The Jiepailing deposit in southern Hunan is a typical large to super-large polymetallic tin deposit enriched in beryllium and other rare metals. To enhance the understanding of the mineralization processes of the Jiepailing deposit, detailed mineralogical, in situ geochemical, and sulfur isotopic analyses were conducted on pyrite closely associated with tin–polymetallic mineralization. Five types of pyrite have been identified in the deposit: (1) euhedral to subhedral medium- to coarse-grained pyrite (PyI) in tungsten–tin ore; anhedral fine-grained pyrite (PyII) in tin polymetallic–fluorite ore; anhedral fine-grained or aggregate pyrite (PyIII) in lead–zinc ore; euhedral to subhedral coarse-grained pyrite (PyIV) in beryllium–fluorite mineralization; and subhedral to anhedral fine-grained pyrite (PyV) in carbonate veinlets developed in the wall rock. Backscattered electron imaging indicates consistent structural features across the five types of pyrite. In situ trace element analysis reveals differences in trace element concentrations among the pyrite types. PyI is relatively enriched in Sn, Cu, and Co. In contrast, PyIII is enriched in Pb, Zn, Sn, and Ti, while PyIV and PyV are enriched in Ag and Sb. PyI has a Co/Ni ratio more than 1, while the Co/Ni ratios in the other four types of pyrite are less than 1. LA-MC-ICP-MS in situ sulfur isotope analysis shows δ³⁴S values ranging from 2.5‰ to 5.8‰ (average 4.3‰, PyI), 2.5‰ to 5.8‰ (average 4.3‰, PyII), −7.6‰ to 9.5‰ (average 3.9‰, PyIII), −3.7‰ to 10.6‰ (average 3.6‰, PyIV), and 6.8‰ to 14.1‰ (average 9.2‰, PyV). Based on previous studies, regional geological background, deposit characteristics, and the in situ trace element and sulfur isotope compositions of pyrite, it is inferred that the various ore bodies in the Jiepailing deposit are products of Late Cretaceous magmatic–hydrothermal activity. The early ore-forming fluid originated from magmatic sources and during the migration into the wall rock and shallow formations, mixed with fluids primarily derived from atmospheric precipitation. Temperature, pressure, and composition changed of the ore-forming fluid which carried a large amount of substances, leading to tungsten–tin, tin polymetallic–fluorite, lead–zinc, and beryllium–fluorite mineralization, followed by carbonation during the late-stage mineralization.

The Youjiang Basin in western Guangxi hosts a major Carlin-type gold ore district and constitutes an essential component of the Yunnan-Guizhou-Guangxi “Golden Triangle”. The Baifeng deposit represents a large-scale gold deposit in western Guangxi, yet the source of gold ore-forming materials for this deposit has not been previously investigated. Based on detailed field geological surveys, vein samples from different fault structures within the deposit were collected for integrated analyses, including apatite geochemistry, fluid inclusion microthermometry, laser Raman compositional analysis, and in situ trace element and sulfur isotope testing of pyrite. The weighted mean U-Pb age of apatite is 306.9 ± 6.5 Ma, inherited precursors captured by the hydrothermal system rather than syn-ore hydrothermal apatite; this age therefore records the formation age of the apatite source rock, not the timing of gold mineralization. Geochemical discrimination diagrams indicate that the apatite is not of sedimentary origin, and its parent source belongs to medium- to high-magnesium magma dominated by melted subducted sediment components. This suggests that the ore-forming fluids/melts and the reservoir of ore-forming metals such as Au were derived from terrigenous sediments subducted during the Late Paleozoic. In the main mineralization stage, pyrite mainly occurs as fine-grained As-rich aggregates with low automorphism. Fluid inclusions yield homogenization temperatures of 230–291 °C (average 266.2 °C) and salinities of 9.6–16.2 wt% NaCl eqv. (average 12.0 wt% NaCl eqv.), characteristic of a medium-temperature and medium-salinity hydrothermal system. Pyrite from this stage contains the highest Au concentration among the three generations and yields tightly clustered δ³⁴S values around −7.55‰ (range −7.43 to −7.65‰), corresponding to the primary stage of Au precipitation and enrichment in the deposit. During the post-main mineralization stage, pyrite mostly occurs as regular polygonal grains with markedly higher automorphism relative to the main mineralization stage. Fluid inclusion homogenization temperatures range from 189 to 276 °C (average 223.1 °C), with salinities of 7.6–17.2 wt% NaCl eqv. (average 11.6 wt% NaCl eqv.). Pyrite Au content decreases while Sb increases. Pyrite δ³⁴S values (−8.32 to −6.88‰) largely overlap with the main-stage range but show greater scatter, indicating weakening of the deep fluid signal and increasing wall-rock interaction. In the late mineralization stage, reactivation of regional faults triggered superimposed modification by late hydrothermal fluids. Pyrite grains in this stage are generally fine. Fluid inclusion homogenization temperatures vary from 131 to 222 °C (average 165 °C), and salinities range from 8.1 to 14.5 wt% NaCl eqv. (average 10.6 wt% NaCl eqv.). F Pyrite Au content reaches its minimum while Sb peaks. Pyrite δ³⁴S shifts markedly to less negative values (−6.06 to −4.29‰, mean −5.42‰), recording a significant change in sulfur source toward oxidized, shallow fluids or wall-rock-derived sulfur. The overall evolution—decreasing temperature, progressive oxidation of the gas phase, and a systematic shift of pyrite δ³⁴S toward less negative values—is consistent with a hydrothermal system evolving from a deep, reducing crustal fluid toward shallower, more oxidizing conditions, with progressive Sb enrichment in residual fluids. This is consistent with the regional Au–Sb association and late stibnite overprinting characteristic of Carlin-type gold deposits.

