葛坪铅锌矿地质特征及成矿阶段划分

葛坪铅锌矿是一个多阶段形成的中温热液充填交代矿床,主要的矿化类型有脉状、稀疏和稠密浸染状等。本文阐述了葛坪铅锌矿的基本地质特征,并通过在野外对矿床不同的成矿作用及矿化蚀变的观察研究,及室内对矿石结构、构造、矿物组合及先后关系的研究,将矿床的形成划分出五个成矿阶段：1早矽卡岩阶段;2晚矽卡岩阶段;3脉状铅锌硫化物阶段;4硫化物-石英阶段;5方解石阶段。     

Crude oil as carrier of gold: petrological and geochemical evidence from Lannigou gold deposit in southwestern Guizhou, China

Organic matter is related closely to mineralization of Lannigou gold deposit in southwestern Guizhou, China. Regionally, the distribution of organic carbon agrees well with that of faults within which gold deposits are hosted. Studies on organic petrology show that pyrobitumen, which is related most closely to mineralization, adheres to quartz vein or fills quartz veinlet. Proton-induced X-ray emission (PIXE) analysis shows an evident abundance of Au in pyrobitumen. Pyrobitumen paragenetically associates with pyrite and arsenopyrite which are the main carrier minerals of Au. The thermal simulation experiment indicates that about 99% of Au will be concentrated in oil phase in the coexisting system of oil and brine and rock. The role of crude oil in ore-forming process is: as carrier of Au, crude oil moves upwards, and undergoes thermal decomposition and thermochemical reduction when it encounters the oxidizing fluid within the Trassic turbidity; Au is thus released from crude oil, reduced and precipitated. Project supported by the Climbing Project (No. PA30) and the National Natural Science Foundation of China (Grant No. 49673190).     

Geological characteristics and mineralization setting of the Zhuxi tungsten (copper) polymetallic deposit in the Eastern Jiangnan Orogen

The Zhuxi ore deposit is a super-large scheelite(copper) polymetallic deposit discovered in recent years. It grew above copper/tungsten-rich Neoproterozoic argilloarenaceous basement rocks and was formed in the contact zone between Yanshanian granites and Carboniferous-Permian limestone. Granites related to this mineralization mainly include equigranular, middle- to coarse-grained granites and granitic porphyries. There are two mineralization types: skarn scheelite(copper) and granite scheelite mineralization. The former is large scale and has a high content of scheelite, whereas the latter is small scale and has a low content of scheelite. In the Taqian-Fuchun Basin, its NW boundary is a thrust fault, and the SE boundary is an angular unconformity with Proterozoic basement. In Carboniferous-Permian rock assemblages, the tungsten and copper contents in the limestone are both very high. The contents of major elements in granitoids do not differ largely between the periphery and the inside of the Zhuxi ore deposit. In both areas, the values of the aluminum saturation index are A/CNK1.1, and the rocks are classified as potassium-rich strongly peraluminous granites. In terms of trace elements, compared to granites on the periphery of the Zhuxi ore deposit, the granites inside the Zhuxi ore deposit have smaller d Eu values, exhibit a significantly more negative Eu anomaly, are richer in Rb, U, Ta, Pb and Hf, and are more depleted in Ba, Ce, Sr, La and Ti, which indicates that they are highly differentiated S-type granites with a high degree of evolution. Under the influence of fluids, mineralization of sulfides is evident within massive rock formations inside the Zhuxi ore deposit, and the mean SO_3 content is 0.2%. Compared to peripheral rocks, the d Eu and total rare earth element(REE) content of granites inside the Zhuxi ore deposit are both lower, indicating a certain evolutionary inheritance relationship between the granites on the periphery and the granites inside the Zhuxi ore deposit. For peripheral and ore district plutons, U-Pb zircon dating shows an age range of 152–148 Ma. In situ Lu-Hf isotope analysis of zircon in the granites reveals that the calculated e_(Hf)(t) values are all negative, and the majority range from -6 to -9. The T_(DM2) values are concentrated in the range of 1.50–1.88 Ga(peak at 1.75 Ga), suggesting that the granitic magmas are derived from partial melting of ancient crust. This paper also discusses the metallogenic conditions and ore-controlling conditions of the ore district from the perspectives of mineral contents, hydrothermal alteration, and ore-controlling structures in the strata and the ore-bearing rocks. It is proposed that the Zhuxi ore deposit went through a multistage evolution, including oblique intrusion of granitic magmas, skarn mineralization, cooling and alteration, and precipitation of metal sulfides. The mineralization pattern can be summarized as "copper in the east and tungsten in the west, copper at shallow-middle depths and tungsten at deep depths, tungsten in the early stage and copper in the late stage".     

