A Preliminary Review of Metallogenic Regularity of Silver Deposits in China

China has widely distributed silver deposits,and is rich in silver resources.Although silver deposits are mainly associated with Pb-Zn deposits,a number of independent silver deposits have also been discovered in recent years.Silver deposits include different types,such as submarine volcanism and continental volcanism related type,intrusion related type,and sedimentary related type.This study summarized the metallogenic regularity of China＇s silver deposits systematically based mainly on the data from 490 silver deposits.It is shown that submarine volcanic sedimentary type,continental volcanic or sub-volcanic type,skarn type,hydrothermal type（including vein type and stratabound type）,sedimentary metamorphic type,sedimentary type and regolith type should be regarded as the most important prediction types of silver deposit.A total of 32 silver mineralization belts and 111 silver concentration areas have been delineated.The map of ＂Spatial distribution of silver mineralization belts in China＂ and other series of maps finished in this study may provide a theoretical basis for the evaluation and prognosis of silver resources potential in China.

Classification,metallogenesis and exploration of silver deposits in Daxing’anling of Inner Mongolia and its adjacent areas

By the end of 2020,83 silver deposits(or ore occurrences),including four super-large-scale deposits,nine large-scale deposits,33 medium-scale deposits and 37 small-scale deposits or ore occurrences,have been proved.The amount of silver metal exceeds 86000 t with average grade of 100 g/t,which makes Daxing’anling region one of the the most important silver ore belt in China.However,the metallogenic characteristics and metallogenesis need to be clarified.The silver deposits in the study area are classified into three main types,which are magmatic hydrothermal vein type,continental volcano-subvolcanic type and skarn type,respectively.The supergiant deposits include the Shuangjianzishan deposit(silver metal amount of 15214 t with average grade of 138 g/t),the Baiyinchagandongshan deposit(silver metal amount of 9446 t with average grade of 187 g/t),the Huaobaote deposit(silver metal amount of 6852 t with average grade of 170 g/t),and the Fuxingtun deposit(silver metal amount of 5240 t with average grade of 196 g/t).The silver deposits are mainly distributed in the central and south of the Daxing’anling area,and mainly formed in the Yanshanian period.The silver polymetallic deposits in the Daxinganling area are significantly controlled by regional faults and the junction zone of volcanic rock basins and their margins.The north-east trending deep faults are the most important ore-controlling structures in this area.The distribution of silver polymetallic deposits along the main faults is obvious,and the intersection area of multiple groups of faults often form important mine catchments.The Permian is the most important ore-bearing formation in this area,but some important silver polymetallic deposits occur in Mesozoic volcanic basins or pre-Mesozoic strata.The magmatic rocks related to mineralization are mainly intermediate acidic or acidic intrusions,intermediate acidic lavas,pyroclastic rocks,and small intrusions of ultra-shallow or shallow facies of the Yanshanian Period.The mineralization element combination is mainly determined by the elemental geochemical background of surrounding rocks or source layers.In addition,the type of deposit,the distance from the mineralization center,and the degree of differentiation of ore-forming rock mass are also important influence factors.The article analyzes the prospecting prospects of each silver deposit type in the study area,discusses the relationship between mineralization center and deep prospecting,and proposes that porphyry silver deposits should be paid attention to.In the prospecting and exploration of silver deposits,comprehensive evaluation and multi-target prospecting need to be strengthened because silver can coexist or be associated with a variety of metals.

Geology and D-O-C Isotope Systematics of the Tieluping Silver Deposit,Henan, China: Implications for Ore Genesis

