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, epsilon Nd(t) ranges from -15.4 to -14.1, and zircon epsilon 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.

Supervised machine learning and deep learning algorithms have been commonly applied in identifying geochemical anomalies related to mineralization. However, the performance of supervised models is often hindered by two critical challenges of training deposit-type locations: (i) the scarcity of known mineral deposits available for training and (ii) the heterogeneity within multivariate spatial data signatures of deposits. While previous studies have attempted to address these issues through various data augmentation techniques and sample refinement strategies, effectively learning from limited and heterogeneous samples remains a significant hurdle. To address these limitations, this paper proposes a novel method that synergistically integrates unsupervised clustering algorithms, namely K-means and hierarchical density-based spatial clustering of applications with noise (HDBSCAN), with model-agnostic meta-learning (MAML). The proposed framework employs unsupervised clustering to partition the heterogeneous deposit-type locations samples into distinct, geochemically consistent subgroups, thereby addressing the issue of sample variability. Subsequently, a cluster-stratified sampling strategy is applied to construct representative few-shot tasks from these subgroups, ensuring that the full spectrum of sample characteristics is captured while preventing model bias. Experimental results demonstrated that this approach significantly outperforms conventional convolutional neural network models. Specifically, the non-augmented HDBSCAN-stratified MAML (HS-MAML-NA) model proved most effective, achieving the highest predictive accuracy with an AUC of 0.868 in predicting 21 deposits. Consequently, this integrated approach enhances the robustness and predictive accuracy in identifying geochemical anomalies related to mineralization, providing a more effective tool for mineral exploration, especially in geologically complex regions with sparse mineral deposits.

The Zaozigou gold deposit in the West Qinling Orogen represents a significant case study for understanding intrusion-related gold mineralization. This study employs an integrated approach, combining Re-Os isotopic dating of auriferous arsenopyrite with chlorite and arsenopyrite geothermometry, as well as fluid inclusion microthermometry, to constrain the timing of mineralization and the thermal evolution of the ore-forming system. Re-Os analyses of arsenopyrite yield an isochron age of 226.81 +/- 4.66 Ma (2 sigma) , broadly coeval with regional quartz diorite (similar to 230 Ma). The initial Os-187/Os-188 ratio of similar to 1.54 indicates a predominantly crustal source for the ore-forming metals. Arsenopyrite geothermometry records high- to intermediate-temperature formation conditions of similar to 300-474 degrees C, with a mean of similar to 391 degrees C. Quartz-hosted fluid inclusions in steeply dipping veins have systematically higher homogenization temperatures (overall mean similar to 245 degrees C), together with relatively restricted salinity and freezing-point ranges, averaging - 2.43 degrees C and 4.03 wt% NaCl eq., respectively. In contrast, fluid inclusions in gently dipping veins show lower homogenization temperatures (overall mean similar to 160 degrees C) and a broader salinity distribution (averaging similar to 3.36 wt% NaCl eq., with a freezing point of - 2.06 degrees C). Chlorite formed after biotite yields distinctly lower temperatures of similar to 185-246 degrees C, with a mean of similar to 227 degrees C, reflecting a late stage cooling hydrothermal overprint.These data define a clear thermal evolution from early high-temperature arsenopyrite formation, through intermediate-temperature fluid inclusion trapping, to late low-temperature chlorite alteration. They support an intrusion-related hydrothermal system in which the quartz diorite supplied heat, volatiles, and metals, while compressional structures within the Jiangligou Formation controlled vertical versus lateral fluid migration, cooling, and gold deposition.

