Quantitative SIMS analysis of trace Au in pyrite using the infinite velocity (IV) method

The quantitative analysis of trace concentrations of Au in pyrite using a new procedure of SIMS quantification is investigated. Analysis of an Au implanted pyrite standard demonstrates the infinite velocity (IV) method as a viable procedure for evaluation of trace concentrations of Au in pyrite. Comparison of naturally occurring trace concentrations of Au in pyrite using standard-derived relative sensitivity factor (RSF) and IV quantification methods is shown as a means of evaluating the chemical environments in which Au is found in pyrite.     

藏南羊卓雍错流域水化学主离子特征及其控制因素

水化学主离子特征是流域湖泊的一个重要特征,对气候以及河流所经地区的环境具有指示作用.本文对藏南羊卓雍错流域水化学主离子组成特征及其控制因素进行分析,结果显示流域内不同水体(湖水、河水、地下水)之间的主离子组成以及水化学类型差异显著.其中,羊卓雍错的水化学类型为SO24--HCO3--Mg2+-Na+,巴纠错为SO24--Mg2+-Na+,沉错为SO24--Na+-Mg2+-Ca2+,普莫雍错为HCO3--SO24--Mg2+-Ca2+,空姆错为HCO3--SO24--Ca2+;流域河水中主要阴离子为HCO3-和SO24-,Ca2+为绝对优势阳离子;流域地下水化学类型则为HCO3--Ca2+.究其原因,流域水体化学组成主要受岩石风化作用控制;除此,羊卓雍错、巴纠错和沉错水化学组成亦受自身蒸发-结晶作用的影响.就入湖河水而言,羊卓雍错入湖河水整体受碳酸盐岩石风化的影响较大,蒸发岩溶解的影响次之;沉错和空姆错入湖河流(卡鲁雄曲)的蒸发岩来源则略大于碳酸盐岩来源;而硅酸盐对流域内河水的水化学性质影响较小.与入湖河水相比,羊卓雍错和沉错湖水的Mg2+、Na+和SO24-含量较高,而Ca2+和HCO3-含量较低.这应该与湖水蒸发强烈使得湖水中Ca2+和HCO3-析出并沉积到湖底有关.而空姆错由于湖泊面积小、入湖河水流量大,致使其湖水与入湖河水的主离子组成差异不显著.     

Diffusion Kinetics of Carbonate Hydroxyapatite （CHAP） for Adsorbing F^- Dissolved in Water

A systematic research was performed about diffusion kinetics of adsorbing F^- dissolved in water for carbonate hydroxyapatite （CHAP） from the natural hydroxyapatite which was modified by adulterating with CO3^2-. The result shows that the speed of F^- adsorption is controlled by membrane diffusion when F^- concentration is relatively low, which is expressed by the kinetic equation of diffusion Q=0.0005（Ci-C）（t-ti）＋0.3967, or by vacancy diffusion when F^- concentration is relatively high, which is expressed by the kinetic equation of diffusion In[C（o, t）]=8.4718-0.5048Int. Based on the feature of CHAP for adsorbing F^- dissolved in water and its special channel of the structure of CO3^3- modified hydroxyapatite, models of vacancy diffusion and membrane diffusion were established.     

炭质泥岩Re-Os和碎屑锆石U-Pb同位素定年对广东大宝山铜矿床成矿时代的约束

Re-Os同位素作为一种强有力的技术工具,在黑色页岩沉积时代的精确定年中得到了广泛应用.随着高精度负离子热电离质谱(N-TIMS)测试技术的发展,炭质泥岩Re-Os同位素年龄测试越来越多地被应用于厘定沉积时代.广东省大宝山铜矿成岩成矿时代争议一直是制约成因机制研究的关键因素.本文通过Carius管中逆王水溶解炭质泥岩粉...     

