青藏高原东缘缅萨洼金矿成矿流体地质地球化学特征

缅萨洼金矿位于中国中轴构造带的中南段,青藏高原的东缘,赋存于金河-箐河断裂带次级断裂羊坪子韧性剪切带中本文根据对该矿床硫化物流体包裹体的氦氩同位素、硫化物的硫同位素以及与硫化物共生的石英的流体包裹体特征、成分以及氢氧同位素组成的测定,讨论了缅萨洼金矿的成矿流体来源及其矿床成因。结果显示,该矿床硫化物流体包裹体中的3He/4He变化较小,为0.69-0.82,显示了地幔流体参与成矿作用的可能性。而4He的含量变化范围较大,一般在2.19-10.62×10-6cm3STP/g(方铅矿除外)与3He/4He相比,40Ar/36Ar的比值则变化较小,一般为251-509。而硫化物的δ34S同位素变化范围在-1.8-2.2‰,平均值为0.5‰,说明硫的地幔来源。与硫化物共生的石英的流体包裹体的类型主要有富液相的盐水溶液包裹体、富气相的盐水溶液包裹体、三相CO2包裹体、纯液相CO2包裹体以及有机流体包裹体。成矿流体的氢氧同位素则显示成矿流体来源于岩浆水(或地幔流体)与大气降水的混合流体,本文认为,缅萨洼金矿的成矿流体为地幔流体与大气降水的混合流体,是渐新世印度大陆与亚洲大陆碰撞之后,该地区大规模走滑与剪切作用过程中,局部伸展作用的产物。     

Heavy metal concentrations and Pb isotopic composition in urban and suburban aerosols of Hong Kong and Guangzhou, South China-Evidence of the long-range transport of air contaminants

Rapid urbanization and industrialization in South China has placed a great strain on the environment and human health. In the present study, the total suspended particulate matter （TSP） in the urban and suburban areas of Hong Kong and Guangzhou, the two largest urban centres in South China, was sampled from December 2003 to January 2005. The samples were analyzed for their concentrations of major elements （Al, Fe, Mg and Mn） and trace metals （Cd, Cr, Cu, Pb, V and Zn）, and for Pb isotopic composition. Elevated concentrations of metals, especially Cd, Pb, V and Zn, were observed in the urban and suburban areas of Guangzhou, showing significant atmospheric trace element pollution. Distinct seasonal patterns were observed in the heavy metal concentrations of aerosols in Hong Kong, with higher metal concentrations during the winter monsoon period, and lower concentrations during summer time. The seasonal variations in metal concentrations of the aerosols of Guangzhou were less distinct, suggesting the dominance of local sources of pollution around the city. The Pb isotopic composition in the aerosols of Hong Kong had higher ^206Pb/^207Pb and ^208Pb/^207Pb ratios in winter, showing the influence of Pb from the northern inland areas of China and the Pearl River Delta （PRD） region, and lower ^206Pb/^207Pb and ^208Pb/^207Pb ratios in summer, indicating the influence of Pb from the South Asian region and from marine sources.     

The Isotopic Composition of Noble Gases in Gold Deposits and the Source of Ore- Forming Materials in the Region of North Hebei, China

1IntroductionOnthenorthernmarginoftheNorthChinaplatformislocatedoneofthemostimportantAu Ag polymetallicore concentratedzones,wherethereareavarietyoforetypes .Soithasbeenat tractingeverincreasingattentionofmanygeologists (PeiRongfuetal.,1 998;ShenBaofengetal.,1 994 ;LuSongnianetal.,1 997;HuShouxietal.,1 994 ;ChenYuchuan ,1 999;ZhaiYushengetal.,1 999) .Manyscholarspresentedtheirresearchresultsinvariousaspects.How ever ,thesourceofore formingmaterialshaslongbeenafocusofdiscussion .Studieso…     

The influence of the limestone-quarry Čertovy schody (Czech Republic) on the precipitation chemistry and atmospheric deposition

Atmospheric precipitation samples were collected in the Bohemian Karst (30 km SW from Prague, Czech Republic) at six localities in the vicinity of the limestone-quarry Čertovy schody during years 1996–2003. Samples were analyzed for major components (Na⁺, K⁺, Mg²⁺, Ca²⁺, F⁻, Cl⁻, NO₃⁻, HCO₃⁻, SO₄²⁻) and trace metals (Cu, Mn, Fe, Zn, Pb, Be, As, Sr, Cd, Al, Cr). Deposition fluxes were calculated from more than 10 000 elemental analyses of samples collected monthly. The fluxes of monitored substances show temporal and spatial variability. The most marked attribute is the strong affection by local emission sources confirmed by the investigation of seasonal variability, temporal trend and correlation analysis.     