The formation mechanisms of Mn(II) carbonate mineralization and the precise sources of metals in ancient sedimentary Mn ore deposits remain subjects of debate. The Ortokarnash Mn ore deposit occurred within a mixed carbonate-siliciclastic sedimentary sequence of the Upper Carboniferous Kalaatehe Formation consisting of three lithological members. In this study, detailed component-specific solution analyses were performed on same sample powders from the Ortokarnash Mn(II) carbonate ores and wall rocks. The acetic acid-soluble fractions (i. e., leachates) in Mn(II) carbonate ores show a distinct PAAS-normalized positive Ce anomalies (3.73 +/- 0.21), negative Y anomalies (0.90 +/- 0.03), and low Y/Ho ratios (22.42-24.84). These are typical features of modern marine hydrogenetic Mn(III/IV) oxide precipitates, indicating that the Mn(II) carbonate mineralization likely the diagenetic product of precursor Mn(III/IV) oxide reduction. The remarkable positive delta 53Cr values (1.04 +/- 0.11 %o) in leachates of the Mn ores further confirm that Mn(II) carbonates formed during diagenesis through the reduction of Mn(III/IV) oxides originally deposited from an oxygenated water column. Moreover, the PAASnormalized REE + Y patterns for leachates in associated wall rocks from the 3rd Member are characterized by no meaningful or a slight positive Ce anomalies (1.03-1.49, mean = 1.17), which is indicative of an active Mn (III/IV) oxide shuttle across a redox-stratified basin water column. The delta 53Cr values (-0.17 to 0.04 %o) in leachates of the associated wall rocks from the 3rd Member lie within or close to the Bulk Silicate Earth, and thus likely indicate discharge of Cr(III) of submarine hydrothermal origin in the local basin. The acetic acid-insoluble fractions (i.e., residues) in wall rocks are characterized by low Th/Sc (0.02-0.24) ratios, slight chondrite-normalized light REE enrichment (Nd/YbN = 2.08 +/- 0.77), primitive mantlenormalized LILEs enrichment, positive U-Pb and negative Nb-Ta-Ti anomalies, and high radiogenic Nd (-3.63 <= epsilon Nd(t) <= 3.94) and low radiogenic Sr (0.704854 <= (87Sr/86Sr)i <= 0.707710) isotope compositions, indicating that siliciclastic debris in wall rocks were likely derived from a depleted mantle source (e.g., WKO mafic volcanic rocks). By contrast, the residues in Mn(II) carbonate ores display low Al/Ti (13.63-21.85) and high Th/Sc (1.04-2.43) ratios, marked chondrite-normalized light REE enrichment (Nd/YbN = 7.52 +/- 2.23), primitive mantle-normalized LILEs enrichment, positive U-Th-Pb and negative Ta-Ti anomalies, and low radiogenic Nd (epsilon Nd(t) = -6.07 +/- 0.40) and high radiogenic Sr ((87Sr/86Sr)i = 0.708064 +/- 0.000612) isotope compositions. These element and isotope geochemical features are consistent with that of felsic/intermediate rocks, suggesting that siliciclastic component in Mn(II) carbonate ores were likely sourced from old crustal units (e.g., Tarim felsic/ intermediate basement rocks). Thus, it has been suggested that the Mn metal was likely derived from submarine hydrothermal vent fluids (delta 53Cr = - 0.03 +/- 0.07 %o), while this hydrothermal vent system likely occurred on an ancient continental crust (epsilon Nd(t) = -6.07 +/- 0.40).

The Laoliwan Ag-Pb-Zn deposit is situated in the southern margin of the North China Craton and represents the first large-scale Ag-Pb-Zn ore deposit discovered in the Xiaoshan District. Ag-Pb-Zn orebodies are structurally controlled by NW- and NNW-trending faults and primarily hosted within early Cretaceous granite porphyry intrusions. In this study, sulfide Rb-Sr isotope dating and C-H-O-S-Pb multiple isotope compositions were conducted to constrain the ore genesis of this deposit. The Rb-Sr isotopic data of sulfides yield a weighted mean isochron age of 132.8 ± 9.5 Ma and an initial 87Sr/86Sr ratio of 0.7115 ± 0.00016, indicating that mineralization occurred during the early Cretaceous and the ore-forming materials were derived from a crust–mantle mixed reservoir. The δ13 C (−1.3‰ to 0.7‰), δD (−96.3‰ to −86.7‰) and δ18OH2O (0.3‰ to 5.6‰) values suggest that the ore-forming fluids were mainly derived from magmatic water with a contribution of meteoric water during mineralization. The δ34S values of sulfides (+2.0‰ to +5.8‰) indicate a magmatic source. The Pb isotope data (206Pb/204Pb = 17.301–17.892, 207Pb/204Pb = 15.498–15.560, 208Pb/204Pb = 37.873–38.029) also reveal that the ore-forming materials originated from the lower crust with a small amount from the mantle source. By integrating geochronological and geochemical data, this study proposes that the Laoliwan Ag-Pb-Zn deposit is characterized as an epithermal deposit, with potential for the discovery of concealed porphyry Cu-Mo mineralization at depth. It is inferred to be related to tectonic–magmatic–fluid activities in the context of early Cretaceous lithospheric thinning along the southern margin of the North China Craton.