The Tieluping silver deposit, which is sited along NE-trending faults within the high-grade metamorphic basement of the Xiong'er terrane, is part of an important Mesozoic orogenic-type Ag-Pb and Au belt recently discovered. Ore formation includes three stages: Early (E), Middle (M) and Late (L), which include quartz-pyrite (E), polymetallic sulfides (M) and carbonates (L), respectively. The E-stage fluids are characterized by δD=-90‰, and δ 18 O=9‰ at 373°C, and are deeply sourced; the L-stage fluids, with δD=-70‰, and δ 18 O=-2‰, are shallow-sourced meteoric water; whereas the M-stage fluids, with δD=-109‰, and δ 18 O=2‰, are a mix of deep-sourced and shallow-sourced fluids. Comparisons of the D-O-C isotopic systematics of the E- stage ore-forming fluids with the fluids derived from Mesozoic granites, Archean-Paleoproterozoic metamorphic basement and Paleo-Mesoproterozoic Xiong'er Group, show that these units cannot generate fluids with the measured isotopic composition (highδ 18 O and δ 13 C ratios and lowδD ratios) characteristic of the ore-forming fluids. This suggests that the E-stage ore-forming fluids originated from metamorphic devolatilization of a carbonate-shale-chert lithological association, locally rich in organic matter, which could correspond to the Meso-Neoproterozoic Guandaokou and Luanchuan Groups, rather than to geologic units in the Xiong'er terrane, the lower crust and the mantle. This supports the view that the rocks of the Guandaokou and Luanchuan Groups south of the Machaoying fault might be the favorable sources. A tectonic model that combines collisional orogeny, metallogeny and hydrothermal fluid flow is proposed to explain the formation of the Tieluping silver deposit. During the Mesozoic collision between the South and North China paleocontinents, a crustal slab containing a lithological association consisting of carbonate-shale-chert, locally rich in organic matter (carbonaceous shale) was thrust northwards beneath the Xiong'er terrane along the Machaoying fault. Metamorphic devolatilization of this underthrust slab provided the ore-forming fluids to develop the Au-Ag-(Pb-Zn) ore belt, which includes the Tieluping silver deposit.

Metallogenic Epoch of Nonferrous Metallic and Silver Deposits in the Jiaodong Peninsula, China and its Geological Significance

As China＇s most important gold-producing district, the Jiaodong Peninsula also contains copper, lead-zinc, molybdenum （tungsten）, and other nonferrous metal ore deposits, but the space-time and genetic relationships with gold deposits remain uncertain. To investigate the temporal relationship between these nonferrous metal and gold ore deposits, We collected the samples from a number of nonferrous metallic and silver deposits and metallogenetic rock bodies in the eastern Jiaodong Peninsula for isotopic dating. The results show that the Re-Os isotopic model ages of the Lengjia molybdenum deposit in Rongcheng range from 114.5 ± 1.8 Ma to 112.6 ± 1.5 Ma, with an average age of 113.6 ± 1.6 Ma; the LA-ICP-MS ^206pb/^238U ages of 33 zircons in the sericitization porphyritic monzogranite that hosts the Tongjiazhuang silver deposit in Rongcheng range between 122 Ma and 109 Ma, with a weighted mean age of 116.04 ± 0.95 Ma; the LA-ICP-MS ^206pb/^238U ages of 31 zircons in the copper metallogenic pyroxene monzodiorite that hosts the Kuangbei copper deposit in Rongcheng range from 126 Ma to 106 Ma, with a weighted mean age of 116.6 ± 1.7 Ma; and the LA-ICP-MS ^206pb/^238U ages of 19 zircons in the pyroxene monzodiorite surrounding the Dadengge gold and multimetal deposit in Weihai range from 113 Ma to 110 Ma, with a weighted mean age of 111.7 ± 0.6 Ma. All these results indicate that the metallogenic ages of the silver and nonferrous metallic deposits in the Jiaodong Peninsula are in a limited range from 118 Ma to 111 Ma. Previous studies have demonstrated that the isotopic ages of gold deposits in the Jiaodong Peninsula range from 123 Ma to 110 Ma, while Weideshanian magmatism occurred between 126 Ma to 108 Ma. Both these ranges are grossly consistent with the metallogenic ages of silver and nonferrous metallic deposits in this study, suggesting that the large-scale mineralization occurred in the Early Cretaceous when magmatic activities were strong. This epoch may be linked to the lithosphere thinning and the thermo-upwelling extension in eastern China at that time. In addition, field investigation also shows that gold and nonferrous metallic deposits are distributed nearby the Weideshanian granite, with the nonferrous metallic deposits lying within or surrounding the granite pluton and the gold deposits outside the granite pluton. We propose the following mineralization scenario： In the Early Cretaceous, an intensive lithospheric extension induced partial melting and degassing of the metasomatized lithospheric mantle, which resulted in the formation of mantle-derived fluids enriched in metal elements. During the rapid process of magma ascent and intrusion, crust-derived fluids were activated by the magmatic thermal dome and served to further extract ore-forming materials from the crust. These fluids may have mixed with the mantle-derived fluid to form a crust-mantle mixing-type ore-forming fluid. The high-temperature conditions in the center or in contact with the granitic magmatic thermal dome would have been favorable for the formation of porphyry-type, skarn-type, and hydrothermal-vein-type ores, thus forming a series of Mo（W）, Cu, and Pb-Zn deposits in the mid-eastern Jiaodong Peninsula. In contrast, the medium- to low-temperature conditions in the periphery of the magmatic thermal dome would have favored the deposition of gold （silver） ores under the appropriate physiochemical and structural conditions. The metaliogenic epoch of the molybdenum, copper, and silver deposits, and their spatio-temporal and genetic relations to the gold deposits, as demonstrated in this study, not only provide important insights to the study of regional metallogeny, our understanding of the metallogenesis of the Jiaodong type gold deposit, and the geodynamic background of the large-scale mineralization in the Jiaodong Peninsula, but also have practical value in guiding the mineral exploration.

