Distribution of δ~(34)S and δ~(18)O in SO_4~(2-) in Groundwater from the Ordos Cretaceous Groundwater Basin and Geological Implications

<正>The Ordos Cretaceous Groundwater Basin,located in an arid-semiarid area in northwestern China,is a large-style groundwater basin.SO_4~(2-) is one of the major harmful components in groundwater.Dissolved SO_4~(2-) concentrations,andδ~(34)S-SO_4~(2-) andδ~(18)O-SO_4~(2-) in groundwater from 14 boreholes and in gypsum from aquifer were analyzed.Results show that SO_4~(2-) in shallow groundwaters originates from precipitation,sulfide oxidation,and dissolution of stratum sulphate,with a big range ofδ~(34)S values,from-10.7‰to 9.2‰,and addition of SO_4~(2-) in deep groundwater results from dissolution of stratum sulphate,with biggerδ~(34)S values,from 7.8‰to 18.5‰,compared with those in shallow groundwater.This research also indicates that three types of sulphate are present in the strata,and characterized by highδ~(34)S values and highδ~(18)O values-style,highδ~(34)S values and middleδ~(18)O valuesstyle, middleδ~(34)S values and lowδ~(18)O values-style,respectively.Theδ~(34)S-SO_4~(2-) andδ~(18)O-SO_4~(2-) in groundwater have a good perspective for application in distinguishing different groundwater systems and determining groundwater circulation and evolution in this area.     

Fluorescence excitation-emission matrix characterization of a commercial humic acid

Excitation-emission matrix fluorescence spectroscopy (EEM) has been widely used to elucidate the origin and structure of humic substances in natural environments. Due to its high sensitivity, good selectivity and non-destructive advantage, the EEM was applied to characterizing a commercial Fluka humic acid (FHA). The results showed that the EEMs of FHA has several Ex/Em peaks. Ionic strength (0-0.05 moL/L KClO4 ) exerted little effect on the fluorescence properties of FHA, while the concentrations (5-100mg/L) of FHA and pH (2-12 ) had significant effects. A red shift in the longer wavelength peak region was observed when the coneentrations or pH values increased. The fluorescence intensity increased with increasing pH, but slightly decreased in the case of pH = 5.0. The protonation constants ( lgK^ HL ) of peak B were calculated to be 3.57 and 3.13, indicating that peak B was due to carboxyl groups. The r(A/B) values range from 0.61 to 2.59. A strong linear relationship between r(A/B) and pH was also observed. This indicates that the fluorescence peaks A and B posses similar inherent fluorescence characteristics.     

东海地区超高压石榴橄榄岩超微构造特征——快速折返的新证据

利用透射电子显微镜对中国大陆科学钻探(CCSD)主孔超高压石榴橄榄岩中石榴石、橄榄石及透辉石的超微构造特征进行了详细研究。石榴石、橄榄石及透辉石中的大部分区域都没有位错,在局部区域发育高密度位错及位错壁。石榴石局部区域的位错密度达到1．34×109／cm2以上,滑移系以1／2<111>{110}为主。在石榴石中发现一部分熔融条带,条带由熔体和磁铁矿球粒构成,在附近的石榴石基体中有高密度的小位错圈。橄榄石局部区域的位错密度达到2．64×108／cm2以上,并发育杆状钛铁矿和含铬钛磁铁矿出溶体。透辉石局部区域发育有位错壁,在部分位错壁部位形成了微裂隙。透辉石内部存在类“多边化”区域,不同区域之间存在小角度差。分析认为该石榴橄榄岩加入俯冲板片之后,在超高压变质峰期及早期快速折返阶段发生了较强的塑性变形,在石榴石、橄榄石及透辉石中形成了高密度的位错、位错壁及亚颗粒。在折返过程中,该石榴橄榄岩曾经发生了减压部分熔融和静态重结晶,导致石榴石、橄榄石及透辉石中大部分区域的位错消失。石榴石中部分熔融条带得以保存,表明在发生减压部分熔融和静态重结晶之后所经历的折返过程非常迅速,具有很高的抬升速率及降温速率。     

Dispersion and immobilization of pollutants in Cretaceous sandstones where U ore was mined by sulfuric acid leaching

The uranium deposit Straz pod Ralskem in the northern part of the Czech Republic was exploited by underground acidic leaching between 1968 and 1996. More than 14000 tons of uranium were produced during this period. More than 4 million tons of H2SO4, 300 thousand tons of HNO3, 120 thousand tons of NH3 and other chemicals were injected in Cenomanian sandstones. The mining has resulted in a large contamination of ground waters. Lateral hydrodynamic dispersion of the pollutants and migration of pollutants across aquitard are a potential hazard to drinking water supply and to surface aquatic environment, Chemical leaching was done by forced circulation of a technological acid solution introduced to the sandstones through injection drill holes and withdrawal of the enriched resulting solution by production wells. The solution is reacting not only with uranium ore, but also with minerals of the rock environment. Hydrogen ions are replaced by uranium and other cations leached from the rock, especially Fe, Al, Be and As. Ammonia remaining after the precipitation of the yellow cake （ammonium diuranate） was rejected underground in spite of that it serves no purpose in the underground leaching. High concentrations of Al, Be, As and ammonium ions in ground water became the most serious ecological pollutant. Modelling of the hydrodynamic dispersion of the pollutants predicts the future risks to local water supplies in 200 to 500 years. A possible way to reduce the risk is an immobilization of the pollutants in deeper parts of the sandstone aquifer. We found that modeling of the geochemical reactions using classical hydrochemical models give unrealistic results because of formation of colloidal particles.     