China's dependence on foreign gold resources has remained high for a long time, therefore it is an urgent and significant task to find and explore a batch of large gold deposits. The medium to low temperature magmatic-hydrothermal gold deposits is the main source of gold in China, thus finding the concealed and deep deposits is a hot topic in mineral exploration work. In this study, we focused on the medium to low temperature magmatic-hydrothermal gold deposits guided by the theory of prospecting and prediction in exploration area. We summarized the basic geological characteristics of medium to low temperature magmatic-hydrothermal gold deposits, and established a prospecting prediction model that includes the metallogenic geological body, mineralization structure and structural plane, and characteristics of mineralization. It provides ideas for prospecting and predicting this type of gold deposit, which could make a breakthrough in the exploration of concealed and deep gold deposits. The medium to low temperature magmatic-hydrothermal gold deposits can be subdivided into two subtypes: mesothermal gold deposit and telethermal gold deposit. They are generally developed in continental block and orogenic belt tectonic setting, hosted by a variety of wall rocks with a wide range of mineralization ages, but mainly clustered at the Mesozoic era. We defined that the metallogenic geological body of medium to low temperature magmatic-hydrothermal gold deposit is the intermediate-felsic intrusions, which presents a spatially dependent (1 similar to 5km), temporally consistent (10Myr), and genetically related relationship with the ore deposit/body. The metallogenic structure belongs to a composite structural system of fold, fault, and magma intrusion. The metallogenic structural plane mainly includes fault, siliceous calcium surface, karst structure and intrusion contact zone, explosive breccia rock, and hydraulic fracture. The mineralization style is controlled by the metallogenic structural plane and can be generally divided into four types: stratiform, veined, massive and composite type. In the early mineralization stage of mesothermal gold deposit, the temperature reach similar to 450 degrees C, and the hydrothermal alteration is widespread, including K-feldspathization, albitization, and dolomitization. In the main mineralization stage, the temperature is similar to 250 degrees C, and the hydrothermal alteration mainly include silicification, sericitization, and illiteization. Au usually coexists with Ag, accompanied by small amounts of Pb, Zn, and Cu. The principal sulfides are pyrite, with minor chalcopyrite, galena, and sphalerite. Conversely, in the main mineralization stage of telethermal gold deposit, the temperature below 250 degrees C, and the hydrothermal alteration mainly include silicification and quartzification. Au coexists with As and Sb, accompanied by trace amounts of Ag, which commonly observed as arsenopyrite and stibnite. The precipitation and enrichment mechanisms of gold include the fluid filling, fluid boiling, fluid mixing, and metasomatism. We established a geological model for mineral exploration prediction based on the center of mineralization is located between the rock mass and the contact zone that extends 2 similar to 3km, forming a binary structural pattern of "upper vein and lower layer" from shallow to deep, as well as the known regularity of lateral prostration of vein-like orebody. Under this model instruction, we redefined the types of gold deposits in major metallogenic zones/belts in China, and discovered new orebody styles and expanded the exploration space in the deep, which can provide more comprehensive insights into understanding of the metallogenic regularity of gold deposits, and make a new breakthrough in the exploration of gold deposits in major metallogenic zones/belts in China.

