magma therefore could be derived from partial melting of Paleoproterozoic crustal materials. The ore-hosting porphyritic dacites have low oxygen fugacity, with ΔFMQ ranging from −4.61 to −2.56, indicating that magmas could have been sulfide-saturated during evolution in deep chambers and precluding the possibility that metals were released from the melt. Zaozigou exhibits characteristics widespread volcanics, massive sulfide mineralization, rare reduced mineral assemblage and discrete alteration zones which are not typical of reduced intrusion-related or porphyry gold systems. We propose that the spatially-related Triassic porphyritic dacite and dike swarm is not genetically related to the ore formation of Zaozigou Au-Sb deposit.

The newly discovered Zaorendao gold deposit is in the Tongren-Xiahe-Hezuo polymetallic district in the westernmost West Qinling orogenic belt. The estimated pre-mining resource is approximately 13.6 t of Au at an average grade of 3.02 g/t. Mineralization is predominantly controlled by NW-trending and EW-trending faults within diorite intrusions and surrounding sedimentary rocks. In the present study, in situ zircon U–Pb geochronology and Lu–Hf isotopic analyses of the ore-hosting diorite at Zaorendao were measured using LA-ICP-MS. The data suggest that the diorite was emplaced at ca. 246.5 ± 1.9 Ma. The large variation of zircon Hf isotopic composition (ɛ_Hf(t) values ranging from −12.0 to −1.8) indicates a two-stage model age (T_DM2) that ranges from 1.4 Ga to 2.0 Ga. Such Lu–Hf isotopic compositions indicate that the diorite was dominantly derived from a Paleo- to Meso-Proterozoic continental crust. The wide range of ε_Hf(t) and the presence of inherited zircon can be interpreted to suggest the mixing of Paleo- to Meso-Proterozoic continental crust with a mantle component. Combining such characteristics with the geochemistry of coeval rocks that are associated with the diorite, we therefore proposed that the gold-hosting Triassic diorite in the Zaorendao gold deposit formed in an active continental margin that was associated with the northward subduction of the paleo-Tethyan ocean.

Whether the genesis of gold deposits in the Northeastern Jiaolai Basin is consistent with that in the Northwestern Jiaodong area remains controversial. This study presents in situ Rb-Sr dating of sericite, along with in situ trace element and sulfur isotope analyses of pyrite in the Longkou gold deposit. The sericite Rb-Sr inverse isochron yields an age of 120.9 ± 2.4 Ma, indicating that gold mineralization occurred in the Early Cretaceous. Two generations of pyrite, Py1 and Py2, were identified. Py1 is anhedral and hosted in relatively low-grade, weakly altered marble wall rock. Py2 is euhedral to subhedral and hosted in relatively high-grade, strongly altered marble ore. The δ³⁴S value of Py1 is 7.38‰, whereas that of Py2 is 6.79‰. The decrease in δ³⁴S values from Py1 to Py2 reflects an increase in the oxygen fugacity of the ore-forming system. These features suggest that fluid–rock interaction led to an increase in oxygen fugacity, thereby triggering gold precipitation. The mineralization age and precipitation mechanism of the Longkou gold deposit are consistent with those of the Northwestern Jiaodong area. The Longkou gold deposit is best classified as a Jiaodong-type gold deposit.

Porphyry systems are currently among the world’s largest repositories of copper, gold, and molybdenite. The depth of ore formation is one of the principle controls on the nature and evolution of magmatic-hydrothermal processes, during which superposition of multiple fluid-flow events inevitably obscures temporal relationships between quartz vein and alteration minerals. This consequently complicates the interpretation of fluid origin and evolution. In this present study, we documented quartz cathodoluminescence (CL) textures that are invisible by transmitted light microscope from porphyry deposits under different environments. Three successive quartz generations are distinguished in both the Wenquan porphyry Mo deposit with depth of ore formation at ~4.5km, and the Taiyangshan porphyry Cu deposit with depth of ore formation at ~2km. A wide variety of CL textures showing quartz crystallization, fracturing and recrystallization are present. Concentric growth and CL-dark bands textures are dominant in both deep and shallow porphyry environments. Core-mantle, cobweb and homogenous textures are restricted to deep environment. Inwardly oriented growth and turbid growth zoning textures are prominent in shallow porphyry environment. A simplified scheme category of specific quartz CL texture is proposed to fingerprint relative depth of ore formation among porphyry systems, providing insights into detailed genetic models reconstruction and mineral exploration.

Three-dimensional (3D) technologies are increasingly used to digitize rocks, minerals, fossils, landforms, and other geological objects, but classroom evidence for their instructional value in mineral and resource geoscience remains limited. This quasi-experimental study examined whether tangible 3D-printed models were associated with higher immediate post-instruction performance than image-based instruction, and how their value varies with the representational demands of different geoscience tasks. The sample included 135 secondary students. The 3D-printing Group (n = 54) used tangible models, whereas the Traditional Group (n = 81) received image-based instruction across four topics: Cradle Stone, the Jiaodong-type Mineral System, Anchiornis huxleyi, and Detached Cave Dwellings. Baseline-adjusted analysis of covariance (ANCOVA) was used as the primary inferential test. The 3D-printing Group showed higher immediate post-test performance (adjusted means: 79.46% vs. 71.51%; difference = 7.95 percentage points; HC3 95% CI: 2.10–13.80; p = 0.008). The largest topic-specific advantage occurred for Anchiornis huxleyi, consistent with a task-dependent interpretation in which printed models are more useful when learning requires three-dimensional morphological interpretation. Questionnaire responses also favored 3D printing, especially for perceived spatial understanding. These preliminary classroom-based findings suggest that 3D-printed models are most useful when they preserve task-relevant spatial, structural, or morphological information.