Geochemistry of Subvolcanic-Type Copper-Silver Deposits in Eastern China

The metallogenesis of subvolcanic deposits is controlled by subvolcanic activities. The copper polymetallic deposits are genetically related to intermediate-acid rocks, and the silver polymetallic deposits are more closely related to acid rocks. The abundance of Cu is relatively high in the intermediate-acid rocks and subvolcanic rocks, whereas the abundances of Pb, An and Ag are high in acid rocks, indicating rich ore-forming elements in original magmas. The study of REEs shows that the magmatic type related to copper deposits is the syntectic type, and that related to silver polymetallic deposits is mainly the re-melting type. The deposits were formed under medium-low temperatures and low salinity. The metallogenic times were the late stage of the early Yanshanian or the late Yanshanian, dating 78–147 Ma.

Isotope Tracing and Prospecting Assessment of Gold-Silver Deposits in Zhejiang Province

Three different types of gold and silver deposits in Zhejiang Province(Huangshan gold deposit, Zhilingtou gold-silver deposit and Haoshi silver deposit) showmarked differences in lead and strontium isotopic composition, suggesting three differentsources and geneses of these deposits. The Huangshan gold deposit features low initial Srisotope ratios and low μ values or low content of radiogenic Pb and its ore-forming materialscame primarily from the upper mantle; the Zhilingtou gold-silver deposit shows high initial Srisotope ratios and high μ values or high content of radiogenic Pb and the ore-forming materialswere derived mainly from the upper crust; and the Haoshi silver deposit has its Pb and Srisotope ratios between the above two cases with the ore-forming materials stemming from boththe mantle and the crust. The characteristic Pb isotopic composition may serve as an indicatorfor prospecting for different types of ore deposits.

Amplified Electrochemical Immunoassay Using HRP Labeled Protein as an Inhibitor to Silver Deposition in the Presence of H_2O_2

A novel electrochemical immunosensor with amplification effect based on the enzyme inhibition of silver deposition was proposed. In this method, the capture antibody was first immobilized onto a gold electrode via a self-assembled layer. After a sandwich immunoreaction, HRP labeled antibody was bound to the gold electrode. The HRP on the electrode inhibited silver deposition when the electrode was incubated in hydroquinone-H2O2 solution and silver ion solution. The linear sweep voltammetry was chosen to detect the deposited silver and the result showed that the peak current was linearly proportional to the content of IgG in the range of 50 to 2500 ng/mL with a detection limit of 35 ng/mL.

Thermodynamic Modelling of Ore-Forming Mechanism of the Changkeng Gold-Silver Deposits in Guangdong Province

The Changkeng gold-silver deposits consist of a sediment-hosted, disseminated gold deposit and a replacement-type silver deposit. The mineralizations of gold and silver are zoned and closely related to the silicification of carbonate and clastic rocks, so that siliceous ores dominate in the deposit. The mineralizing temperature ranges mainly from 300 to 170℃, and K+, Na+, Ca2+, Mg2+, and Cl- are the major ions in the ore-forming fluid. Calculations of distribution of metal complexes show that gold is mainly transported by hydrosulphide complexes, but chloride complexes of silver, iron, lead, and zinc, which are transformed into hydroxyl and hydrosulphide complexes under neutral to weak-alkaline circumstances in the late stage, predominate in the ore-forming solutions. Water-rock interaction is confirmed to be the effective mechanism for the formation of silver ores by computer modelling of reaction of hydrothermal solution with carbonate rocks. The solubility analyses demonstrate that the precipitation of gold and silver-bearing minerals taking place under weak-acid conditions and near-neutral to weak-alkaline conditions, respectively, is the main or favourable factor for the ore zonation and separation between gold and silver.