Fluid mixing as the mechanism of formation of the Dajing Cu-Sn-Ag-Pb-Zn ore deposit,Inner Mongolia

Dajing Cu-Sn-Ag-Pb-Zn ore deposit, in the Inner Mongolia Autonomous Region of China, is a fissure-filling hydrothermal ore deposit. The δD values of quartz-hosted inclusion water are centered at −100%.– −130%.. The δ³⁴S values of sulfide ore minerals and δ¹³ C values of carbonate gangue minerals vary from −0.3%. to 2.6%. and from −2.9%. to −7.0%., respectively. Integrated isotopic data point to two major contributions to the mineralizing fluid that include a dominant meteoric-derived groundwater, and sulfur and carbon species from hypogene magma. Linear trends are exhibited on the gaseous H₂O versus CO₂ plot, and plots of CO, N₂, CH₄, and C₂H₆. It is shown by quantitative simulation that magma degassing cannot explain the linear trends. Hence, these linear trends are interpreted in terms of mixing of CO₂-rich magmatic fluid with meteoric-derived groundwater. The groundwater circulated in Paleozoic sedimentary rocks and absorbed CO, N₂, CH₄, C₂H₆ and radiogenic Ar from organic matter. Cooling effects resulting from mixing have caused the precipitation of ore minerals.     

Exhalative supergenic uranium,thorium and marcasite occurrences in quaternary volcanites of central Italy

In the Quaternary alkali-potassic volcanites of Northern Latium, there are classical solfataras related to volcanic structures, and very large kaolinized fields, at the borders of the volcanic systems (perivolcanic), related to pre-volcanic tectonic structures. In the solfataric type of mineralization thorium and sulphur ores in an opaline matrix are prevailing; in the perivolcanic type of deposit are prevailing uranium ores in very regular layers associated with kaolin. Marcasite-pyrite beds and lenses are common in both of them. The mineralization processes start with the oxidation of H₂S coming out from volcanic edilices or from large faults. The origin of U and Th concentrations is to be seen in the anomalous high content of radioactive elements in the alkaline rocks, and in their enrichment in ground waters. The perivolcanic uranium mineralizations are of some economic interest: the ore deposition is controlled by ground water level in reducing conditions determined by H₂S, not unlike to the principal sedimentary uranium ores known in the continental environment.     

福建皇山铅锌多金属矿地质特征及成矿标志

文章介绍了福建皇山铅锌矿矿区地层、构造和岩浆岩,通过对矿体地质特征的描述、岩浆岩化学成分组成特征及成矿条件分析,提出矿区找矿标志。     

Discovery of seismites in Upper Sinian stratiform lead-zinc deposits in Dadu River valley, Sichuan, China: Implication for ore genesis

A number of lead-zinc sulphide deposits have been discovered in recent years in dolo- mitic rocks of the Upper Sinian Dengying Formation in the Dadu River valley region, Sichuan Province, China. The lead-zinc mineralization is closely associated with a black siliceous exhalite that has been traced over 50 km of strike. This makes Dadu River valley the most extensive stratiform non-ferrous sulphide horizon having been discovered to date in China. In a previous study by the first author (LIN), these deposits were recognised as belonging to the broad spectrum of lead-zinc sedimentary exhala- tive (SEDEX) deposits. In this paper, seismites and seismogenetic structures occurring in close association with the Dadu River valley mineralized zone are described. The close spatial and temporal relationship between the seismites and mineralization provides strong evidence for the hypothesis that the lead-zinc SEDEX deposits formed in direct response to earthquake activities around the Sinian-Cambrian boundary. The earthquakes are postulated to be an effective dynamic mechanism for triggering the upward migration of deep circulating ore fluids along synsedimentary growth faults and their exhalation onto the sea-floor to form the extensive deposits of stratiform lead-zinc sulphide ore.     

