The δ60/58Ni Values of Twenty‐Six Selected Geological Reference Materials

The high‐precision δ^60/58Ni values of twenty‐six geological reference materials, including igneous rocks, sedimentary rocks, stream sediments, soils and plants are reported. The δ^60/58Ni values of all samples were determined by double‐spike MC‐ICP‐MS (Nu Plasma III). Isotope standard solution (NIST SRM 986) and geological reference materials (BHVO‐2, BCR‐2, JP‐1, PCC‐1, etc.) were used to evaluate the measurement bias and intermediate precision over a period of six months. Our results show that the intermediate precision of Ni isotope determination was 0.05‰ (2s, n = 69) for spiked NIST SRM 986 and typically 0.06‰ for actual samples, and the δ^60/58Ni _{NIST SRM 986} values were in excellent agreement with previous studies. Eighteen high‐precision Ni isotope ratios of geological reference materials are first reported here, and their δ^60/58Ni values varied from ?0.27‰ to 0.52‰, with a mean of 0.13 ± 0.34‰ (2s, n = 18). Additionally, SGR‐1b (0.56 ± 0.04‰, 2s), GSS‐1 (?0.27 ± 0.06‰, 2s), GSS‐7 (?0.11 ± 0.01‰, 2s), GSD‐10 (0.46 ± 0.06‰, 2s) and GSB‐12 (0.52 ± 0.06‰, 2s) could potentially serve as candidate reference materials for Ni isotope fractionation and comparison of Ni isotopic compositions among different laboratories.     

Homogeneity testing of microanalytical reference materials by electron probe microanalysis (EPMA)

Homogeneity testing of candidate reference materials requires distinguishing the effects of measurement uncertainty of the analytical method from true compositional variations within the material. Many in situ microanalytical techniques do not allow classical ANOVA homogeneity testing due to the infeasibility of truly replicated analyses on the same analysis volume. This also applies to the analysis of beam-sensitive and light element-bearing materials by electron probe microanalysis (EPMA). This reality has led me to reconsider the homogeneity index approach used in the testing of microanalytical reference materials by EPMA. Based on statistical considerations, I show that the homogeneity index is suitable for statistical significance testing using F and chi-squared statistics and allows estimating the contribution of compositional heterogeneity to the total uncertainty budget of the referenced values. However, there are problems of bias and masking of small compositional variations by measurement uncertainty. This contribution shows the strong impact of the total number of measurements on the resolution of a microanalytical homogeneity study and discusses how to quantify the relative contribution of heterogeneity to the total uncertainty budget. I present an example of EPMA to illustrate this approach and show some pitfalls and limitations in its application.     

高水速凝材料-软土微观结构的SEM研究

高水速凝材料是一种新型的固体混合材料,它与普通硅酸盐水泥相比有许多独特的特点：(1) 水用量大;(2) 速凝早强;(3) 可泵时间长;(4) 良好的塑性特性;(5) 极限荷载后强度具再发展性能。虽然,高水速凝材料在煤炭和冶金系统得到了较广泛的应用,取得了较好的技术经济效益,然而,在其它领域还未曾应用过。为了探索高水速凝材料在软土地基方面的应用前景,笔者采用扫描电镜研究了高水速凝材料-软土凝固体的微观结构。研究结果表明,纯土的土颗粒之间只有原生矿物的几何堆积,而没有牢固的连接。但由于高水速凝材料的加入,彻底改变了土体结构。在高水速凝材料-软土凝固体中,主体结构为钙矾石结晶体形成的“空间网状结构”;辅助结构为在碱性环境中土颗粒之间的离子交换、团粒化作用和碳酸化作用所形成的微晶体与凝胶体结构。因此,高水速凝材料在地基处理方面具有较好的应用前景。     

Analysis of Sediments and Soils by X-Ray Fluorescence Spectrometry Using Matrix Corrections Based on Fundamental Parameters

Wavelength dispersive X-ray fluorescence spectrometry (WD-XRF) is widely used for the analysis of soils and sediments using well characterised procedures. However, difficulties can occur with samples such as unknowns containing small amounts of ore materials and samples collected from contaminated sites where trace elemental concentrations can exceed the concentration range for routine analysis. We studied the performance of a commercially available method, based on fundamental parameters (FP) to correct matrix effects. The spectrometer was originally calibrated with elemental or simple compound calibrants. Samples were analysed as pressed powder pellets. Eighteen sediment and soil reference materials, three of them with certified values for some of their constituents, were used to evaluate accuracy, by comparing results with recommended values and their standard deviations (RV ± 2s) or certified values and their confidence intervals (CV ± Cl). When results fell systematically outside these intervals, calibrations were refined with geochemical reference materials. The best agreement of results with recommended and certified values was obtained when the contents of H₂O and C in each sample were included as matrix constituents during calculations. The detection limits of trace elements tended to be relatively high, because the measuring conditions employed were not maximised for sensitivity. The main advantage of the method tested was that it enabled the analysis of samples with high concentrations of trace elements and the determination of elements such as F, Bi, Sb and W, which are not commonly included in quantitative XRF analysis of geological samples.     

