Hebei GEO University

ABSTRACT This study presents petrological, geochemical and geochronological data from the Cangjinyu mafic–ultramafic complex in the Beishan Terrane, northwestern China, aiming to clarify the origin of its Ni–Cu sulphide mineralisation and the regional tectonic evolution. LA–ICP–MS zircon U–Pb dating of olivine gabbro and gabbro reveals crystallisation ages of 278 and 276 Ma, respectively, indicating the emplacement timing of the complex. Re–Os isotopic dating of pentlandite gives an isochron age of 277 Ma, consistent with the host rock ages, suggesting a magmatic sulphide liquid immiscibility origin for the deposit. Geochemical analyses show that the rocks have tholeiitic affinities, low SiO 2 (41.33–50.79 wt.%), enriched heavy rare earth elements and depletions in high‐field‐strength elements, with negative Nb–Ta–Ti anomalies typical of arc‐related magmatism. High La/Nb (2.40–7.37) and low La/Ba (0.03–0.13) ratios indicate a subduction‐modified lithospheric mantle source metasomatised by fluids from ancient subducted plates. The complex formed in a post‐subduction extensional setting after the closure of the Paleo‐Asian Ocean, with magmatic evolution driven by fractional crystallisation and crustal contamination (1%–10%), leading to sulphide saturation and mineralisation.

The Abaga volcanic field of Inner Mongolia, northern China, is situated west of the Daxinganling-Taihangshan gravity lineament and within the eastern part of the Central Asian orogenic belt (the Xing-Meng orogenic belt). This volcanic field consists of alkali basalts and tholeiites. Previous studies reported eruption ages (14.57−2.55 Ma; Luo and Chen, 1990; Ho et al., 2008; Zhang et al., 2016; Wu et al., 2023) based solely on exposed samples. The range of eruption ages and the chronostratigraphic stages of the study area, based on drill core and outcrop samples, have not been deciphered until now. In addition, the petrogenesis of the tholeiites remains poorly understood. In this study, we present Ar-Ar ages, major and trace element data, and Sr-Nd-Pb-Hf-Mg isotopic values for drill core and outcrop samples from the Abaga basalts. These data are used to identify the eruption stages of this volcanic field, determine whether sedimentary carbonates were present in the magma source, and discuss the genesis of both the alkali basalts and the tholeiites. Based on Ar-Ar dating results and the geological features of the basalts, four eruption stages have been identified. The earliest effusive eruption dates back to 21.38 Ma, which is ∼6.81 m.y. older than previously reported ages. In addition, the Abaga alkali basalts display concentrations of TiO2 (2.57−3.58 wt%) and Na2O + K2O (4.05%−6.36%), along with CaO/Al2O3 (0.58−0.95), Hf/Hf* (0.46−0.83), and Zr/Hf (41.24−47.23) ratios. Their δ26Mg (−0.43‰ to −0.31‰) and δ66Zn (0.47‰−0.50‰; Liu et al., 2022) values are similar to those of carbonated basalts, demonstrating that their magma source was metasomatized by recycled carbonates. The modeling results for δ26Mg and (Zn/Fe) × 104 values illustrate that <10% carbonate was added to the mantle source. Compared to the alkali basalts, the tholeiites display higher Hf/Hf* values (0.78−0.89) and δ26Mg ratios (−0.35‰ to −0.24‰) and lower TiO2 abundances (2.50%−2.91%), CaO/Al2O3 values (0.68−0.85), and Zr/Hf ratios (38.57−42.08). These characteristics suggest that the tholeiites may have been generated by interactions between alkali basalts and the lithosphere. The two-end-member mixing calculation using 143Nd/144Nd and δ26Mg values demonstrates that the addition of 20%−60% lithospheric melt to the alkali basalt can account for the petrogenesis of the tholeiites. Subduction of the Pacific plate likely contributed to the addition of carbonate to the mantle source. In conclusion, these newly reported data provide new insights into the petrogenesis of the basalts.