江西省会昌县淘锡坝大型锡矿床构造控矿机制探讨

淘锡坝锡矿床是近年探明储量达大型的锡矿床,是一种新的锡矿类型-隐爆层间裂隙带型。文章介绍了该矿床的地质特征和矿化特征,对矿区的构造进行了重点解剖,对构造控矿机理进行了探讨,提出火山机构及北东向断裂是矿区的控岩构造,控制了白垩纪成矿花岗岩体的侵入就位。而火山岩中大范围的隐爆层间裂隙带是良好的容矿构造,矿体赋存其中呈似层状,局部膨大形成厚达数十米的＂锡矿包＂。通过研究构造与矿化富集的内在联系,总结了该矿床的成矿规律。     

江西潭坑铅锌（银）矿床特征及成因分析

江西省潭坑铅锌（银）矿区位于北武夷铅锌银成矿带内,本文系统阐述了矿区地质和矿床特征,并对矿床的成因进行了探讨。认为本区铅锌（银）矿床,经历了火山喷发沉积和后期热液充填两大成矿期,与次火山岩体（流纹斑岩）有密切的关系,属次火山热液矿床。     

Fluid mixing as the mechanism of formation of the Dajing Cu-Sn-Ag-Pb-Zn ore deposit,Inner Mongolia ——Fluid inclusion and stable isotope evidence

Since the 1990s, interest in the magmatic fluids and their relation to mineralization has been re-aroused[1—6]. Studies on stable isotopes of low-sulfidation deposits commonly show the predominance of meteoric water[7]. Paradoxically, the evidence for me…     

Crust-mantle interaction and its contribution to the Shizhuyuan superlarge tungsten polymetallic mineralization

The Qianlishan granite, which is closely related to the Shizhuyuan tungsten polymetallic mineralization, is aluminous alkali-type granite. The intimate temporal and spatial association among the basaltic, syenite and granitic rocks in the mining area, and their major and trace elements, and Nd, Pb, Sr, O isotopic compositions indicate that the crustal-mantle interaction probably was an important constraint on, and participated in, the formation of the superlarge ore deposit.     

印度尼西亚西加里曼丹省吉打邦县马拉乌铅锌矿床地质特征

马拉乌铅锌矿床为印度尼西亚西加里曼丹（Kalimantan）省吉打邦县近年来发现的铅锌银矿床。该矿矿体顶板为黄铁矿化含碳质泥砂岩,矿体底板为玉髓状硅质岩。矿体呈侧羽状、脉状及透镜状。矿区通常发育的蚀变有硅化、泥化和绿泥石化等。主要矿物组合有方铅矿、闪锌矿、黄铁矿、磁黄铁矿、黄铜矿、斑铜矿、辉锑矿以及自然金、银金矿、辉银矿等,通过对矿石组构等综合分析,表明该矿床的成因是岩浆期后热液充填交代矿床。     

广东始兴南山矿区钨锡多金属矿床特征及资源潜力

广东始兴南山钨锡多金属矿床位于南岭成矿带东段,是中国地质调查局南京地质调查中心在新一轮钨多金属矿找矿工作实施中根据＂模型找矿＂找到的具有大型远景的钨锡钼铋多金属矿床。最新研究和工程钻探成果显示矿区分南北两个矿带,已圈定规模较大的钨锡多金属矿脉（体）10多条（个）,矿化类型有矽卡岩型、蚀变花岗岩型（云英岩型）、斑岩型和石英脉型。各种类型的矿体在空间上既有独立产出,又有共存一体、相伴而生,构成＂多位一体＂的复合矿床。其中以矽卡岩型钨锡铋多金属矿体、斑岩型钨钼多金属矿体和蚀变花岗岩型钨钼多金属矿体规模最大。本文通过该区地质、地球化学及主要钨锡钼铋多金属矿体特征的分析研究,指出了南山矿区的资源潜力,提出南山地区钨锡钼铋多金属矿的找矿方向。     

Classification and origin of natural gases from Lishui Sag,the East China Sea Basin

