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Characteristics of Cobalt-bearing Minerals in Hydrothermal Cobalt Deposits in Northeastern Hunan Province and Their Implication for Mineralization
Juntao NING, Baoliang HUANG, Guojun DONG, Yueqiang ZHOU, Zhuolong GAO, Bo KANG
Gold Science and Technology    2023, 31 (4): 531-545.   DOI: 10.11872/j.issn.1005-2518.2023.04.118
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A series of hydrothermal cobalt polymetallic deposits in northeastern Hunan Province occurr along the Changsha-Pingjiang fault zone,the middle section of the Jiangnan orogen belt. These deposits are hosted in the tectonic-hydrothermal alteration belt at the footwall of the Changsha-Pingjiang fault zone,and controlled by the fault zone and its secondary structures.However,the occurrence state of cobalt and cobalt-containing minerals in the whole belt isn’t sufficient,which restricts the understanding of the metallogenic process of cobalt in the belt.The detailed mineralogical observation,TIMA analysis and EPMA showed that the pyrite is the main sulfide and also an important cobalt-containing mineral in the Hengdong deposit.It exhibits a complex textural characteristics,that is,the cobalt-rich pyrite with silk-shaped,ring-shaped or irregularly at the edge replaced by the cobalt-poor pyrite at the core.The cobalt-rich pyrite has a clear oscillating zone exhibits high Co (up to 3.52%) but low Ni contents (≤0.09%). The complex zoning indicated that fluid-coupled dissolution and precipitation mechanism was responsible for the formation of Co-rich pyrite. In comparison,cobaltite ore is the most important cobalt-bearing mineral in the Jintang cobalt polymetallic deposit,which is closely related to pyrite,marcasite,and arsenopyrite,and occurs as an isolated granular form or wrapped in arsenopyrite particles.The particle size of cobaltite is between 3 μm and 45 μm. The contents of Co,Fe,and Ni of cobalt vary from 9.51% to 23.21%(average is 15.50%),4.33% to 17.66%(average is 9.46%),and 5.52% to 15.24%(average is 9.31%),respectively.Combied with the occurrence form of cobalt in the Jingchong cobalt-copper polymetallic deposit,it could be concluded that the cobalt-containing minerals vary from cobaltite to pyrite along the Changsha-Pingjiang fault zone from southwest to northeast.Furthermore,the Co contents in cobaltite increases tend to while Ni contents decreases,and the high content of Co in pyrite decreases.The mineralizing disparity could be explained by controlling factors such as ore-forming fluid migration direction and physical-chemical conditions(e.g.,pH value and fS2). Combined with Co(-polymetallic) orebodies controlled by the NE-trending Changsha-Pingjiang deep fault zone,it was proposed that the southwestern part of the deep fault in Lianyunshan area would be the focus of next cobalt exploration in northeastern Hunan Province.

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Particle Flow Simulation Study on the Propagation Law of Stress Wave at Nonlinear Deformation Joints
Weihua WANG, Ruixin HUANG, Jie LUO
Gold Science and Technology    2023, 31 (4): 580-591.   DOI: 10.11872/j.issn.1005-2518.2023.04.175
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Rock joints have significant influence on the propagation of stress waves in jointed rock mass.Study on the propagation law of stress waves in jointed rock mass is of great practical significance and theoretical value for rock blasting,earthquake engineering and explosion protection.The code was written by FISH language to modify the normal stiffness of micro-joints in the smooth joint model,and a particle flow model of rock joints with nonlinear deformation characteristics was established.The propagation characteristics of stress waves across single nonlinear deformed joints were analyzed,and the influence laws of joint stiffness,stress wave amplitude and stress wave frequency on the transmission and reflection coefficients were obtained.The interaction mechanism between stress wave and joint was revealed from microscopic perspective.The results show that the joint equivalent stiffness has a great influence on transmission and reflection coefficients of the stress wave.The larger the equivalent stiffness is,the larger the transmission coefficient is,and the smaller the reflection coefficient is.When the joint stiffness reaches a certain critical value,the transmission coefficient increases slowly and tends to a constant value.With the increase of the amplitude of incident wave,the transmission coefficient is increasing and reflection coefficient is decreasing.The stress wave transmission coefficient decreases with the increase of incident wave frequency,and the joint shows high frequency filtering.