The Guposhan ore field, located in the Nanling metallogenic belt, is well known for large-scale Sn-W mineralization genetically linked to the Late Jurassic Guposhan pluton. The Lisong pluton, a product of regional magmatism, occurs in the central part of the Guposhan ore field. However, the critical factors responsible for the absence of intensive Sn polymetallic mineralization in the Lisong pluton remain poorly understood. Our geochronological results show that the coarse-grained hornblende-bearing and hornblende-free biotite monzogranites of the Lisong pluton were emplaced at 162.9 ± 1.5 Ma and 162.2 ± 2.3 Ma, respectively, which are contemporaneous with the Guposhan pluton. Geochemically, these intrusions are characterized by high SiO₂, Al₂O₃, and total alkalis (K₂O + Na₂O), high Ga/Al ratios (3.09–3.69), and peraluminous compositions (A/CNK = 1.15–1.23), consistent with high K calc-alkaline A-type granites. Similar to the adjacent Guposhan pluton, the Lisong granites yield variable _εHf(t) values from −3.0 to 5.7, apatite ⁸⁷Sr/⁸⁶Sr ratios of 0.69747–0.71190, and old two-stage Hf model ages (T_DM2) of 0.85–1.40 Ga. These features suggest that the Lisong and Guposhan granites may share a common magma source involving mixing of crustal and mantle-derived melts. Apatite grains from the Lisong granites display negative Eu anomalies (δEu = 0.03–0.22) and near-normal to positive Ce anomalies (δCe = 0.99–1.07), which we interpret to reflect plagioclase fractional crystallization and reduced melt conditions, respectively. Bulk rock geochemistry and multi-element systematics of the Lisong granites indicate that they represent early-stage magmatic products. Their relatively low differentiation signatures were unfavorable for Sn enrichment and mineralization in the melt, which likely explains the lack of intensive Sn polymetallic mineralization in the Lisong pluton.

Artificial-source frequency-domain electromagnetic methods are important tools for deep mineral exploration and concealed geological structure detection. Apparent resistivity is a key parameter linking measured electromagnetic fields to the interpretation of subsurface electrical structures, and its calculation method directly affects geological interpretation and engineering applicability. Although substantial efforts have been devoted to the theoretical development, data processing, and practical application of different apparent resistivity formulations, most previous studies have focused on the analysis and improvement of a single method. Systematic comparisons of the main apparent resistivity formulations under unified conditions remain limited, particularly in terms of deep basement characterization, anti-interference performance, and engineering applicability. To fill this gap, this study systematically compares the $E\text{–}{E}_x$ wide-field apparent resistivity, the $E\text{–}{E}_x$ far-zone apparent resistivity, and the $E\text{–}{Z}_{xy}$ Cagniard apparent resistivity. Through theoretical derivation, forward modeling of typical one-dimensional models, and field verification, the differences among these three formulations in geological characterization, anti-interference capability, and engineering applicability are analyzed, with the aim of clarifying their applicable boundaries and selection principles for artificial-source frequency-domain electromagnetic exploration.