格陵兰海近海海域夏季海水水质特征分析

2010年7月,在北京青少年科技俱乐部组织的北极科学考察活动过程中,对斯瓦尔巴德群岛、格陵兰岛以及冰岛的近海海域进行表层海水水样、冰样及陆地径流的采集。对采集样品的9项指标分析结果表明,海水样品中未检到F^-和NO₃^-;其他离子含量的排序依次为:Cl^-,Na⁺,SO₄^2-,Mg²⁺,K⁺,Ca²⁺,与自然海水常规离子含量的排序基本一致;各离子含量与氯度的比值与恒比定律中给出的值基本一致,证明了北极海水主要受到陆地降水直接补给。近岸海水的离子含量远远低于远岸海水的原因是由于冰川融化,通过地表径流的方式补给表层海水有关。斯瓦尔巴德群岛的地表径流中存在有NO₃^-,但对所采海水样品的检验中,未检测到NO₃^-,说明地表径流中的NO₃^-在海水的对流等作用下得以充分稀释。     

GHR1 Zircon – A New Eocene Natural Reference Material for Microbeam U‐Pb Geochronology and Hf Isotopic Analysis of Zircon

We present multitechnique U‐Pb geochronology and Hf isotopic data from zircon separated from rapakivi biotite granite within the Eocene Golden Horn batholith in Washington, USA. A weighted mean of twenty‐five Th‐corrected ²⁰⁶Pb/²³⁸U zircon dates produced at two independent laboratories using chemical abrasion‐isotope dilution‐thermal ionisation mass spectrometry (CA‐ID‐TIMS) is 48.106 ± 0.023 Ma (2s analytical including tracer uncertainties, MSWD = 1.53) and is our recommended date for GHR1 zircon. Microbeam ²⁰⁶Pb/²³⁸U dates from laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) and secondary ion mass spectrometry (SIMS) laboratories are reproducible and in agreement with the CA‐ID‐TIMS date to within < 1.5%. Solution multi‐collector ICP‐MS (MC‐ICP‐MS) measurements of Hf isotopes from chemically purified aliquots of GHR1 yield a mean ¹⁷⁶Hf/¹⁷⁷Hf of 0.283050 ± 17 (2s, n = 10), corresponding to a εHf₀ of +9.3. Hafnium isotopic measurements from two LA‐ICP‐MS laboratories are in agreement with the solution MC‐ICP‐MS value. The reproducibility of ²⁰⁶Pb/²³⁸U and ¹⁷⁶Hf/¹⁷⁷Hf ratios from GHR1 zircon across a variety of measurement techniques demonstrates their homogeneity in most grains. Additionally, the effectively limitless reserves of GHR1 material from an accessible exposure suggest that GHR1 can provide a useful reference material for U‐Pb geochronology of Cenozoic zircon and Hf isotopic measurements of zircon with radiogenic ¹⁷⁶Hf/¹⁷⁷Hf.     

Accurate Measurement of Lithium Isotopes in Eleven Carbonate Reference Materials by MC‐ICP‐MS with Soft Extraction Mode and 1012 Ω Resistor High‐Gain Faraday Amplifiers

Lithium isotopes in carbonate rocks and minerals can serve as important tools for assessing palaeoclimates and palaeoenvironments. However, carbonate bulk rock samples are commonly mixtures of carbonate and silicate minerals, which require the complete digestion of the carbonate without digesting the silicate. Additionally, the low Li content (ng g^?1 level) in carbonates provides an additional challenge. Hence, despite their wide applications, few carbonates have had their δ⁷Li values characterised, particularly carbonate reference materials, which hinders comparisons of Li isotope measurement results obtained in different laboratories and the further application of Li isotopes in geological studies. This study aimed to provide precise and accurate δ⁷Li values for carbonate reference materials based on an evaluation of sample leaching and the Li purification method for carbonates, as well as the adoption of soft extraction and 10¹² Ω amplifiers to increase the intensity/blank ratio and matrix effect on Li isotope measurement. The precision and accuracy of the proposed procedure were verified by analysing synthetic carbonate samples and mono‐elemental Li solutions. With the developed method we provide δ⁷Li values for eleven carbonate reference materials with a precision of ~ 0.4‰. The accuracy of the δ⁷Li values was validated using the standard addition method.     