Characteristics of Ore-forming Fluid of the Gaoshan Gold-Silver Deposit in the Longquan Area, Zhejiang Province and its Implications for the Ore Genesis

The Gaoshan gold-silver deposit, located between the Yuyao-Lishui Fault and Jiangshan- Shaoxing fault in Longquan Area, occurs in the Suichang-Longquan gold-silver polymetallic metallogenic belt. This study conducted an investigation for ore-forming fluids using microthermometry, D-O isotope and trace element. The results show that two types of fluid inclusions involved into the formation of the deposit are pure liquid phase and gas-liquid phase aqueous inclusions. The homogenization temperature and salinity of major mineralization phase ranges from 156~C to 236~C （average 200~C） and 0.35% to 8.68% （NaCleqv） （average 3.68%）, respectively, indicating that the ore-forming fluid is characteristic of low temperature and low salinity. The ore- forming pressure ranges between in 118.02 to 232.13＂105 pa, and it is estabmiated that the ore- forming depth ranges from 0.39 to 0.77 km, indicating it is a hypabyssal deposit in genesis. The low rare earth elements content in pyrites, widely developed fluorite in late ore-forming stage and lack of chlorargyrite （AgCI）, indicates that the ore-forming fluid is rich in F rather than CI. The ratios of Y/ Ho, Zr/Hf and Nb/Ta of between different samples have little difference, indicating that the later hydrothermal activities had no effects on the former hydrothermal fluid. The chondrite-normalized REE patterns of pyrites from country rocks and ore veins are basically identical, with the characteristics of light REE enrichment and negative Eu anomalies, implying that the ore-forming fluid was oxidative and derived partly from the country rocks. The JD and jlSo of fluid inclusions in quartz formed during the main metallogenic stage range from -105%o to -69 %0 and -6.01%o to -3.81%o, respectively. The D-O isotopic diagram shows that the metallogenic fluid is characterized by the mixing of formation water and meteoric water, without involvement of magmatic water. The geological and geochemical characteristics of the Gaoshan gold-silver deposit are similar to those of continental volcanic hydrothermal deposit, and could be assigned to the continental volcanic hydrothermal gold-silver deposit type.

Isotope Geochemistry of Erentaolegai Silver Deposit, Inner Mongolia, China

Detailed studies have been conducted on the geology and geochemistry of the deposit and granite in the mining district in the last two decades, and by comparing this deposit with other typical epithermal deposits in the world, it is clear that the Erentaolegai silver deposit is a lower-sulfidation, adularia-sericite-type epithermal silver deposit and the bulk mineralogy of this deposit is consistent with low-sulfidation epithermal mineralization. Determined by the Rb-Sr isochron method, the age of magmatic intrusives in the mining district is 120 Ma. So, it can be concluded that the local areas were marginally subjected to the movement in Late Yanshanian and produced granitic magma, and about 29% mantle material, as is calculated, was involved in magmatism. The magma experienced crystallization-differentiation, resulting in the formation of granite and quartz porphyry; the latter was the product of violent granitic magma crystallization-differentiation, so silver was enriched in later petrogenetic stages and post-petrogenetic ore fluids from which Ag was derived dominantly. Oxygen and hydrogen isotopic characteristics indicate that meteoric waters on the Earth’s surface played an important role in the formation of granitic magma and the deposit: (1) contributing a lot to the fundamental complex partial melting; (2) contributing a lot to magma crystallization-differentiation, and bringing silver into the magma which is eventually responsible for the formation of quartz porphyry; and (3) contributing a lot to the formation of great amounts of ore fluid. The lead isotopic characteristics show that the silver and lead have an affinity for each other.