脉状铅锌（铜、银）多金属热液矿床研究进展

目前在矿床学分类研究中对沉积岩容贱金属矿床的命名和分类尚未统一,其中一类赋矿围岩为沉积岩、矿体受构造(断层、褶皱等)控制呈脉状产出的、成矿金属为铅锌铜银多金属的矿床成为缺失环节,缺少系统的归纳总结。但该类矿床是造山作用的产物,对其进行归纳综合分析,有助于了解造山作用中的矿质迁移和沉淀过程。本文将该类矿床资料收集,对其成矿特征、控矿构造、成矿流体、矿质来源等进行分析总结。研究表明,此类矿床与造山作用或造山带有着紧密的联系。成矿物质表现为多源性,包括基底围岩、岩浆来源以及幔源贡献。成矿流体具有岩浆流体、变质流体、盆地卤水等多种来源,部分矿床的成矿流体受大气水影响。该类型矿床与MVT铅锌矿床有相似之处,但在成矿环境、控矿因素、金属来源以及成矿流体来源等方面有较大差异。     

煤中硫研究现状

从煤中的无机硫、有机硫、亲硫元素及煤中硫成因等四方面总结了煤中硫的研究现状。     

An averaging procedure for layered materials

In order to model thin‐layered soils a special averaging procedure is proposed. It works with very few restrictions imposed on the constitutive equations used for individual materials. General considerations are followed by an example from open pit mining industry. Geometrical non‐linearity is considered. The proposed method is not necessarily restricted to the problems of soil mechanics. It could also be applied on composite materials. Copyright © 2000 John Wiley & Sons, Ltd.     

陆架边缘海沉积物有机碳矿化及其对海洋碳循环的影响

边缘海沉积物是海洋重要的碳储库,其内部的碳循环主要是由有机质矿化分解过程来驱动的。有机碳进入边缘海沉积物后,矿化分解为溶解无机碳(DIC)进入沉积物孔隙水并扩散到上层水柱,参与海洋系统碳循环;同时还有部分DIC与钙镁等离子结合形成自生碳酸盐,保存于沉积物碳库。从生物地球化学角度探讨有机质埋藏机制和效率,在此基础上重点综述沉积物硫酸盐还原、产甲烷和甲烷厌氧氧化过程的耦合机制,以及有机质矿化对自生碳酸盐形成的影响等方面的研究进展,以期加深对陆架边缘海沉积物在全球碳循环收支平衡中的作用及其气候环境效应的认识。     

Evaluation of Simultaneous Analyte Leaching/Vapour Phase Introduction for Direct Osmium Isotope Ratio Measurements in Solid Samples by Double-Focusing Sector Field ICP-MS

The analytical performance of a method for Os isotope ratio measurement by double‐focusing, sector field ICP‐MS (ICP‐SFMS) was evaluated. The method is based on several optimised, concurrent processes: Os extraction from samples in hot concentrated nitric acid; separation of Os from the digest solution by the formation of volatile osmium tetroxide accelerated by continuous hydrogen peroxide addition; transport of analyte vapour by an oxygen flow into the ICP; and isotopic determination by ICP‐SFMS. Due to the very efficient utilisation of analyte (approaching 0.5‰), Os isotope ratio measurement could be performed at low pg levels. Combined with an ability to process sample sizes up to 2 g (up to 50 g if the organic matrix of biological or botanical samples is eliminated by ashing), materials with Os concentrations in the low, or even sub pg g^?1 range could be determined by this method. Given that two complete digestion/distillation systems were available for interchangeable use, throughputs of up to fifteen samples per 8 hour shift could be achieved. The method precision, evaluated as the long‐term reproducibility of ¹⁸⁷ Os/¹⁸⁸Os ratio measurements in a commercial Os reference sample containing 0.5 ng Os, was 0.16% relative standard deviation (RSD, 1s). The method has been applied to perform replicate ¹⁸⁷ Os/¹⁸⁸ Os ratio measurements on a suite of fifty reference materials of various origins and matrix compositions, with Os concentrations varying from < 0.1 pg g^?1 to > 100 ng g^?1, yielding an average precision of 3% RSD. Though none of the materials tested are certified for Os content or Os isotope composition, comparison of the obtained data with published Os isotope information for similar sample types revealed close agreement between the two. The method can also be used for the simultaneous, semi‐quantitative determination of Os concentrations.     

Engineering characteristics and uses of duricrusts in Australia

The uses and shortcomings of duricrusts (ferricrete, calcrete and silcrete) in engineering construction (as used for road‐base, aggregate, foundation materials and aquifers) are reviewed. Australian production of these materials represents about one‐third of all unprocessed road‐base and they are especially important as pavement courses for lightly trafficked, low‐cost rural and outback roads. However, duricrusts are regarded as marginal materials at best because of their typically poor grading, particle unsoundness, high fines plasticity, and absorption of water and bitumen. These materials are used because they are available locally in areas that are otherwise lacking in hard rock materials, such as deeply weathered and sedimentary rock terrains. The weathering profiles of which they form part are characterized by high permeability (despite being clay‐rich), variable cementation, low compressibility and a tendency to become weaker with depth. Although the more indurated layers are unrippable, they are also difficult to blast. Pedogenic (nodular) duricrusts were formerly sought for natural road‐base, because they occur widely and require only rudimentary processing. However, well‐cemented groundwater (vadose) duricrusts are now the preferred deposits, even though they require crushing and screening. Ferricrete is the most widely exploited of the duricrusts for engineering purposes, especially in northern and southwestern Australia, although calcrete is important in South Australia and in the Murray Basin. Silcrete is only a minor source of aggregate and road‐base, mainly in western Queensland.