Machine learning (ML) models have been successfully adopted to delineate prospecting regions for a specific type of mineral deposit in data-driven mineral prospectivity mapping (MPM). The primary objective of the ML-based MPM is to effectively integrate multi-source mineral exploration information and enhance its predictive capability and precision. Prior studies demonstrated that one may achieve an improved performance MPM by using models trained by exploration targeting criteria closely associated with mineral deposits, along with coherent training samples with similar multivariate spatial data signatures. Random Forest (RF), Support Vector Machine (SVM), and Multi-Layer Perceptron (MLP) are employed to conduct mineral prospectivity maps in this study. By employing the Permutation Feature Importance and SHAP (SHapley Additive exPlanations) analysis from a global interpretable perspective, this study successfully identified the main impactful evidence layers contributing to mineralization predictions. Furthermore, the application of local interpretability through SHAP analysis facilitated the identification of regions where evidence layers provided consistent contributions to predictions, demonstrating a similar multivariate spatial data signature. By employing interpretable machine learning techniques, not only is the explainability of the model’s predictions significantly improved, but the performance of MPM is also markedly enhanced. Utilizing models trained on exploration targeting criteria closely associated with mineral deposits, along with coherent training samples characterized by similar multivariate spatial data signatures, the final probability map achieved an AUC value of 0.970 and exhibited strong spatial correlation with known deposits. This approach effectively delineates high-probability areas, thereby optimizing the identification of potential mineralization zones and providing guidance for future copper exploration efforts in the Qulong-Jiama district.

The Qiubudong silver deposit on the western margin of the Fuping ore cluster in the central North China Craton is a representative breccia-type deposit characterized by relatively high-grade ores, thick mineralized zones, and extensive alteration, indicating considerable potential for economic resource development and further exploration. Previous studies on this deposit have not addressed its genetic mineralogical characteristics. This study focuses on pyrite and quartz to investigate their typomorphic features, such as crystal morphology, trace element composition, thermoelectric properties, and luminescence characteristics, and their implications for ore-forming processes. Pyrite crystals are predominantly cubic in early stages, while pentagonal dodecahedral and cubic–dodecahedral combinations peak during the main mineralization stage. The pyrite is sulfur-deficient and iron-rich, enriched in Au, and relatively high in Ag, Cu, Pb, and Bi contents during the main ore-forming stage. Rare earth element (REE) concentrations are low, with weak LREE-HREE fractionation and a strong negative Eu anomaly. The thermoelectric coefficient of pyrite ranges from −328.9 to +335.6 μV/°C, with a mean of +197.63 μV/°C; P-type conduction dominates, with an occurrence rate of 58%–100% and an average of 88.78%. A weak–low temperature and a strong–high temperature peak characterize quartz thermoluminescence during the main mineralization stage. Fluid inclusions in quartz include liquid-rich, vapor-rich, and two-phase types, with salinities ranging from 10.11% to 12.62% NaCl equiv. (average 11.16%) and densities from 0.91 to 0.95 g/cm3 (average 0.90 g/cm3). The ore-forming fluids are interpreted as F-rich, low-salinity, low-density hydrothermal fluids of volcanic origin at medium–low temperatures. The abundance of pentagonal dodecahedral pyrite, low Co/Ni ratios, high Cu contents, and complex quartz thermoluminescence signatures are key mineralogical indicators for deep prospecting. Combined with thermoelectric data and morphological analysis, the depth interval around 800 m between drill holes ZK3204 and ZK3201 has high mineralization potential. This study fills a research gap on the genetic mineralogy of the Qiubudong deposit and provides a scientific basis for deep exploration.

The Weishancheng area of Tongbai County, Henan Province, is an important Au-Ag polymetallic ore concentration area in China, characterized by a widespread distribution of plutons and frequent magmatic activities. To investigate the genetic relationship between magmatism and the mineralization of gold and silver polymetallic deposits in the area, this study focuses on the porphyritic monzogranite of the Liangwan pluton and the biotite granite of the Taoyuan pluton in detail. The zircon U-Pb age of the Liangwan pluton is 128.5 +/- 0.7 Ma, placing its intrusion age in the Early Cretaceous. Similarly, the zircon U-Pb age of the Taoyuan pluton is 431.3 +/- 2.7 Ma, indicating an intrusion age in the Early Silurian. Petrogeochemical analysis reveals that both the Liangwan and Taoyuan plutons exhibit high SiO2, Na2O and Al2O3 contents, along with low MgO, Fe2O3 and CaO contents, indicating a (high-K) calc-alkaline series, and have the properties of peraluminous I-type granite. The total rare earth elements (REE) concentrations are low, with noticeable fractionation between light and heavy REE, and a negative Eu anomaly. High-field-strength elements (such as Nb, Ta, P, Ti) are depleted, while the large-ion lithophile elements (such as Rb, K, Pb) are enriched. The epsilon(Hf)(t) values of the Liangwan and Taoyuan plutons range from -16.1 to -18.8 and from 11.0 to 14.6, respectively. The mean values of Hf two-stage model ages (T-DM2) are 603 Ma and 2230 Ma, respectively. These results suggest that the Liangwan pluton may have formed through partial melting of ancient crustal materials in the Palaeoproterozoic, during extensional tectonic events following the subduction of Izanagi Plate. It appears closely linked to Au-Ag mineralization in the ore concentration area. The Taoyuan pluton likely originated from the depleted mantle and experienced some degree of crustal contamination. However, it is unrelated to regional mineralization.