Photocatalytic degradation of dimethomorph on nanometer titanium dioxide by silver depositing in aqueous suspension

A series of catalysts of nanometer TiO2 were prepared by silver depositing. The photocatalytic degradation of dimethomorph in an aqueous suspensions by silver depositing with nanometer titanium dioxide as catalyst was investigated by radiation of UV-light and sunlight. A pseudo-first-order kinetic model was used to describe the results. The effects of the dosage of catalyst, oxidant, pH and radiation source on degradation were examined. The experimental results show that the decomposed rate of DMM is 94% when the dosage of catalyst is 1.25g/L and the concentration of DMM is 100mg/L under the conditions of solution pH of 7, the air flow of 1.5L/min and shining for 5h by UV-light. When it is shined by sun-light under the same condition, the decomposed rate of DMM is 48%. The mechanism of decomposition was discussed based on the data by analysis of LC-MS.

A novel electroless silver depositing method for magnesium alloys

Depositing silver on magnesium alloy by both electroless plating and organic coatings was studied. The organic coating was made by immersing samples in organosilicon heat-resisting varnish. In this method the organic coating acts as interlayer between the substrate and silver film. When the reaction starts, silver deposits directly on the interlayer. X-ray diffraction and SEM analysis were used to determine the composition and morphology of the interlayer and silver film. The potentiodynamic polarization curves for corrosion studies of coated magnesium alloys were performed in a corrosive environment of 3.5% NaCl(mass fraction) at neutral pH (6.9). The results indicate that compared with the substrate, the corrosion resistance of coated magnesium alloys increases greatly. Moreover, the method proposed in this work is environmentally friendly, non-toxic chemicals were used. In addition, it provides a new concept for the corrosion inhibition of magnesium alloys.

Zircon SHRIMP U-Pb Dating and Geochemical Characteristics of Late Variscan Granites of the Daitongshan Copper Deposit and Lamahanshan Polymetallic-Silver Deposit, Southern Daxing'anling, China

Daxing＇anling （大兴安岭） area is one of the regions that Phanerozoic granites are extremely developed in NW China. At present, the Hercynian granitoid research lags behind the Mesozoic granitoid research. In this article, we have taken systematic petrochemistry and geochronology researches on the Hercynian granitoids in Daitongshan （代铜山） copper deposit and Lamahanshan （喇嘛罕山） silver poly- metallic deposit, which were located at southern section of Daxing＇anling metallogenic belt. Zircon SHRIMP U-Pb dating results show that, the granite aplites in Daitongshan and the gneissic granites inLamahanshan were formed at （265±5）-（268±9） Ma and （252±2）-（252.6±3.4） Ma, respectively, which were both the products of late Herynian tectonic-magmatic events. Samples from Lama- hanshan are characterized by high SiO2 （69.72 wt.%-74.65 wt.%）, high potassium （3.53 wt.%-4.55 wt.%） and low P205 （0.03 wt.%0.12 wt.%）, aluminum saturation index （A/CNK） range from 0.95 to 0.98, Rb, Nd and K are en- riched, whereas the elements such as Nb, Ta, P and Ti are depleted, which belong to I-type grani- toids. Characteristics of samples from Daitong- shan are similar to H-type granitoids. The magmasource may be mostly originated from the lithospheric mantle component which were transformated or affected by the subduction components, and its formation may be closely related with the subduction and orogenesis of the Paleo-Asian Ocean.

Ore fluid of the Tieluping silver deposit of Henan Province and its illustration of the tectonic model for collisional petrogenesis, metallogenesis and fluidization

The Tieluping silver deposit, located in the NE-trending faults within the metamorphic basement of the Xiong'er Mountain, is a typical altered fracture type deposit. Its ore-forming process includes three stages with temperatures concentrated at 373℃, 223℃ and 165℃ respectively. With δD=90‰, δ13CCo2 =2.0‰ and δ18O=8.94‰, the early stage fluid was generated from reworking and metamorphism of the carbonate rich formation; the late one, with δD=-70‰, δ13CCo2 =-1.2‰, δ18O=-1,89‰, was meteoric hydrothermal solution; and the middle, δD=-109‰, δl3CCO2=0.1‰, δ18O=1.79‰, might be a hybrid mixed by reworking-metamorphic fluid and meteoric hydrothermal solution. Crystallized rapidly in the condition of fluid-boiling and fluid-mixing, the middle stage minerals have far more fluid inclusions with higher content of ions, higher ratios of H2O/CO2 and KN/MC. Consequently, they have much more ore elements such as gold compared with those of the early and late stages. It was the northward intracontinental subduction along the Machaoying fault during the Mesozoic collision between the South China and North China paleo-continents that intrigued large-scale fluidization and magmatism and- led to the appearance of more than 10 large and medium hydrothermal deposits, including the Tieluping silver deposit. The study on ore-forming fluidization of the Tieluping silver deposit proves the CPMF model.

