The porosity and permeability of the rock surrounding lead–zinc deposits are key factors for controlling the migration and precipitation of ore-forming hydrothermal fluid. In this paper, the Huize super-large lead–zinc deposit was taken as the case study, and variations in the porosity and permeability of the wall rocks and their relationship with the orebody were analyzed by using CT scanning technology. The experimental results showed that the average pore radius of dolomite with a decreasing distance to the orebody ranged from 1.60 to 1.65 μm, increasing to 1.77~2.05 μm. The CT porosity increased from 2.76%–2.81% to 3.35%–3.99%. The average pore throat length decreased from 29.57–39.95 μm to 13.57–16.83 μm. In the research, it was found that the hydrothermal fluids rich in chemical elements changed the properties of the surrounding rocks. Temperature rise will lead to dolomitization of limestone and recrystallization of dolomite. This process led to an increase in the porosity of the wall rocks. During the formation of the orebody, the metal minerals in the hydrothermal fluid entered the pores of the rock. As a result, the pore radius and pore volume of the wall rocks were reduced, along with the pore throat radius and pore throat length. Therefore, the wall rock pores near the orebody were isolated from each other, and the permeability of the surrounding rock decreased. The variation characteristics for the porosity and permeability of the dolomite at various distances from the mine can be used to discover orebodies.

The Chang’an Chong Cu-Mo deposit is located in the Chang’an Cu-Mo-Au ore cluster in the southern Ailaoshan tectonic belt in southwestern China. There are six intrusive bodies in the mining area, among which the No.Ⅱ intrusive body is the largest and most closely related to Cu-Mo mineralization of skarn. The No. 1 main orebody is composed of the No. 1 copper orebody and No. 1 molybdenum orebody, which are distributed in parallel with similar shapes. In this paper, the age of skarn is determined by the LA-SF-ICP-MS U-Pb dating of garnet, and it is nearly consistent with the age of alkaline porphyry in this region (41–32 Ma). Compared with the U-Pb age of zircon from the ore-bearing porphyry and the Re-Os age of molybdenite, the U-Pb age of garnet was consistent with them within error, indicating that they were the same mineralization event, which further proves that the porphyry-skarn Cu-Mo-Au mineralization event along the Ailaoshan-Red River fault zone mainly occurred at 38~32 Ma. In-situ S isotope results show that the δ³⁴S mean values of disseminated pyrite (PyI), pyrite of sulfide veins (PyⅡ) and chalcopyrite (Ccp) in the main mineralization period are 2.35‰, 3.60‰ and 0.55‰, respectively. These δ³⁴S values are similar to those of magma and slightly enriched in δ³⁴S, and the δ³⁴S value of chalcopyrite is mainly concentrated near 0‰, so it can be considered that the S of the ore-forming fluid came from magmatic-hydrothermal fluids. Based on the comprehensive analysis of the regional metallogenic background, deposit chronology and isotope geochemistry, it is concluded that the Chang’an Chong Cu-Mo deposit was formed in an intra-plate post-collision strike-slip environment.

Metal mining affects an estimated 479,200 km of river channels worldwide, and contaminated sediments threaten aquatic ecosystems and human health long after mining ceases. This study examined 53 surface sediment samples from the Xiaozi River and six tributaries in a historical coal-mining area of Chongqing, southwestern China. As, Cd, Pb, Hg and Cr were evaluated using the geoaccumulation index, potential ecological risk assessment and freshwater sediment quality guidelines; differences among rivers were tested with the Kruskal–Wallis test, and sources were explored using APCS–MLR and PMF. Hg and Cd showed the greatest enrichment (mean geoaccumulation indices 1.19 and 0.35). Hg exceeded the background value at all sites and dominated potential ecological risk, accounting for 93.4% of the maximum risk index (914) in the Xibu River. Cr exceeded the probable effect level at 19 sites, whereas As and Hg showed localized exceedances. Concentrations of As, Cd, Pb and Cr differed significantly among rivers (p < 0.01), whereas those of Hg did not. Both receptor models identified Cr–Pb and As–Cd components, whereas Hg was associated mainly with a separate component. These findings identify Hg as the main management priority, together with tributary-specific monitoring of As, Cd and Cr.