The newly discovered vein-type Shirengou gold deposit on the northern edge of the North China Craton contains at least 8.69 tons of Au at an average grade of 9.80 g/t. Six auriferous quartz veins have been identified within Upper Jurassic rhyolitic breccia-bearing crystal-lithic tuff, and they follow NW-trending secondary faults. Gold mineralization was closely related to silicification, with pyrite as the predominant ore mineral. Four mineralization stages can be discerned, involving Stage I milky quartz, Stage II quartz-pyrite, Stage III gray quartzpolymetallic sulfide, and Stage IV quartz-calcite +/- pyrite. Zircon U-Pb dating of a pre-ore porphyryritic rhyolite dike sets an upper age limit on the gold mineralization of -131.1 Ma. Two-phase and single-phase aqueous inclusions were observed in quartz related to all four mineralization stages. From Stage I to Stage IV, the fluid inclusion homogenization temperatures decrease from respectively 257-340 degrees C to 230-277 degrees C, 201-250 degrees C and 161-200 degrees C, with corresponding salinities of 3.39-9.21, 2.24-8.00, 1.22-7.59, and 0.18-3.55 wt % NaCl equivalent, respectively. Thus, the ore-forming fluid can be described as moderate-high temperature, moderate-low salinity H2O-NaCl fluids. The delta 34S values of sulfides vary from 0.0 to 5.3 parts per thousand, indicating that the S was derived primarily from magmatic source(s), with some contribution from the metamorphic rocks of the surrounding Jianping Group. In-situ LA-ICP-MS trace element analysis of sulfides, together with our new age data, suggest that the ore-forming fluid was initially of Early Cretaceous magmatic-hydrothermal origin, and subsequently modified by interaction with the wall rocks of the Jianping Group, extracting the ore-forming metals from these rocks into the fluids.

The East Qinling Molybdenum Belt (EQMB), which is located on the southern margin of the North China Craton (NCC), is the largest Mo province in the world. This belt hosts a significant number of Mesozoic magmatic-hydrothermal Mo deposits and a small portion of pre-Mesozoic Mo deposits. Understanding the mineralization timing and mechanism of the unique pre-Mesozoic Mo deposits is essential to comprehend the evolution of the EQMB, the pre-Mesozoic Mo enrichment, and the Mesozoic Mo mineralization event. The recently discovered Zhaiwa deposit is a porphyry Mo deposit located in the Xiong’er Terrane of the EQMB. In this study, five molybdenite samples from the Mo-bearing quartz veins were analyzed for Re-Os isotopes composition. These samples yield an isochron age of 1794 ± 45 Ma, which represents the age of mineralization. The mineralization is mostly hosted within the biotite-amphibole plagiogneiss and granite porphyry. LA-ICP-MS U-Pb data of zircons constrain the crystallization age of the granite porphyry to be at 1791 ± 16 Ma. The close spatial and temporal association suggests that the granite porphyry is the causative rocks of the Mo mineralization. The δ34S values of pyrite vary from 5.3 to 6.8‰, suggesting that the S was mainly derived from magmatic source. The intrusion of magmas and associated Mo mineralization are contemporaneous to the regional Xiong’er volcanism that occurred during the late Paleoproterozoic. The Xiong’er volcanism was triggered by partial melting of lithospheric mantle in an extensional setting. The results of our study provide robust evidence for a late Paleoproterozoic Mo metallogenic event along the southern margin of the NCC. Future exploration should also consider the potential of late Paleoproterozoic porphyry Mo mineralization existing in the EQMB, which is closely associated with the Xiong’er volcanism.