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Study on the Formation Mechanism of Altered Rock Type Gold Mineralization of Huangjindong Gold Deposit in Jiangnan Orogenic Belt
Ke XU, Deru XU
Gold Science and Technology    2022, 30 (2): 151-164.   DOI: 10.11872/j.issn.1005-2518.2022.02.139
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Quartz (carbonate) vein type and altered rock type ores are the most important ore types in hy-drothermal gold deposits,and the quartz vein type ores are widely studied. However,altered rock type ores are much less well studied due to the complexity of mineral compositions and unavailability for fluid inclusion and geochemical analysis. Compared with quartz veins,altered rock ores generally has a lower grade but larger reserve,which is of great significance for gold exploration. Altered rock ores,closely associated with fluid-rock interactions,represent a typical mineralization style in hydrothermal gold deposits. In the Huangjindong gold deposit of the Jiangnan orogenic belt,South China,altered slate ores are mostly developed in the bleaching alteration zone.Previous research demonstrates that the alteration associated with mineralization mainly include sericitization,silicification,carbonatization and sulfidation,but the gold precipitation mechanism of altered slate ores remains indistinct. Based on field work, and petrographic observations,altered rock type ores in the Huangjindong gold deposit commonly occur in the bleaching alteration zone with a remarkable color transformation from greenish grey to yellow-pale grey.The bleaching alteration zone generally distribute symmetrically along carbonate-quartz veins and mainly characterized by the occurrence of siderite spots,as well as sericites and cryptocrystalline quartzes. Abundant gold-bearing sulfide in altered slates aggregate near carbonate spots,sharing similar geochemical compositions with those in quartz veins viaElectron Probe Microanalysis (EPMA).These sulfides locally crosscut siderite grains,as well as the cementing of partially dissolved siderite grains by quartz,demonstrating that the fading alteration took place before gold mineralization and likely generated by the reaction of CO2-rich fluids with host rocks. Tescan Integrated Mineral Analyzer (TIMA) analysis shows that two alteration zones have been observed in the altered slate,from the proximal to the distal side of the carbonate-quartz vein are silicification and sericitization,respectively. Micro area X-ray Fluorescence Surface Scan (μ-XRF) elemental mapping on carbonate-quartz vein and adjacent alteration zone suggest that most elements have obvious zoning. Mg,Fe and Mn are aggregated into spots in the alteration zones because of the appearance of siderite. Si is abundant in silicification zone,K and Al contents are high in sericitization zone. These results show that large amounts of siderite spots are generated during the pre-mineralization fluid-rock reaction,and thus provide favorable chemical traps for gold mineralization. The chemical reaction between gold-bearing fluid and siderite spot occurs during the ore-forming period,and contributes to gold mineralization by triggering sulfidation,which is the major genesis for the altered slate ores in the Huangjindong gold deposit.

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Study on the Structure and Evolution of Rare Earth Trade Network Along the Belt and Road
Shuitai XU, Caiwei MA, Wenxing ZHU
Gold Science and Technology    2022, 30 (2): 196-208.   DOI: 10.11872/j.issn.1005-2518.2022.02.168
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Rare earth is a strategic and key metal mineral resource that promotes high-quality development of national economy and global economic restructuring. The Belt and Road Initiative provides major opportunities for rare earth trade among countries. Based on the trade data of rare earth related products along the Belt and Road from 2013 to 2019 in UN Comtrade, the network structure characteristics and evolution process of rare earth trade along the Belt and Road were explored from individual and overall levels by using complex network analysis method. At the individual level, the position and evolution trend of countries along the route in the rare earth trade network were explored based on the degree centrality, intermediate centrality, proximity centrality and point intensity of network nodes. At the overall level, the characteristics of network density, small-world network, and community structure were analyzed to explore the overall characteristics and evolution rules of network. The results show that: (1)From 2013 to 2019, the Rare earth trade network of the Belt and Road presents the characteristics of a “small world”, but the network density is low and the accessibility of the overall network structure is weak. (2)As an important participant in the Belt and Road rare earth trade, China has always played a core role in the trade network and has absolute influence and control over rare earth trade. (3)Due to industrial proximity, trade and transportation costs, cultural differences, countries with similar geographical locations have closer rare earth trade links.(4)The trade of rare earth terminal application products is the main aspect that affects the development of rare earth trade in the Belt and Road. Therefore, the research believes that the following measures can provide a basis for China’s rare earth trade strategy and policy formulation and the optimization of rare earth trade pattern. Firstly, strengthen infrastructure construction and reduce the impact of geographical location on the Belt and Road rare earth trade cooperation.Secondly, strengthen rare earth trade links among core countries in various regions to further consolidate China’s core position in the Belt and Road rare earth trade network.Thirdly, reduce rare earth trade barriers, improve the smooth flow of rare earth trade activities and the development of trade networks along the Belt and Road.Finally, expand rare earth trade cooperation partners and promote the diversification of rare earth trade market targets along the Belt and Road.

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Progress and Prospects of the Preparation of Cementitious Materials Based on Nonferrous Metallurgical Slags
Lijie GUO, Lei ZHANG, Wenchen LI
Gold Science and Technology    2020, 28 (5): 621-636.   DOI: 10.11872/j.issn.1005-2518.2020.05.128
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Nonferrous slag,a by-product of the nonferrous metal smelting process,can be used as a replacement for cement in the preparation of cementitious materials,which is a critical way to utilize large amounts of non-ferrous metallurgical solid waste resources.This study systematically analyzed to shed light on the latest research progress and achievements on the cementitious materials mainly prepared with the non-ferrous metallurgical slags both in China and abroad.Particularly,five aspects are emphasized in this paper,which are the composition and structural characteristics of nonferrous slag,potential cementitious properties,the activation method of slag,the preparation methods of cementitious materials,and the performance of its cemented body,respectively.The results showed as below:First,the mineral composition and structures of nonferrous slag differed widely.The crystallization of silicate mineral is almost complete and has high chemical stability,but the content of the vitreous body is lower.Second,the evaluation method of nonferrous slag potential gelling activity and the activity evaluation criteria are inconsistent.Third,the combination of phase modification and compound activation method could effectively improve the gelling activity of nonferrous slag.Fourth,nonferrous slag cementitious materials has good durability and high-temperature resistance and has certain properties of heavy metal solidification.At present,the preparation of cementitious materials based on nonferrous slag is mainly laboratory-based with few examples of large-scale industrial applications.The fundamental reason is that the problem of low and insufficient activity of nonferrous metallurgical slag has not yet been completely solved.As such,changing the structural characteristics of non-ferrous metallurgical slag is the key to overcoming the obstacles to its large-scale industrial utilization.Followed by this,the paper next discussed some important issues involved in the preparation process of cementitious materials and highlights the importance of the establishment of a non-ferrous metallurgical slag cementing system configuration database,the use of molecular research on simulation optimization of activation methods,and the development of simple and efficient activation methods,all in an effort to hasten the expansion of the future industrial application of non-ferrous slag cementitious materials preparation technology.