九岭式狮子岭岩体型稀有金属成矿作用研究进展及其找矿意义

赣西北是我国重要的稀有金属成矿区,成矿作用主要集中于武功山隆起和九岭隆起,其中的武功山隆起产有我国最大的岩体型稀有金属矿床414矿,在九岭隆起是否也能找到类似于414的大型稀有金属矿床成为业界关注的焦点。本文在华南稀有稀散和稀土矿产调查评价项目开展过程中,查明了赣西北九岭地区的狮子岭岩体也存在类似的稀有金属矿化,矿化主要赋存于黑磷云母—含锂白云母碱长花岗岩、锂(白)云母碱长花岗岩和黄玉锂云母碱长花岗岩三类岩石中,三类岩石的分带特点与武功山隆起雅山含矿岩体从Ⅴ带的二云母碱长花岗岩到Ⅱ带的黄玉—锂云母—钠长石花岗岩演变趋势有非常明显的相似性。同时,详细的矿物学研究表明,狮子岭岩体稀有金属矿化特征与414矿也存在一定差异,如狮子岭黄玉—锂云母碱长花岗岩中磷锂铝石超常富集,含量可到4%～5%,已成为矿石中锂的主要载体之一;岩体中绿柱石、富钽锡石、铌钽铁矿、钽铌铁矿等工业稀有金属矿物也普遍存在,这些发现为该地区Li、Be、Ta及Sn的找矿工作部署提供了直接依据。同时,文章对九岭地区锂矿资源的成矿潜力、成矿机制以及华南地区岩体型锂矿找矿方向进行了探讨,深化了稀有元素在花岗岩类中成矿作用的认识,对华南地区稀有金属的找矿工作可能也将产生积极的影响。     

离子色谱法测定冰川末端大气PM2.5可溶性离子及其来源解析

为了研究祁连山西段冰川末端地区大气PM_2.5细粒子中可溶性无机离子组分的变化特征,于2011年采集了一批大气PM_2.5的Telfon滤膜样品,并应用离子色谱对可溶性离子进行了分析。样品采用超纯水超声萃取各种水溶性离子,优化的萃取溶液体积为25 mL,萃取时间为30 min,萃取液用0.45μm纤维滤膜过滤,各种离子在一定浓度范围内线性关系良好,相关系数r>0.999。所测样品的阴阳离子中,SO₄^2-、NO₃^-、Ca²⁺、和NH₄⁺的质量浓度约占到水溶性离子总量的88%。可溶性离子浓度呈现出春夏高、秋冬低的季节变化特征,夏季可溶性离子浓度最高。     

铝土矿(岩)型锂资源及其开发利用潜力

铝土矿常共伴生Li、Zr、Nb、Sc等三稀元素,是潜在的巨大沉积型锂资源库。铝土矿中锂的赋存状态和分布规律研究,对丰富发展锂矿成矿理论和实现铝土矿资源的综合利用意义重大。文章系统收集了中国山西、河南、广西、贵州、云南和重庆等地区铝土矿床的地球化学、矿物学、年代学资料,探讨了锂的赋存、分布规律、影响因素和综合利用前景。黔北、渝南、豫西、晋中北铝土矿区的古风化壳沉积型富锂铝土矿(岩),成矿时代为晚石炭世本溪期和中二叠世梁山期,锂主要富集于含矿岩系中、下部致密块状铝土岩(高铝黏土岩)-硬质黏土岩中,其A/S值为1.1～1.8,w(SiO_2)为25%～45%,w(Al_2O_3)介于35%～55%,而在土状铝土矿中w(Li)偏低。锂主要以离子交换和离子吸附2种形式赋存在高岭石、绿泥石、蒙脱石等黏土矿物中,并且当黏土矿物含量高、种类多时,w(Li)更高。铝土矿(岩)型锂是沉积型锂资源的重要而巨大的来源,黏土提锂在实验和工业上的进展为铝土矿中锂的综合利用提供了广阔前景。