The Xiling gold deposit (>592 t @ 4.02 g/t) in the eastern Zhaoyuan-Laizhou gold belt of the Jiaodong Peninsula, is currently the largest gold deposit and deepest gold mine in China. This study presents microthermometric fluid inclusions data on quartz gangue, as well as trace element and S isotope data on pyrite from different mineralization stages and depths in the Xiling gold deposit to provide new insights into the spatio-temporal evolution of the ore-forming fluid that led to a giant Early Cretaceous gold deposit in the Jiaodong Peninsula. The delta S-34 values of pyrite range from 7.5 to 15.2 parts per thousand, but vary temporally and spatially, reflecting a changes in physicochemical conditions as the ore-forming fluid migrated to different crustal levels over time, also suggesting Precambrian basement as the principal sulfur source. Trace element analyses of pyrite revealed that ore-forming metals were scavenged from the wall rock and then incorporated into the pyrite. Fluid inclusions data reveal that the ore-forming H2O-CO2-NaCl +/- CH4 fluid had a medium to high temperature (283-401 degrees C), medium-low salinity (1.91-8.00 wt% NaCl equivalent), analogous to most gold deposits in the Jiaodong Peninsula. Intensive interaction between the ore-forming fluid and wall rock changed the physicochemical conditions of fluid, leading to gold precipitation. The study supports the notion of the ore fluid of Jiaodong-type gold deposit having originated from a metasomatized lithospheric mantle.

The southern Great Xing’an Range is the most critical Sn-polymetallic metallogenic belt in northeast China. However, the tectonic setting of the Early Cretaceous magmatic-metallogenic ”flare-up“ event remains uncertain. This paper presents an integrated study on the occurrence, petrology, zircon U-Pb ages, whole-rock geochemistry, and in situ zircon Hf isotopes for Wenduerchagan granites of Xi Ujimqin Banner, central-eastern Inner Mongolia. These granites consist primarily of granite porphyry（with ages of 137 ± 1 Ma and 138 ± 1 Ma） and（porphyritic） alkali feldspar granite（with an age of 141 ± 2 Ma）, corresponding to the early Early Cretaceous. They are A-type granites characterized by high silicon, alkali, and TFe O/Mg O contents while being depleted of Ba, Nb, Ta, Sr, P, and Ti. They show right-dipping trend rare-earth element distribution characteristics with negative Eu anomalies（Eu/Eu * = 0.01–0.20） and weak heavy rare-earth element fractionation（（Gd/Yb） N = 0.77–2.30）. They demonstrate homogeneous zircon Hf isotopic compositions(positive ε Hf （t） values from +5.3 to +7.1 and young two-stage Hf model ages of 851–742 Ma) and high zircon saturation temperatures（av. 810°C）. These geochemical characteristics indicate that Wenduerchagan granites originated from the partial melting of juvenile crust under high-temperature and low-pressure conditions. Wenduerchagan granites most likely formed in a post-collisional compression-extension transition regime caused by the closure of the Mongol–Okhotsk Ocean, when combined with regional geology. Such a transition regime can probably be attributed to the upwelling of the asthenospheric mantle caused by the break-off of a subducted Mongol–Okhotsk oceanic slab. Upwelling asthenospheric mantle provided sufficient energy and favorable tectonic conditions for magmatism and mineralization of the Early Cretaceous.