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Deep Prospecting and Mineralization Characteristics of the Yinshan Copper Polymetallic Deposit in Jiangxi
Jinshan HU, Fulin HU, Jingang LIU, Ning LI, Guoliu HU, Guoguang WANG
Gold Science and Technology    2020, 28 (5): 688-700.   DOI: 10.11872/j.issn.1005-2518.2020.05.067
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The deep exploration project of Yinshan copper polymetallic mine in Dexing,Jiangxi Province undertaken by Jiangxi No.4 Nonferrous Geological Exploration Team has achieved important exploration results. The newly proved resource reserves (331+332+333) are 540 000 tons of copper,230 000 tons of lead + zinc,57 tons of gold,914 tons of silver and 5.93 million tons of sulfur. It is equal to increasing the scale of a large copper mine,a large gold mine,a medium-sized lead-zinc mine and a near large silver mine. In this deep exploration,the original geological logging of more than 100 000 meters of drilling and more than 17 000 meters of tunnel has been carried out. 35 900 basic analysis samples have been taken and various rock and ore test samples matching with the exploration stage have been sent for inspection. In order to further expand the prospecting in the deep part of Yinshan,evaluate the prospecting potential in the deeper part of the mining area and predict the favorable space for ore generation,through the detailed geological observation and recording of various prospecting projects in the deep exploration,combined with the rock and ore test work,further systematically summarize the results of the exploration report,analyze and study the basic geological conditions and metallogenic characteristics of the deposit formation,so as to extract the results.The new understanding includes:(1)Yanshanian Yinshan subvolcanic body is closely related to mineralization,3# dacite porphyry is related to copper gold mineralization,5# quartz porphyry is related to lead zinc silver mineralization.(2)The altered quartz diorite in Caledonian period appears in many places on the outer side of the 3 Ying’an porphyry in Jiutong district,which,together with sericite phyllite and blasting breccia,forms the ore bearing surrounding rock in the Ninth-Xishan district.The opened magmatic activity channel is favorable for the emplacement of the 3 rock body related to the mineralization in Yanshan period.(3)The two flanks of Yinshan anticline are associated with the fracture structure belt,which is the main ore controlling structure.The northwest wing is associated with the East-West fracture structure belt,which is extremely developed with a wide strike and a long extension length. The south-east wing develops the North-South fracture structure belt,which is characterized by a short strike and a scattered distribution,which results in the north-west wing of Yinshan anticline controlling the occurrence and distribution of most ore bodies.(4)The location and shape of the orebody are directly controlled by the main fault and its associated network fractures on both sides. The sulfide vein continuity in the main fault controls the continuity of the ore body. The fine network vein ore is the main mineralization type,and the thick and large ore bodies are often composed of several main fault surfaces close to each other,such as the Ninth-Xishan District copper ore body.(5)The hydrothermal alteration associated with mineralization is a low-temperature alteration combination mainly composed of sericitization,carbonation and chloritization,which is lack of high-temperature potassium silicate salinization of porphyry deposits.The deep orebody of Yinshan copper polymetallic mine has not been closed,especially the outer contact zone on both sides of the deep 3 Ying’an porphyry at the turning part of Yinshan Ninth-Xishan area and the deep part of known orebody inclined extension are the best direction for subsequent ore prospecting.

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Distribution Characteristics of Gold Deposits in Africa and Exploration Suggestions
Sihong JIANG, Lili ZHANG, Yifei LIU, Gaofeng LI, Genyuan JI
Gold Science and Technology    2020, 28 (4): 465-478.   DOI: 10.11872/j.issn.1005-2518.2020.04.083
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Africa is the most important gold producing area in the world,and one of the hot spots to attract gold exploration investment as well.Based on the systematic collection and processing of the advances of the previous research on typical gold deposits and regional metallogenesis in the African continent,the spatial and temporal distribution of gold deposits in the African continent is summarized briefly in this article,which made the achievements below.The African continent consists mainly of four ancient cratons (i.e.Kalahari Craton,West Africa Craton,Congo Craton,and Sahara Meta-Craton) and Neoproterozoic orogenic belts developed around these cratons,as well as some Mesozoic basins developed on the cratons.The gold deposits predominantly occur in the ancient craton,especially in the Kalahari Craton in southern Africa and West African Craton in north-western Africa,where are the world famous gold producing areas.A small proportion of gold deposits are distributed in the Neoproterozoic orogenic belts,such as the Nubian Shield,and other Pan-African orogenic belts.There are many types of gold deposits in African,including conglomerate,orogenic,VMS,intrusion-related,porphyry,epithermal and IOCG types,with the former two being the most important types.The ore-forming age of gold deposits in Africa is mainly concentrated in three periods,i.e.Archean,Paleoproterozoic and Neoproterozoic.The enrichment of huge-sized conglomerate-type gold deposits in the Witwatersrand Basin of South Africa may be mainly related to their paleo-sedimentary environment,i.e.the alluvial braided river plain,while the gold enrichment in West African Craton,as the most important Paleoproterozoic gold region in the world,mainly attributes to the large amount of carbonaceous in the strata.Although many world-class gold deposits have been found in the African continent,their prospecting potential remains significant,especially in the search for orogenic gold deposits,as both the ancient craton and the Neoproterozoic orogenic belt occurring around the craton are favorable tectonic environments for the formation of orogenic gold deposits.For the gold exploration in the African continent,it is suggested that not only pay much attention to the deep prospecting of discovered gold deposits,but also to searching for the semi-buried and buried deposits,especially in the shallow covered areas of West African Craton and Congo Craton.By means of advanced geophysical,geochemical and remote sensing,the breakthrough of gold prospecting is expected.