Natural gases discovered up to now in Lishui Sag, the East China Sea Basin, differ greatly in gaseous compositions, of which hydrocarbon gases amount to 2%–94% while non-hydrocarbon gases are dominated by CO₂. Their hydrocarbon gases, without exception, contain less than 90% of methane and over 10% of C₂ ⁺ heavier hydrocarbons, indicating a wet gas. Carbon isotopic analyses on these hydrocarbon gases showed that δ ¹³C₁, δ ¹³C₂ and δ ¹³C₃ are basically lighter than −44‰, −29‰ and −26‰, respectively. The difference in carbon isotopic values between methane and ethane is great, suggesting a biogenic oil-type gas produced by the mixed organic matter at peak generation. δ ¹³ \( C_{CO_2 } \) values of nonhydrocarbon gases are all heavier than −10‰, indicating a typical abiogenic gas. The simulation experiment on hydrocarbon generation of organic matter in a closed gold-tube system showed that the proportion of methane in natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit is obviously higher than that in natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit, consequently the proportion of heavier hydrocarbons of the former is remarkably lower than that of the latter. Moreover, δ ¹³C₁ values of natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit are about 5‰ heavier than those of natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit while δ ¹³C₂ and δ ¹³C₃ values of the former are over 9‰ heavier than those of the latter. Currently the LS36-1 oil-gas pool is the only commercial oil-gas reservoir in Lishui Sag, where carbon isotopic compositions of various hydrocarbon components differ greatly from those of natural gases produced by the Lingfeng Formation organic matter but are very similar to those of natural gases derived from the Yueguifeng Formation organic matter, therefore, natural gases in the LS36-1 oil-gas pool are mainly derived from the Yueguifeng Formation lacustrine source rock rather than the Lingfeng Formation marine or Mingyuefeng Formation coal-measures source rocks.

     

Classification and origin of natural gases from Lishui Sag,the East China Sea Basin

Natural gases discovered up to now in Lishui Sag, the East China Sea Basin, differ greatly in gaseous compositions, of which hydrocarbon gases amount to 2%–94% while non-hydrocarbon gases are dominated by CO₂. Their hydrocarbon gases, without exception, contain less than 90% of methane and over 10% of C₂ ⁺ heavier hydrocarbons, indicating a wet gas. Carbon isotopic analyses on these hydrocarbon gases showed that δ ¹³C₁, δ ¹³C₂ and δ ¹³C₃ are basically lighter than ?44‰, ?29‰ and ?26‰, respectively. The difference in carbon isotopic values between methane and ethane is great, suggesting a biogenic oil-type gas produced by the mixed organic matter at peak generation. δ ¹³ \(C_{CO_2 } \) values of nonhydrocarbon gases are all heavier than ?10‰, indicating a typical abiogenic gas. The simulation experiment on hydrocarbon generation of organic matter in a closed gold-tube system showed that the proportion of methane in natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit is obviously higher than that in natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit, consequently the proportion of heavier hydrocarbons of the former is remarkably lower than that of the latter. Moreover, δ ¹³C₁ values of natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit are about 5‰ heavier than those of natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit while δ ¹³C₂ and δ ¹³C₃ values of the former are over 9‰ heavier than those of the latter. Currently the LS36-1 oil-gas pool is the only commercial oil-gas reservoir in Lishui Sag, where carbon isotopic compositions of various hydrocarbon components differ greatly from those of natural gases produced by the Lingfeng Formation organic matter but are very similar to those of natural gases derived from the Yueguifeng Formation organic matter, therefore, natural gases in the LS36-1 oil-gas pool are mainly derived from the Yueguifeng Formation lacustrine source rock rather than the Lingfeng Formation marine or Mingyuefeng Formation coal-measures source rocks.     

UV irradiation of natural organic matter (NOM): impact on organic carbon and bacteria

UV-induced transformation of dissolved organic matter (DOC) is often accompanied by reduction of molecular weight and aromaticity and an increase of low-molecular weight (LMW) matter that can be utilized as a substrate by heterotrophic bacteria. Moreover, the generation of reactive transients and mineralization of DOC occurs. For a better understanding of the modification that starts after irradiation and to distinguish between possible chemical and biological modifications, we selected different natural organic matter (NOM) from Norway and Germany. The aqueous solutions were treated by UV irradiation and divided into two aliquot samples. NaN₃ anti-bacterial treatment was applied to one sample, and high-pressure size-exclusion chromatography (HPSEC) analysis was used for both. In all samples, we found typical modifications of NOM after UV irradiation. Incubation (>7?days) of UV-irradiated NOM samples resulted in lower levels of LMW matter and increased aromaticity. Parallel to these changes of carbon fractions, an increase in bacterial cell numbers was observed. Addition of NaN₃ to NOM, however, inhibited the reduction of LMW matter, indicating that microbial activity accounted for the observed changes in NOM. Analysis of the bacterial community composition by denaturing gradient gel electrophoresis (DGGE) of the amplified 16S rRNA genes revealed that bacterial communities of non-irradiated and UV-irradiated NOM were different and that UV selected for specific members of ??-proteobacteria, ??-proteobacteria, and Bacteriodetes. Our results imply that after UV-irradiation of NOM, specific bacterial members are well adapted to low pH, high LMW DOC concentrations, and oxidative stress, and therefore thrive well on UV-irradiated humic matter.     