在大量典型矿床剖析的基础上,以矿物学、岩石学、矿床学、构造地质学、地球化学等基础理论为指导,以大量实地观察和实验数据为支撑,通过总结矿山深部和外围找矿实践和典型矿床研究成果,按照成矿作用内因和外因相结合的辩证思维,成矿作用时间、空间、物质能量相统一的综合思维,以及元素地球化学分类和找矿预测矿床分类的比较思维,提出成矿地质体、成矿构造和成矿结构面、成矿作用特征标志等概念.成矿地质体是形成矿床主要矿产、决定主成矿阶段空间位置的成矿地质作用的实物载体,划分为沉积作用、火山作用、岩浆作用、变质作用和大型变形作用形成的 5 类成矿地质体.成矿结构面是赋存矿体的各类界面,包括构造界面、岩性界面、物理化学转换界面;成矿作用特征标志是能够直接指示矿体赋存位置和对找矿预测具有特殊意义的标志.依据成矿地质作用对中国主要矿床类型进行梳理划分,归纳总结了主要矿床类型的地质特征,构建了反映矿体赋存位置的成矿地质体-成矿结构面-成矿作用特征标志"三位一体"找矿预测地质模型.在此基础上,提出勘查区找矿预测的工作方法,对矿床学研究、找矿预测、矿产勘查工作具有重要的指导意义.

This paper is the result of mineral exploration engineering.[Objective] The Zhongshangou gold deposit is located in the north margin of North China Craton and the south side of ShangyiChongli-Chicheng deep fault.It is one of the typical gold deposits in Zhangjiakou-Xuanhua gold concentration area,Hebei Province.This paper discusses the characteristics and evolution of ore-forming fluids,in order to provide a theoretical basis for the exploration of the deposit.[Methods] This paper summarizes the regional mineralizing setting,geological characteristics of the mining area,ore body and ore characteristics.Representative samples from four metallogenic stages were selected to conduct research on fluid inclusion petrography and micro thermometry,hydrogen and oxygen isotopes,and helium and argon isotopes.[Results] The results indicate that it can be divided into four metallogenic stages:K-feldspar-pyrite-quartz stage（Ⅰ）,milky white quartz-pyrite stage（Ⅱ）,smoky gray quartz-sulfide stage（Ⅲ） and sulfide-poor-carbonate stage（Ⅳ）.Gas-liquid twophase primary fluid inclusions are mainly developed in each mineralization stage.The temperature measurement data of fluid inclusions show that the homogenization temperature and salinity of main ore-forming stage are respectively 210-250 and6.01%-13.62%NaCleqv.Hydrogen and oxygen isotope show that δ 18 O H2O and δD V-SMOW values are respectively-2.97‰-6.96‰and-94.6‰--80.2‰,which show that the δ 18 O H2O values drift to the atmospheric water line and show a linear change.Helium and argon isotope of the pyrite show that ~3He/~4He values are 1.82×10 -7 -9.24×10 -7 , 40 Ar/ 36 Ar values are 699.9-2200.4,R/Ra values are0.13-0.66,radiogenic 40 Ar * values are 55.89%-86.57%,and mantle derived helium values are 2.00%-10.86%.[Conclusions] The ore-forming fluid has experienced a continuous evolution process from medium-high temperature and medium-low salinity to low temperature and medium-low salinity.The main ore-forming stage experienced strong boiling.In the late stage of mineralization,there mixed in a large amount of meteoric water.With the development of mineralization,the proportion of mantle derived materials in mineralization increased gradually.The ore-forming fluid has the characteristics of magma fluid mixed with the crust and mantle.To sum up,the ore-forming fluid of Zhongshangou gold deposit is characterized by the intrusive rock related telluride-gold deposit.

成矿地质体找矿预测理论与方法的创建为中国勘查区找矿工作提供了理论指导和方法遵循,已广泛应用于矿集区、老矿山深部与外围的找矿预测和矿产勘查中.在河南省银洞坡金银矿集区、甘肃省早子沟金矿、四川省拉拉铜矿集区等83 个矿集区和 168 座矿山取得了良好的找矿效果.该理论方法的核心是构建成矿地质体-成矿构造和成矿结构面-成矿作用特征标志"三位一体"找矿预测地质模型.总结了应用成矿地质体找矿预测理论与方法开展找矿预测工作的流程和要点:开展预研究提出找矿思路,研究典型矿床确定主攻矿床类型;研究成矿地质体确定找矿方向,研究成矿构造与成矿结构面确定矿体赋存位置,研究成矿作用特征标志提供矿体赋存依据,构建找矿预测地质模型确定成矿作用中心;综合地质、物探、化探方法,预测深部矿体空间位置;探矿工程验证实现找矿突破.本次研究为找矿预测工作提供了思路和示范,为新一轮找矿突破战略行动提供了支撑服务.