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Genetic Types and Prospecting Significance of Liumei Gold Deposit,Guigang,Guangxi Province,China
Gang CHEN, Maohong CHEN, Kezhong MA, Rui GE, Shenxiang GUO, Qiqiang WU, Qisheng YUAN
Gold Science and Technology    2020, 28 (4): 479-496.   DOI: 10.11872/j.issn.1005-2518.2020.04.050
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Liumei gold deposit is located in the northeast of Dapingtianshan stock,Guigang,Guangxi Province.According to mineral composition and pulse cutting relation,the deposit hydrothermal activity process is divided into four stages:(1)quartz-pyrite stage;(2)pyrite arsenopyrite-quartz stage;(3)galena-sphalerite-chalcopyrite-tennantite-ankerite-quartz stage;(4)quartz-ankerite stage.The second stage as the main metal-logenic stage.The main gold carriers are arsenopyrite and pyrite. EPMA analysis shows that Au mainly exists in the form of “invisible” submicroscopic-supermicroscopic inclusion gold.Fluid inclusion test shows that the inclusions in quartz or calcite are mainly gas-liquid two-phase,the average temperature in the main metallogenic stage is about 181 ℃,the average salinity [w(NaCl)] is 9.36%,and the density is 0.946 g/cm3, indicating that the ore-forming fluid is low-temperature,low-salinity,low-density fluid.The hydrogen and oxygen isotopic composition (δD value between -73‰~-57‰,δ18OH2O value between 2.3‰~6.1‰) indicates that the ore-forming fluid may be related to the magmatic hydrothermal fluid and was mixed by meteoric precipitation in the later period.The value of the gold-bearing δ34S is between -0.8‰ and 0.5‰,indicating that the ore-forming material comes from magmatic rock.These features indicate that Liumei gold deposit is very different from typical carlin-type gold deposits,especially it is lack of characteristic of the low temperature carlin-type gold mineral combination (orpiment-realgar-cinnabar),but instead contain more base metals mineral galena-sphalerite-chalcopyrite),so it is closer to related to magmatic activities of distal low temperature hydrothermal deposit.Based on the spatial distribution characteristics of regional ore deposits and rock masses,the metallogenic model of Dapingtianshan magmatic hydrothermal system for porphyry gold and copper deposits (Longtoushan gold deposit),skarn-type silver lead and zinc deposits (Touzha Ag-Pb-Zn deposit) and distal low temperature hydrothermal gold deposits (Liumei gold deposit) is proposed.The model implies that there should be intermediate temperate hydrothermal vein and skarn type silver-lead-zinc deposits deep in Liumei gold deposit and in the direction of Dapingtianshan rock mass.The model of magmatic hydrothermal metallogenic system established in this paper has important guiding significance for similar ore deposits in Dayaoshan area.

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Prospecting Model and Metallogenic Prediction of Yandan-Yantang Gold Deposit in Leye County,Guangxi
Yunzhong QIN, Haijun SONG
Gold Science and Technology    2020, 28 (3): 317-327.   DOI: 10.11872/j.issn.1005-2518.2020.03.168
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Yandan-Yantang gold deposit is located in Leye County,Guangxi,which is a large-scale carlin-type gold deposit,with a gold resource of more than 20 tons,newly discovered in Yunnan-Guizhou-Guangxi “Golden Triangle” area,China.The deposit is located in the northwest of Lingyun-Leye isolated carbonate platform,Guangxi.The host rock is calcareous sandstone with mudstone of Baifeng Formation of Middle Triassic.The orebodies are mainly controlled by anticlines and faults.The orebodies mainly occurs as vein type one in fault fracture zone,and a small amount are stratabound orebodies.The largest orebody is located in the core of the anticline and controlled by F1 fault,inclining northward,with a dip angle of 30°~60°,a width of 1.0~38.8 m,a length of nearly 2.5 km,a depth of 50~400 m,and Au grade of 0.50×10-6~7.00×10-6 in general,and the average grade is 2.0×10-6.The main mineralization and alteration are silicification,kaolinization,pyritization,arsenopyrite mineralization and stibium mineralization.The gold bearing minerals are arsenian pyrites and arsenopyrites.It has a typical combination of low temperature elements such as Au-As-Sb-Hg.Generally,it has typical carlin-type gold deposit characteristics.The results of soil and rock geochemical survey show that the Au and As elements in the ore-bearing fracture zone have good coincidence,they are all located in the core of anticline and distributed along the striking of F1 fault.However,only As anomaly appears in the east of the fault,which is consistent with the feature that As is the front halo of orebody in carlin-type gold deposit,suggesting that the orebody may lie to the east.The geophysical data of TDIP and CSAMT show that the gold orebody has the characteristics of low resistivity and high intensification rate.The high intensification anomaly of TDIP lies to the east,which also shows that the gold orebody tends to extend to the east.Based on the geological characteristics and geophysical and geochemical anomalies,it is considered that the F1 reverse fault in the core of anticline is the main ore-controlling fault,and the orebody has the trend of lying to the east,suggesting that the deep part of the mining area has good ore prospecting potential.