内蒙古东部阿荣旗地区晚白垩世孤山镇组的建立

通过1：25万阿荣旗幅地质调查，在阿荣旗孤山镇-东亚东镇一带发现一套酸-中酸碱性火山岩石组合，时代为晚白垩世，将其新建岩石地层单位——孤山镇组。孤山镇组主要分布于大杨树盆地南部，由流纹岩、流纹质火山碎屑岩、粗面岩和英安岩组成，上覆地层为嫩江组，下伏地层为甘河组。岩石高碱（Na2O＋K2O=7．83％-10．28％），属酸碱性系列。轻稀元素土富集，δEu=0．39-1．07；Nb、Ta基本无亏损，P、Ti强烈亏损，可能形成于陆内断陷盆地活动结束时期。     

日照胡家岭石榴单辉辉石岩体的地球化学特征及其成因

与原始地幔相比,苏鲁超高压变质带的日照胡家岭石榴单辉辉石岩体全岩化学成分易熔组分均较高,而难熔组分均较低,全岩的Si O2含量为44.04%~50.50%,高MgO(12.77%~18.73%),高CaO/Al2O3(1.6~8.0),低碱,Mg#的变化范围为74.82~86.13,成分特点类似铝亏损型科马提岩。稀土元素配分型式为典型的单斜辉石稀土元素配分型式,重稀土元素相对亏损,(Gd/Yb)N=3.51~5.87。铂族元素的总体丰度为19.18×10-9~59.44×10-9,变化范围较大,高于地幔橄榄岩的丰度,(Pd/Ir)N具有8.58~11.07的正斜率。这些特点表明形成石榴单辉辉石岩的岩浆为地幔源区残留石榴石、主要熔出单斜辉石的高程度部分熔融的产物,折返前可能由单斜辉石 石榴石相组成。铂族元素丰度高、正斜率的特点表明其分布受到了地幔高程度部分熔融的控制且没有硫化物的分离,说明熔浆中硫是不饱和的。     

金云母-蛭石间层矿物的酸浸取物与酸蚀机理研究

对采自新疆尉犁蛭石矿的金云母蛭石间层矿物样品进行了酸处理实验研究。在样品化学成分和XRD分析的基础上,研究了样品酸处理后酸浸取物的化学组成、含量及结构变化特征;分析讨论了金云母蛭石间层矿物在酸处理过程中不同阳离子浸出率的变化规律和酸蚀机理。结果表明,层间可交换性阳离子的氧化物CaO和Na2O的酸浸取率最高,层间不可交换性阳离子的氧化物K2O次之,八面体中阳离子的氧化物MgO、Fe2O3和Al2O3具有较高的酸浸取率,而四面体阳离子的氧化物Si O2的酸浸取率最低;金云母蛭石间层矿物中蛭石晶层含量高的样品酸浸取率高,金云母蛭石间层矿物的耐酸蚀性能不如金云母。     

封闭酸溶-等离子体质谱法分析超细粒度地质样品中42个元素

采用封闭压力酸溶，电感耦合等离子体质谱法（ICP—MS）测定了超细样品的42个元素，研究了样品的粒度、分解条件、取样量对分析准确度和精密度的影响。结果表明，用超细粉碎样品（〈30μm），取样量减小至2mg仍能保证取样代表性，总用酸量可减至0．5mL，反应时间也可大大缩短。采用超细样品可更好地发挥ICP—MS技术高灵敏度的效能，从而达到保护环境、降低分析成本、提高分析效率的目的。     

常见酸根离子浓度的激光拉曼光谱定量分析

探讨利用激光拉曼光谱法对微量包裹体溶液中常见酸根离子成分（氯离子、硫酸根和乙酸根）进行定量测量。依据酸溶液某些拉曼光谱参数（如拉曼强度、半高宽和谱峰面积等）与对应振动的分子或离子团数量有密切的定量关系，估算酸溶液中离子或分子的浓度。结果表明，硫酸和乙酸溶液的拉曼光谱特征峰参数与浓度呈良好的线性关系；电解质水溶液拉曼峰的形变参数WA1／WA2、WH1／WH2可用于估算氯离子浓度。运用多元统计学的方法，拟合出盐酸、硫酸和乙酸溶液的浓度与各拉曼参数的回归方程。     

藏东南错那县麻玛沟角闪岩相石榴辉石岩成因研究

在藏东南错那县西南约20km的麻玛沟中发现了呈透镜体产出于石榴石矽线石片麻岩中的石榴辉石岩,其矿物组合为石榴石 透辉石 石英 铁角闪石 磁铁矿,并含有锆石、磷灰石等副矿物。石榴石呈他形产出,以铁铝榴石和钙铝榴石端员组分为主,贫镁铝榴石组分,并具成分环带:核部相对富铁铝榴石分子,贫镁铝榴石分子,而边部则相反。透辉石同样富铁、贫镁,Fe2 /(Fe2 Mg)比值一般大于0.6。铁角闪石呈熔蚀状被透辉石和石榴石所包裹,或产出于自形的透辉石颗粒之间,以贫钛为特征。该岩石的全岩成分以SiO2(59%～61%)、Fe2O3(全铁)(18%～19%)、CaO(12%～13%)和Al2O3(5.3%～5.4%)为主。运用石榴石-单斜辉石温压计估算出该岩石石榴石与透辉石的平衡温压条件分别为650～700℃、0.8～1.0GPa。这些特征表明该石榴辉石岩很可能系富铁的斜长角闪岩在中地壳尺度发生脱水所形成的残余。本文研究提供了一个角闪岩相石榴辉石岩的实例。