Regional curtain grouting for water interception serves as a critical technique for achieving safe and efficient mining under complex hydrogeological conditions in deep mine deposits. This study focuses on the Cuihongshan Iron-Polymetallic Mine, where repeated incidents of water inrush and sand outbursts have occurred due to complex hydrogeological conditions. By identifying the water-conducting pathways and characterizing the spatial distribution of relative aquitards within the mining area, a precise hydrogeological model was established. On this basis, the engineering application and performance evaluation of horizontal curtain grouting were systematically investigated. Through field monitoring and multi-method joint analysis, the water-blocking effectiveness of the grouting technique was comprehensively assessed. The results demonstrate a significant sequential reduction in grout take per meter for primary, secondary, and tertiary grouting holes, indicating a clear cumulative grouting effect. The grout effectively filled karst fractures, forming a continuous and stable water-resisting curtain. The project successfully severed the hydraulic connection between the highly water-rich Quaternary aquifer and the mine workings, substantially reducing mine water inflow. This study provides important theoretical support and practical reference for water hazard control in similar deep metal mines.

This paper focuses on the limitations of single-layer supervision and overconfident one-hot targets in Multi-codebook Vector Quantization (MVQ) for knowledge distillation. To this end, we enhance MVQ by integrating multi-layer supervision and label smoothing. The implementation involves two key steps: during the knowledge extraction phase, knowledge is drawn from multiple teacher layers instead of a single one; during the knowledge transfer phase, label smoothing is applied to the one-hot codebook index targets. Cross-modal experiments on image (CIFAR-100) and speech (AISHELL-1) tasks show that multi-layer supervision and label smoothing can improve student performance in a complementary manner: multi-layer supervision provides a direct and robust gain, whereas the benefit of label smoothing is obtained through careful tuning of its noise parameter. Our work provides a straightforward enhancement for MVQ-based knowledge distillation and suggests that future work could explore dynamic noise scheduling for further performance improvement.

Abstract The monogamy and polygamy properties of quantum entanglement characterize fundamental constraints on the distribution of entanglement in multipartite quantum systems. In this paper, we investigate tighter monogamy and polygamy relations for multipartite entanglement. By establishing a new mathematical inequality, we derive a family of improved monogamy and polygamy inequalities for tripartite quantum systems and further extend these results to general multipartite systems. Comparisons with existing results show that the obtained bounds are tighter. Illustrative examples are provided to demonstrate the effectiveness of the proposed relations.

Water plays a critical role in the formation of large igneous provinces (LIPs) and deep-Earth material cycling. However, directly quantifying water content in ancient mantle sources remains a challenge. Here we developed a novel clinopyroxene-based hygrometer using a comprehensive dataset of 316 experimentally crystallized clinopyroxene samples with known equilibrium melt water contents. Based on this dataset, we trained and tested multiple machine learning models to predict water content from the major element composition of clinopyroxene. The S-MKL algorithm, a combination of a stacking-based representation learning framework (S-RL) and multiple kernel learning (MKL), achieved superior predictive accuracy and was selected as the optimal model. We applied this new hygrometer to clinopyroxene phenocrysts from the Permian Emeishan LIP in SW China. The results reveal a hydrous mantle source for the Emeishan LIP, with water contents comparable to those of backarc basin basalt. A pronounced decrease in the gradient of water content was identified from southwest to northeast, reflecting mantle source heterogeneity linked to Paleo-Tethyan oceanic slab subduction and stagnation in the mantle transition zone. Fractional crystallization modeling confirms that this gradient represents source-level variations rather than shallow processes. We conclude that fluids released from the stagnant slab metasomatized the mantle, enhancing its fertility and contributing to LIP generation. This study quantitatively establishes a link between slab-driven mantle hydration and LIP emplacement, highlighting the importance of plume-slab interactions and deep-Earth water recycling.