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Research on Destress Effect of Ground Pressure Control for the Time-space Mining Sequence at Depths
Shibo YU, Xiaocong YANG, Ye YUAN, Zhixiu WANG
Gold Science and Technology    2020, 28 (3): 345-352.   DOI: 10.11872/j.issn.1005-2518.2020.03.026
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The regional time-space mining sequence is one of the important strategic methods for underground pressure management at depths and destress mechanical effect is closely related to the time-space mining sequence itself. Aiming at the large-area mining mechanical model of three-dimensional mining sequence from the centre to the periphery at depths, based on the stress transfer process and characteristics of rockburst stress hazard, the stress evolution laws and changes of rockburst stress hazard were studied during the mining process from a single stop to multiple stopes.The research results show that the three-dimensional mining sequence from the center to the periphery at depths can gradually realize the gradual transfer of high stress and the gradual transition of stress hazard around the mining operation area.The destress effect of ground pressure control for the time-space mining sequence at depths is to achieve the desired destress environment reconstruction and the progressive transfer of the stress hazard through the reasonable setting of the three-dimensional mining sequence.The mutual feedback analysis technology based on the combination of numerical simulation and microseismic monitoring could realize high integration of large area numerical simulation and big data of microseismic monitoring, real-time dynamic analysis and tracking evaluation, and it is an effective method to evaluate the destress effect of ground pressure control for the time-space mining sequence at depths.The essence of the destress effect of ground pressure control for the time-space mining sequence at depths is the idea to actively create low stress destress zone in the high-stress environment.This idea had been applied at Nickel Rim South mine in Canada, which had achieved a good destress effect and realized reasonable management for ground control. It is believed that this idea has important guiding significance for deep and ultra-deep mining in China.

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Geochemical Characteristics,Zircon U-Pb Age and Geochronological Significance of Diabase in Heiniu’ao Gold Deposit,Baoshan Block,Western Yunnan
Ying LUO,Yingxiang LU,Xuelong LIU,Shunrong XUE,Shuaishuai WANG,Zhenhuan LI,Changzhen ZHANG,Jianhang CHEN
Gold Science and Technology    2020, 28 (1): 1-11.   DOI: 10.11872/j.issn.1005-2518.2020.01.128
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The special geotectonic location of Baoshan block makes it undergo a series of Tethys evolutionary activities with frequent regional tectonic-magmatic activities.Granite is developed from Paleozoic to Cenozoic.In addition,a large number of basic intrusive rocks occurring as dikes and dikes are also developed in the region.Previous research and analysis of granite in the region is relatively systematic,but the study and analysis of basic rocks in the region,especially basic dikes commonly developed in typical polymetallic ore areas in the ore concentration area,is relatively weak.Previous studies and analyses only the chronology of diabase and its relationship with mineralization in the Hetaoping lead-zinc polymetallic ore area.The study and analysis of the petrogenesis of basic rocks is almost blank.Therefore,the diabase porphyrite in typical boreholes of Heiniu’ao gold deposit has been systematically analyzed in terms of petrochemical characteristics and zircon U-Pb dating in LA-ICP-MS in situ.The main elements of Heiniu’ao diabase porphyry are characterized by low SiO2,low TiO2,high Al2O3,low MgO,high FeOT and low K2O,belonging to the shoshonite series.Trace and rare earth elements are characterized by enrichment of light rare earth elements (LREE) and large ion lithophile elements (LILE) and depletion of high field strength elements(HFSE),suggesting that their source areas are lithospheric mantle.The content of Cr and Ni in the rocks is obviously lower than that in the original basalt magma,indicating that the magma may have undergone the crystallization separation of olivine and pyroxene.The obvious negative anomalies of Nb and Ta suggest that they were contaminated by crustal materials during the process of magma emplacement.The tectonic environment is consistent with the tectonic background of Jinchanghe diabase and Hetaoping diabase,which are intraplate extensional environments.The diagenetic age of the diabase porphyrite obtained in the mining area is (212.0±4.9) Ma,which is similar to the diagenetic age of the Hetaoping diabase obtained by predecessors (195.0±5.3) Ma,and that of the Jinchanghe diabase (217.3±5.8) Ma are all Late Triassic.It shows that the basic dikes in the area are the products of the Triassic magmatic activities.The closure of the Triassic Paleo-Tethyan Ocean resulted in the collision between Baoshan and Simao blocks,which resulted in extensional activities in Baoshan block.The basalt magma originating from the mantle emplaced upward along the weak tectonic zone to form diabase porphyrite of this time limit,and experienced crystallization differentiation and crustal contamination during the process of magma emplacement.