Determination and thermal stability experiments of red pigment from large-scale silver deposit hosted in the Sinian strata in South China and their significance

Over the past years a kind of red organic pigment was found in various strata in Chi-na. Recently, the authors have discovered the similar red pigment in a large-scale sil-ver deposit hosted in the Sinian black shale, and confirmed that the pigment is an

Geological and geochemical and genetic studies of Yuxi silver deposit in east Tianshan, Xinjiang

1 Geology Yuxi silver Deposit is located at mountain area of Tuzileike Salt 152 Km south to the Hami in XinjiangAutonomous Region. The ore is of the medium size and may be expected to be larger. Its geotectonicbackground belongs to Middle Tianshan crystalline block. The southeast part of regional Yuxi fracturezone, which is made up of a series of secondary faults and slivers-containing fragment tiering, ductileshear zones, and fracture zones, crosses the orefield. The exposed rocks in the orefield are mainly MiddleProterozoic Xingxingxia Group (Chxn), Kawabulak Group (Jxkw) and Upper Permian Darequanzi Formation. Kawabulak Group is a mineralizing wall rock, which is composed of magnesium-rich carbonate andunderwent high greenschist facies metamorphism. It is divided into five laryers by rock. Silver mineraliza-

Erentaolegai silver deposit in Inner Mongolia as an example of epithermal deposit

1 Comparison with the characteristics of geology and geochemistry of typical epithermal silverdeposit Erentaolegai silver deposit is located to the west bank of Kelulun river in the Xibarhuyou Banner,south-west of Manzhouli. The geotectonic is the joint of Hailar basin and Manzhouli-Xinbarhuyou Banner’svolcanic mole track. The stratas in the mining area are upper Jurassic Tamolangou formation andShangkuli formation: the former consists of andesite mainly and the latter is divided into three parts fromtop to bottom, namely rhyolite, decite, trachyte. The types of igeous rock in the mining area are graniteand quartz porphyry, both with age (120 ±6) Ma as determined by the Rb-Sr isochron. The principalstructures in the mining areas are faults, trending SN, NW, NE, mainly SN. The ore bodies are controlledby faults. It is a large-scale silver deposit found recently. Many years’ research shows that it is a silverepithermal deposit. Table 1 lists a comparison with the typical silver epithermal deposits.

CHEMICALLY DEPOSITED SILVER FILM USED AS A SERS-ACTIVE OVER-COATING LAYER FOR POLYMER FILM

When colloidal silver particles were chemically deposited onto polymer film as an over-coating layer, surface-enhanced Raman scattering (SERS) spectra could be collected for the surface analysis. SERS measurements of liquid crystal film were successfully performed without disturbing the surface morphology.

Comparative Study of the Silver Nano-/Microstructures Deposited from Aerosol and Fog

A comparative study of the structure and fractal properties of arrays of the silver nano-/micro-particles deposited on the silicon substrate both from the aerosol and fog showed that the form of the silver individual particles and nano-/microstructures greatly depends on the deposition conditions. By passing an aerosol through isopropyl alcohol, the formation of fractal aggregates of the silver nano-/micro-particles both in the air and in alcohol was observed. Deposition of the silver nano-/micro-particles in the atmosphere of the saturated isopropyl alcohol vapours led to formation of fog. Microdroplets of the silver colloidal solution were deposited on the substrate. The further evaporation of alcohol created the silver nano/microstructures in the form of annular layers. It was found that the concerned annular layers contained silver particles of the same shape in the form of a Crescent (or Janus-nano-/microparticles). The nature of discovered effects is discussed.