THREE-DIMENSIONAL ELECTRIC MISE-A-LA-MASSE SURVEY OF AN IRREGULAR LEAD-ZINC-COPPER DEPOSIT IN CENTRAL SWEDEN *

The principle of the mise-á-la-masse method is to earth one current electrode of a pair in a conducting mineral show (in a borehole, in an outcrop etc.) and measure the resulting distribution of electric potentials. The distribution will, to some extent, reflect the geometry of the ore mass of which the mineral show forms a part. In a mise-á-la-masse survey of a lead-zinc deposit in Central Sweden electric potentials were measured on the surface of the ground as well as in some 25 drillholes, in either case with earthings (successively) in three different parts of the irregular ore deposit. Besides this, measurements were made in drillholes with earthings in two further drillholes. Geologic correlation between the drillholes is difficult in the present case on account of the irregular geometry of the ore deposit. However, the mise-á-la-masse measurements clearly showed the dip and the pitch of the ore body, established connections between the different ore widths encountered in the various holes, and yielded information about the shape of the ore mass. In particular, the survey showed that the ore lenses must be crescent-shaped rather than tabular, and the dip was indicated to be westerly, instead of easterly as originally presumed. Three-dimensional models of equipotential surfaces were constructed from the observed drillhole and surface potentials (using transparent plastic sheets and thin copper wire) and these helped to elucidate the mass geometry further. The surface and underground potential data collected in the present case should be of nterest to geophysicists working on analytic continuation problems.     

河南范疙瘩金矿床矿体定位的构造控制

范疙瘩金矿位于熊耳山断隆的东南部,马超营断裂带的北侧,金矿体产于北西向M14断裂带内。本文通过研究断裂构造的方向、规模、分布特征,分析断裂活动历史及矿体产出特征,总结成矿规律。金矿体严格受M14断裂控制,离断裂越远金矿化越弱,M14断裂带倾向上引张部位及断裂分支复合部位是金元素的富集地段,是成矿有利部位。     

富营养化湖泊沉积物有机质矿化过程中碳、氮、磷的迁移特征

采用室内培养的方法,以富营养化湖泊太湖为例,研究了沉积物有机质矿化过程中碳、氮、磷的迁移特征.结果表明,在沉积物中的有机质矿化过程中,碳以溶解性无机碳释放至水中,同时以CH4和CO2形式释放至大气中,培养结束时,CH4和CO2累积排放含量分别为1492.21和498.96 mg/g(dw),其中CH4占气态碳的89.16%(以C质量计);此外,大量的氮、磷营养盐释放至上覆水体,水中总氮、总磷和铵态氮的最高浓度分别是初始浓度的62.16、28.16和139.45倍,而硝态氮浓度在整个培养过程中逐渐下降,培养末期浓度是初期的0.21倍;厌氧条件下,沉积物有机质的矿化,不仅可以生成大量的CH4、CO2气体,还能够促使沉积物中铵态氮和磷的释放;而沉积物有机质矿化释放的碳、氮、磷营养元素又能加剧湖泊富营养化程度,促进湖泊水体的初级生产力,从而增加湖泊沉积物有机质输入.这样的循环方式可能是湖泊富营养化自维持的重要机制之一.     

3D joint inversion of Gradient and Mise-à-la-Masse borehole IP/Resistivity data and its application to magmatic sulfide mineral deposit exploration

Gradient and Mise-à-la-Masse IP/Resistivity surveys were conducted on a group of 19 boreholes in Eagle’s Nest, Eagle One magmatic sulfide deposit in northern Ontario, Canada. The surveys were conducted as a follow-up to the many drilled boreholes, some of which missed the target. The surveys were intended to map the distribution of the ore mineralization, outline the deposit hosted by mafic and ultramafic rocks and then guide the drilling of new boreholes. Joint Gradient and Mise-à-la-Masse data inversion produced 3D chargeability and conductivity models. The inverted 3D models in turn help delineate the outline of the mineralized zone, and determine the shape, size, strength and economic viability of the deposit. The Gradient array determined the direction of the mineralization with respect to the boreholes, and the Mise-à-la-Masse array examined the highly conductive subsurface bodies and their surroundings. The mapped ore zone shows close similarity to the 0.5 Cu% and 1.05 Ni% iso-surfaces that are produced from core assay result confirming the reliability of the results obtained in this study.