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Two Dimensional Evaluation Model of Goaf Stability Based on Variable Weight Contact Cloud
Hongwei DENG,Weiyou ZHANG,Songtao YU,Yuxu GAO
Gold Science and Technology    2020, 28 (1): 32-41.   DOI: 10.11872/j.issn.1005-2518.2020.01.052
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The instability of the goaf poses serious threat to mine safety,and its stability is affected by many uncertain factors.Therefore,it is very important to evaluate the stability of the goaf.Many factors affect the result in the evaluation process,for instance,many ambiguity and randomness information exist in the evaluation of the goaf stability,the evaluation index interval normally distributed,dynamic combination of different evaluation index affect the weight values,and the inconsistency of the indicator level.In order to solve these problems,a two-dimensional evaluation model of goaf stability based on variable-weighted cloud was established.On the basis of comprehensive consider the actual situation of the goaf and related research results,the stability evaluation system and grading standards of the goaf were established.The digital characteristics of the contact cloud of each evaluation index belonging to different levels were calculated respectively,and then the contact cloud maps were generated by using the contact cloud generator and Rstudio software.Substituting the measured values of the sample indicators into the contact cloud model to calculate the degree of certainty of the contact cloud.After that,the subjective weight and objective weight were calculated by using the analytic hierarchy process and the entropy weight method respectively.Considering the advantages and disadvantages of the subjective and objective weighting methods,the game theory was used to fuse these two empowerment methods to obtain the optimized comprehensive weight.Considering that comprehensive weights calculated by game theory were constant weight,which could not reflect the influence of the index value on the weight,the variable weight theory was used to change the weight to obtain the variable weight,so as to better display the effect of dynamic change of the index value on evaluation result.The comprehensive determination degree of the goaf was then obtained by calculating the certainty degree of measured index value belongs to each contact level cloud and the final variable weight.After that,the stability level of the gob was determined according to the principle of maximum membership degree.In order to solve the problem of inconsistent index level attribution,fuzzy entropy was introduced as the second dimension evaluation auxiliary parameter to characterize the stability complexity of the goaf.The model was applied to engineering practice and compared with traditional cloud model and matter-element extension model,the evaluation results are basically the same.The results show that the stability evaluation model of the goaf is scientific and reasonable,and it provides a new idea for the stability evaluation of goaf and the stability evaluation of similar projects.

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Pyrite Typomorphic Characteristics:Implication for Deep Gold Mineralization in the Sanshandao Gold Deposit,Jiaodong Peninsula
Yumin CHEN, Huafeng ZHANG, Congying ZHANG, Huanlong HU, Zhaokun WANG, Qingdong ZENG, Hongrui FAN
Gold Science and Technology    2019, 27 (5): 637-647.   DOI: 10.11872/j.issn.1005-2518.2019.05.637
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The study of genetic mineralogy of pyrite could provide the important information for the estimation of deep mineralization potential.The deep drilling (ZK96-6,2 735.70 m) at the Sanshandao gold deposit uncovered that the mineralization could still extend to the depth (-2 613 m to -2 684 m) along the Sanshandao fault zone.Therefore,this study will focus on the genetic mineralogy of pyrite from the deep drill of Sanshandao gold deposit (-2 613 m to -2 684 m),exploring the indicators of typomorphic characteristics of deep pyrite for the deep mineralization.The detailed observation was given to the geometry typomorphic characteristics of different stages of pyrites.The contents of the major and trace elements of different stages of pyrites were analyzed by electronic probe and ICP-MS,respectively.The thermoelectrometry apparatus was operated in order to explore the thermoelectric characters of all stages of pyrites.The pyrite of quartz-gold-pyrite stage in deep gold orebody shows larger grain size than pyrite in other stages, which indicates that ore-forming fluids in this stage attained the supersaturation condition and amounts of pyrite precipitated.A lot of reduced sulfur could be fixed into pyrite,which led to the destability of Au-S complexes and gold precipitation.Selected trace elements contents of pyrite in deep gold orebody (-2 613 m to -2 684 m) were drawn in the (Au+Bi+Cu+Pb+Zn)-(As+Sb+Ba+Ag+Hg)-(Ti+Cr+Co+Ni) triangle discrimination diagram,which indicates gold orebody in this location belongs to the middle part of the whole orebody and the depth still has the gold mineralization potential.The occurrence rate of P-type pyrite and the gold grade show positive correlation,which indicates that the coprecipitation of P-type pyrite and gold.This relationship could be used as the criterion for the deep prospecting of gold and also indicate the enormous potential of gold mineralization in the depth of Sanshandao gold deposit.

