Heavy metals and As (HMs) pollution in mining areas are a widespread environmental concern. In this study, ground water, surface water, and sediment samples around the Dexing area, one of the largest Cu-polymetallic ore clusters in China, were collected to examine the concentrations and distributions of As, Cd, Cr, Cu, Hg, Pb, and Zn. Pollution indices, geo-accumulation index, and potential ecological risk index were used to estimate the pollution characteristics and ecological risk of HMs. The results show that the major pollutants in the surface water were Cd, Cu, Zn, and Pb, while the dominant ecological risk of HMs in the sediments originated from Cu, As, Hg, and Cd. Moreover, HMs in the surface water and sediments exhibited substantial spatial heterogeneity in the study area, indicating a severely disturbed environment due to mining activities. The proportions of HM pollutions were higher in the Dexing River and its tributaries than in the Le’an River and its tributaries. The surface water pollution was predominant at the tributaries closest to the mine area, while the sediment contamination has been expanded several kilometers downstream of the major rivers. Overall, the ecological risk of HMs was higher in the sediments than in the surface water.

Geogas-carried metal prospecting, an integral part of deep-penetrating geochemistry, is potentially effective in the geochemical exploration of concealed ore deposits. However, its principles and applicability remain controversial. This study summarizes and discusses the progress in geogas-carried metal prospecting in China. The method comprises three constituents: geogas, nanoparticles, and their vertical transportation. Researchers have failed to determine the exact contributions of different sources of geogas. Studies on Pb isotopes, rare earth element patterns of geogas, the comparisons between metals in soil, geogas, and ore geochemistry, and characteristics of nanoscale metals in earthgas (NAMEG), confirmed the relationship between NAMEG and concealed ore deposits. A statistical analysis of field experiments and applications showed that geogas-carried metal prospecting is applicable for the geochemical exploration of magmatic and hydrothermal Cu, Au, Zn, Pb, U, Sn, and Ag deposits and is suitable for most geochemical landscapes except deserts and cold swamps. Finally, genetic models of NAMEG anomalies were constructed. High-permeability migration channels are critical in the formation of NAMEG anomalies over concealed ore deposits. Future work entails applying geogas-carried metal prospecting to certain types of ore deposits and geochemical landscapes and studying NAMEG to provide quantitative information for targeting concealed ore deposits.

As China’s third-largest lead–zinc ore field, the Xicheng Ore Field has significant potential for discovering concealed deposits. In this study, a tectono-geochemical survey was conducted, and 1329 composite samples (comprising 5614 subsamples) were collected from the central part of the field. The dataset was analyzed using staged factor analysis (SFA) and concentration–area (C–A) fractal model. Four geochemical factors were extracted from centered log-ratio (CLR)-transformed data: F_2-1 (Ag–Pb–Sb–Hg), F_2-2 (Mo–Sb–(Zn)), F_2-3 (Au–Bi), and F_2-4 (W–Sn). Known Pb–Zn deposits coincide with positive F_2-1 and negative F_2-2 anomalies, as identified by the C–A fractal model, suggesting these factors are reliable indicators of Pb–Zn mineralization. Five Pb–Zn exploration targets were delineated. Statistical analysis and anomaly maps for F_2-3 and F_2-4 also indicate the potential for Au and W mineralization. Notably, some anomalies from different factors spatially overlap, indicating the possibility of epithermal Pb–Zn mineralization at shallow depths and mesothermal to hyperthermal Au and W mineralization at great depths. Overall, the integration of tectono-geochemistry, targeted and composite sampling, SFA, and C–A fractal modeling proves to be an effective and economical approach for identifying and enhancing ore-related geochemical anomalies.