内蒙古赤峰双尖子山银多金属矿床成矿流体来源及金属沉淀机制探讨

双尖子山超大型银多金属矿床是大兴安岭成矿带最具代表性的热液型银矿床,也是目前亚洲最大银矿。该矿床热液作用可划分为Ⅰ、Ⅱ两期,第Ⅰ期又可划分三个成矿阶段,依次为成矿阶段(Ⅰ-1)(主要为黄铁矿+方铅矿+闪锌矿+银矿物+石英组合,分布在北西走向矿脉)→成矿阶段(Ⅰ-2)(主要为方铅矿+银矿物+闪锌矿+石英+方解石组合,分布在北北东走向矿脉)→成矿阶段(Ⅰ-3)(含金石英+方解石脉组合,分布在近东西走向矿脉)。第Ⅱ期为胶结硫化物脉的无矿石英脉,主要是石英+少量方解石组合。该矿床流体包裹体以L型和V型为主,总体属于中低温-低盐度流体。成矿阶段(Ⅰ-1)流体包裹体均一温度介于171℃～280℃之间,平均228℃,盐度介于0.53%～12.73%(NaCl_(eqv))之间,平均3.48%(NaCl_(eqv));成矿阶段(Ⅰ-2)流体包裹体均一温度介于109.3℃～258.0℃之间,平均193.3℃,盐度介于0.18%～22.38%(NaCl_(eqv))之间,平均4.20%(NaCl_(eqv));第Ⅱ期热液流体包裹体均一温度介于238.7℃～362.9℃之间,平均275.9℃,盐度介于0.35%～2.24%(NaCl_(eqv))之间,平均1.05%(NaCl_(eqv))。方解石δ~(13)C介于-11‰～-7.4‰,δ~(18)O_(SMOW)介于1‰～4.5‰;石英和方解石δD_(H_2O)变化于-145‰～-65‰,δ~(18)O_(H_2O)变化于-12.5‰～4.6‰,表明流体为岩浆水和大气降水的混合来源;金属硫化物~(40)Ar/~(36)Ar值介于294.75～303.92,~3He/~4He值介于0.25～0.81Ra,显示壳源流体特征。双尖子山矿床成矿流体具有脉冲式活动、多阶段演化和多来源特点,成矿流体具有从相对的高温高盐度向低温低盐度演化规律。岩浆水与循环大气降水的混合作用可能是本矿床金属沉淀的主要机制。双尖子山矿床属于与壳源岩浆活动有关的中浅成-中低温热液型银多金属矿床。     

辽东宽甸地区硼酸盐矿床成矿时代的限定：来自SHRIMP锆石U Pb年代学和硼同位素地球化学的制约

辽宁宽甸地区砖庙硼矿区的硼矿体呈层状或透镜状赋存于古元古代辽河群里尔峪组火山—沉积建造下部的蛇纹石化大理岩之中。本研究对矿区内外的伟晶岩和变粒岩中的电气石进行了LA-MC-ICP-MS硼同位素微区原位测试,分析了矿床成因;同时对栾家沟矿段矿体上盘含电气石变粒岩和斜长角闪岩进行了SHRIMP锆石U-Pb定年,探讨了成矿时代。得到以下数据和认识:1矿区伟晶岩中电气石的δ11 B为10.9‰~12.7‰,变粒岩中电气石的δ11B为5.7‰~7.6‰,矿区外伟晶岩中电气石的δ11B为-9.9‰~-9.2‰,变粒岩中电气石的δ11 B为-8.3‰~-5.9‰。硼同位素组成往外降低的现象说明,围岩及侵位其中的伟晶岩的B同位素组成均受硼矿床影响,硼矿可能是海相蒸发沉积成因;2含电气石变粒岩核部岩浆锆石的207 Pb/206 Pb加权平均年龄为2174±10Ma,代表了辽吉裂谷早期的火山喷发时代,亦大致代表了初始的含硼蒸发岩的沉积时代上限,根据硼同位素研究结果,可将宽甸地区硼矿的初始沉积成矿时代限定在2.17Ga;3斜长角闪岩重结晶锆石207 Pb/206 Pb加权平均年龄为1869±28Ma,代表了吕梁运动所引起的区域构造热事件和混合岩化作用的时间。     

The Influence of CO on the Carbon Isotopic Composition of CH4 in Closed Pyrolysis Experiment With Coal