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Trace Elemental Compositions of Iron Oxides from the Lannitang Porphyry Cu-Au Deposit in the Zhongdian Region (Northwest) and the Geological Significances:A LA-ICP-MS Study
Jianheng GUO, Chengbiao LENG, Xingchun ZHANG, Wei ZHANG, Chongjun YIN, Lujia ZHANG, Zhendong TIAN
Gold Science and Technology    2019, 27 (5): 659-677.   DOI: 10.11872/j.issn.1005-2518.2019.05.659
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The Zhongdian area, located in northwestern Yunnan, is an important porphyry belt in China. It hosts a large number of Triassic intermediate-felsic porphyritic intrusions and porphyry deposits such as Pulang porphyry Cu-Au, Xuejiping porphyry Cu, Chundu porphyry Cu, Langdu Cu skarn and Lannitang porphyry Cu-Au deposit. The Lannitang porphyry Cu-Au deposit is located in west belt of the Zhongdian area. The magnetite in Lannitang porphyry Cu-Au deposit is widespread and it occurred as disseminated and vein types in potassic and chlorite-sericite alteration zone.Specularite is also observed frequently in the post-mineralization dolomite-quartz coarse veins.We conducted the petrography and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to determine the texture and composition of iron oxides (magnetite and specularite). In this study, we identified three types of magnetite. Type-Ⅰ magnetite is disseminated in potassic alteration of deposit. It is generally contains ilmenite lamellas. Type-Ⅱ and Type-Ⅲ magnetite are occurred in magnetite single vein and magnetite-bearing quartz stockwork vein separately. Type-Ⅱ and Type-Ⅲ are distributed in potassic and chlorite-sericite alteration zone. The LA-ICP-MS analyses show that Type-Ⅰ magnetite is relatively rich in V, Ni and Mg than other two types of magnetite. Type-Ⅱ and Type-Ⅲ magnetite are more enriched in Mn, Zn, Sn, Sc and high-Ni/Cr ratio than Type-Ⅰ magnetite.Type-Ⅱ and Type-Ⅲ magnetite has similar content of many trace elements. The concentration of Cr,Ga,Ni and Co in specularite is obviously lower than those of magnetite. The ilmenite lamellae and low-Ni/Cr(Ni/Cr<1) ratio revealed that Type-Ⅰ magnetite belongs to igneous magnetite. Type-Ⅱ and Type-Ⅲ are distributed in veinlets and displayed high-Ni/Cr ratio (Ni/Cr>1). We suggested that they are hydrothermal magnetite. Type-Ⅰ magnetite (igneous) is intergrown with hydrothermal minerals including chlorite and sericite and it has quiet similar contents of Ti, Al and Cr with the other two hydrothermal magnetite.We suggest that Type-Ⅰ magnetite (igneous) experienced late-stage fluid alteration, which induced the loss of Ti, Al and Cr.The similar content of trace element between Type-Ⅱ and Type-Ⅲ magnetite indicated that they may precipitate from same period of fluid.In combination with previous studies, we propose that the presence of elements such as Al, Mn, Mg and Sc are in solid solution within magnetite (and/or specularite),but the Ca, S, Cu, Ba, Sr and Zr may be present in micro-/nano-scale mineral inclusions.The widespread presence of magnetite-hematite and specularite in the potassic alteration zone and low Mn concentration of magnetite indicates a high oxygen fugacity of the Lannitang porphyry Cu-Au deposit (magnetite-hematite buffer).

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Features of Major Gold Metallogenic Fracture Belt in Northwestern Jiaodong
Fengli XIAO,Qingdong ZENG,Fengshan MA,Zhaokun WANG,Zhifu SUN,Zongfeng SUN
Gold Science and Technology    2018, 26 (4): 396-405.   DOI: 10.11872/j.issn.1005-2518.2018.04.396
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Over 4 500 tons of gold reserves have been proved in Jiaodong area,and Jiaodong area has become one of the important world-class gold cluster areas. Altered rock type,quartz vein type and interlayer fracture zone type gold ores are the major gold ore type in Jiaodong area,these gold ores are controlled by major regional faults,secondary faults and interlayer slide faults. Altered rock type gold deposit is the most important gold deposit in Jiaodong area. The discovery super-large gold deposits are controlled by Sanshandao,Jiaojia and Zhaoping faults,over 3 300 tons gold reserves have been proved in these three major faults. Sanshandao,Jiaojia and Zhaoping faults are characterized by poly-stage activities:early stage ductile shear deformation characterized by mylonite and mylonitic rocks,middle stage brittle deformation characterized by the cataclastic rock (or breccia),and late stage compressional deformation characterized by the fault gouge. The gold mineralization in Jiaodong area is closely related to the middle stage brittle deformation,and the gold mineralization occur within the catclastic(breccia) zones.The research shows that the three major faults still have huge exploration ore potential.

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Preliminary Discussion on Minerogentic Series of Gold Deposits in Qinghai Province
Tong PAN,Fude WANG
Gold Science and Technology    2018, 26 (4): 423-430.   DOI: 10.11872/j.issn.1005-2518.2018.04.423
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There are abundant gold resources in Qinghai Province.Based on the study of mineral resources potential in Qinghai Province,the metallogenic characteristics,gold types,ore control conditons and spatial distribution of gold deposits in Qinghai Province were analyzed,and the metallogenic regularity of gold deposits was put forward.The gold mineralization in Qinghai Province was divided into five metallogenic periods of the Pre-Cambrian,Early Paleozoic,Late Paleozoic,Late Mesozoic and Cenozoic,and the spatial distribution features of gold deposits in each metallogenic period were summarized.Based on the characteristics of the representative gold deposits in the main metallogenic belts,the gold mineralization series in Qinghai Province was established for the first time,and suggestions for future prospecting and exploration of gold deposits in Qinghai Province were proposed.