河北平山县秋卜洞银矿为隐爆角砾岩型矿床,为寻找近矿标志,对该矿区的角砾岩体特征及围岩蚀变元素地球化学特征进行了研究.对角砾岩的地质、岩性、角砾特征(形态、大小、成分)、胶结物特征进行统计分析,结果发现:①由浅部到深部角砾形态为棱角状→次棱角状→次圆状;②角砾大小在浅部呈现由边部向中心减小的趋势,钻孔中角砾大小空间变化不明显;③角砾成分由浅到深从以浅粒岩为主,转变为以石英斑岩为主,中部角砾成分稍复杂;这种特征指示角砾岩体的形成依次受控于气爆(岩粉胶结)、液爆(金属硫化物胶结)与浆爆(岩浆胶结)作用.围岩蚀变过程中元素地球化学特征表明,该过程带入的组分为SiO2、CaO、MgO等,迁出的组分为K2 O、Na2 O、Al2 O3、Fe2 O3、FeO、Sr、Ba等,成矿元素Au、Ag、Cu、Zn、Sb、Pb等含量明显增加,鉴于Fe、Cu、Pb、Zn等以硫化物形式存在,稀土元素特征显示成矿环境由氧化条件逐渐转变为还原条件.综合研究揭示,该矿床形成经历了至少 3 个阶段流体沸腾作用,银卸载成矿在隐爆角砾岩形成的基础上,绢英岩化(带)与黄铁矿化叠加形成,因此,这 2 种蚀变的出现是靠近矿体的有利标志.

锰矿是中国大宗紧缺战略性矿产,在现代工业中具有广泛用途.近年来锰资源的战略地位急剧提升,锰资源勘查也日益受到重视.确定Mn元素在中国的浓度和分布对寻找新的锰矿床和缓解锰资源短缺至关重要.依托中国地球化学基准计划采集 3392 个汇水域沉积物样品数据,首次提供了中国深层土壤Mn地球化学背景和异常空间分布数据.全国汇水域沉积物深层样品Mn的平均含量为610 mg/kg,背景值为574 mg/kg.依据全国汇水域沉积物深层样品地球化学数据,以85％累积频率为异常下限,共圈定出 31 个Mn地球化学异常,归为 15 个地球化学省.根据Mn异常空间分布,结合地质背景和矿床分布,提出 8 处异常具有进一步寻找锰矿的远景区.

西昆仑玛尔坎苏锰矿带晚石炭世沉积岩系发育中国最富的大型碳酸锰矿床.含锰岩系岩相古地理在控制沉积锰矿形成方面具有重要意义,但目前对玛尔坎苏锰矿带晚石炭世岩相古地理特征缺乏系统研究.通过对该锰矿带内典型地段沉积剖面沉积相展布规律研究,表明矿带两端及中部含锰岩系(C2 k)表现为浅水环境碳酸盐岩台地相沉积特征;而在穆呼-玛尔坎土和奥尔托喀讷什矿区含锰岩系则主要发育深水台盆相沉积.斜坡相-台盆相沉积时空变化特征反映海进-海退沉积旋回.海进-海退事件可能与区域构造作用下发育的同生断裂活动有关.同生断裂可能控制该地区次级裂陷盆地沉积,进而控制金属锰的浓集和沉淀.

降低勘查风险、实现科学找矿一直是国内外矿产勘查界不断探索的前缘领域和研究热点,而勘查区找矿预测理论与方法是解决这一难题的有效途径.该方法将成矿作用内因(元素的地球化学特征)和外因(地质作用类型)相结合,构建以成矿地质体、成矿构造与成矿结构面和成矿作用特征标志为主要内容的找矿预测地质模型,通过大比例尺构造蚀变填图、物化探测量和专题研究等综合方法,预测推断矿体赋存位置,最后通过工程施工,发现并查明工业矿体(矿床).依据勘查区找矿预测理论与方法,在四川拉拉铜矿、新疆玛尔坎苏锰矿带穆呼?玛尔坎土锰矿及内蒙古大兴安岭南段敖脑达坝地区锡多金属矿开展找矿预测,取得了较好效果.