A low-mature coal (R_o=0.4%, from the Manjia'er depression, Tarim Basin, China) was subjected to closed system pyrolysis, in sealed gold tubes, under isothermal temperature conditions. The carbon isotopic compositions of the pyrolyst fractions (hydrocarbon, CO₂, CO, etc.) at two temperature points (350°C and 550°C) were measured. The results showed that {ie359-1} value is generally heavier at 350°C than that at 550°C, because the high abundance of CO generated at low temperature would greatly influence {ie359-2} value, and the retention time of CO in gas chromatograph is close to that of CH₄. But CO is formed through chemical reaction of the oxygen-containing functional group −C=O, e.g. lactones, ketones, ether, etc. at low temperature, while CO₂ comes mainly from decarboxylization. The carbon isotopic composition of coal gas from Lanzhou Coal Gas Works was definitely different from that of thermally pyrolysed products from coal. The {ie359-3} value of coal gas was abnormally heavier than {ie359-4}. At the same time, the reversed sequence ({ie359-5}) of {ie359-6} and {ie359-7} happened. The bond energy of free ions generally decides the sequence of generation of hydrocarbon fractions according to the chemical structure, whereas the stability of pyrolysate fractions and their carbon isotope fractionation are affected by the C−C bond energy. This study was supported by the National Basic Research (973) Program of China (No. 2001CB209102).     

The impact of thermal maturity level on the composition of crude oils,assessed using ultra-high resolution mass spectrometry

We have examined, using a 12 Tesla FTICR-MS instrument, the impact of varying thermal maturity level on a suite of 9 related crude oils charged from source rocks covering most of the liquid petroleum generating portion of the oil window (0.68–1.11% vitrinite reflectance equivalent (%Re)). The sample suite was analyzed as whole oils under three different conditions, electrospray ionization (ESI) in positive and negative ion mode to analyze basic and acidic components, respectively, and atmospheric pressure photoionization (APPI) in positive ion mode, for sulfur and hydrocarbon species.Increasing oil maturity level had a strong influence on the composition of all compound classes in the oils with several major observations evident:The relative apparent abundances of all heteroatom containing compound classes detected in this study, using all ionization modes, decrease systematically with increasing oil maturation levels. Both aromatic hydrocarbons, detectable in APPI mode, and NSO compound classes (detectable in both ESI and APPI modes), as broad classes, are becoming more aromatic (shift to a greater predominance of higher DBE group members) and dealkylated (decreasing average molecular mass of individual compound groups), with increasing maturation level in the oil suite. Several putative oil maturity level dependent, molecular ratios were identified in the study. Of particular note, the relative abundance ratios of heteroatom compound classes tentatively identified as alkylated carbazoles, quinolines and benzothiophenes, compared to their benzannulated homologues are very sensitive to maturation level. Several groups of compounds show interesting and specific carbon number distributions, suggesting there may be hints of specific molecular markers in the FTICR-MS data. One observation of note is the strong increase in the relative abundance of protonated hydrocarbon components with DBE 5. We speculate this might reflect the presence of previously unreported higher molecular weight diamondoid (diamantane) species in oils with up to 40 carbon atoms or more, at advanced maturity levels. Such species may prove very valuable as molecular markers in highly mature fluids, such as those currently being produced from some shale reservoirs. Covariation of quantitative GC–MS data for alkylated hetero aromatic sulfur and nitrogen compounds in this oil suite, together with the corresponding FTICR-MS data from compounds believed to be, based on accurate mass, alkylated sulfur and alkylated nitrogen compounds, suggests that FTICR-MS already has some very rudimentary quantitation capabilities.     

The Influence of Element Diffusion at the Sediment—Water Interface on the Basic Chemical Composition of Overlying Water Mass in Lake Lugu,China

Little work has been done on the influence of seiments on the basic chemical composition of overlying water mass.This paper deals with the vertical profile of the basic constituents such as Ca^ ,K^ ,Na^ ,and HCO3^-,as well as of pH in the overlying water mass and sediment porewater of Lake Lugu-a semi-closed,deep lake in Yunnan Province.The reand sediment porewater of Lake Lugu- a semi-closed,deep lake in Yunnan Province.The results revealed that those basic constituents may diffuse and transport from bottom sediments to overlying water mass through porewater.In the paper are also quantitatively evaluated the diffusive fluxes and the extent of their influence on overlying water mass,indicating that the lake sediment-water interface diffusion plays an important role in controlling the basic chemical composition of water in the whole lake.