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The Geological-Geophysical-Geochemical Three Fields Anomalies Coupling Theory and Its Application in the Positioning Prognosis of Concealed Gold-Polymetallic Deposits
Baolin ZHANG,Yana MIAO,Yanping SU,Huizhong LI
Gold Science and Technology    2018, 26 (4): 431-442.   DOI: 10.11872/j.issn.1005-2518.2018.04.431
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The studies of theories and technologies for positioning prognosis of concealed ore deposits are hot points and difficulties of international mining science communities. In combination with the experiences of scientific prospecting for concealed ore deposits over 20 years,and aiming at the difficulties of prospecting for concealed gold-polymetallic deposits,it is proposed that there must be a combination of geology,geophysics and geochemistry,the favorable metallogenic structural sites (ore-housing structures or ore-bearing tectono-lithological facies zones) should be the targets of positioning prognosis,the relationship between geology and geophysics should be understood and interpretated comprehensively.The three basic principles of the “geological-geophysical-geochemical three field anomalies coupling theory”,i.e. predicting target,scale and accuracy,are expounded.The basic meaning and main points of metallogenic geological structural filed,geochemical field and geophysical field are introduced.The integrated geological-geophysical-geochemical technological combinations which have been proven effectively are recommended. In the end,three instances are displayed to present the workflow and practical effect of applying the theory and technologies.

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Geochronological Study on the Jinshan Orogenic Gold Deposit in the Qinhang Metallogenic Belt
Guoguang WANG,Chao ZHAO,Pei NI,Zheng LIU
Gold Science and Technology    2018, 26 (4): 443-453.   DOI: 10.11872/j.issn.1005-2518.2018.04.443
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Qinhang metallogenic belt is located along the suture zone between Yangtze and Cathaysia blocks in South China,and its northeastern section is featured by large scale Cu-Au-Pb-Zn-Ag polymetallic deposits.Jinshan gold deposit is one of the largest gold deposits in this belt,the ore genesis and formation age remain in dispute.On the basis of detailed ore deposit geology and fluid inclusion studies,the quartz vein type orebodies was selected to conduct quartz fluid inclusion Rb-Sr isotope dating.The results show that samples from the V5 gold orebodies give a quartz fluid inclusion Rb-Sr isochron age of (751±98)Ma,and those from the V7 gold orebodies yield a quartz fluid inclusion Rb-Sr isochron age of (754±62)Ma.Two ages are consistent with the error ranges.In addition,the initial87Sr/86Sr values of fluid inclusions hosted in auriferous quartz are (0.7056±0.0039)~(0.7103±0.0025),suggesting that the ore-forming fluids were derived from the low maturity basement strata.To sum up,Jinshan gold deposit belongs to the Neoproterozoic orogenic gold deposit,instead of Caledonian or Yanshanian periods of tectono-magmatic products.

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Stability Analysis of Deep Stope Based on Regional Microseismic Activity
WU Hao, CHEN Bingrui, CHI Xiuwen, WANG Bo, XU Shida, JIANG Hongbo
Gold Science and Technology    2018, 26 (3): 325-333.   DOI: 10.11872/j.issn.1005-2518.2018.03.325
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Hongtoushan copper mine is one of the metal mine with largest mining depth in China,and the problem of ground pressure is prominent.In order to analyze the stability of deep stope and prevent the failure of surrounding rock,a high precision Zhongke microseismic monitoring system has been established in No.47 stope of -707 mining level in Hongtoushan copper mine.The positioning accuracy of the system can meet the requirements of mine production with multi-mined areas through artificial blasting test.The real-time monitoring results show that the stress of surrounding rock of No.47 stope is adjusted quickly,no obvious increase of microseismic activities after large blasting,and there is a positive correlation between field operations such as second blasting and ore extraction activities and microseismic activities.During the mining process,the microseismic active zone is mainly located near No.3502 tunnel,the ore outlet,-707 main roadway and the stope near the ventilation shaft 2.It is found that the first three areas exist significant dynamic failures by on-site reconnaissance,which matched the monitoring results.The stability analysis of surrounding rock based on regional division is helpful to explore the relationship between microseismic activities and large blasting,second blasting and ore extraction activities,and analyze the dominant factors of surrounding rock failure.
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Carbon-Oxygen Isotopic Characteristics and Its Significance of Sanbao Mn-Ag Deposit in Laojunshan Ore District,Southeastern Yunnan Province
DU Shengjiang, WEN Hanjie, QIN Chaojian, LU Shufan, YAN Yongfeng, YANG Guangshu
Gold Science and Technology    2018, 26 (3): 261-269.   DOI: 10.11872/j.issn.1005-2518.2018.03.261
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A systematic study of carbon-oxygen isotope and electron microprobe for Sanbao Mn-Ag deposit was carried out.It was found that the carbon isotope composition of primary rhodochrosite and coexisted calcite were negative and the oxygen isotopic value were positive,while the carbon isotope value of wall rock was near zero.The results show that the carbon in Sanbao Mn-Ag deposit mainly derives from the mantle source or deep magma system,but its carbon isotope value of this deposit doesn’t completely within δ13C value of deep mantle.It implies that the carbon in the ore-forming fluid may derive mainly from deep system,at the same time,atmospheric precipitation is added to cyclic leaching partial carbon produced from wall rock.The morphology of the ore bodies is stratoid layers,lentoid and lenticular and cystic,rather than typical of layered structure. Additionally,some magmatic accessory minerals such as zircon and rutile are discovered in the Mn-Ag ores.Comprehensive analysis show that the genetic type of Sanbao Mn-Ag deposit belongs to hydrothermal origin and not marine sedimentary deposit.Therefore,this study not only reports characteristics of stable carbon-oxygen isotope but is helpful to deepen the understanding on deposit genesis,broaden exploring information and improve prospecting effect.
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