Ultrapotassic lamprophyre dykes are spatially closely related to gold deposits in collision tectonic belts. However, the potential implication of these lamprophyre dykes to gold deposits remains poorly constrained. Abundant ultrapotassic lamprophyre dykes in the Baiyun gold deposit of Liaodong Peninsula, NE China, are closely associated with Au orebodies. This presents an excellent opportunity to investigate the genesis and tectonic significance of these dykes, as well as their potential connection to gold mineralization. Here, based on LA-ICPMS zircon U-Pb age, petrogeochemistry, and Sr-Nd-Hf isotopic composition characteristics, we studied the ultrapotassic lamprophyre dykes in the Baiyun gold deposit. Zircon U-Pb dating of lamprophyre dykes is 225.7 ± 1.3 Ma, which is consistent with the previous auriferous pyrite Re-Os data results within error, indicating that the lamprophyre dykes and gold deposits formed simultaneously in the Late Triassic, which coincided with the exhumation of the deeply subducted South Chin Block (SCB). The lamprophyre dykes belong to the shoshonitic series (K₂O + Na₂O = 6.39–7.57 wt.%, K₂O/Na₂O = 3.99–8.74) and are enriched with magnesium (MgO = 5.33–6.40 wt.%, Mg^# = 58–65), barium (Ba = 2225–3046 ppm), and strontium (Sr = 792–927 ppm), and their (⁸⁷Sr/⁸⁶Sr)_i isotopic composition ranges from 0.712514 to 0.714831, ε_Nd(t) ranges from −15.4 to −14.1, and zircon ε_Hf(t) values range from −14.3 to −12.5. These correspond to Paleoproterozoic model ages between 2.1 and 2.3 Ga, which are comparable to the ultra-high-pressure metamorphic rocks with the SCB nature found in the Dabie–Sulu orogenic belt. The results demonstrate that the overlying lithospheric mantle was possibly metasomatized by subducted SCB-derived melts before magma generation under the North China Block (NCB) in the Late Triassic. The lamprophyre dykes with high Nb/U and Th/Yb values, enriched Ba, Sr, REE, Na₂O + K₂O, K₂O/Na₂O, and the LOI demonstrate that the metasomatic agents were hydrous, high-pressure melts. These melts likely resulted from the partial melting of subducted continental crust, which is attributed to phengite breakdown in the subduction continental channel. The silica-rich melts migrate from the plate into the sub-continental lithospheric mantle (SCLM) and form potassic- and volatile-enriched metasomatized SCLM. Subsequently, the partial melting of metasomatized SCLM due to the decompression and thinning may be the main mechanism to generate the syn-exhumation ultrapotassic magma in a post-collision setting. This study suggests that the SCLM, metasomatized by melts derived from continental crust, plays a key role in generating volatile-rich hydrous SCLM during the continental subduction and collision stage. In contrast, during the post-collision stage, as tectonic forces transition from compressional to extensional, the abundant volatiles and ultrapotassic magma produced from the partially melted and metasomatized lithospheric mantle may significantly contribute to the transportation, enrichment, and precipitation of gold through magmatic-hydrothermal processes, facilitating the formation of gold deposits.

锂是新能源领域不可替代的关键金属,已成为矿产勘查和地质研究的热点。我国南方地区的四川、江西、湖南是最重要的锂资源基地。近二十年来,花岗岩、伟晶岩等硬岩型锂矿取得重大找矿突破,此外,滇-黔-桂地区发现大量黏土型锂矿化线索。然而,相比于锂成矿理论的显著进展,不同类型锂矿的区域地球化学特征研究明显不足。本文利用中国南方水系沉积物76元素数据,绘制了锂地球化学图。以锂47.7×10^-6为异常下限,圈定了16个锂地球化学省。已知锂成矿带与锂地球化学省空间上相互吻合,约83%的已知锂矿位于锂地球化学省内。此外,提取并对比了花岗岩型、伟晶岩型和黏土型锂矿区与非矿区76种元素、26个地球化学指标的差异,结合基于随机森林的指示元素重要性度量结果,建立了不同类型锂矿的区域地球化学勘查标志。伟晶岩型锂矿区微量元素Li、Be、Rb、Cs、Ta、W、Sn、B强烈富集,As、P、F、Th、U相对富集,Zr、Ti相对亏损;主量元素Al₂O₃含量较高,K₂O含量较低;Li/Y值较高。花岗岩型锂矿区微量元素Li、Be、Cs、Nb、Ta、Bi、W、Sn、Rb、U、F、B相对富集,Ti、Co、Ni、Sr、Ba、V、P相对亏损;具有较高的Rb/Sr和较低的Nb/Ta、Zr/Hf、K/Rb值;δEu显著负异常。黏土型锂矿区域地球化学特征为富集微量元素Li、Sc、V、Ga、Nb、Th、U、Mo、REE、Cr;主量元素Al₂O₃、Fe₂O₃^T相对富集,无显著的δEu负异常。综上,区域化探可以在"以锂找锂"基础上,利用不同类型锂矿的特征性指示元素组合圈定锂找矿远景区。